Philosophical Letters of David K. Lewis, Volume 2: Mind, Language, Epistemology 0198855842, 9780198855842

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PHILOSOPHICAL LET TERS OF DAVID K . LEWIS

Philosophical Letters of David K. Lewis VOLUME 2 Mind, Language, Epistemology

Edited by

HELEN BEEBEE A.R.J. FISHER

1

1 Great Clarendon Street, Oxford, OX2 6DP, United Kingdom Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide. Oxford is a registered trade mark of Oxford University Press in the UK and in certain other countries Compilation, preface, introduction, and editorial matter © Helen Beebee and A.R.J. Fisher 2020 Letters © the Estate of David Kellogg Lewis 2020 The moral rights of the authors have been asserted First Edition published in 2020 Impression: 1 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, by licence or under terms agreed with the appropriate reprographics rights organization. Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above You must not circulate this work in any other form and you must impose this same condition on any acquirer Published in the United States of America by Oxford University Press 198 Madison Avenue, New York, NY 10016, United States of America British Library Cataloguing in Publication Data Data available Library of Congress Control Number: 2020938867 ISBN 978–0–19–885584–2 Printed and bound in Great Britain by Clays Ltd, Elcograf S.p.A. Links to third party websites are provided by Oxford in good faith and for information only. Oxford disclaims any responsibility for the materials contained in any third party website referenced in this work.

Dedicated to the memory of Steffi Lewis

PREFACE David Kellogg Lewis (1941–2001) was a highly influential figure of analytic phil­oso­ phy. His work had an impact on most areas of analytic philosophy, including the topics of this volume: Mind, Language, and Epistemology. Today his work continues to be studied and examined as contributions to ongoing discussions. At the same time he is fast becoming an important figure in the history of analytic philosophy. For, as Gilbert Ryle once remarked, ‘History begins only when memory’s dust has settled’ (Ryle 1956, 1), and analytic philosophy is on the cusp of treating its phil­oso­ phy of the late twentieth century as a historical era and its major philosophers as historical figures. As a historical figure of this sort, Lewis’s correspondence is an important resource for understanding his views and his place in the history of ana­ lytic philosophy. The present book is Volume 2 of this two-volume collection of Lewis’s letters. As edi­ tors we selected letters for this volume from the many thousands of pages that consti­ tute Lewis’s correspondence. As with Volume 1, we arranged the letters of this volume under general headings that correspond roughly to an area of philosophy that Lewis was interested in and contributed to. We have provided necessary edi­tor­ial remarks and simply offered the letters as they are to the philosophical public and others interested in Lewis’s work. We hope that his letters are used as a primary resource for scholarship on Lewis’s philosophy. We followed the same editorial rules in editing this book as we did for Volume 1. We direct the reader to the Key to Symbols for various devices we used for annotating the text. The letters published in this book are from the David Lewis Papers, C1520, Princeton University Library (https://findingaids.princeton.edu/collections/ C1520), except for Letter 421. To Jerome A. Shaffer, 3 October 1964, which is in the pos­ session of Samuel C. Wheeler III. The versions of the letters published here are based on the copies in the David Lewis Papers. One of us (Anthony) had the pleasure of working closely with Lewis’s cor­res­pond­ ence in 2014–16 at the Lewises’ residence before it was kindly deposited by Steffi Lewis in the Princeton University Library in February 2016. Building on her earlier efforts, we had the idea of publishing a comprehensive and systematic selection of Lewis’s letters (one-sided) as part of a project funded by the AHRC in the UK. Without Steffi’s initial toil and vision we would have had an even higher mountain to climb in editing this work. We are greatly indebted to her. Analytic philosophy owes her a great debt as well.

viii Preface We also thank Steffi – as copyright holder and literary executor – for permission to publish Lewis’s letters, courtesy of Princeton University Library, and John Cooper for his assistance. We thank Brianna Cregle, Don C. Skemer, and other staff at Princeton’s Firestone Library for their archival expertise. We thank Samuel  C.  Wheeler III for providing a copy of Letter 421. To Jerome  A.  Shaffer, 3 October 1964. We thank Aaron Wilson, Maeve MacPherson, Andries De Jong, Simon Walgenbach, Justin Mullins, and Kendall Fisher for transcribing letters at Manchester. We also thank those who contributed to the Lewis crowdsource transcription project on crowd­ crafting.org, especially Abigail Thwaites, Sara L. Uckelman, Antony Eagle, Michael Bench-Capon, Peter Schulte, Nat Tobris, Daniel Kodsi, Ali Can Epozdemir, Manuel Lechthaler, Nir Av-Gay, Colin Mullins, and Alexandra Hall. We thank Mike McLeod for transcribing the letters to D.M.  Armstrong and are especially grateful to Peter Anstey for answering our queries and supplying documents as we worked through the correspondence between Armstrong and Lewis. We thank John Bigelow and Steffi Lewis for transcribing the letters to Jack Smart. We thank Sally Evans-Darby and Jonathan Farrell for proofreading the letters of this volume. Thanks to Jonathan Farrell and Simon Walgenbach for compiling the index of this volume. For consult­ ing the original version of Lewis’s letters and helping us with missing references, we thank Brian Ellis, Stephen Hetherington, Lloyd Humberstone, Angelika Kratzer, Fabrizio Mondadori, and Thomas Pink. Thanks to Brian Ellis, Sonya M. Davis (wife of Lawrence  H.  Davis), Franz Kutschera, Tom McKay, Gary  H.  Merrill, Terence Parsons, and Arnim von Stechow for kind permission to publish portions of their letters to Lewis. Finally, we acknowledge the generous support of the Arts and Humanities Research Council for its funding of the project The Age of Metaphysical Revolution: David Lewis and His Place in the History of Analytic Philosophy [grant no.: AH/N004000/1] and are grateful to our project team members: Frederique Janssen-Lauret and Fraser MacBride. HB & ARJF Manchester, UK 31 August 2019

CON TEN TS Introduction List of Letters Key to Symbols Feature Letter

xi xxiii xxxiii xxxv

LETTERS Part 4:  Mind  Part 5:  Language  Part 6:   Epistemology 

1 215 383

References  Index of Terms and Names  Index of Lewis’s Works Cited  Index of Recipients 

559 573 584 586

I N TRODUCT ION David Lewis was a highly influential philosopher in the analytic tradition. In almost every area of philosophy he offered some original theory or analysis that moved the debate forward or affected the terms in which it was understood. Because of the importance of his work he is set to become a central figure in the history of analytic philosophy. But, since his writings remain part of many ongoing disputes, he also continues to be significant for contemporary analytic philosophy. Only now have his letters come to light and are ready to figure in proper treatments of his work. His let­ ters offer insights into the context in which he developed his theories and provide new material for interpreting his arguments and doctrines. They will most certainly play an important role in any analysis of his place in the history of analytic phil­oso­ phy and have an impact on further investigations of his views and evaluations of the debates he engaged in. Lewis was a prolific, reliable, and judicious correspondent. On any given day he might write, say, three letters of two or three pages on wholly distinct topics (time travel, truth in fiction, and deontic logic, for example). He would go to great lengths to respond adequately and respectfully to every letter he received, although he was selective in providing comments on the papers often enclosed. When he did provide comments or respond to an argument he gave substantive remarks that invariably got to the heart of the matter; much work published by philosophers in the second half of the twentieth century is the better for Lewis’s comments on a draft. Lewis’s letters were usually full of rich philosophical content written with the same clear and careful prose and lightness of touch that we see in his published writings. Often a letter to someone outside philosophy or starting out in the field was the perfect occa­ sion for Lewis to explain and justify his views, particularly his general conception of philosophy or an important piece of his metaphilosophy. This volume is broken up into three parts: Mind, Language, and Epistemology. As with Volume 1, these categories include more than the standard topics and trad­ition­al problems that are typically associated with each category. In Part 4, there are letters not only on Lewis’s answer to the mind-body problem but also letters on proposi­ tional attitudes, intentionality, the purely subjective character of conscious e­ xperience, materialism, perception, colour and colour-experiences, and two-dimensional semantics (to the extent that it relates to issues that fall under phil­oso­phy of mind). Part  5 contains letters on meaning and reference as well as grammar in language,

xii Introduction vagueness, truth in fiction, and paraconsistent logic. Part  6 includes familiar ­epistemological topics such as the analysis of knowledge and the problem of scepti­ cism, but it also includes Lewis’s work on decision theory and rationality. Since the concept of chance and probability affected his theory of decision and rationality, his wide-ranging work on probability and the varied sub-topics that fall under it (e.g. probabilities of conditionals) is also included in this Part. Some letters on counterfac­ tuals relevant to probability are included here, which again goes to show how interconnected these topics were for Lewis. Part  6 is less unified than the others; nonetheless it brings together letters that fall under the general headings of rational­ ity (Bayesian epistemology, for instance) and theory of knowledge. It also houses some letters that did not quite fit in any category – for example, a handful of letters on moral philosophy appear here. Part 4: Mind begins with letters on materialism and the identity theory of mind. It is commonly accepted that Lewis’s encounter with J.J.C.  Smart in his sem­inar on space and time at Harvard University in the Fall semester of 1963 marks the crucial moment when Lewis adopted the identity theory. Indeed, it provided the impetus for Lewis to develop his novel argument for the identity theory. In Smart’s seminar, so Smart tells us, it was Lewis who taught Smart how to formulate the identity theory, not the other way around (O’Grady 2001; Armstrong 2002, 134). However, Lewis’s sympathies for the identity theory predate Smart’s seminar. As an undergraduate at Swarthmore College (1957–62) and at the University of Oxford (1959–60), Lewis signed on to Rylean behaviourism, with clear materialist mo­tiv­ations. At Swarthmore he was taught by Jerome  A.  Shaffer, whose article ‘Could Mental States Be Brain Processes?’ (1961) was one challenge among many to Smart’s instant classic ‘Sensations and Brain Processes’ (1959). Towards the end of Lewis’s first year at ­graduate school he wrestled with Shaffer’s (1961) arguments against the identity the­ ory. In explaining how he would save the identity theory against Shaffer’s arguments Lewis thereby indicated his initial attraction to it and its prospects. His response to Shaffer hinges on the correct formulation of the view. For Lewis, the identity between mind and brain holds not between mental states and brain processes but rather between mental states and brain states, which are both had by a person (Letter 420. To Jerome  A.  Shaffer, 12 March 1963). He brought this improved formulation of the identity theory to Smart’s seminar the following academic year. As a result of his lengthy correspondence with Smart in 1964 and 1965, Lewis began to write his first publication, ‘An Argument for the Identity Theory’ (1966a), which served as his term paper for Donald C. Williams’s metaphysics course (Spring semester, 1965). One of Lewis’s developments of Smart’s view is his generalization of Smart’s topic-neutral account of sensation-reports. Lewis took this generalization as one ingredient for constructing an argument for the identity theory that did not

Introduction

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appeal to ontic parsimony. For Lewis, these topic-neutral translations of mental reports involve some sort of analytic necessity and he was quick to see the connec­ tion here with his previous behaviourist self. As he writes: ‘it inherits the behaviorist discovery that the (ostensibly) causal connections between an experience and its typical occasions and manifestations somehow contain a component of analytic necessity’ (Lewis 1966a, 21). Another important step in his argument for the identity theory is the unity of sci­ ence programme (Oppenheim and Putnam 1958). Lewis signed on to the programme in order to substantiate the claim that physical things, physical states, and physical laws can satisfy the functional specifications of mental states. He reasoned that sci­ ence is able to discover that some brain state—say, C-fibres firing—plays the role of pain and that therefore the mental state of pain is identical with C-fibres firing. In later letters of Part 4 Lewis reflects on this early commitment of his and explicitly maintains it, with some qualification (see Letter 519. To Philip Kitcher, 2 January 1998). After his 1966 article Lewis realized that Smart’s topic-neutral translations of ­sensation-reports have the form of a Ramsey sentence; hence folk psychology itself can be Ramsified accordingly (Letter 426. To J.J.C. Smart, 16 May 1967). This resulted in Lewis writing ‘Psychophysical and Theoretical Identifications’ (1972a) and then ‘How to Define Theoretical Terms’ (1970b) in quick succession. Relatedly, his theory of mind needed to account for multiple realizability of mental states. In letters from the late 1970s and early 1980s he expounded his type-type identity theory, which he considered to be slightly different to Armstrong’s take on the issue, even though they are seen as fellow advocates of Australian materialism. In addition, Lewis expressed his preferred understanding of the differing ways to characterize functionalism about the same time it became a standard view in analytic philosophy of mind. On one reading he took himself to be a functionalist, but on another he did not. The core difference is that Lewis identifies pain with the state that fills the pain-role, whereas a functionalist like Hilary Putnam identifies pain with the property of being-in-whicheverstate-occupies-the-pain-role. Lewis admits that there is such a property and that human beings and, say, dolphins can both be in such a state, yet he maintains that this prop­ erty is not the property of pain (see, for instance, Letter 435. To Neil Lubow, 28 April 1973 and Letter 445. To D.M. Armstrong, 19 June 1978). Sometimes the absence of a discussion of a certain topic can tell us just as much about the development of Lewis’s thought as its presence. Here is one case in point. There are few letters surrounding the organic development of his theory of mental content as spelled out in ‘Radical Interpretation’ (1974). In his October 1970 letter to Donald Davidson he briefly mentions the outline of this project and simply asks for the reference of Davidson’s ‘Mental Events’ (1970). But that is about it. Later on Lewis reflects on the source of his approach in ‘Radical Interpretation’ and states that it is

xiv Introduction due to decision theory as opposed to being a derivative reaction to Davidson’s inter­ pretationism. Lewis says to Michael McDermott: What I had mostly in mind under the heading of constitutive rationality wasn’t so much deductive logic as the fit between actions and belief and desire. Yes, this does sound like Davidson – though without his irrealism and without his emphasis on the interpreter. But still more, it should sound like decision theory, and the project of recovering subjective probabilities and utilities from the agent’s dispositions to choose between gambles. That was the common source for Davidson and for me. (Letter 503. To Michael McDermott, 8 April 1993, p. 162)

It is no surprise, then, that Part 4 lacks letters on this topic from this period (although, of course, as the quotation from the letter to McDermott shows, he does discuss ‘Radical Interpretation’ later in this Part in various places). In contrast, in the late 1970s Lewis had plenty to say in correspondence about propositional attitudes (e.g. belief, desire, etc.) and their alleged ‘objects’. His ‘Attitudes De Dicto and De Se’ (1979a) is widely regarded as his major contribution to the subject. By 1977 he had come to realize that, strictly speaking, the best hypothesis is that there are no propositional attitudes as such; instead the objects of attitudes are properties. To believe something is to ascribe a certain property to oneself. There are many letters from this period that explain this idea and his motivation for adopting it, beginning with his letter to John Perry in 1977 and continuing with letters to Robert Stalnaker in 1979 and 1980. These letters provide useful context and shed light on many facets of the theory as expounded in the published article. During this same period Lewis tackled problems concerning the purely subjective character of conscious experience and confronted the objection that materialism cannot account for the fact that conscious experiences have a qualitative ‘feel’ to them. A vague expression of the ability hypothesis is set out in letters to Terence Horgan in 1974 and to Patricia Kitcher in 1978. He bluntly states that to have a men­ tal state just is to feel it. There is nothing more to the concept of ‘knowing what it is like’ to experience something. If there is some further genuine knowledge, it is some kind of know-how. Naturally, there are many letters leading up to his important paper, ‘What Experience Teaches’ (1990), wherein he presents and defends the ability hypothesis, along with subsequent reactions. The above summary touches on most of the main debates and proposals up to 1980, except for Lewis’s views on colour and perception. From 1980 onwards, his letters discuss the same topics in concert with the impact of his published work on analytic philosophy of mind. By the mid-1990s he had published ‘Reduction of Mind’ (1994b), which prompted further correspondence. The debates in Part 4 and Lewis’s reactions leading up to his death were going strong and continuing to grow as more

Introduction

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philosophers were contributing to the literature, especially David Chalmers and his influential The Conscious Mind (1996) and a posteriori (Type-B) materialism. Lewis’s analytic or commonsense functionalism (as it is now often called) remains one of the most complete and systematic materialist views in the philosophy of mind. Part 5: Language begins with letters concerning Lewis’s dissertation, Conventions of Language (1967), which became his first book, Convention: A Philosophical Study (1969). The letters to his advisor W.V. Quine document his attempts to complete his disserta­ tion and reveal his afterthoughts that led to revisions to the book version of the project. Lewis looked to the machinery of game theory to underpin the concept of a convention. For Lewis, some convention C is, roughly speaking, some regularity in conduct of people in some population or community who solve a certain iterated coordination problem. Language can then be understood in terms of convention in a non-circular fashion. Some population or community thereby adopts a certain lan­ guage based on some convention where that convention involves individuals of that population or community speaking truthfully in that particular language. The con­ vention as such is anchored in the behaviour of the people in the given population or community. One overt influence here is Thomas Schelling’s Strategy of Conflict (1960), which Lewis read as an undergraduate. He achieved further fluency in decision and game theory by working at the Hudson Institute as a graduate student, writing many papers on applications of game theory, especially in connection with nuclear deterrence and other geo-political problems. Towards the end of writing his dissertation he found a way to incorporate referential semantics into his theory of convention (Letter 544. To W.V. Quine, 18 October 1967). This development figured in the latter half of the book. Another development—mentioned briefly in the Introduction to Volume 1—is the final section of Convention, where Lewis suggests that analyticity should be handled in terms of possible worlds. While Convention constitutes a response to Quine’s rejec­ tion of the analytic/synthetic distinction, Lewis makes it clear that issues to do with analyticity were not his central motivation (see Letter 126. To W.V. Quine, 1 October 1968, Volume 1: Part 2: Modality).1 As his letters show, ‘Languages and Language’ is a ‘reader’s digest’ version of Convention, first written in 1968 as he finished the book, but revised later (with improved analyses), particularly in light of comments by Jonathan Bennett in 1972. It was the 1972 version that was eventually published in 1975, which, incidentally, predates ‘Radical Interpretation’ (1974). Lewis took up his first position, at UCLA, in the Fall semester of 1966. Soon after arriving he absorbed the philosophical activity there, especially on philosophy of 1   For letters that are not in the Part we are presently discussing, details of the volume and Part in which they are located have been supplied.

xvi Introduction language and linguistics. Richard Montague was a major presence in the department and in all likelihood encouraged Lewis to study linguistics—both theoretical and empirical. The letters from his time at UCLA—for instance, to Terence Parsons and Barbara Partee in the late 1960s—capture his efforts to construct what he thought was a simple and elegant theory of semantics founded on Ajdukiewicz categorial grammar. His approach is arguably different to both Montague’s approach and to transformational grammar, although, of course, Lewis borrows several ideas from Montague—e.g. the use of indexes and coordinates. Lewis’s important article from this period is ‘General Semantics’ (1970a). In this paper, his somewhat modest goal is to give a story about what sort of thing a meaning is and to give an account of ‘the form of the semantic rules whereby meanings of compounds are built up from the meanings of their constituents’ (Lewis 1970a, 18). He wants to give a theory that applies to logically possible languages, not just to natural or artificial languages. His aim is not to specify systematically the intensions of simple and complex expressions in some natural language like English (which he considered to be an ambitious aim). In short, he wants to give a characterization of possible grammars (or languages) as ‘abstract semantic systems whereby symbols are associated with aspects of the world’ (1970a, 19). Thus, it is a truly general semantics, despite his modest goal. The question of how a population or community might use or speak a language is addressed in Convention (1969) and ‘Languages and Language’ (1975b). Letters from subsequent years (mostly in the 1970s and 1980s) contain elaborations or clarifica­ tions of his theory of meaning and reference, especially in response to criticisms and further developments by such philosophers as Rolf Sartorius, Tyler Burge, Michael Devitt, Margaret Gilbert, Seumas Miller, and John Hawthorne. Another important doctrine of Lewis’s from his early period is the RamseyCarnap-Lewis doctrine of theoretical terms (as he preferred to call it). Arguably, it is one of his most important theories because it is not only at the centre of how he formulated many of his philosophical theories, but also underpins some aspects of his philosophical method. It has had a lasting influence more widely on analytic phil­ oso­phy, with philosophers in Australia adopting it as a core doctrine of the ‘Canberra plan’ (see Braddon-Mitchell and Nola 2009). Lewis’s first point of contact with Ramsey’s method of eliminating theoretical terms was to do with the question of reduction of theories. The primordial pieces of his ‘How to Define Theoretical Terms’ (1970b) stem from his course notes and term paper for Israel Scheffler’s philosophy of science course in the Spring semester of 1964. As he explained to Grover Maxwell, his point was to expound one way that reduction can proceed between two theories (Letter 547. To Grover Maxwell, 20 February 1968): he did not think this is the only way to reduce one theory to another. From here he saw its wide-ranging applications— from philosophy of mind to value theory. The upshot is that a Ramsey sentence

Introduction

xvii

contains in effect functionally defined terms such that each term in the given sen­ tence is replaced by a quantifier that specifies some feature concerning the entity that fills some corresponding role. As Lewis makes clear, the elimination of a newly intro­ duced (theoretical) term is a vindication of it and so does not entail any kind of elim­ inativism about that term or what that term is about (see Letter 448. To Colin McGinn, 10 February 1979, Volume 2: Part 4: Mind). A recurring theme throughout Lewis’s philosophy is that of entities filling speci­ fied roles in our theories—whether they are roles in commonsense thought or philo­ sophical theory. If an entity does not fill a certain role, it does not deserve to be called the associated name. Naturally, we cannot devote the necessary space to a full ­exposition of the general methodology encapsulated in the Ramsey-Carnap-Lewis doctrine of theoretical terms, but it is one aspect of his larger methodology that will surely continue to exert a strong influence on analytic philosophy. The various let­ ters that concern his doctrine of theoretical terms reveal the beginnings of it in his thought, alongside his theory of mind, and demonstrate several applications of it. Because of its wide-ranging applications many instances of it are found throughout every category in both volumes. Two other topics in Part 5 that are worth mentioning explicitly are his analysis of the concept of truth in fiction and his theory of vagueness. His theory of how to make sense of truth in fiction was originally a section of Counterfactuals, which he excised from the book. Truth in fiction involves intensional operators, e.g. ‘in fiction f. . .’. These operators receive a possible-worlds treatment in terms of truth at a pos­ sible world; what is true in fiction f is what would be true if fiction f were told not as fiction but as known fact (Lewis 1978, 42). More precisely, Lewis continues, ‘what is true in the Sherlock Holmes stories is what would be true, according to the overt beliefs of the community of origin, if those stories were told as known fact rather than fiction’ (Lewis 1978, 45). Hence he thought that his analysis of this concept would be suitable for inclusion in Counterfactuals (1973b). As he mentions to Kendall Walton, he would have published the paper before 1978 but had to rewrite certain parts of it to deal with Kripke’s objection that fictional characters such as Sherlock Holmes do not exist at any possible world (Letter 581. To Kendall Walton, 10 September 1975). Arguably, some ideas from his work on truth in fiction helped him elsewhere. For example, one way he deals with alleged contradictions in fictional stories is to carve out maximally consistent fragments of the fiction in question (see Letter 585. To Philip and Patricia Kitcher, 13 April 1976). He adopts a similar method of fragmentation in reaction to the threat of paraconsistent logic—see, for instance, Letter 592. To Allen P. Hazen, 22 July 1980, also in Part 5. Lastly, as many philosophers familiar with Lewis’s work will know, one of his con­ tributions to the topic of vagueness is his widely discussed article on Gareth Evans

xviii Introduction against vague objects: ‘Vague Identity: Evans Misunderstood’ (Lewis 1988c). Lewis’s goal in this short paper is to set the record straight about how to understand Evans’s thesis in ‘Can There Be Vague Objects?’ (1978). In brief, Lewis thought that a ­dialectical subtlety was readily overlooked in discussions of Evans’s proof that no identity statements are ever vague. The origin of Lewis’s paper was a letter to Hazen, who had sent Lewis a draft manuscript on Evans’s article. Lewis explains to Hazen what he takes to be the upshot of Evans’s article: We think there are vague identities. I think Evans thinks so too. We think there’s a fallacy in the stated proof that identities are never vague. I think Evans thinks so too. But what does the vague-objects man think? We can diagnose the fallacy, but the vague-objects man cannot accept our diagnosis. So (unless he can tell an alternative story of where the fallacy lies) he’s stuck with the argument that we consider fallacious, and he’s stuck with the unwelcome conclusion that identities are never vague. Because he thinks that vagueness is in the world, rather than thinking of vagueness as semantic indeterminacy, an escape route from this unwelcome conclusion is barred to him. (Letter 589. To Allen P. Hazen, 15 November 1978, p. 294, Lewis’s italics)

Lewis saw Evans as attacking the view that the source of vagueness is the world (and vague objects contained therein) as opposed to semantic indeterminacy in language. And in later work Lewis explicitly defends the view of vagueness as semantic indecision (see, for instance, Lewis 1993). Several philosophers wrote further articles in reaction to Lewis’s article and many of his letters from the 1980s and 1990s specifically deal with these reactions. We should mention that two important letters on Lewis’s theory of vagueness are not in Part 5, namely Letter 735. To Timothy Williamson, 21 May 1999 and Letter 736. To Timothy Williamson, 19 June 1999. These letters are in Part  6 because their main subject matter and context concern epistemology. Debate about how to interpret Lewis’s official theory of vagueness is a live issue and several letters by Lewis help to clarify his exact position on supervaluationism (see, for instance, Nolan 2018). Part 6: Epistemology, as mentioned above, contains letters not only on trad­ition­al topics in epistemology but also on decision theory, rationality, chance, credence, and probability. There are also a few letters that fall squarely within philosophy of sci­ ence, which was another of Lewis’s research interests early on in his career. Indeed, when Lewis was hired by UCLA, the Chair of the Philosophy Department—Donald Kalish—saw Lewis as continuing the Philosophy of Science programme at UCLA that was developed by Hans Reichenbach and then Rudolf Carnap. One letter of note in the first batch from this Part is to Richard Jeffrey in July 1969. It outlines Lewis’s plans to complete an introductory textbook on Carnap-Hintikka con­firm­ation the­ ory. The book project did not materialize as his writing efforts were diverted to other

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matters, but this letter indicates the extent to which he was immersed in philosophy of science and logic, especially at UCLA.2 In the early 1970s, Lewis became interested in decision theory and theories of rationality. Letter 651. To Paul Teller, 29 February 1972 covers the argument he sketched in a handout that Teller incorporated into his oft-cited article on diachronic Dutch book arguments (Teller 1973). This handout and the corresponding letter form the basis of Lewis’s much later paper ‘Why Conditionalize?’ (Lewis 1999, 403–17). There he offers his explanation as to why a rational agent should conditionalize on their total increment of experiential evidence. At about the same time, he was con­ cerned with issues to do with probability and in particular how probability affects our best theories of rational decision. Hence the letters on probability are grouped with letters on decision theory and rationality. For Lewis, within the Bayesian tradition (broadly construed), rational credences are modelled as subjective probabilities. Such credences can come in degrees. He rec­ ognized that credences are governed by typical probability axioms and he attempted to draw a connection between a rational agent’s credences and that rational agent’s beliefs concerning objective chance. The letters from 1972 to 1978 largely focus on probability and its relation to decision theory. A couple of months after he wrote to Teller about conditionalization he began to correspond with Robert Stalnaker about how conditionalization interacts with probabilities of conditionals. The letters to Stalnaker and William Harper from this period showcase how Lewis rejected the the­ sis that probabilities of conditionals are to be equated with conditional probabilities, which he discussed in ‘Probabilities of Conditionals and Conditional Probabilities’ (Lewis 1976). Then in 1973 and 1976 we see Lewis explaining to Ernest Adams his motivations behind what he dubbed ‘the Principal Principle’ in ‘A Subjectivist’s Guide to Objective Chance’ (1980c) (see Letter 656. To Ernest Adams, 28 April 1973). From there Lewis’s interests in probability deepened and he went on to argue for a causal version of decision theory. His letters on his topic display some of his most positive traits as a philosopher. As much as philosophy is about criticizing a theory or arguing against competing hypotheses, it should also involve trying to find common ground between rival theories. For instance, his paper ‘Causal Decision Theory’ (1981b) contains insightful comparisons among several versions of causal decision theory. Some of his letters about causal decision theory—such as Letter 675. To Wlodek Rabinowicz, 11 March 1982—display the same kind of tendency. Subsequent letters on his work on decision theory provide further clarifications and reflections as other philosophers examined his work and contributed to the same body of literature.

  See his ‘Confirmation Theory’ manuscript, written in 1969 (Janssen-Lauret and MacBride forthcoming).

2

xx Introduction By 1989 the letters in Part  6 begin to address more traditional problems in e­ pistemology. The change occurs with Letter 701. To Richard Cartwright, 4 September 1989, which is of general significance because it informs Lewis’s philosophical method and his view on the nature of philosophical disputes. Having read Cartwright’s Introduction to Philosophical Essays (Cartwright 1987), he wrote to Cartwright, ­elaborating on his view that the goal of philosophy, at the end of the day, is to find a reflective equilibrium for oneself between commonsense belief and philosophical theory (which for Lewis are both kinds of opinion). Strikingly, Lewis added that ‘once the well worked-out menu of philosophical theories is before us, phil­oso­phy is a matter of opinion’ (1983c, xi). One sticking point between Cartwright and Lewis is what to say about ultimate impasses in philosophical disputes. In such cases Lewis maintained that philosophy is a matter of opinion. However, one need not be less sure of the disputed claim even if the dispute is irresolvable. If the claim in question— say, that there are no true contradictions—is part of what it is, by one’s own lights, to be reasonable, one can continue to believe it and be as sure of it, even if one’s ­opponent insists, perfectly coherently by their own lights, that it is they who are being reasonable (by being more ‘open-minded’ about logic, say). Besides the impasse about the nature of logic with Graham Priest, Lewis men­ tions the debate between a Moorean and a sceptic. Similarly, there is an impasse, but the Moorean who claims that she knows she has hands is entirely correct. Of course, the sceptic may introduce remote sceptical possibilities that become relevant, thereby temporarily undermining the Moorean’s knowledge claim. ‘But I can truly say, even then, that under more ordinary circumstances I can truly say that I know that I have hands’ (Letter 701. To Richard Cartwright, 4 September 1989, p. 488). These remarks look forward to his ground-breaking article ‘Elusive Knowledge’ (1996a). Three years later he extends this interesting discussion in Letter 709. To Paul Benacerraf, 14 January 1992. At this point he begins to work on the core of his con­ textualist epistemology. Lewis’s contextualism has its origins in discussions from the 1970s with Peter Unger, who originally defended a novel form of scepticism in Ignorance: A Case for Scepticism (1975). Lewis’s contextualist reaction to Unger appeared initially in his ‘Scorekeeping in a Language Game’ (1979d, 355). In August 1992, he was prompted to flesh out his view after hearing about Stephen Hetherington’s lecture on ‘Lacking Knowledge and Justification by Theorising about Them’.3 In Letter 713. To Stephen Hetherington, 2 August 1992, Lewis proposes that subject S knows that p iff it is not the case that there is some possibility of not-p not eliminated by evidence held by S, where context allows S to ignore certain possibilities (thus rendering them irrelevant).   This 1992 paper would eventually become ‘Elusive Epistemological Justification’ (Hetherington 2010).

3

Introduction

xxi

Epistemology then becomes the task of characterizing the circumstances under which possible scenarios are properly ignored. Contextualism has grown into a lead­ ing position in epistemology. It is fair to say that Lewis’s ‘Elusive Knowledge’ was partly responsible for this, along with the work of Stewart Cohen (1986), Barry Stroud (1989), Keith DeRose (1995), and Hetherington (2010). Several letters on con­ textualism are to these philosophers, displaying how Lewis’s view developed in con­ nection with, and sometimes in contrast to, other well-known contextualist views in epistemology. In sum, Lewis’s contributions to the philosophy of mind, philosophy of language, and epistemology have played a major role in shaping the central debates and issues in these areas of philosophy. The letters in this volume are a testament to this achieve­ ment. Furthermore, the letters in this volume reveal how Lewis developed his ideas, arguments, and theories as he added to the unfolding conversation about t­ opics in these areas. We expect that this volume will also add to current debate and give researchers and scholars a body of work by Lewis that will aid in better understand­ ing his theories and arguments concerning mind, language, and epistemology.

LIST OF LET TERS Part 4:  Mind Letter

Recipient

Date

Page

420

Jerome A. Shaffer

12 March 1963

3–4

421 422

Jerome A. Shaffer J.J.C. Smart

3 October 1964 18 February 1965

4–6 7–11

423

J.J.C. Smart

27 February 1965

11–13

424 425 426 427 428 429 430 431 432 433

J.J.C. Smart Jerome A. Shaffer J.J.C. Smart J.J.C. Smart Keith Campbell J.J.C. Smart J.J.C. Smart Donald Davidson Hidé Ishiguro Donald Davidson

?–8 May 1965 5 April 1967 16 May 1967 17 October 1967 11 December 1967 20 April 1968 7 May 1968 7 October 1970 13 October 1970 4 April 1972

13–15 15–17 17–18 18–19 20–1 22–6 27–9 29–30 30–2 32–3

434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449

Henry W. Kissling Neil Lubow Sydney Shoemaker Terence Horgan Terence Horgan Terence Horgan John Perry Hartry Field Patricia Kitcher Allen P. Hazen William G. Lycan D.M. Armstrong Patricia Kitcher George Bealer Colin McGinn Robert C. Stalnaker

5 February 1973 28 April 1973 7 May 1974 7 November 1974 23 November 1974 16 December 1974 10 October 1977 13 November 1977 24 February 1978 13 June 1978 19 June 1978 19 June 1978 8 August 1978 4 February 1979 10 February 1979 8 March 1979

34 34–6 36–7 37–9 39–40 41 42–3 43–5 45–7 47–9 49–51 51–4 54–5 55–6 56–9 60–2

List of Letters

xxiv 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465

J.J.C. Smart J.J.C. Smart Robert C. Stalnaker Frank Jackson Donald Nute Frank Jackson Robert C. Stalnaker Frank Jackson Adam Morton Jerry A. Fodor Frank Jackson John Bigelow Steven E. Boër and William G. Lycan Brian Ellis John Bigelow Robert C. Stalnaker

23 March 1979 11 April 1979 28 May 1979 22 June 1979 20 August 1979 31 August 1979 10 September 1979 17 September 1979 8 February 1980 4 April 1980 24 April 1980 17 July 1980 23 July 1980 24 July 1980 20 August 1980 14 November 1980

63–4 65–6 66–8 68–72 73–4 74–7 77–8 78–80 81 82 82–4 84–7 87–8 89–90 91–3 93–7

466

Sydney Shoemaker

2 December 1980

97–100

467 468 469 470 471 472

Laurence Nemirow D.M. Armstrong Max Cresswell and Arnim von Stechow Kim Sterelny and Frank Jackson Max Cresswell Arnim von Stechow

20 February 1981 11 June 1981 17 June 1981 22 June 1981 11 August 1981 18 October 1981

100–1 101–4 104–8 108–11 112–13 113–15

473 474 475 476 477 478 479 480 481 482 483 484 485 486 487

Ian Hacking Kendall Walton Philip Kitcher and Patricia Kitcher Thomas McKay Terence Horgan Frank Jackson and Valina Rainer Terence Horgan Ted Ziolkowski Terence Horgan Carolyn McMullen Paul Teller David Austin David Brooks Reinaldo Elugardo Frank Jackson

12 February 1982 25 March 1982 3 April 1982 24 April 1982 22 March 1983 29 March 1983 16 April 1983 24 May 1983 11 July 1983 17 November 1983 21 November 1983 19 March 1984 13 July 1986 2 May 1988 14 June 1988

115–16 116–17 118–20 120–2 122–3 123–5 125–6 126–7 127–8 128–31 131 132–4 134–5 135–6 136–7



List of Letters

xxv

488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522

Simon Blackburn William G. Lycan Laurence Nemirow Ned Block David Velleman Frank Jackson and Philip Pettit Philip Pettit Carol Rovane Carol Rovane Daniel Dennett W.L. Craig Jerry A. Fodor Earl Conee J.J.C. Smart Ned Block Michael McDermott Michael Smith Michael McDermott Ned Block Myles Burnyeat and Peter de Marneffe David J. Chalmers Georges Rey David J. Chalmers Christopher S. Hill Robert Adams Frank Jackson David J. Chalmers David J. Chalmers William G. Lycan Jamie Dreier D.M. Armstrong Philip Kitcher David J. Chalmers David J. Chalmers Philip Kitcher

17 June 1988 24 June 1988 4 October 1988 2 June 1989 4 October 1989 27 December 1989 13 February 1990 9 October 1990 26 December 1990 21 January 1991 21 January 1991 6 March 1991 17 September 1991 4 October 1991 26 January 1993 8 April 1993 1 August 1993 2 August 1993 3 January 1994 25 March 1994 11 June 1994 28 July 1994 8 August 1994 4 October 1994 21 October 1994 27 October 1994 30 November 1994 2 December 1994 18 December 1994 2 January 1995 25 October 1995 2 January 1998 5 January 1998 29 January 1998 13 February 1998

138–9 139–43 143–4 144 145 146–7 147–8 148–9 149–52 152 153 154 155–6 156–60 160–1 161–2 162–6 167 167–8 169–70 170–2 172–3 174 175 176–7 177–8 179–81 181–3 183–4 184–5 185–8 188–90 190–1 191–2 192–3

523 524 525

Robert C. Stalnaker David J. Chalmers Terence Horgan

26 February 1998 1 May 1998 28 May 1998

194–5 195–6 197–8

List of Letters

xxvi 526 527 528 529 530

John Heil Allen P. Hazen Delia Graff Michael Tooley Frank Jackson

8 June 1998 6 August 1998 24 August 1998 16 October 1998 9 November 1998

199 200–2 202–3 203–4 205

531 532 533

Daniel Dennett Frank Jackson Delia Graff

7 December 1998 6 August 1999 14 October 1999

205–6 206–7 207–8

534

David J. Chalmers

8 December 1999

208–9

535

David J. Chalmers

10 December 1999

209–10

536 537

David J. Chalmers David J. Chalmers

26 December 1999 14 January 2000

210–11 211–12

538 539

Mark Johnston David J. Chalmers

27 September 2000 6 May 2001

212–13 213–14

Part 5:  Language Letter

Recipient

Date

Page

540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559

W.V. Quine W.V. Quine W.V. Quine Thomas C. Schelling W.V. Quine W.V. Quine John Winnie Grover Maxwell J.J.C. Smart Terence Parsons Terence Parsons George Lakoff Terence Parsons Nelson Goodman Barbara Partee J.J.C. Smart Richard Montague Fabrizio Mondadori Fabrizio Mondadori Fabrizio Mondadori

9 February 1965 21 May 1965 21 November 1966 5 October 1967 18 October 1967 27 November 1967 30 January 1968 20 February 1968 24 July 1968 1 September 1968 26 September 1968 27 September 1968 15 October 1968 13 October 1969 12 November 1969 17 April 1970 27 July 1970 9 October 1970 19 November 1970 4 December 1970

217 218 219 219–20 220–1 221–2 222–3 223–4 224–6 226–7 227–30 230–3 233–4 234–5 235–6 237–8 238–9 239–41 241–3 243–5

560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597

List of Letters Fabrizio Mondadori F. Jeffry Pelletier Rolf Sartorius Pavel Tichý Jonathan Bennett Jonathan Bennett Harry A. Lewis Kit Fine Edward L. Keenan Edward L. Keenan G.H. Merrill G.H. Merrill G.H. Merrill Terence Parsons Tyler Burge Tyler Burge William M. Schuyler, Jr. William M. Schuyler, Jr. Michael Devitt Michael Devitt J.J.C. Smart Kendall Walton Nuel Belnap Saul Kripke G.H. Merrill Philip Kitcher and Patricia Kitcher Peter Lamarque Peter van Inwagen Philip Kitcher Allen P. Hazen Angelika Kratzer J. Michael Dunn Allen P. Hazen Robert B. Brandom and Nicholas Rescher Lloyd Humberstone Robert Solomon William G. Lycan Kendall Walton

xxvii 7 January 1971 11 January 1971 21 March 1971 30 March 1971 31 December 1971 10 January 1972 12 February 1972 19 February 1972 14 April 1972 14 May 1972 17 September 1972 4 October 1972 16 October 1972 14 March 1973 21 October 1973 5 November 1973 24 April 1974 3 June 1974 20 January 1975 2 May 1975 13 May 1975 10 September 1975 29 October 1975 7 November 1975 2 December 1975 13 April 1976 28 February 1977 9 May 1977 23 February 1978 15 November 1978 9 July 1979 9 September 1979 22 July 1980 19 December 1980

245–6 246–8 248–50 250–1 251–3 253–4 254–6 256–8 258–61 261–3 263–4 265 266 267–8 268–70 270–2 272–3 274–5 275–8 279–81 281–2 282 283–4 284–6 286–7 288 289–90 290–1 291–2 293–5 296–7 297–9 299–300 301–2

22 May 1981 19 June 1981 2 September 1981 21 December 1981

302–3 303–6 306–7 307–8

xxviii 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636

List of Letters F. Jeffry Pelletier Saul Kripke Saul Kripke Thomas Kuhn and Philip Kitcher Thomas Kuhn Margaret Gilbert Arnim von Stechow Julia Driver Julia Driver Arnim von Stechow Arnim von Stechow Julia Driver Marvin Belzer Graham Priest S.R. Miller Frank Jackson Gregory Currie Terence Horgan Terence Horgan R.M. Sainsbury David E. Over R.M. Sainsbury David E. Over Graham Priest Graham Priest Graham Priest Marga Reimer Graeme Forbes Max Cresswell Roy Sorensen Thomas McKay Frank Jackson Thomas McKay John Hawthorne Terence Horgan Scott Soames Scott Soames David Sosa Peter Vanderschraaf

13 September 1982 11 November 1982 12 November 1982 14 January 1983 16 April 1983 24 May 1983 24 May 1983 27 May 1983 27 June 1983 29 June 1983 21 July 1983 27 September 1983 30 September 1983 3 October 1983 2 December 1983 10 July 1985 20 August 1985 23 December 1985 18 February 1986 4 October 1988 25 January 1989 26 January 1989 27 February 1989 31 August 1989 19 November 1989 13 February 1990 24 September 1990 3 December 1990 13 March 1991 21 May 1991 20 February 1992 6 April 1992 27 May 1992 15 June 1992 2 February 1994 11 December 1994 12 December 1994 18 October 1995 13 December 1996

308–9 309–10 310 310–13 314–15 315 316–17 317–18 319 319–21 321–3 323–4 324–6 327–8 328–30 330–2 332–4 334–6 336–8 338–9 339–41 342–3 344 345–7 347–8 348–50 350–2 352 353–4 354–5 355–6 357 357–8 358–9 359–60 360–3 363 364–5 365–6

637 638 639 640 641 642 643

List of Letters Brian Skyrms Frank Jackson and Philip Pettit David Kaplan Richard Joyce Richard Joyce Simon Blackburn Denis McManus

xxix 24 January 1997 30 March 1998 4 February 1999 20 July 2000 23 July 2000 17 November 2000 20 November 2000

366–7 367–71 371–3 373–6 377–8 378–80 380–1

Part 6:  Epistemology Letter

Recipient

Date

Page

644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671

Michael A. Slote Michael A. Slote Jane Shelby Richardson Michael A. Slote Peter Unger Jordan Howard Sobel Richard Jeffrey Paul Teller Robert C. Stalnaker William L. Harper William L. Harper Robert C. Stalnaker Ernest Adams Richard Jeffrey Franz Kutschera Ernest Adams Ernest Adams Allan Gibbard Jordan Howard Sobel R.N. Giere Brian Skyrms Lawrence H. Davis R.N. Giere Brian Skyrms Gregory Kavka Brian Skyrms John Pollock Allan Gibbard

16 February 1966 2 March 1966 2 February 1967 16 May 1967 16 January 1968 3 December 1968 17 July 1969 29 February 1972 21 April 1972 18 May 1972 31 May 1972 31 May 1972 28 April 1973 26 March 1974 26 November 1975 12 November 1976 19 November 1976 17 May 1977 20 May 1977 10 October 1977 15 December 1977 24 January 1979 25 May 1979 29 June 1979 10 July 1979 19 September 1979 19 June 1980 14 August 1980

385–8 388–9 389–90 391 391–2 392–3 394–5 396–7 397–401 402–3 403–5 405–6 406–7 407–8 408–10 410–12 412–13 414–15 415–16 416–17 418–20 420–1 422 422–3 423–4 424–5 425–8 428–9

xxx 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710

List of Letters D.H. Mellor Ellery Eells D.H. Mellor Wlodek Rabinowicz Frank Jackson Bas van Fraassen and Calvin Normore Frank Jackson Frank Jackson Paul Horwich Allen P. Hazen Ellery Eells William J. Talbott Frank Jackson Frank Jackson Jordan Howard Sobel Robert Aumann Brian Skyrms Frank Jackson and Philip Pettit Bas van Fraassen Huw Price Philip Pettit and Michael Smith Henry Krips Frank Jackson Jonathan Gorman Charles Pigden John Leslie D.H. Mellor John Leslie John Leslie Richard Cartwright Graham Oddie Daniel M. Farrell Daniel M. Farrell Alexander Rosenberg Dorothy Edgington Philip Pettit Philip Pettit Paul Benacerraf Nicholas Denyer

20 November 1980 15 December 1980 14 October 1981 11 March 1982 23 November 1982 26 November 1982 16 December 1982 13 January 1983 25 March 1983 11 July 1983 30 November 1983 22 June 1984 30 January 1986 18 February 1986 19 May 1986 30 June 1986 26 September 1986 23 June 1987 14 March 1988 17 May 1988 29 July 1988 24 August 1988 27 February 1989 19 April 1989 30 April 1989 17 June 1989 28 August 1989 1 September 1989 4 September 1989 4 September 1989 4 October 1989 28 March 1990 24 September 1990 31 December 1990 11 June 1991 14 August 1991 23 September 1991 14 January 1992 10 March 1992

429–31 431–2 432–4 434–7 437–9 439–40 441–4 444 444–5 446 447–8 448–9 449–51 451–3 453–6 456–9 459–60 461–3 464–5 465–6 466–8 468–71 471–2 472–3 473–4 475–9 479–81 481–3 483–6 486–8 488–9 489–90 490–1 491–2 492–4 494–7 497–8 498–500 500–1

711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742

List of Letters Nicholas Denyer Keith DeRose Stephen Hetherington Krister Segerberg Michael McDermott Stephen Hetherington Barry Stroud Stephen Hetherington Trenton Merricks Stewart Cohen Peter Unger Robert Nola Keith DeRose Jonathan Vogel Stewart Cohen Michael Strevens Graham Oddie John Bigelow Bredo Johnsen Robert Black Fred Feldman Stewart Cohen Keith DeRose Bredo Johnsen Timothy Williamson Timothy Williamson Robert Fogelin Adam Elga Adam Elga Keith DeRose Bradley Monton Bradley Monton

xxxi 1 April 1992 9 April 1992 2 August 1992 26 January 1993 6 December 1993 9 February 1994 9 February 1994 9 March 1994 14 July 1994 11 August 1994 26 September 1994 2 October 1994 28 November 1994 21 February 1995 1 March 1995 19 May 1995 4 August 1995 7 December 1995 21 January 1997 27 February 1997 12 June 1997 3 June 1998 19 August 1998 15 April 1999 21 May 1999 19 June 1999 13 October 1999 15 September 2000 4 October 2000 9 November 2000 12 February 2001 9 April 2001

502–3 503–4 504–6 506–7 508 508–9 509–10 511–13 513 513–16 517 517–18 519–21 521–4 524–5 525–6 526–7 527–9 529–31 532 533–6 537 538–9 539–41 541–8 548–9 550–1 551–3 553–4 555 555–7 557–8

KEY TO SYMBOLS /to/

No such word in MS. It has been inserted by the editors.

Melbourne

Word crossed out in MS. Such instances are only indicated so as to give sense.

Conjectural restoration of disfigured word(s) in MS, except for ordered pairs.

Word(s) torn away, unreadable, or concealed in MS.

[. . .]

Editorial redaction of content.

[comment]

In-text editorial comment.

All footnotes have been inserted by the editors except for footnotes signified by an asterisk or similar, non-numerical symbol. Instances of ellipses without square brackets are in MS. Cases of non-italicized text in square brackets are in MS. Typographical and minor grammatical errors have been silently corrected.

PART 4 Mind

420.  To Jerome A. Shaffer, 12 March 1963 Line St. Somerville, MA Dear Jerry, Not a proper letter; I’ve been re-reading your ‘Mental States and Brain Processes’1 and I have an idea about it. We want to protect the identity theory against the argument

1. Brain processes have location, namely in the brain. 2. Mental states cannot have location (except the location of intentional ­objects of mental states, namely pains, which is something entirely different, and needn’t be an existing place at all). 3. Coincidence in location is a necessary condition of empirical identity. 4. So mental states cannot be empirically identical to brain processes.



You defeat the force of the argument by claiming that premise 2 is an inessential feature of the concept of mental state, remediable if psycho-physical correspondence holds. I think the argument is sound, and I don’t want to use your out. But I think that the argument only shows us that it is not strictly correct to formulate the identity theory as identity of mental states and brain processes. Rather, it should be put as the identity of mental states with their corresponding physical states, which physical states consist of the occurrence of brain-processes. Now the mental states and physical states alike are states of a person, and not in him. So they’re in the same boat with regard to location. Strictly, I suggest, no states are said to have location; rather, they are states of something (a bearer) which has location. (This is why I don’t want to use your move: it sacrifices an important regularity governing states in ­general.) And since processes have location, states of something consisting of the occurrence of processes within it cannot be strictly identical with those processes. (Of course we may usually treat them as interchangeable. And it would be pedantic to the point of falsification to say that on my view the theory that mental states are identical to brain processes is refuted by the argument from location, without any explanation!) Now we’re home with identity between physical and mental states of a person (or, states of a person qua physical description and qua related to behavior) provided it is empirically necessary that the two correspond perfectly. Yours truly,   ‘Could Mental States Be Brain Processes?’ (Shaffer 1961).

1

Philosophical Letters of David K. Lewis

4

PS. Walter Taylor asks me to ask you: it is said that Scriven writes science fi ­ ction under a pseudonym. Does he, and if so what is it? Is there any likelihood you’ll be at Brandeis?

421.  To Jerome A. Shaffer, 3 October 19641 [Cambridge, MA] Dear Jerry, Harvard didn’t forward your paper2 and letter; so I got them two weeks ago, just at the beginning of the rush getting settled, registered, cross-registered, and so on. I’m working for Aiken’s ideologies course again with more sections and better pay. As it happens I’m taking no philosophy courses at Harvard; going to Putnam at MIT (Philosophy of Language) and Goodman at Brandeis (Theory of Symbols) and maybe doing a little thesis work under Scheffler in Quine’s absence. Also learning programming at MIT and taking a quantum theory course at Harvard. Mostly this year is just waiting for another chance at the Metaphysics prelim. I don’t need to prepare myself much better (though I will go to Williams’ course next term, there’s nothing useful this term), I just need to wait for spring when it’s given. I won’t really get down to business on the thesis until it’s over, in case I have to move. I had a good summer at Hudson.3 Mostly worked on various problems about defense,* in order to make up my mind whether or not I think it’s safe to buy a big shelter and Nike-X program. As you probably know, many people are afraid that if we do it sets off more arms racing. (For instance Jay Stone says so in the September Bulletin of the Atomic Scientists; I may write them a letter criticising what he says.) I’m sure there is such a danger under some circumstances, but I think such circumstances might be avoided, and if they were it would be worthwhile to spend a much greater fraction of our strategic budget (at either a high or low level) on shelters and antimissile defense. This group-effort introductory text sounds promising. I fear it may take as long to be done as some other group-effort books; like, say, the Schilpp Carnap.4 What is the situation at Swarthmore? I guess Beardsley is senior (assuming you don’t make a religion type chairman!) but wouldn’t take the job, making it either you

  This letter was kindly supplied by Samuel C. Wheeler III.   ‘Persons and Their Bodies’ (Shaffer 1966).    3 Hudson Institute.   *  in the narrow sense 4   The Philosophy of Rudolf Carnap (Schilpp 1963). 1 2



421.  To Jerome A. Shaffer, 3 October 1964

5

or an outsider, no? Are Jaegwon Kim and Sklar still there? A source here says that Michigan is (rightly) very pleased to have a real chairman. Grice’s stuff sounds interesting; possibly, but not probably, also relevant to my thesis. Is it to be published, or is it available in CASBS papers? As for Firth – I find him very good on some things (especially his Sense Data & Percepts and his senses of certainty)5 and quite unhelpful on others. When Austin was at Harvard, Firth fought him on sense-data throughout a faculty seminar, and Firth hasn’t got over it to this day. No lesser Oxfordness can phase him. (Interruption now while the man puts in my phone.) I said, following Putnam, that if a machine won the Turing game – behaved intelligently – with the wrong internal mechanism, it wouldn’t be intelligent. You say, what if humans have the same sort of internal mechanism? We don’t know well what kind they have. I answer that it is conceivable – remotely conceivable – that all human intelligence should be an illusion, because humans behave as they do by table lookup or by hypothetical precognitive telepathy to determine the reaction of some really intelligent being to their next moves. (Note that the hypothetical precognitive tel­ep­ athy way of simulating intelligence depends on the existence – possibly merely of the possibility – of some being which behaves intelligently not by hypothetical precognitive telepathy.) I add that we may not know much about brain mechanisms, but we surely do enough to exclude table-look-up simulation of intelligence: we can calculate a minimum length of the table and a maximum storage capacity of the brain, both very conservatively, and we will pretty surely find that there is too little storage to hold the table, by very many orders of magnitude. (Yet the table could still be held in a psionic field of now-undreamt-of properties, so this isn’t quite conclusive.) As to the persons paper:6 I couldn’t really tell whether or not you were saying things that I could accept as a materialist. You call a person a non-physical entity, yet I don’t think you wish to claim that a person is composed out of anything but matter obeying its ordinary laws (nor to claim the opposite, since you emphasize our ig­nor­ ance). So how is a person a non-physical entity? In that persons are individuated by different rules than bodies (this I accept). Bodies are physical entities; why can’t you say that persons are different, overlapping, (probably) physical entities? That preserves your claim that persons are not identical with the bodies they own. I want to take a harder materialist line: the relation between a person and the body he owns is contingent identity. If a person switched bodes, he would own, and be contingently identical with, one body at any time; that is, time-slices of the person would be contingently identical with time-slices of various bodies, and the person would own, and be contingently identical to, a body-like discontinuous physical entity consisting   ‘Sense-Data and the Percept Theory’ (Firth 1949, 1950).   ‘Persons and Their Bodies’ (Shaffer 1966).

5 6

Philosophical Letters of David K. Lewis

6

of a sum of time-slices of various bodies, presumably exactly one at every time in his lifetime. A disembodied person would not own, nor be identical with, any body. The issue between us is a general metaphysical issue: if the principle of individuation of As is different from the principle of individuation of Bs, does it follow that no A can be contingently identical to any B? I say, no it does not follow; I believe you say it does follow. Since this is a general issue, you should look at a place where it arises amidst less ignorance and less historical background than in the case of identity of persons and bodies. For an analogy, take the case of fires and hunks of burning stuff. (Fuel.) They are individuated differently; the fire can move from the newspaper to the log, and so on. I am inclined to say, mostly for economy, that the fire is contingently identical to a hunk of burning matter, or a sum of successive time-slices of burning matter. I think you should certainly agree that the burning matter is the fire’s body; i.e. the relation between fire and burning matter is the same as between person and body. I think there is more doubt whether I am right that the fire is identical to the burning matter; but if it is, then so is the person identical to the living, thinking body. If you accept the analogy, whichever conclusion you draw, I think you would do well to discuss it. For even if you still think the person is not identical to the body, it casts light on the potentially mysterious ownership relation to say that it’s the same as the relation between the fire and its fuel. And the analogy makes it clear that the person isn’t the ghost in the body, just as the fire isn’t the ghost in the fuel. By the way, why do you concede to Shoemaker even that if a person were changing bodies frequently we couldn’t tell he was doing it? If we had gear to watch all the available bodies all the time, and high-capacity data processing to look for continuities in behavior from one body to another, and if the subject was ingenious and trying very hard to help us, I think we might manage quite a high frequency of changes. The limit arrives when he is in no body long enough to initiate a visible movement, but we might still push it farther with encephalography. You answer the twin problem by saying: their experiences don’t diverge, because of our set-up; yet they might. This isn’t good enough. You might develop a split personality, hence two divergent sets of experiences; yet until you do you’re one person, not two because you might become two. Thanks very much for the paper. I’ll be glad to see what becomes of it; and I’ll be glad to see what becomes of the survey paper7 in the textbook.8 I don’t anticipate being in Philly in the near future; any hope you’ll be here? Anyway, I’ll probably see you at the meetings if they’re in a reasonable place and look somewhat good. Yours, David   ‘Recent Work on the Mind-Body Problem’ (Shaffer 1965).   Philosophy of Mind (Shaffer 1968).

7 8



422.  To J.J.C. Smart, 18 February 1965

7

422.  To J.J.C. Smart, 18 February 1965 Kirkland St. Cambridge, MA Dear Jack, (I’m not in flight with TWA; just laid in a supply of air-letter sheets when I was.) I got your cable, and I sent in the form with your name as reference, along with Aiken and Quine. Right; you wait till you hear from them. Thanks very much, and thanks especially for cabling. It turned out they wanted the form returned ‘immediately’ and I’d let it sit for a week or so while I finished grading the final for Aiken’s course. The fellowship provides all the money I need for a year while I write a thesis. I don’t see much difficulty finishing in that time, since I have a plan already. I want to finish next year, so that Steffi and I can get out at the same time. Quine has agreed by mail to supervise the thesis, starting this coming summer. The topic is linguistic rules by tacit convention, with a view to defining good approximations to intensional ­concepts without circularity. It’s very gratifying that Quine considered my line promising, considering what it’s supposed to do! All this is contingent on the metaphysics prelim this May, of course. It’s supposed to be more traditional this year; that would be good for me, though bad for some of the Cavell types. I’m going to Williams (his usual course minus the ontology part), Goodman at Brandeis (detailed course on Structure of Appearance)1 and Albritton’s Aristotle course (shows signs of spending all term on the Categories). All good solid courses, and good for the exam – nobody believes I like such stuff, they all think it’s just cramming for the exam! Of course the trouble last year was more in exam-writing than in knowledge, but that doesn’t mean it couldn’t be overcome by more knowledge. I’ve just read, and much enjoyed, Kuhn’s Structure of Scientific Revolutions.2 It’s something like Feyerabend’s line, but it doesn’t depend on a fishy theory of change in meaning. He plays around with the notion that a change in theoretical framework is somehow a change in the world itself, but that can be ignored without harm to the rest of his argument, and he himself is uneasy about it. (And while I’m speaking of books to read: I enjoyed Cooper’s Creek.3 Thanks for mentioning it.) I’ve been wondering why you say that secondary qualities like colors are (crudely) dispositions, powers to produce discriminatory responses. Why not say that they are whatever physical qualities it is that produce the discriminatory  (Goodman 1951).   2 (Kuhn 1962).   3  (Moorehead 1963).

1

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Philosophical Letters of David K. Lewis

responses? For you, to say ‘this is red’ is to say (mostly) that a normal percipient would discriminate it from some things (specified) but not from others. I suggest rather, that it is to say that this possesses whatever (presumably) physical quality it is that is common to some things (specified) and not others, and that causally explains the discriminatory responses of normal percipients. Thus the color red is a physical quality, as it turns out, namely the quality of having absorption and reflection spectra in a given complicated class, or spectra related to the spectra of nearby things in a given complicated way; but the color red is defined in terms of human discriminatory responses, as you want it to be. I think this is very analogous to the difference between taking mental states as disposition to behavior, and taking mental states as functional states, presumably contingently identical to some physical states, but defined in terms of the behavior they normally cause and the stimuli they are normally caused by. And if colors were functional states explaining dispositions to produce responses, and defined as such, rather than being the dispositions to produce responses themselves, you would not have to bring in the power to produce inner experiences at all, and so Bradley’s circle between your account of color and your account of color-experiences would not be possible. You used the power to produce experiences in order to allow that everything might change color systematically, without changing the discriminatory responses; but on my theory you could just say  that for the colors to change was for the qualities which causally explain the ­dis­crim­in­atory response to change. (continued on another sheet) Yours, 19 February 1965 Dear Jack, I’ve been thinking about identity of states, or indeed of attributes in general. Putnam argued last year (but he might not now): what does an identity theorist mean by claiming that a mental state M and a physical state P are identical? He doesn’t just mean that M occurs if and only if P does (psychophysical parallelism); he claims more than that. But he doesn’t mean that necessarily M occurs if and only if P does, for he thinks the identity of M and P is contingent; he claims less than that necessarily M if and only if P. But what condition of identity exists intermediate between coextensiveness and necessary coextensiveness? But his argument proves too much. We must be able to individuate states, or attributes, other than by necessary coextensiveness. For attributes must be able to have definite descriptions which hold accidentally. For instance, consider the definite description: the color which is common to precisely four cars on this block. Consider



422.  To J.J.C. Smart, 18 February 1965

9

the definite description: the color common to almost all ripe tomatoes. Now I think these are two definite descriptions which refer to the same attribute (namely the color red). If so, just as the morning star is identical to the evening star, so it should be the case that the color which is common to precisely four cars on this block is identical to the color which is common to almost all ripe tomatoes. But this identity is not the identity of necessary coextensiveness. It is certainly not necessary that all and only the things that have the color common to the four cars have the color common to the tomatoes, for it is not necessary that there be precisely four red cars on this block, nor that tomatoes be red. So I think necessary coextensiveness cannot be the correct principle for individuation of attributes, including states, in general, though it may be the correct principle for individuating attributes under descriptions of the form: the attribute of being . . . I take it a functional state-description, like: ‘the state which is caused by organic damage in most cases, and which causes pain-behavior in most cases’, is a definite description of a (presumably) physical state; but it is a description in terms of an accidental property of that state; the essential property of that state being that it is the state in which a certain pattern of neuron-firings is going on. Thus I accept the option of what Quine calls essentialism for attributes, including states (though I do not for individuals), and I claim that attributes are to be individuated by necessary coextensiveness of descriptions only when the description is essential. Attributes are to be individuated by their essences, but may be identified by their accidents, that is, may be referred to by definite descriptions in terms of their accidents. What do you think of this? It seems to me that without some such theory of essences of states, we have no way to explain how psychophysical identity goes beyond psychophysical parallelism, unless it is necessary psychophysical identity, which is absurd. The innate ideas symposium was good, except for Goodman, who had an offday. I don’t know if it’s available in mimeo.4 I’ll ask when I next go to a BU colloquium. Chomsky took his usual line: how can infants learn something so complicated as a phrase-structure-plus-transformational grammar of a natural language so fast, with so little reinforcement and so little linguistic data? (Notice that otherwise apparently equally intelligent apes cannot.) This ability must be explained by the hypothesis that they have an innate grammar-schema of a special sort to which they fit the data; the schema makes the job easier by settling many alternatives a priori. We can find out how determinate the innate schema is by looking for linguistic universals. Putnam said you don’t need an innate schema to explain linguistic universals; you can explain them by a single source of language, by interaction of languages, or by the fact that there’s only one efficient way in which a language can possibly work.   See ‘Symposium on Innate Ideas’ (Chomsky, Putnam, and Goodman 1967).

4

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Chomsky said that universals weren’t meant to be evidence for the innate schema; rather, given that you believe in the innate schema, they’re evidence for how de­ter­ min­ate it is. Putnam and Chomsky disagreed how special the general phrasestructure-plus-transformational pattern is. Chomsky thinks it’s one of many antecedently plausible ways a language could have been constructed; Putnam guesses you could prove it’s the only way, or the best way, to meet human needs for flexibility, brevity, and easy analysis of input. But mainly Putnam argued that Chomsky makes unclear what he’s claiming. Is the innate schema nothing but an innate capacity to learn phrase-structure-plustransformational languages easily? Then we certainly have it, but it doesn’t have any explanatory force, being identical to what it explains. Putnam agrees that we have an ability that simple Skinnerian learning theory cannot explain, but he thinks it’s no news that Skinnerian learning theory is inadequate. We presumably have some sort of innate heuristics by the aid of which we catch onto complex projectible re­gu­lar­ ities; but why should there be special-purpose ones for catching onto the regularities of language? Why shouldn’t there just be an application to linguistic data of generalpurpose problem-solving systems (which might be either hardware or software, I guess; special neural circuitry or special ways of using ordinary neural circuitry)? Even if we pick up phrase-structure-plus-transformational systems much more easily than we pick up other comparably complicated systems, that might be explained not by the existence of a special-purpose system for learning language, but rather by the strengths and weaknesses of a general-purpose problem-solving, pattern-learning system. So Chomsky gives us a false alternative: either we have innate and specialized capacities, or we learn by a big network of individually conditioned responses, as e.g. Skinner would have it. Putnam says there’s a middle ground more plausible than either (and I guess he’s right). See Chomsky’s review of Skinner in the Katz and Fodor book;5 most of Chomsky’s case is there. You may know that my application for a Junior Fellowship for the coming year fell through, for administrative reasons. I’ll be nominated again for the year after next if I want; with better chances if the prelim is passed and a thesis is started, and because they will have more openings. Also, I will try to have some publications by then; I’ve got various things lying around to be worked up and submitted when I get time. All  short, mostly criticisms. The best one is against Scriven’s fishy argument for the essential unpredictability of human nature;6 but that ought to wait until Scriven publishes a version of his argument better than the one that’s out now in the Colodny book.7 The argument is this: if you can predict my behavior, I can (in principle) always   ‘A Review of B.F. Skinner’s Verbal Behaviour’ (Chomsky 1964).   ‘Scriven on Human Unpredictability’ (Lewis and Richardson 1966). 7   ‘The Frontiers of Psychology: Psychoanalysis and Parapsychology’ (Scriven 1962). 5 6



423.  To J.J.C. Smart, 27 February 1965

11

duplicate your prediction (by using the same laws and data you use) and falsify it by acting otherwise. Thus I render myself unpredictable without having to resort to indeterminate physical systems to guide my choice. I say that Scriven has shown that any predicter can be frustrated, but he has not shown that any human action is unpredictable; the action which frustrates one predicter could always have been predicted (forgetting physical indeterminacy) by another, faster, predicter. For I think that what will happen between two people each trying to think one step beyond the other, and each provided with all necessary knowledge and calculating ability, is this: either there is no deadline, and they will both go on forever; or there is a deadline, and then the slower one will not have finished his task by the time it arrives. If the predicter is slower, he will not have finished predicting that the avoider (the one trying not to be predicted) will have duplicated the predicter’s prediction and decided to frustrate it. If the avoider is slower, he will not have finished duplicating the predicter’s prediction, so he will not know how to frustrate it. If you ask him, Scriven will stipulate that the predicter has enough time; and he will stipulate that the avoider has enough time. He’s welcome to stipulate either, but not both; for the time the predicter needs depends on the time the avoider has, and conversely. We can stipulate that Oscar runs faster than Elmer, or we can stipulate that Elmer runs faster than Oscar, but we can’t stipulate both at once. If we try to provide both the predicter and the avoider with enough time (or computing speed), we will have to give them both an infinite amount; so I guess Scriven has proved the essential unpredictability of some processes that take infinite time or go through infinitely many distinct steps in finite time; but that’s of no interest. Yours, David

423.  To J.J.C. Smart, 27 February 1965 Kirkland St. Cambridge, MA Dear Jack, The Wilson progresses. It remains only to write a thesis prospectus for them. Thanks again. As I understand you, if red-responses to things were explicable by some simple physical quality of the things – say, emission and reflection of monochromatic light

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Philosophical Letters of David K. Lewis

between x and y Angstroms – then you would have been willing to say that red was a functional state (whatever it is that is common to some things and explains the dis­ crim­in­atory responses) contingently identical to the physical quality. Your objection is just that the physical quality in fact turns out to be ‘highly complex and perhaps infinitely disjunctive’ (and, I would add, perhaps relational, dependent on the visual context). But I don’t see why that matters. And it does seem to me important to get the experiences out of the definitions of secondary qualities altogether, since as Bradley says you need the secondary qualities in the definition of the experiences;1 but I don’t see how to get the experiences out without either falsely denying that colors might change although the discriminatory responses did not, or making sense of change of colors without change of the responses by explaining it in terms of change of the physical qualities contingently identical to the colors. I take it that for you and Putnam (as of Minds & Machines) alike,2 mental states are functional states, contingently realized in brain hardware. You and I want to add to this that for a system of states to be realized in hardware is for each state of the system to be contingently identical to a structural state of the hardware. OK so far? Now the trouble is that Putnam objects in general to the notion of contingent identity of attributes (including states). The argument is simply that if attributes are identical just in case they are necessarily coextensive, then if they are identical they are necessarily identical. There is no place left for contingent identity. Now I do not have my own theory of how attributes are to be individuated, but the one Putnam uses as his premise must be wrong: it rules out not only the controversial accidental identity of functional and structural states, e.g. mental and brain states, but also unproblematic cases of accidental identity of attributes, like the identity of the color common to precisely four cars on this block and the color of tomatoes. Here I more or less stop; I have no positive theory of identity of attributes, but Putnam’s theory, with its bad consequences for us, won’t do. I only add this: sometimes necessary coextensiveness is the correct criterion of identity, for instance when attributes are referred to by the corresponding predicates: e.g. the attribute of being a bachelor is identical to the attribute of being an unmarried male precisely because necessarily all and only bachelors are unmarried males. But when attributes are referred to some other way (including by functional-state names) some other criterion of identity must come into play. But I have no good idea what, and I have no idea how to ­formally characterize the two ways of referring to attributes.

1   ‘Critical Notice of Philosophy and Scientific Realism by J.J.C. Smart’ (Bradley 1964, 262–7). See also ‘Sensations, Brain-Processes, and Colours’ (Bradley 1963, sec. 2). 2   ‘Minds and Machines’ (Putnam 1960).



424.  To J.J.C. Smart, ?–8 May 1965

13

Many thanks for your comments. I’m interested to know what you say on ­criti­cism of theories. Will the Melbourne paper be published? Yours, David [. . .]

424.  To J.J.C. Smart, ?–8 May 1965 [Cambridge, MA] Dear Jack, Sure there are extra-theoretic standards of acceptability for theories, and they’re roughly the sort of thing anti-Popperological confirmation theorists like Goodman, Hempel, etc. say they are: formal simplicity, elegance, economy, use of familiar concepts so far as possible. But I say, contra the anti-Popperologists that the extrasystematic standards do not determine what theory wins, or what theory ought to win. They only determine – very effectively – what theories get taken seriously as candidates for acceptance, what theories get proposed and debated by reputable ­people. They don’t make fine discriminations that would settle live controversies, but they do get the credit for the fact that nobody conjectures that emeralds are grue, nobody conjectures that the gravitational constant is about to double tomorrow for the first time in history, nobody conjectures that there’s a Cartesian demon. More seriously, they get the credit for the fact that nobody reputable listens to cranks like Velikovsky.1 They rule out all the theories which have explanatory adequacy but are crazy – and they rule out the crazy theories so decisively that we may forget that the crazy theories needed to be ruled out somehow. Only then, after the extrasystematic standards have kept the crazy theories from ever getting proposed seriously at all, do the remaining candidates fight it out Popperologically. It’s a two-stage process, and serious proposal is the transition from the first (non-Popperological) to the second (Popperological) stage of getting accepted. And that’s how it has to be: the extrasystematic standards don’t make fine enough discriminations to narrow the field down to one ‘simplest’ theory; Popperological competition would be swamped unless there were some sort of tough pre-screening to keep out the cranks – to say nothing of things like the theory that emeralds are grue, theories which flunk the extrasystematic standards so badly that even cranks don’t propose them. 1   Immanuel Velikovsky (1895–1979), independent scholar and author of the controversial Worlds in Collision (Velikovsky 1950).

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I have thought from time to time that we ought to find great differences in methodology between sciences that do and that do not confidently anticipate that they will get reduced. Those which do anticipate reduction ought to tolerate ap­proxi­ mate laws and complex laws and local laws and exceptions to laws to a much greater degree than those that do not anticipate reduction; for they will eventually get the simplicity, exactness, and universality they want on the reducing level. It seems a bit much to ask nature to be governed by simple, exact, universal laws on several levels at once! This is related to your account of e.g. biology as materialists conceive of ­biology; I am saying that materialists and emergentists can’t be expected to use the same standards for what is a satisfactory theory in biology, for materialists will use the standard of propensity to getting reduced. (I first put this as a difference between sciences that do or do not anticipate reduction; really it ought to be a difference between factions in any science, though in some sciences, say meteorology, the reduction-anticipating faction is dominant and sets standards for everybody. In  psychology, however, disagreement on in-principle or in-practice reducibility probably does have a great effect on preference among theories.) The enclosed paper on mind-body (a term paper for Williams)2 covers the points we’ve been discussing this year, except for the matter of secondary qualities (discussed obliquely on p. 9MP 2 and in note 5). The strategy followed is new to me, though it’s really implicit in your ‘What is going on in me is like what goes on when . . .’ formula; I’ve never seen the identity theory defended against epiphenomenalism except as an economizing measure and an elimination of occult entities. For anybody except Williams, I ought to say more about introspection. I want to say that introspective avowals and subsequent introspective experience of an experience are not incorrigible, although they are included in the definitive causal syndrome of the introspected experience and therefore are necessarily typically caused. I want to say that simultaneous introspective experience of an experience may be incorrigible, but if so it’s because of logical relations between the causal syndromes of the two experiences and therefore explicable on my theory. In the simplest case, I would say that a dizzy feeling and the introspective simultaneous awareness of that dizzy f­eeling have precisely the same definitive causal syndrome, and therefore are one and the same experience, and that’s why so-called introspective knowledge of the dizzy feeling is infallible. The highly intensional stuff in the second half of the first part gives me a pain.  I  think it’s unavoidable, however, if we’re to avoid letting the I.T.  become ­indistinguishable from the kind of epiphenomenalism that says that neural states are perfectly correlated with experiences. I do end up tolerating a purely logical sort of 2   ‘How to Establish the Identity Theory’, 1 May 1965; term paper for Donald C. Williams’s PHIL157 Metaphysics: Problems and Principles of Cosmology, Spring semester 1965. A revised version of this paper was published as ‘An Argument for the Identity Theory’ (Lewis 1966a).



425.  To Jerome A. Shaffer, 5 April 1967

15

dualism, namely the dualism of experiences = neural states vs. havings of experiences. Notice that the same logical dualism turns up elsewhere in purely physical contexts; it’s just one of the obnoxious features of attribute theory. When I first came upon the  argument for it, however, I thought I’d have to abandon the I.T.  At that point I  just  had the neural states vs. the havings of experiences (attributes expressed by experience-ascriptions) and hadn’t thought to distinguish the experiences from the havings of them, as I later did. By the time I finished the first part of the paper I felt like turning nominalist for life! Williams will certainly find the theory unsatisfactory, for he’s hopelessly immersed in the ‘phenomenological fallacy’; he thinks that for the I.T. to work there has to somehow be a redness in the brain for there to be experience of redness. However, he thinks that there may be a redness in the brain in virtue of the following theory: qualities are gestalt-fusions of structures of relations, and there may be in the brain an isomorph of the structure of relations which constitutes redness in external things. I’m sorry I can’t give Williams a theory he’d accept, for I’ve come to be quite sympathetic with almost all of what he’s doing. You give the formula: pain is what’s going on in me when I am stuck with a pin or. . . . Then you say, rightly, that pain is conceptually independent of pins, so this formula just gives the ‘general purport’ of pain-avowals. And likewise no doubt for needles, broken glass, hot stoves. . . . But why not say that pain is what is going on in me when the surface of my body is damaged, which would be general to almost all ways of introducing the notion of pain? Plus a response condition: e.g. that pain (typically) prevents one from attending to other things. By the way, I think common psychological knowledge (classification of states by causal roles) is a good example of a science which anticipates reduction.*

425.  To Jerome A. Shaffer, 5 April 1967 UCLA Los Angeles, CA Dear Jerry, [. . .] You say I say most sensations have causes is a tautology.1 Agreed. I’m committed to something of the sort; perhaps to the analyticity of most sensations hitherto have had *   The catch being that it anticipated reduction to a science of souls, and unexpectedly got reduced – or is being reduced – to neurology instead.

 Cf. Philosophy of Mind (Shaffer 1968, 20–1).

1

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either causes or effects. I don’t mind. Remember that the definitive typical causes and effects of experiences may often (but not always) be other experiences. It might even be that for any experience, its causal syndrome consists mostly of other experiences. Does that help? How about a dual causation theory? Suppose there are correlation laws that certain non-physical states occur if and only if correlated physical states occur simultaneously. (For convenience let any disjunction of physical states be a physical state.) Suppose those physical states occupy the definitive causal roles of experiences. And suppose the physical causal order is self-contained: any law about the succession of physiological states alone (without mention of non-physical states) follows from general laws of physiology etc. (together with facts about the physiology of the brain). Then the correlated physical and non-physical states are indistinguishable with respect to laws: that is, they have precisely the same lawful connections with other states. Do they therefore have precisely the same causal connections? I say not: the non-physical states are caused by their physical correlates (and all causes thereof) but have no effects. They are epiphenomena. Why? I don’t think I have to say why; it’s obvious according to well-disciplined common sense. If not so in this case, it will be in analogous cases: I mentioned the power-on light on a motor, which does not cause the motor to go although it is a ­lawful correlate of the current that does cause the motor to go. However, I think ­perhaps I can say why the non-physical states do not cause succeeding physical (or non-physical) states. Already in my second paper for you in Phil. 1 I adopted a counterfactual analysis of causation;2 and I still do. The non-physical state doesn’t cause a  succeeding state because without it, the succeeding state would have happened anyway. (For the physical correlate of In entertaining a counterfactual supposition (here, that the non-physical state does not occur) we are considering a situation as close to the actual situation as it can be, consistent with the supposition. I claim that on the theory I have described, the situation in which the non-physical state fails to occur because the correlation law is broken is closer to the actual situation than any situation in which the non-physical state fails to occur because its physical correlate fails to occur. But if you ask how I tell which possible situation is closer to the actual situation I have no answer. If you reject this line of argument in my last paragraph, and say that the nonphysical states and their physical correlates have precisely the same causes and effects, you get the conclusion that both occupy the definitive causal roles of experiences, hence that there are two parallel streams of experiences. You say: is that not a possible view? Sure it’s possible; but I expect it to be repugnant to any dualist. If any   ‘On Causality and Natural Laws’, Fall semester 1958, Swarthmore College.

2



426.  To J.J.C. Smart, 16 May 1967

17

dualist does accept it, he agrees with me that certain experiences are physical states – he just believes in non-physical experiences as well. I think this dualism would be scientifically indefensible, but that’s another story; I promised in the first paragraph that I would not need to make a case for the identity theory on grounds of economy.3 My dissertation is done, and I passed the oral during Christmas vacation; it remains only for the overseers to vote. We’ll be east in June for Harvard commencement (but probably not for long); and perhaps again at the end of the summer. I forget where your Council summer circus is to be; we have a poster around, though. Let us know if you’ll be out here ever! It’s not so bad in Los Angeles; there’s nothing bizarre wrong with it (as eastern myth claims), it’s just a bit crowded and ugly. Much like the Baltimore Pike. Have you seen Peter Unger on knowledge in the last J. Phil.?4 I think it’s a very good paper, and at least as important as Gettier’s.5 Yours, David

426.  To J.J.C. Smart, 16 May 1967 UCLA Los Angeles, CA Dear Jack, Had you noticed that our topic-neutral translations of mental sentences are Ramsey sentences? Start from the Fodor-Sellars line: mental terms are theoretical primitives introduced by the postulates of a theory, the theory being commonsense psychology and the postulates being the truisms thereof. Suppose I say ‘I am in pain’, and to help you understand what I mean by pain I recite all the truisms of commonsense psychology. Now take the Ramsey sentence of the whole business; it turns out to be our topic-neutral translation of ‘I am in pain’. Perhaps the analogy is closer if we take not the ordinary Ramsey sentence ‘There are states S1 . . . Sn which satisfy the truisms of common-sense psychology, and that I am in state Si’, but rather the Ramsey sentence with a uniqueness claim: ‘There is a unique n-tuple of states S1 . . . Sn which

  That is, the first paragraph of (Lewis 1966a).   ‘Experience and Factual Knowledge’ (Unger 1967). 5   ‘Is Justified True Belief Knowledge?’ (Gettier 1963). 3 4

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satisfy the truisms of commonsense psychology, and I am in state Si’. This explains the suggestion of uniqueness in ‘Whatever is going on in me . . .’ and in my use of a definite description: ‘I am in the state Si such that there is a unique n-1-tuple of states S1 . . . Si-1 Si+1 . . . Sn such that S1 . . . Sn satisfy the truisms of commonsense psychology’. On the GDY lectures:1 Harvard University Press has accepted my thesis.2 They could publish it next spring, but they and I would be perfectly willing to postpone it for a few months, so that it wouldn’t be out before the fall of 1968. So if you were interested, it could be used for lectures that summer. Things are going pretty well. Steffi has passed her German exam, and is taking and liking a good set of courses; I am working on various rather technical projects in the vicinity of philosophy of science. We don’t like Los Angeles much better than we did, but one big improvement should come this summer when we look for a better place to live. (Another big improvement should come tomorrow: today it’s extremely hot and smoggy, due to a ‘Santa Ana wind’ off the desert.) We’re both driving now, an unfortunate necessity, but we enjoy it well enough. Yours, David   & Steffi

427.  To J.J.C. Smart, 17 October 1967 UCLA Los Angeles, CA Dear Jack, Which part of my current views on secondary qualities are you unsure you understand? I say, first, that the two properties I and II are not identical. I say, second, that I’m not sure which of the two is the secondary quality. Suppose the dis­crim­in­ atory response associated with red is R, and the property which tends to cause R in percipients is, as a matter of fact, P. Now consider a state of affairs different from the actual one, with different physical laws, such that in that state of affairs the property which tended to cause R was not P but rather P*. Speaking hypothetically of that state of affairs, which things should we call red? Those which possess P, the property which actually causes R? Or those which possess P*, the property which (in the hypothetical case in question) causes R? Things which possess P* would be the ones   Gavin David Young Lectures, University of Adelaide.   Convention: A Philosophical Study (Lewis 1969).

1 2



427.  To J.J.C. Smart, 17 October 1967

19

which had my property II: the property of having whichever property it is which causes R. But the things which possess P would be the ones which had my property I: the property which does (in fact) cause R. So, in that case, which would be red? That’s the issue. Here’s my theory – very tentative – of laws. Suppose God has decided to write for us a textbook of unified science. He wants it to be complete as far as possible – every truth should follow from what the textbook says, or anyhow as many as ­possible. He also wants it to be short, and otherwise simple. But these two virtues trade off: the closer it is to being complete the less simple it is. Suppose you have 1) a measure of degrees of completeness 2) a measure of simplicity 3) a set of indifference curves telling you how these commodities trade off. A textbook is ideal if A) every word of it is true, and B) it is on the best attainable indifference curve. A law is a sentence which is general in form and which follows from the content of every ideal textbook. Thus I think of God as being like human scientists in trying to get a simple yet possible axiomatization of a body of facts; but unlike human scientists in that he’s trying to axiomatize not the totality of observations to date and expected, but rather the totality of truths. This gives a theory of lawhood not relative to the present state of science, but still relative to standards for a good systematization – relative, that is, to a completeness measure, a simplicity measure and an indifference map for trading off completeness and simplicity. When I saw your note in the last Australasian1 I wondered if you’d heard of Everett’s relative state interpretation of quantum mechanics. This is a piece of speculative metaphysics on a grand scale – branching parallel worlds – justified on grounds of contributing to simplicity in physical theory. It has been ignored, but I often think it is quite convincing. Look at 1) Shimony, ‘Role of the Observer in Quantum Theory’ in American Journal of Physics vol. 31, no. 10, Oct. 1963; and 2) Everett, Reviews of Modern Physics, 29, 454 (1957), also comments by John Wheeler, same place.2 Yours, PS Thanks for mentioning Hinckfuss. We’ll read the book review,3 and anything else we may find.

  ‘The Unity of Space-Time: Mathematics Versus Myth Making’ (Smart 1967).   ‘Assessment of Everett’s “Relative State” Formulation of Quantum Theory’ (Wheeler 1957). 3   ‘Critical Notice of Robert Colodny (ed.) Beyond the Edge of Certainty’ (Hinckfuss 1965). 1 2

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428.  To Keith Campbell, 11 December 1967 UCLA Los Angeles, CA Dear Mr. Campbell, Many thanks for your interesting paper on colours.1 However, I think it would be too bad if you did manage to convert Smart;2 I don’t think you have any decisive objection to a disjunctive physical realism. Let’s stick with a fixed illumination (and background) A for our coloured objects; it’s a later question whether there is any interesting way to select this to be ‘standard’. Consider a certain property P. This is to be a second-type property: a property of properties of objects. This will be the kind of property I called a ‘causal role’ in my paper on the identity theory ( J. Phil 1966). A property Q of objects has property P just in case any object with a property Q in illumination A tends to produce rednessimpressions (or redness-discriminatory-responses; doesn’t matter which for this purpose). So roughly P is the property of being a property which tends to produce redness-impressions. Some properties of objects have property P, others don’t. Which properties have P depends on the prevailing physical – and perhaps psychophysical – laws. Thus P is a contingent property of properties. We hope it turns out that all the properties of objects which have property P  are physical properties. But whether or not they’re all physical, there’s a set of ­properties which have the property P. The disjunction of these is also a property of objects. (It’s the most inclusive property of objects which has the property P.) It’s this disjunction which I take to be the colour red. You ask how to find out whether a physical property J belongs to the disjunction. I say, by finding out whether J is one of the properties which has P. In short, as you say, by finding out whether J things (in A) look red. Why does it follow that ‘the doctrine of colour as an intrinsic physical property has been abandoned’? A disjunction of intrinsic physical properties is still an intrinsic physical property. Nor is it an arbitrary disjunction: we’ve included just those physical properties which have P. (As well as any non-physical properties – none, we hope – that may also have P.) Of course, the colour red is only contingently identical to a certain disjunctive physical property; it could have been other physical properties that had P. So there’s this surprise: the intension of ‘red’ is determined not by the property which is the   ‘Colours’ (Campbell 1969).   Handwritten note by Lewis (to himself) in left margin of his copy: ‘Campbell said he hoped to accomplish this’. 1 2



428.  To Keith Campbell, 11 December 1967

21

colour red, but by the fixed second-type property P which the former property is required to have. sometimes thinks that a property, being an intensional can only be denoted by names which necessarily denote that property – in contrast to people, for instance, who can have names like ‘the third man to say “hello” to me today’ which happens to denote Jones but might have denoted Smith instead. But this is a false contrast. A property, like a person, can contingently happen to have a property; and a property can be identified by properties it just happens to have. Consider, for instance, the property measured by the instrument with patent #123456789. This property may happen to be conductivity; but it’s a contingent matter what property it is. I take the name ‘the colour red’ to denote a property in a similar way; to denote whichever is the most inclusive property which has property P. There’s an alternative view which seems disagreeable, but which I don’t know how to attack. Instead of saying (I)  The colour red is the most inclusive property which has P what about saying (II)  The colour red is the property of having some property which has the ­property P forming a property of objects from the property P of properties of objects by means of an existential quantifier over properties of objects? The difference shows up this way. Suppose that in the actual world the properties which have P are Q1, Q2, Q3 and disjunctions thereof; and in particular Q, the disjunction of all of them. Suppose that in some other possible world – different laws – the properties which have P are R1, R2, R3 and disjunctions thereof; and in particular R, the disjunction of all of them. Assume no overlap between Q and R. Now in that other world, which is red: something with property Q or something with property R? On theory I – disjunctive realism – the colour red is the property Q, since Q is the property which actually has P. So in the other world, the thing with Q is red and the thing with R isn’t. On theory II, in the other world the thing with R is red and the thing with Q isn’t, since in that world it’s R that has P. I’ve neglected the part about adaptation. I think it’s on the side of the observer that you’re most likely to find standard conditions. How about saying just that the observer has been isotropically illuminated with light of a frequency distribution like that in A for a long time? I’d be glad to hear any comments on this. I’m also sending Smart a copy. Yours, David Lewis I’ve just been invited to a conference in Hawaii March 11–14, & will probably accept. See you there? Steffi sends greetings.

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Philosophical Letters of David K. Lewis

429.  To J.J.C. Smart, 20 April 1968 UCLA Los Angeles, CA Dear Jack, Many thanks for the pictures! One of them is one of the best we have of Steffi. The photographer tends to get left out – like Keith Gunderson’s own eyes. It looks as if nothing will come of my plan to talk the department into using its spare change to bring a visitor from Australia for our winter term. They had other ideas they want to try first. Cheng has not yet sent me the tape of my talk.1 I’d like to have that in the book2 with as little change as possible; then write the stuff up as a paper called ‘How to Define Theoretical Terms’ with some new material,3 and only a passing mention of mental states. In the first place, such books are obscure; I don’t want this to appear only there. In the second place, I can do better than I did in the talk. And in the third place, as you know, Cheng wants to finish the book in quite a hurry. I’m working on the new paper; I want to have it duplicated for my Φ science class by the middle of May, so I can send you a copy at that stage. I enclose a copy of my paper on modal logic4 and how to do without it, if only you’re prepared to tolerate ontic commitment to possible worlds and their inhabitants. Also a thermofax of the very end of my book,5 which is a polemic to the effect that the possible worlds are no more occult than sets. Another remark ought to be added: ‘actual’ appears as a predicate of the system. Actuality seems to be mysterious, unanalyzable, ineffable; but it is not. ‘Actual’ is an indexical predicate exactly analogous to ‘present’ – on any given occasion of utterance, in any possible world, it denotes just those things which are in the same world as the occasion of utterance! Another thing I should have emphasized more than I did: the counterpart relation will of course be extremely context-dependent. Some of the arguments which purport to show that persons are not identical with their bodies can be treated as fallacious by reason of a concealed shift from one counterpart relation to another, the two being equally natural in different contexts. I’ve started to read Between Science and Philosophy;6 thank you for having them send me the copy. I’m pretty sure I’ll use it next time I teach my Φ science course; I’m 1   ‘Psychophysical and Theoretical Identifications’, read at the Philosophical Problems of Psychology Conference, University of Hawaii, March 1968. 2   Philosophical Aspects of the Mind-Body Problem (Cheng 1975).    3  (Lewis 1970b). 4   ‘Counterpart Theory and Quantified Modal Logic’ (Lewis 1968). 5   Convention: A Philosophical Study (Lewis 1969, 203–8).    6  (Smart 1968).



429.  To J.J.C. Smart, 20 April 1968

23

not at all happy with any other text, except the little Hempel introduction, which is so baby it needs lots of supplementation. I’ve been using a very miscellaneous collection of articles, parts of books, and duplicated notes; so there’s lots of reading that’s not quite self-contained, the students have to organize for themselves, the selections duplicate each other quite a lot. I’ll still have to give them extra material on Bayesian confirmation theory, which evidently you respect less than I do. I think it a good reconstruction of standards of rationality we would like to live up to – something like general equilibrium in economics. Then we can get a more realistic account by noticing that Bayesian rationality requires enormous amounts of memory and calculation, so we cut corners in a way we hope won’t take us too far away. I wish I knew a good easy book on Bayesian confirmation theory – perhaps a Bayesian’s textbook for an introductory statistics course. Various books I’ve looked at recently have been disappointing. Now to the paper on colors;7 I have some middle-sized remarks. 1) Top of page 2: the patterns of response will not have changed. Or rather: they will change momentarily, but return to what they were after a little while. Just at first, the novelty will be so distracting that it’s a good guess that all our discrimination will deteriorate. 2) Bottom of page 2. I’ve not read the Harrison paper, but if people have reported it correctly, it’s silly and irrelevant. There are permutations of the colors that do preserve all degrees of similarity, and there are permutations that don’t. Yours, of course, is one that does. If carelessly described, it might sound like one that doesn’t; but you’ve described it properly. And everyone knows it’s the similarity-preserving permutations (reflections through the center, rotations of the disk, and com­bin­ ations of these) that make the interesting puzzles. 3) Middle of page 3. I think the differences between my theory and Armstrong’s are the following; what we agree on is that names of colors denote (if anything) the appropriate presumably physical properties of surfaces of objects. A) If there were only a hellish disjunctive property, and no simple one, common to the normal examples of red things and occupying the definitive causal role of redness, I’d say redness was a hellish disjunctive property; Armstrong would say there was not such a thing as redness. B) If, in some possible world w, the definitive causal role of redness were ­occupied by the physical property which, here in the actual world, occupies the definitive causal role of blueness, I’d say that ‘redness’ denotes that ­property in the world w; Armstrong would say that ‘blueness’ denotes that property in the world w, just as in the actual world. That is, Armstrong thinks that color-names   ‘On Some Criticisms of a Physicalist Theory of Colors’ (Smart 1975).

7

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denote the same property in every possible world. Accordingly, his analysis doesn’t mention the causal roles; though he’d agree with me that redness is in fact what occupies the causal role of redness in the actual world. You’d better check this with Armstrong to see that I have him right, if you want to use it. 4) Top of page 4. Here it says that Smith carries on when an instance of snarkhood is mentioned. On the next page, he does it when he is presented with one. Which do you want? I should think the latter; you don’t want to get noise because of the intentionality of mentioning. Best to keep the example simple, and not bring in anything troublesome which you don’t have to have. But if Smith is to react when presented with an instance of snarkhood, you’ll have to change it a bit: neutrons are always present, prime numbers never are. You can still have a mixture of categories: an archbishop or a windstorm or a crooked grin. 5) I would defend the view that hellish disjunctive properties are still properties by giving a theory of what properties are: functions from possible worlds to sets of things therein. For instance, the property of being a horse is the function which, for every world, gives you the set of its horses. (Alternatively: a function from pairs to truth-values 0 and 1; or – on condition that everything is in precisely one world – a big set of things taken from many worlds, e.g. the set of all actual and possible horses.) Such functions are perfectly good set-theoretic entities, provided you’re ontically committed to the possibles. Now the point is that everyone agrees that hellish disjunctive sets and functions are still sets and functions! 6) Middle of page 4. I don’t think it’s by any means settled that colors are hellish disjunctive and idiosyncratic, though we certainly ought to be prepared in case they are. We know that they are not certain simple physical properties: yellowness is not the property of radiating monochromatic light at 5893 Å, unfortunately! But consider the continuum-dimensional space of all spectrums; so far as I know, it may still be possible that each color occupies a fairly simple-shaped volume of this space, say a hypersphere. And when you say ‘this is because infinitely many different mixtures of wavelengths can produce the same discriminatory response’ that, of course, is not at all decisive. Suppose a certain response is produced by just those mixtures in which at least 60% of the energy is within the band 5893 Å ± 272. Infinitely many mixtures – but not hellish disjunctive. You could describe the property by an infinite disjunction of spectra, but that would be an unnatural way to describe it; and, of course, any property you like can be described by an infinite disjunction. 7) Is it OK with you that colors should turn out to be physical properties of objects by virtue of their environments? E.g. yellowness might be the property of having a spectrum which is much more concentrated in the yellow band than the average spectrum of the surroundings, or something of that sort. Campbell and



429.  To J.J.C. Smart, 20 April 1968

25

Armstrong seem to think this is an important issue. One is tempted to say that, if so, color would be a property of the object-plus-environment, or a relation rather than a property; but both of these are wrong. The property of being within ten miles of an ocean is a property of me; not of me-plus-the-ocean, not a relation of me to the ocean. Of course, it’s a property I have by virtue of a relation of me-plus-the-ocean, or by virtue of a relation of me to the ocean. Some of Campbell’s objections seem to turn on the notion that if the color of something depends on its environment, and if we can’t specify a non-arbitrary standard environment, then colors aren’t properties of the colored objects. 8) Top of page 5. You mention that ‘snarks’ might be taught ostensively, instead of being defined by specifying the causal role of snarkhood. If it were taught ostensively, it would have the same denotation in the actual world, but it would have a different sense. That is, it would have a different denotation in other possible worlds in which that causal role has a different occupant. Armstrong thinks color-names are taught ostensively. That’s why (3,B above) he thinks they denote the same property in every world, if I’m right that he does think so. 9) It’s N.L. Wilson who first discovered that true statements of property identity can be contingent. I hate to credit this to him, since it ought to have been obvious and not need discovering; but in fact it wasn’t obvious, not even to Quine. I don’t know the reference.8 10) I think the ‘everything could look grey’ argument can be treated as a modal equivocation. It’s parallel to the fallacious argument that, since the Boston strangler might have led an innocent life, therefore it cannot be correct to define ‘the Boston strangler’ as ‘the person who recently strangled many people in Boston’, since what would be true by definition under that definition could in fact have been false. The statement ‘It might have been that everything looked grey to everyone (typically, indeed invariably so!) yet somehow we discriminated just as we actually do’ is equivocal. We are asked to consider a possible world in which the property P, which in the actual world occupies the causal role of greyness-sensations, does not occupy that role. We are talking of this world from the standpoint of the actual world. Now, shall we say that an inhabitant of that world who has property P is having a greynesssensation? In that case, we are giving ‘greyness-sensation’ the denotation it has in the actual world. On this construal, the statement is true, but no problem to us. Or shall we say that an inhabitant of that world who has property P is not having a greynesssensation, since he is not having the property which, in his own world, occupies the causal role of greyness-sensations? On that construal the statement is false. And it

  It is ‘The Trouble with Meanings’ (Wilson 1964).

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is only on the second construal that the statement would have conflicted with the definition of greyness-sensations by their causal role. (By the way, exactly the same argument and rejoinder could be used for the inhabitants of another actual planet as for the inhabitants of another possible world.) 11) Page 9, top. You’d like to do things extensionally and set-theoretically. Why? If it’s because you think (rightly) that intensional language is best taken as disguised, implicit talk about a suspect metaphysical realm of unactualized possibles, do you mind A) the fact that unactualized possibles are involved at all, or B) the fact that you’re using a difficult funny logic to talk about them, a logic whose principles are unclear? If it’s B, I suggest the cure is to talk about them explicitly, in an or­din­ ary first-order (or set-theoretic) language. If it’s A, tell me what considerations make poss­ibles suspect which do not also make sets suspect, in view of the Gödel-Cohen independence results? Quine talks about ‘overpopulation’, but no set-theorist has a right to that complaint; Quine also worries about individuation of possibles, but that’s a problem only if you think there are things that belong to two different worlds. 12) A rather trivial afterthought. Page 5, middle. I started to quibble and say: conductivity isn’t a property, since it’s a matter of degree. It’s a magnitude, that is a relation of things to real numbers. But of course ordinary language is on your side; properties do admit of degrees. This is some reason in favor of using the more obviously technical term ‘attribute’, as Quine does. Still, why don’t you change the ex­ample to suppress irrelevant noise! Yours, David PS Thanks for the encouragement about the holes!9 Still, I think plenty of things ought to take priority. I thought of Analysis not because they have a sense of humor but because I suspect they haven’t – I’d enjoy getting them to print the holes in the belief that it was a serious contribution to ontology. I have another ambition: I’d like to get hold of a reasonably complicated generative grammar for English, and  supply it with a suitable disgustingly profound vocabulary, plus some special rules like: Proper noun → pronoun + ‘itself’

If all went well, I’d like to try to get people to believe that the randomly got output (perhaps post-edited) was the latest from Germany, Yale, or some such place.

  ‘Holes’ (Lewis and Lewis 1970).

9



430.  To J.J.C. Smart, 7 May 1968

27

430.  To J.J.C. Smart, 7 May 1968 UCLA Los Angeles, CA Dear Jack, Let me sketch a proof of my assertions that the sentences given on page 122, lines 8 and 32, are not equivalent to translated modal sentences.1 Consider two ­situations. The actual world is one of two possible worlds. The two worlds are exactly A alike. However, nothing in either world is a counterpart of anything in the other. B The actual world is the only possible world. Suppose also that the actual world contains a unique object a such that ψ@a; and suppose also that ϕ@a. Both the sentences in question turn out to be false in ­situation A, true in situation B. However, it is easy to verify that any translated modal sentence, and hence any equivalent of a translated modal sentence, is either true both in A and in B or false both in A and in B – the replica of the actual world makes no difference. Situations A and B are, of course, contrary to the intended interpretation of counterpart theory! But they do not violate the postulates, so it is OK to use them for independence proofs. Perhaps there could be a general procedure to decide whether a given sentence of counterpart theory is equivalent to a translated modal sentence; but I don’t know of any such procedure. As you say, the procedure mentioned at the top of page 119 only decides whether the sentence of counterpart theory is itself a translated modal sentence. I quite agree that counterpart theory isn’t modal logic. It’s a substitute for modal logic. You can use it metalinguistically to do semantics for modal logic, but that seems roundabout and pointless. I’d like to regard modal sentences simply as abbreviated sentences of counterpart theory, according to my translation rules. However, in practice we can get along without this sort of abbreviation, simply talking explicitly about the worlds and their inhabitants. (Other kinds of abbreviated notation are very helpful, however.) The concept of counterpart is indeed ‘somewhat subjective’ – to put it mildly! But if my translations are really translations, the sub­ ject­iv­ity was there all along in modal logic, just hidden. The translations are not ne­ces­sar­ily a vindication of quantified modal logic; it is neither more nor less clear than counterpart theory; and because of the subjectivity of the counterpart relation, the clarity of counterpart theory leaves much to be desired.   ‘Counterpart Theory and Quantified Modal Logic’ (Lewis 1968, 122).

1

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I don’t think I made clear what I meant by my suggestion that a color might occupy a simple-shaped hypervolume in the continuum-dimensional space of spectra. A spectrum – a point in the space – was not meant to be just a combination of wavelengths (a spectroscope spectrum); it was meant to be a function giving light intensity at each wavelength (a spectrophotometer spectrum). A reasonable metric on this space might take the distance between two spectra to be the mean square ­difference of intensities, averaged over all visible wavelengths. You asked: suppose we start with a spectrum C in, let’s say, the yellow hypervolume. If we add to C some very low-intensity light with spectrum Cʹ far outside the yellow hypervolume, then won’t the sum C* (that is, C + Cʹ) be indistinguishable from C? Yes it will. But if the average intensity of Cʹ is enough less than the average intensity of C, and if C is in the interior rather than on the boundary of the yellow hypervolume, and if the metric of the space is something like the one I mentioned above, then C* will be inside the yellow hypervolume too. I’m ashamed to say that I’ve only just seen through a silly worry I had about the definitions of sensations and secondary qualities. Let S be a secondary quality (say, yellow) and let M be the corresponding mental state (sensation of yellow). Then I want to say that M is definable, roughly as that state of percipients which tends to be caused by perceptions of objects having S; and I also want to say that S is definable, roughly, as that state of objects which tends to cause M in percipients. Both def­in­ itions seemed fine by themselves; but I had the idea they couldn’t both be right because we’d got in a circle. Of course we do get a circle if we try to use the two definitions together, to define either M or S in terms of neither M nor S. But that doesn’t discredit the definitions, as I should have known. S is definable in terms of M; M is definable in terms of S. To introduce both M and S, starting with neither, the definitions must be supplemented either by some ostension or by some contingent information. There’s no problem. I think I understood this perfectly well when I first proposed causal-role definitions of secondary qualities; I only got confused about it later on. The paper on theoretical terms2 has been stalled, but now I see what to do. It’s a great nuisance having non-denoting terms around! All sorts of ordinary moves don’t work properly. Unfortunately, the usual cures for non-denotation make more trouble for me than they cure. I hope I’ll be able to send you the thing before too much longer. Many thanks for the comments on the comments on colors, and for the comments to the counterpart paper. I must confess I hadn’t thought how to prove the non-equivalence assertions on page 122; I’d just tried all the obvious candidates and   ‘How to Define Theoretical Terms’ (Lewis 1970b).

2



431.  To Donald Davidson, 7 October 1970

29

found that my sentences weren’t equivalent to the translations of any of those! I’m glad you prodded me into doing the job properly! Yours, David Steffi sends greetings; her exams are moving toward the present at the rate of one day per day.

431.  To Donald Davidson, 7 October 1970 St. Catherine’s College Oxford, England Dear Donald, Barry Stroud has just lent me a duplicated copy of your paper ‘Mental Events’.1 He thinks it has appeared, but forgets where, and I haven’t seen it. (It’s related to a  project I’d like to undertake someday, as follows: what happens to Quine’s doctrine  of indeterminacy of translation given a rich ontology? I think it can then be  resolved into about half a dozen different theses – A underdetermined by B, B underdetermined by C, . . . – which can usefully be separated because the different underdeterminations differ in plausibility and in importance (if true). One of these underdeterminations would be the underdetermination of subjective prob­ abil­ities and utilities of propositions by the set of laws governing the agent’s stimuli and responses, together with the physiological explanation of these laws.)2 So I’d be grateful if you could tell me where the paper appears. Footnote 8 in the paper is wrong!3 I’m not inclined to ‘take events as universals’, and wasn’t when I wrote ‘An Argument for the Identity Theory’. I see how I misled you by careless writing: I said that experiences, and states in general, were to be taken in the paper as universals. Then I said I would not distinguish between events, states, and various other things. I didn’t mean to suggest, as I evidently did, that I thought that events were indistinguishable from states taken as universals; I intended only to be explicitly neutral about whether there is any overlap between the states I discuss and the events and what-not that other identity theorists discuss. Smart tells me that when you were in Australia to give the Gavin David Young Lectures, you were able to get NSF support not for the lecturing, but somehow for   (Davidson 1970). Reprinted in Essays on Actions and Events (Davidson 1980).   Cf. ‘Radical Interpretation’ (Lewis 1974). 3   ‘An Argument for the Identity Theory’ (Lewis 1966a). 1 2

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being around to talk to the Australians between lectures. I’d better try to apply for the same sort of grant, but I don’t understand very well what sort it was. Could you please advise me? Sincerely,

432.  To Hidé Ishiguro, 13 October 1970 Headington Hill Oxford, England Dear Hidé, Thank you for the copy of your paper on seeing-as.1 I don’t find myself in very serious disagreement with what you say about my ‘Percepts & Color-Mosaics . . .’ paper;2 I think there’s less difference between our views than you think there is. Say that you look at a certain well-known picture, and first you have the visual experience D of seeing it as a duck-picture and a little later you have the visual ex­ peri­ence R of seeing it as a rabbit-picture. (Say that there’s no change in the ink on the page, the illumination of the page, the position of the page and of your head, etc.; and say that it does not seem to you that there is any such change. Thus you went from D to R by a modification: by a change of percept without any percept of change.) It’s common ground between us that we might legitimately call D and R two visual experiences, or we might legitimately call them the same visual experience – it’s OK to have a finer and coarser way of individuating experiences and to go back and forth between the two ways as convenient. Our problem is to say what is the close relation which holds between D and R, and which doesn’t hold between just any pair of visual experiences, which justifies us in calling them the same experience (if we like). Several answers that might be given: ( 1) D and R are caused by exactly the same stimuli (or, if you prefer, by exactly the same external state of affairs). (2) D and R are experiences in which exactly the same external object is seen – the surface of a sheet of paper, with a pattern of ink on it, illuminated in a certain way, located in a certain position . . .

1   It is not clear whether the paper is ‘Imagination’ (Ishiguro 1967) or some other paper of hers that was never published. 2   ‘Percepts and Color Mosaics in Visual Experience’ (Lewis 1966b).



432.  To Hidé Ishiguro, 13 October 1970

31

( 3) The color-mosaic experience which would have resulted from perceptual reduction of D is exactly the same as the one which would have resulted from perceptual reduction of R (if you had performed perceptual reductions of D and of R, as in fact you did not), (4) D and R, even if not reduced, both contain a common color-mosaic experience as their phenomenal core. Now I have no objection to (1), or to (2) – I take it (2) is the answer you prefer – as answers to the question above. But for some purposes we’d like an answer that doesn’t refer in any way to the external causes of visual experience, and then (1) and (2) aren’t eligible. Subject to a qualification I’ll mention later, I’d then opt for (3); and I think that, subject to the same qualification, you don’t object to that. We can add that, as an empirical hypothesis, (3) holds because (1) or (2) hold. (I’m not sure if (1) and (2) are very different – maybe they imply each other in the presence of certain auxiliary premises which will be true in the situation we’re imagining.) If we disagree, it’s on what to say about answer (4). An old-fashioned or simpleminded color-mosaic theorist would accept (4) outright. Roderick Firth, in the paper which I’m discussing in my paper, would reject (4) outright; and so, I think, would you. I would accept (4), but I would interpret (4) so that it would mean the same as (3). If (4) were understood to say something more than (3) – something added, that explains why (3) is true – then I would reject (4) so interpreted, just as you would. Admittedly, it’s a bit far-fetched to understand (4) as saying nothing more than (3); but the point of the paper is that given certain assumptions – what I call the ‘Distribution Premise’ – it’s not so far-fetched as it seems. There’s an analogy, though a remote one, between the relation of literally having a common central part and the relation that holds between D and R according to (3): that is, the relation of having in common a potentiality to be modified by perceptual reduction into a certain colormosaic experience. One might well think that the analogy is too far-fetched, and that to understand (4) as meaning no more than (3) is too misleading to be tolerated; but I don’t think so. Now for the qualification: I was granting (3) for the sake of the argument, but I’m not convinced that it’s true, because I’m not convinced that people are really able to perform thorough perceptual reduction. My paper, you recall, was an attempt to reconcile Firth’s sort of percept theory with a fairly simple-minded color-mosaic theory; and so I didn’t dispute points that Firth was prepared to concede to the colormosaic theorist. One of these conceded points was that any visual experience could in principle be subjected to perceptual reduction, with a determinate color-mosaic as outcome. Maybe so, if you’re good at doing it, as impressionists and some old-fashioned psychologists are supposed to be; but I know that I can’t get very far if I try it!

Philosophical Letters of David K. Lewis

32

A minor point about the top paragraph on page 16: I don’t say that you’re always aware that two of your experiences have – or in more innocent language, could be perceptually reduced to – a single common color-mosaic. You might laboriously discover that D and R can be reduced to the same color-mosaic. You might be unwilling to believe it at first – you might never come to believe it. Just because (3) is non-committal about external causes of experience doesn’t meant that it’s especially easy to verify (3). For (3) – and hence (4) if understood as saying no more than (3) – is not simply about the content of a single one of your experiences. Rather it states a rather complicated relation involving several of your visual experiences and the transitions between them; and not only your actual experiences and their transitions, but possible ones as well. I hope I’ve understood you; and I hope I’ve remembered what I was up to in my paper, which I haven’t thought about for quite a while. We come up to London (down to London, since it’s from Oxford?) often enough; but I’m not sure when next. We’d be very glad to come to dinner on some trip before long. We hadn’t thought of coming to meetings of the British Society for Philosophy of Science or the Aristotelian Society, since we haven’t seen programs, and since I didn’t know whether they would be open to non-members. There are one or two papers per week here throughout the term, but not all of them sound tempting, and it would be interesting to know what’s on in London. Greetings to you both from both of us, Yours,

433.  To Donald Davidson, 4 April 1972 [Princeton, NJ] Dear Donald, Preliminaries: let’s try to define on remembering a certain experience (experiencetype, not particular event) from time t. Take it that experiences are certain properties of persons (at times). Take it that believing is already understood. Regard ‘x has a memory trace of e at t’ as being of the form: the memory-trace relation holds between x, e, and t. Abbreviate ‘the memory-trace relation’ by ‘M’. The common-sense theory of memory, simplified, is as follows. (Notation: x is a variable over persons, e over experiences, t over times, R over relations.) 1

1   It is not clear what prompted Lewis to write Davidson this letter, but it is possible that it arose from personal conversation.



433.  To Donald Davidson, 4 April 1972

33

Recording law: C"x , e, t, if x has e at t, then M(e, x, tʹ) for all tʹ after t. Readout law: C"x , e, t if M(e, x, t) and x considers at t whether he ever had e, then x believes at t that he did once have e. M is a theoretical term of this theory. We define it on the principle: M =df that which does what M is commonly reputed to do. More precisely: M =df that relation that satisfies the Recording law and the Readout law. Yet more precisely (C is causal necessity):  M =df ℩ RC(("x, e, t, if x has e at t then R(x, e, tʹ) for all tʹ>t) & ("x, e, t if R(x, e, t) and x considers at t whether he has ever had e, then x believes at t that he did once have e)). Now we have defined M, the memory-trace relation, and so are free to use it in other definitions. x remembers at tʺ e from t =df (1) x had e at t, (2) M(x, e, tʹ) for all tʹ > t , (3) x believes at tʺ that x had e at t, (4) (2) because (1), and (5) (3) because (2). If you wish to eliminate the defined term M in this definition – not that there’s any reason to – you get a definiens equivalent to this: (1) x had e at t, (2) $R [R(x, e, tʹ) for all tʹ > t, and R is the unique relation that satisfies the Recording law and the Readout law], (3) x believes at tʺ that x had e at t, (4) (2) because (1), and (5) (3) because (2). This is deliberately crude and simplified except as regards the issue: how do you make sure the causal chain is of the proper sort? David

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434.  To Henry W. Kissling, 5 February 1973 [Princeton, NJ] Dear Mr. Kissling: Professor Kaufmann has passed on to me your letter and your notes toward a new physical theory. I have read the notes, but I am afraid I do not find them interesting, and I am returning them to you. Let me tell you of an unpopular idea of my own, which explains why I have not given your work a more careful and open-minded reading. It seems to me that openmindedness in science is more of a vice than a virtue, and that too much of it would guarantee a halt to the progress of scientific knowledge. The reason is that there are infinitely many theories that could be proposed; a really open-minded scientist would have so little time to spend on any one of them that no theory at all would be given a chance to prove its merit! The method of open-mindedness would lead to nothing but a chaos of new beginnings. A better method is the one that scientists actually follow: dogmatic concentration on the orthodox theory so long as that theory seems to have a chance of working, and open-mindedness only in times of crisis. That way many the­or­ ies are dismissed without a fair hearing – as I am dismissing yours – but at least one theory gets a real run for its money. One is better than none, and it takes so much intellectual effort and material resources to test even one theory that one theory at a time is the most we should try for – except, as I say, in times of crisis when the one theory we have been working on seems to have decisively failed. But this is not such a time of crisis. I should say that the same goes, at least to some extent, for philosophy. Philosophers tend to be too open minded to persevere on programs that seem to have promise of success, and philosophy is a chaos of new beginnings. Sincerely, David Lewis

435.  To Neil Lubow, 28 April 1973 Princeton University Princeton, NJ Dear Neil, I like your draft chapter about my stuff on mind-body identity.1 The exposition is accurate and clear; the objections are ones that I take seriously – which is not to say 1   The Mind-Body Identity Theory (Lubow 1974, ch. 3), which became ‘On Defining Mental State Names’ (Lubow 1977).



435.  To Neil Lubow, 28 April 1973

35

that I find them conclusive! Thank you for letting me see it. I have comments on various points. Page 4, line 3. The second conditional is what I had for a long time, but at last I realized that it wasn’t right, and in the final published version of ‘Psychophysical . . .  Identifications’ I changed it to (in your notation)

ØVx T[ x ] ® t = * 1

where the consequent means that all the T-terms are denotationless. The consequent of the former version,

ØVx x = t

only means that at least some of the T-terms are denotationless, which isn’t enough. This is a drawback of my condensed notation; there’s no similar problem in ‘How to Define Theoretical Terms’. Page 6. Premise (2) as it stands would have to come not from the ‘basic materialist principle’ by itself but from that plus some particular findings of physiology. The basic principle says that an occupant of causal role R must be some or other physical state; but premise (2) goes further and says what physical state it is. Page 11, top. In the X-world, pain doesn’t have its usual behavioral effects; yet perhaps it still has enough of its definitive typical effects to occupy the proper causal role. For definitive effects don’t have to be behavioral. See ‘An Argument . . .’, middle of page 21. Even in the X-world, pain causes typical mental effects: aversion to the supposed cause, distraction, . . . . Take those away too, and then I think the story of pain in the X-world will become incoherent. (Though you could still say that an X-worlder is in pain, meaning that he is in the state which is pain for us.) Page 13, top. It’s senseless to say ‘Lewis is in pain for Lewis’ not because it – or what you mean by it – is a false proposition, but merely because you’ve expressed a true proposition by a grammatical construction which doesn’t happen to be part of the language. We don’t have such a construction because we don’t need to have it – our concern is always with the question of whether x is in the state that occupies the role of pain in x’s case, never with whether x is in the state that occupies the role of pain in y’s case. Page 17, bottom. I agree that the only way to avoid mistaken species-specificity is to be somewhat abstract in specifying the stimuli and responses involved in de­fini­ tive causal roles. But I don’t share your fear that this will put the definitions beyond the reach of common sense. Perhaps you and I disagree on what it is for someone to know the platitudes. He doesn’t have to be able to state them, or even to know the technical vocabulary in which they might best be stated. (This is relevant also to an objection you make on pages 8–9, regarding the use of jargon in stating them.) It’s

Philosophical Letters of David K. Lewis

36

enough if he could recognise them as being something he believed all along, when and if someone else formulated them and explained to him what they meant. Page 19, top. Strictly speaking, I do think that if common-sense psychology were doubly realized in Jones’s case, Jones never would be in pain or any other mental state! That is not paradoxical; it only goes to show that we don’t – don’t for very good reasons – insist on speaking so strictly. Under double realization, there is no state that precisely occupies the definitive role of pain for Jones, but there are two states (three if you count the disjunction of the first two) that almost do, so it would be no surprise if we said that Jones was in pain when he occupied one or more of the states that almost occupy the role of pain. We wouldn’t say what’s true – that Jones isn’t exactly in pain, i.e. isn’t in the state that uniquely occupies the role – because, for all practical purposes it’s more convenient to class Jones with those who really are in pain than with those who aren’t in pain for more mundane reasons. Analogy, due to Peter Unger: what’s in the can of peanuts isn’t a (perfect) vacuum, but there are good reasons for speaking loosely and calling it a vacuum although we know better. Page 20, formula (10). I should think you want to try a modal version here: pain for y is that state x such that, necessarily, y is in x iff y is in some state z such that Rzy. That will give you propriety. It remains a modification of my treatment: you have what I called in ‘How to Define . . .’ the diagonalized sense of ‘pain for y’. Page 12, middle. If Lewis and Putnam are both in pain, I agree that they are in the same state, or at least that there is a state that they’re both in, and each is in this state by virtue of being in pain: namely, they’re both in the state of being-in-whicheverstate-occupies-the-role-of-pain. But this state isn’t the same as the state pain; and that’s different in the two cases. I can agree with you in finding a sense in which they’re in the same state; we only disagree about whether there can also be a sense in which they’re in different states. Sincerely, David

436.  To Sydney Shoemaker, 7 May 1974 [Princeton, NJ] Dear Sydney, Many thanks for your paper ‘Functionalism and Qualia’.1 Lack of time and indecision about the issues prevent me from having much to say about it; but   (Shoemaker 1975).

1



437.  To Terence Horgan, 7 November 1974

37

c­ ertainly I would agree that the inverted qualia and absent qualia objections to functionalism can be overcome – and without the cost in plausibility of denying that intersubjective spectrum inversion is possible. I am inclined tentatively to think of the matter like this: the degree of generality of the functional role definitive of sensations is somewhat indeterminate. The sensation of red is what ordinarily plays a certain causal role – in me? in all human beings? in all sentient creatures? If both there is uniformity and I’m an exception to that uniformity, then there are two states with a claim to be, as it might be, the sensation of seeing red. There’s the state I’m in when red things are before me, which typically for me but exceptionally for us occupies the proper role; and there’s the state I’m in when green things are before me, which typically for us but not at all for me occupies the role. I think we make sense of inverted spectra and – equally important – of the fact that the possibility of inverted spectra is problematic by leaving this indeterminacy open. And I think it must be kept open also for other reasons. Settle it in favor of the state that occupies the role for me – or worse still, for me now – and you’re no better off than a behaviourist in providing for the amputated brain whose experiences do not occupy at all their proper causal roles. Settle it in favor of the state that occupies the role for everyone always (with a few exceptions) and you require an implausible presupposition that Martian brains and ours must be alike if Martian experiences and ours are to be alike. Only if you blur matters can you both have a sense in which the brain in the jar sees red (he’s in the state that occupies the role for us but not for him) and an equally good sense in which the Martian sees red (he’s in the state that occupies the role for him but not for us). You asked me to check your footnote 18 – it looks fine. Yours,

437.  To Terence Horgan, 7 November 1974 [Princeton, NJ] Dear Professor Horgan, Thanks very much for your interesting and good paper on psychophysical identity and causation.1 I think I agree with pretty much everything in it except for one step – one very important step! I think you tacitly accept a certain questionable 1   ‘Reduction, Causation, and the Mind-Body Problem’, which became ‘Reduction and the Mind Body Problem’ (Horgan 1976).

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premise; it lands you in a lot of trouble; and you find the best possible way out of that trouble except for rejecting the premise that got you into it in the first place. I part company with you at the place where, getting ready to argue against identity of properties in the cases needed to give psychophysical identity for events, you quietly change the subject. On page 8, you’re speaking of the property pain. On page 9 you’re speaking of the intension of the predicate ‘is in pain’. I agree that the intensions of the predicates ‘is in pain’ and ‘has P’ differ. I would willingly put this by saying that the properties expressed by these two predicates differ. (I say that a predicate expresses a property iff, at every world, just those things that have the property at that world belong to the extension of the predicate at that world.) But I don’t therefore agree that the property pain is not identical to the property P! Rather, I hold a  different non-identity thesis: the property pain is not the same as the property expressed by the predicate ‘is in pain’. Whenever a term a is a non-rigid designator of properties, the property actually designated by a is not the same as the property expressed by the predicate ‘has a’, ‘is in a’, or whatever such form is appropriate. Thus it is that the color of the sky, namely blue, is not the same as the property expressed by ‘has the color of the sky’. A blue thing under a red sky at another world has the former property but not the latter. Only if a is a rigid designator, one that designates the same property at all worlds, is it correct that the property designated by a is also the property expressed by the predicate ‘has a’. You may have slipped carelessly from the property (actually) designated by ‘pain’ to the property expressed by (in other words, the intension of ) the predicate ‘is in pain’. If so, shame on you. But what is more likely is that you accept the premise that ‘pain’ is a rigid designator, designating everywhere the same property no matter what the physiological (or other) facts may be. If you do, then indeed you are entitled to argue as you do against psychophysical identity. But the rigidity premise is the key to the argument, and you ought to defend it. Once you focus on that premise, indeed, it’s easy to see that it amounts to exactly a rejection of any ­contingent identity thesis about the nature of pain. I’ve long known that my form of the identity thesis is completely untenable unless I accept that ‘pain’ is a non-rigid designator like ‘the color of the sky’. Many people take it to be obvious that ‘pain’ is rigid; so for instance in Kripke’s discussion of the mind-body problem (‘Naming and Necessity’ 335–6),2 he just says that the contrary view – the view I hold – is self-evidently absurd. Argument stops there, but I don’t agree. I don’t have any trustworthy naïve judgements about whether that which actually is pain might have existed without being pain (or about whether particular pain-events might have existed without being pain-events). Let’s see what theory says. We agree, I think, that the premise that ‘pain’ is rigid leads 1) to the success of   (Kripke 1972).

2



438.  To Terence Horgan, 23 November 1974

39

your argument against contingent identities; 2) to a prima facie plausible case that particular pains are epiphenomenal; 3) thence, by generalization to widespread epiphenomenalism; 4) thence to the conclusion that there are no actions, i.e. that no bodily movements are caused by beliefs and wants. Your way out – an ‘intimate connection’ which isn’t identity but has the same effect that identity would have on the counterfactual dependences between mental and physical events – seems to me to be ten­ able, but a bit ad hoc. I would much prefer to continue to believe that ‘pain’ is non-rigid. Two minor comments. I don’t think the counterfactual analysis of causation that you seem willing to accept combines very well with your acceptance of Kim’s treatment of events. There’s plenty of counterfactual dependence among Kim-events that is clearly not causal. I would take this to show that many Kim-events are not events, nor correlated in any natural way with events. This is not to deny that an identity or reducibility thesis about Kim-events might not have an interest of its own, apart from the question whether they’re rightly called events. Also, I found it a little misleading that you first said that you would assume a Humean conception of caus­ ation as involving general laws, but then turned out to be willing to work within a counterfactual analysis. Historically, the latter is also Humean; but it’s not in the trad­ition from Hume to Mill to Hempel and Mackie that I thought you had in mind. General laws enter the analysis only indirectly, if at all. Sincerely, David Lewis PS I enclose a few offprints3 that are relevant to what I say in the letter, though most likely you’ve seen these papers already. Note especially ‘How to Define Theoretical Terms’, 435–437.

438.  To Terence Horgan, 23 November 1974 Princeton University Princeton, NJ Dear Professor Horgan, Good; I’m glad we agree on the main point: that your argument depends on a premise that I must reject and that you’re willing to defend, namely that such terms as ‘pain’ are rigid designators. 3   ‘How to Define Theoretical Terms’ (Lewis 1970b); ‘Psychophysical and Theoretical Identifications’ (Lewis 1972a).

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Philosophical Letters of David K. Lewis

Your defense of the premise, however, puzzles me. Why do you think that I leave out the raw feels, our non-inferential acquaintance with our own pains, and in general the sensuous or phenomenal aspect of the mental? Getting out of philosophical jargon and into plain English, it seems that you think I deny such platitudes of common-sense psychology as that pains are feelings, that we feel our pains, that we can tell when we’re in pain simply by feeling the pain, that we’re consciously aware of our pains, and so forth. But I wouldn’t wish to deny those platitudes, any more than I would wish to deny the ones about the causal connections of pain to stimuli and to behavior. And why do I have to deny them? Remember that the causal role of a mental state, on my view, includes its causal relations not only to stimuli and behavior, but also to other mental states. If you’re conscious of a pain, it gives rise to various beliefs and desires in you; that is, it tends to cause certain other mental states. Part of the definitive causal role of pain is that, except in certain exceptional cases, we’re conscious of it. There could be no zombie or imitation man who had states that occupied the role of pain but was not conscious of pain, since states that failed to produce other states in the way that constitutes consciousness would thereby fail to occupy the role of pain. (Of course I do think a being could have states that occupy the role of pain without feeling what is for us pain – but I don’t think that’s what you meant.) Anyway, what does all this about leaving or not leaving out the phenomenal aspect have to do with rigidity? It seems to be quite a different line of attack. I wouldn’t mind saying that a predicate like ‘has pain’ or ‘is the color of the sky’ non-rigidly ascribes or predicates the same property that is non-rigidly designated by the corresponding term ‘pain’ or ‘the color of the sky’. I also welcome the suggestion that ‘having pain caused him to wince’ is true because the property designated by the gerund is the property non-rigidly ascribed by the predicate. I wouldn’t like to use the word ‘express’ in a corresponding way, since I think there’s hope of fostering a standardized and unambiguous technical usage in which predicate F expresses property P iff, at every world, just those things that have P at that world belong to the extension of F at that world. I’ve worried off and on about whether the property of having pain (meaning now the property expressed by ‘has pain’ in the sense just explained) might not serve as well as pain itself in realizing common-sense psychology. I’m inclined to think that it can’t, indeed that it isn’t the sort of property that can occupy any causal role at all; but this is just a hunch, and I can’t back it up. There’s certainly a problem here. I think I do know this much, though: just because two properties are co-extensive at our world, it doesn’t follow that they are causally indistinguishable. Many thanks for your further comments. Sincerely, David Lewis



439.  To Terence Horgan, 16 December 1974

41

439.  To Terence Horgan, 16 December 1974 [Princeton, NJ] Dear Professor Horgan, Many thanks for your further letter. Deadlock fast approaches; but let me comment very briefly on two of the points you make. On inverted spectra: certainly I have to hold that it’s impossible, indeed contradictory, to suppose that you and I are alike both in our functional organization and in the states that occupy the causal roles, and yet your experience when red things are before your eyes is like mine when violet things are before my eyes. You say it’s never­the­less quite easy to imagine that this might be so, and perhaps it is. I’m by no means clear on what it is to imagine a state of affairs, especially if it’s not some ­experience of my own; but I’m inclined to think that whatever the right account of imaginability is, imaginability is not a reliable test of possibility. It seems to me that I can’t imagine some actual states of affairs – curved space-time, for instance. On the other hand, I can imagine the plots of some science fiction stories I take to be contradictory: stories of time travelers who succeed in changing the past, or of trav­ el­ers who go from one possible world to another. I’m well aware that I may be slipping from one sense of ‘imagine’ to another; but I doubt that I have a grasp on any one sense in which both it’s true that imaginability is a good test for n ­ on-contradiction and I can imagine the inverted-spectrum case that’s impossible according to my ­theory. On knowing what pain is like: I agree that there’s a state we call ‘knowing what pain is like’, which we can’t attain by any amount of knowledge of the definitive causal role of pain and of the state that occupies that role, and which we can attain simply by being in pain. What is this knowledge, if not knowledge of which ‘Raw feel’ it is that accompanies the typical causes and effects of pain? It seems on my view that there is no new knowledge to be had by experiencing pain, any more than you could learn something new about hyper-tension by having that. I’m inclined to accept this consequence of my view, and reply to the objection by claiming that knowing what pain is like is not some sort of factual knowledge. Rather, it’s an ability that we come to acquire by having pain: the ability to know at once when we are in the state with the appropriate causal role. It’s knowledge-how. Will you be at the Washington APA meetings? I hope to meet you if you are. Sincerely,

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Philosophical Letters of David K. Lewis

440.  To John Perry, 10 October 1977 Princeton University Princeton, NJ Dear John, I’ve meant to write you a long letter about self-locating beliefs – I found your paper1 extremely interesting, and the last part of it crystalized some things I’ve been thinking confusedly about for a long time. I’ll say something very brief here, but if I wait for time to write a long letter I’ll wait a long time. That would be too bad, because I want to include a request; I have a graduate student, David Lumsden, who is writing a dissertation about de re attitudes, especially de re attitudes about oneself.2 I wonder if he could have a copy of your paper? Since he’s in England I don’t want to lend him mine, and don’t want to make a copy for him without your permission. I’ll make him a copy if you’re willing; or you could send him one at 2 Lancaster Drive, London N.W.3. Here’s a brief comment. In Hintikka’s set-up, taken realistically, all contingent beliefs are self-locating. To believe that Gold is a stable element is to locate myself in  a  certain region of logical space: the region consisting of the worlds at which Gold is a stable element. From this standpoint it seems arbitrary to think that there are self-locating beliefs with respect to logical space but not any with respect to ­physical space. Couldn’t I know exactly where in logical space I live, but yet be ignorant where in physical space I live? At a certain world W there are two gods: one lives atop the tallest mountain and throws down manna, the other atop the coldest mountain and throws down thunderbolts. Each knows that he lives at world W, but neither knows which he is. Each knows only that he’s one of the two. A haecceitist might conclude that their self-location in logical space is imperfect: there are two worlds Wʹ and Wʺ rather than one world W; Wʹ and Wʺ are quali­ ta­tive­ly alike but differ with respect to who’s who; each god is ignorant of whether he lives in Wʹ or Wʺ. To an anti-haecceitist like myself, this seems to posit occult differences between worlds. So I have to say that not all ignorance is ignorance of one’s location in logical space. (I here ignore mathematical and modal ignorance; that’s another story.) How could this be? There are no propositional attitudes. The real objects of attitudes are properties. In believing, we self-ascribe properties; in wanting we want-to-have   ‘Frege on Demonstratives’ (Perry 1977).   Individuals, Belief and Communication (Lumsden 1979).

1 2



441.  To Hartry Field, 13 November 1977

43

properties; etc. The reason I, unlike Hume, can’t truly self-ascribe the property of being Hume is just that I don’t have the property of being self-ascribed. In believing the proposition that Gold is stable, I self-ascribe the property: ­living in a world where Gold is stable. Propositional objects can be traded in for property objects. But not vice versa, as witness the case of the two gods – or not unless you believe in Haecceitism! Cf. Quine on egocentric propositional attitudes and centered possible worlds in ‘Propositional Objects’;3 note that a class C of centered worlds corresponds to a property of points: the property that point p has at world w iff w-centered-on-p belongs to C. I wasn’t much interested in this when I read it, thinking that the use of centering was an unnecessary substitute for the use of a counterpart relation. But I take it that often for treating de re attitudes, the appropriate counterpart relation would emphasize similarity in relation to myself; and to do that we first need to identify who at another world is myself. The use of centering simply dodges that problem entirely; but at the price – if price it be – that the object isn’t propositional at all. I think I’ve ended by writing most of what I thought I didn’t have time to write; so this is the long(ish) letter after all! Yours, David

441.  To Hartry Field, 13 November 1977 [Princeton, NJ] Dear Hartry, At last I’ve read your ‘Mental Representation’;1 I like it very much. I wish I had time to write a long letter of comment (or better, a chance to talk to you about it) but I simply don’t; I’m graduate adviser. At a few points I feel slightly misrepresented, though for the most part you’ve got my views just right. If I’ve left this until too late it’s not serious, and it’s entirely my own fault. But if changes are still possible I’d appreciate them. (1) Page 8. Am I committed to the view that objects of belief are coarse-grained propositions? I hope not – unlike Stalnaker, I’ve had no very settled view on the matter. I think you’ll find

  (Quine 1969).

3

  (Field 1978).

1

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Philosophical Letters of David K. Lewis

only this much: that in some places I speak of the objects of attitudes as propositions; and that in different places I take propositions as sets of worlds, but with the warning that the terminology isn’t standardized and that this construal won’t fit all that’s been said about propositions. (2) Page 23. What I think is that the hypothesis of inner representation is plausible, not unfounded, neurophysiological speculation; but not so well-founded that I want to presuppose it in doing philosophy. (3) Page 25 and footnote 19. Do I believe that all psychological properties require a physical realization? Depends what you mean by require. Materialism is probably true, but not necessary – ‘require’ suggests something stronger. (4) Footnote 28. According to Lewis, ‘the property of being in pain’ and ‘pain’ refer to different properties. But I should think ‘the property of pain’ refers to the same property as ‘pain’. Let me say a little bit about the question itself. Consider a parallel to Brentano’s problem. Many seemingly physical properties appear to relate things to non-physical abstract entities called numbers. What kind of physical relation can a seven-gram stone bear to a non-physical, abstract entity: the number seven? I take it this problem has been well and truly solved. First, for any particular abstract relatum (seven, say) the property of bearing the mass-relation to it (the property of weighing seven grams) is a perfectly good physical property. Second, the mass-relation is that relation of things to numbers such that certain physical relations between the things mirror certain arithmetical relations among the assigned numbers. If those two things are said, they make the mass-relation enough of a ‘physical relation’ to content any materialist who is not also a nominalist. I don’t say this is the only possible way to answer the parallel to Brentano’s problem, but it seems to be one good way. Why not a parallel answer to Brentano’s problem: what sort of physical relations could there be between people and propositions? The relation to propositions is well-defined (though I could not define it) by a requirement that there be some sort of isomorphism of structure, and the relation is physical because, for any given proposition p, the property of believing p is a physical property. The orthographic accident view is bad, sure enough; but the bad view has a right consequence, namely that it suffices to make belief physical that particular belief-properties are physical properties. I don’t say that this is the only answer to Brentano’s problem that might succeed – that would be sensible, well-founded speculation, but still speculation I’d rather keep clear of. It is the only way I can now think of to say how there could be a ‘physical relation’ of people to propositions. The question is: do you mean the hypothesis of inner representations to be  anything beyond the hypothesis that this sort of solution works? Maybe so, maybe not. It depends on how much you claim when you claim that the representations are either sentences or sentence-analogs. If you mean sufficiently little else by  ‘sentence-analog’ you might just mean ‘element of a physical structure having



442.  To Patricia Kitcher, 24 February 1978

45

enough isomorphism to the abstract structure of propositions to make possible physical relations occupying the roles of belief, etc’. In short: if you’re sufficiently agnostic about what the language of thought might be like, then I’m prepared to agree with you that the only known solution to Brentano’s problem involves positing a language of thought. Like you, I am not saying that there could be no alternative account. Unlike you, I want to leave the question open in doing philosophy. Yours,

442.  To Patricia Kitcher, 24 February 1978 Princeton University Princeton, NJ Dear Pat, No more folders – we’ve had admissions folders, job-applicant folders, 1st-year student in difficulty or not in difficulty folders, . . . . One thing that doesn’t come in folders is your partial analysis paper,1 which I’ve finally had time to read. What I mostly think is that you let the anti-materialist advance too far before you try to stop him. It’s an interesting second line of defence. I haven’t seen anything like it, except that it’s parallel to what I think I believe about the partial analyzability of colors. I don’t think I have any objection to it, except for my doubt that such a move is needed. Let me get to the main point later, after mentioning small stuff. [. . .] Now for the main point, to the effect that you give too much ground before you stop and defend. Page 3, first full paragraph. I favor the still quicker way. ‘Pain’ designates any state which stands in certain causal relations; I remain loyal to my theory; a person who is in a state with the stipulated causal connections is in pain. The ob­ject­or says, seemingly with your concurrence: even if he feels nothing? I say: how can you be in pain and feel nothing? Pain is a feeling! Whatever sort of physical or non-physical state it may be, whatever causal or what-not analysis we give, it remains that someone who is in pain, properly so-called, has a feeling. To be in pain, to have pain, to feel pain – these mean the same. To say that a person might be in a state that stands in the right causal connections and feel nothing is simply to deny that a certain feeling, namely pain, is correctly defined as the occupant of a causal role. There’s no question   ‘Two Versions of the Identity Theory’ (Kitcher 1982).

1

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of talking about pain and leaving out any reference to what it’s like for the sentient being who has it. I’ll tell you what it’s like: it hurts! Else it isn’t pain. Something funny has happened to the question ‘What is it like to . . .?’ in recent discussions. Outside philosophy, it would be a perfectly good answer to a question ‘What is it like to take such-and-such drug?’ to say, for instance, that if you take that drug you feel first giddiness and thirst, then moderate pain all over, then severe pain in the head. That is, the question is answered by a list of the feelings you’ll have if you take the drug. So equally the question ‘What is it like to be in pain?’ ought to be answered adequately by a list of feelings you’ll have in that case. The list is short: pain. But that’s too simple, and some philosophers think there ought to be a fancier answer. There’s a whole vocabulary that’s grown up for talking about that elusive fancier answer: phenomenal qualities, raw feels, qualitative states. . . . It seems to me that if this fancy vocabulary makes sense at all, it’s just a new way of talking about such states as, for instance, pain. If you have pain, you have the feeling pain; and if you have that feeling, then you have that raw feel, your state has the phenomenal quality of being painful, it has the qualitative character of pain, . . . . Anybody who believes a causal-role analysis of pain redescribed as a phenomenal feel, qualitative character, or what have you. Call it what you will, it’s still just pain. Same for Nochromo. You describe him as having no awareness of quality, but as having a state that occupies the causal role of seeing blue. From the second part of the description I should conclude that he does see blue (with the caveat that he’s in a state that occupies the role for him, but not in the state that occupies the role for most of us). But if so, then how does he lack awareness of quality? For what does that mean if not, for instance, seeing blue? So either I don’t know what you mean by awareness of quality, or else the second part of your description of Nochromo contradicts the first part. He’s no counter-example to a functional or causal role analysis so long as he’s impossible; and that’s what I should call him. There is a problem for me. Not that Nochromo, Imitation Man, and various other victims of absent qualia are possible and my theory has no place for them; but that they can be described in such a way as to seem possible even to philosophers of materialist leanings. But I suppose this is just the paradox of analysis. If an analysis is right but not obviously right, it will not be obvious that descriptions of cases of analysans-without-analysandum describe impossibilities. But surely at least some ana­ lyses are unobviously right, so intuition is no sure guide to possibility. But it’s one thing to ask you to agree that philosophers sometimes misjudge whether their proposed counter-examples really are possible, another to try to persuade you that the story of Nochromo is inconsistent. I suppose the thing to do is to offer you approximations to the story of Nochromo that we can agree are possible, in the hope that you’ll admit that Nochromo may have borrowed some of his apparent possibility



443.  To Allen P. Hazen, 13 June 1978

47

from his possible approximations. Thus it’s certainly possible for there to be a Nochromo whose state doesn’t occupy the causal role of seeing blue quite well enough to qualify as seeing blue, and yet whose state will fit at least much of the description you gave. And there’s a sense in which I agree that Nochromo doesn’t see blue no matter how well his state occupies the role, if he doesn’t have the state that occupies the role for us. But either of these approaches makes your description of Nochromo possible only at the cost of making him useless as a counter-example. I’m going to a conference at Rice and giving a paper to be called ‘Mad Pain and Martian Pain’;2 it’ll be relevant to some of what I’ve been saying. I have to write it in the next month, and I’ll send you a copy. Before that you’ll be getting something else, claiming that the objects of propositional attitudes are properties rather than propositions3 – it’s related to John Perry’s paper ‘Frege on Demonstratives’, recently in ΦR. Our travel plans for the next few months mostly point south and west rather than north, unfortunately. Steffi’s job at Drew with a MWF schedule ties her down pretty thoroughly until it’s time to leave for Australia. Any hope that you’ll be down here? Yours, David

443.  To Allen P. Hazen, 13 June 1978 [Princeton, NJ] Dear Allen, Many thanks for your letters and paper. I’m sorry I’ve been so long in getting around to answering. One reason is a paper on probability,1 which I’ll send you; another is my duties as bureaucrat in charge of the Department’s graduate students; but the main thing is plain procrastination. I worry somewhat about arguments like yours that there’s no limit to the cardinality of the worlds; but take some comfort in the fact that we can go enormously far beyond the range of possibilities we would envision for any purpose except that of the cardinality argument without blowing up the cardinality beyond beth-2. That seems some (weak) reason for putting a ceiling over the possible cardinalities.  (Lewis 1980b).   3 ‘Attitudes De Dicto and De Se’ (Lewis 1979a).

2

  ‘Probabilities of Conditionals and Conditional Probabilities’ (Lewis 1976).

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I agree: what leads me to prefer properties to propositions can be accommodated by the view of etherialized sentences as objects of thought.2 Just make sure that Etherialese contains an analogue of ‘I’ – or better (consider the insomniac) an ­analogue of ‘I-now’. That view doesn’t have to take de se as a special case of de re, because it’s not clear that believing de re of x that Fx comes out to be believing Fn(x) where n is the function that assigns to x the right (ethereal or inner) name. It might be done more in the style of Kaplan ‘Quantifying In’,3 where you existentially quantify over names suitably related to x: believing de re of x that Fx is believing Fa for some a such that aRx. That is to say, that no particular name is required in order to believe de re of x that Fx, whereas a particular name (etherialized or inner ‘I’) is required in order to believe de se of ­oneself that F(oneself). I see that one might characterize states of the head by assigning objects that ain’t in the head (e.g. sentences of inner speech plus their interpretations); but in the process you will also implicitly (if not explicitly) assign other objects that are in the head. And, barring magic, what the head does will depend on the latter. Thus: because the head is in state S and the outer world is in state X (color works by electromagnetic radiation, etc.) the object of thought is O; had the world been rather in state Xʹ the word-dependent object of thought would rather have been Oʹ; etc. Then we have a world-independent object of thought: the function that assigned O to X, Oʹ to Xʹ, etc. For instance, you believe the sign is blue. Let’s grant that the meaning of the outer or inner predicate ‘is blue’ ain’t in the head. It depends on the way color works. If color works in way W1, blue is property P1, if in way W2 it’s P2, etc. But then I’m inclined not to take the proposition that the sign is blue (or rather, the self-ascribed property of confronting a blue sign) as object; take instead the proposition that if W1, the sign has P1; if W2, it has P2, etc. (or the property of confronting a sign that has P1 if W1, P2 if W2, etc.). This is compatible with the assignment of world 2   Hazen is attracted to what he calls the ‘sentency’ view of propositions. On this view, a proposition is an ‘etherial’ sentence that is made up of ‘etherial’ predicates, names, or logical constants. Roughly speaking, to ascribe an attitude to some person is to reproduce ‘the pattern of different etherial names in the proposition to which the person the attitude is ascribed to has the attitude’ (Letter from Allen P. Hazen to David Lewis, 29 March 1978, p. 2). Hazen continues: ‘Neatly, if you take this view to be one about inner speech or the language of thought – Castañeda’s he corresponds to an internal analogue of the pronoun I. With a bit more forcing if you think about propositions as etherial sentences containing etherial names: we have to assume that every haver of propositional attitudes bears a special relation to some etherial name of himself – the etherial I (as the song in Sound of Music goes, “Mi, a name I call myself”)’ (Letter from Allen P. Hazen to David Lewis, 29 March 1978, p. 3). The point of Hazen’s suggestion is that this explains the motivation for conceiving of objects of propositional attitudes as properties; or better, propositions qua properties. 3   (Kaplan 1968).



444.  To William G. Lycan, 19 June 1978

49

correct use of a term of art like ‘object of thought’. But if it’s possible to assign worlddependent objects, then also it’s possible to omit those aspects of the object that depend on what’s outside the head. Admittedly, this complicates the connection between objects of thought and inner speech, but I don’t mind that. On saying that it had better be contingent which world is actual: I think I did intend to speak of what you called realization. That is, of a property which might have belonged to any world, but does in fact belong to this one. (Or rather, in the context of pp. 31–2, of a property which might have belonged to any abstract ersatz world, but does belong to the one that matches the unique concrete world.) I couldn’t say outright that it is the property that belongs at every world to that world (and that’s all there is to it) but of course that’s the conclusion I mean to reach after giving other views a run for their money. Thank you for the paper on natural deduction for counterfactuals with ‘actually’. Our plans for the summer and fall are quite uncertain, owing to the illness of Steffi’s father. I’m on leave this fall, but Steffi has a job (one year fill-in at Princeton) so we’ll mostly be here. I’m going to a conference in Germany 18–23 September, so there’s some possibility that I may pass through Dublin after that, or that Steffi and I both may get there in the first half of September. [. . .] Maybe the reason you have to go to so much trouble to open the door of a train is so that you won’t open it accidentally at speed, say by leaning on the handle. European trains with inside handles are designed so that the handle will be hard to work, and they have very prominent warnings. Best wishes. Yours,

444.  To William G. Lycan, 19 June 1978 [Princeton, NJ] Dear Bill, I never answered your letter of two months ago; and there was no good chance to talk about it in the hustle at Western.1 I don’t know quite what it is to be a functionalist; but yes, it would be at least a characteristically functionalist sort of view that my madman isn’t in pain. So I don’t   University of Western Ontario.

1

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know if I’m a kind of functionalist that rejects that plank of the platform, or a kind of non-functionalist that agrees with many parts of functionalism. Armstrong, by the way, might be more of a functionalist than I. He writes ‘my preliminary intuition is that the Martian is in pain in the same sense that we are, but I am not so sure about the Madman’. And ‘. . . the Martian is a more secure case of pain than the madman’. And ‘. . . I am inclined to think that the mad Martian is in pain in some secondary sense – just as I think the earthly madman is in pain in some ­secondary sense’. (All these from a letter to me in April.)2 What I probably said in discussion was that if ‘pain’ is used de re (and anything can be used de re) then it makes no difference whether it’s also rigidized. That doesn’t mean that it is rigid, but rather means that it’s hard to get a test case, because whatever could be explained as rigid use could also be explained as non-rigid but de re. Thus on page 6 I say ‘Pain might not have been pain’. You could take this as ‘Pain (rigid) might not have been pain (non-rigid)’ but you could also take it as de re: ‘Pain (non-rigid, but it doesn’t matter) is such that it might not have been pain (non-rigid, and this time it does matter)’. Is there maybe a distinction without a difference, so that a theory of de re occurrences and a theory of rigidization of non-rigid terms in certain contexts are equivalent descriptions of the same phenomena? Maybe so if (as you suggest) any term is susceptible to rigidization according to the latter view. A computer is performing a certain kind of multiplication (K-multiplication) just when there’s a current in a certain wire (the K-mechanism). Now cut the wire out of the central processor (crippling the computer but not wrecking it) and put it in the  computer’s air-conditioning circuit instead. Is the computer now performing K-multiplication just when there’s a current in that wire? (Or implant it in the air-conditioning circuit of another computer.) Is that computer performing ­ K-multiplication just when there’s a current in that wire? Of course not. Now replace the removed wire with a similar wire, only made of gold instead of silver – except for this one repaired computer, none has such a prosthesis, all the rest have silver wires. Now does the repaired computer perform K-multiplication when a current passes through its prosthetic K-mechanism: through the gold wire that’s been put into the central processor in place of the silver wire that earlier was removed and used to patch the air-conditioning circuit? Of course. The moral, I think, is that neural states can be things like having a signal on whatever wire is in a certain place in the circuit diagram. (Maybe this is what people mean when they say that being functional or structural is a matter of degree.) They don’t have to be things like having a signal on a certain particular piece of wire. Wires   Letter from D.M. Armstrong to David Lewis, 13 April 1978.

2



445.  To D.M. Armstrong, 19 June 1978

51

are interchangeable parts, like atoms. I suppose neurons are interchangeable parts too, but of course I can’t be so very sure of that. So I don’t say the strange things you expected me to say about the transplanted and then replaced K-mechanism. I think it raises an interesting question all the same. Why say, as I obviously should say, that what occupies the causal role of K-pain in you is current in whatever wire is hooked in at a certain place, rather than current in that particular wire which is in fact hooked in? I don’t owe you a justification of saying that; it seems the right thing to say just in response to a question ‘what state occupies such and such causal role?’ regardless of the importance of the answer to a theory of mind. But it would be nice, as part of the understanding of causation rather than as part of the philosophy of mind, to know why. Enjoy Australia! Yours, Still and all, this is not to say that K-multiplication is simply a functional state. For I want to say that a defective computer might perform K-multiplication although its doing so does not have the right causes and effects; and that the computer is in a state which is K-multiplication, but might not have been if the computer had been designed somewhat differently. (Or if it had been somehow rearranged not by design.) But the state of which I say that won’t just be current in a particular wire. It will be a state which you can’t characterize from the automaton-theoretic machine table, but can characterize from the circuit diagram – current flowing through the wire (whatever wire that may be) that connects this bit to that bit of the circuitry. I don’t mean that only a computer that fits the diagram perfectly can be in the state that occupies the role, but there had better be a good deal of the circuitry left intact. (On the other hand a very different computer can be in some state that occupies the role.)

445.  To D.M. Armstrong, 19 June 1978 [Princeton, NJ] Dear David, Many thanks for your interesting and useful letter of comment on my ‘Mad Pain . . .’ paper.1 I’m sorry I’ve taken more than two months to get around to answering, what with end-of-term rush.

  ‘Mad Pain and Martian Pain’ (Lewis 1980b).

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Philosophical Letters of David K. Lewis

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1)  I agree that not the whole of common-sense psychology enters into the concept of a mental state, and the part that says that pain causes groaning and writhing is a likely candidate for the non-conceptual part. (The news that the people who signify agreement by moving the head sideways also manifest pain by whistling wouldn’t be a very great surprise.) That pain is caused by some sort of damage to the body seems to me to belong to the conceptual part, though maybe the details of which kinds of damage (or impending damage) do and don’t cause pain seem less so. What I was doing on page 1 was to say more than my case required: the madman’s pain doesn’t at all occupy the usual causal role, so you won’t make it fit by any proposal (otherwise plausible or not) for how to delineate the conceptual and the non-conceptual parts of the role. 2 )  I might not mind saying that the madman is in pain in some ‘secondary’ sense; but I don’t understand what I would be conceding if I agreed to that. What makes a sense ‘secondary’? I want to do justice to a naïve inclination I feel to say that the madman is in pain. I can certainly do so and yet agree to ‘different sense’. (People in fact are much too willing to agree that there are different senses, as if ‘X in different senses’ meant no more than ‘different kinds of X’!) 3 )  I didn’t want to explain what functionalism was because I don’t want to get into pointless disputes about terminology. I have no idea whether you and I are properly called functionalists. (One possibility, given your reservations about the madman, is  that you are and I’m not.) Obviously I agree with large parts of views that are ­generally called ‘functionalist’. But obviously I disagree with things that some ­functionalists believe. I reject this: ‘Pain’ rigidly designates a single property; this property belongs to every being (actual or possible) who is in some or other state that occupies a certain role (for it, at that time). And this: A being is in pain if and only if it is in some or other state that occupies a c­ ertain role (for it, at that time). If those formulations are essential to functionalism, I’m no functionalist. Nor is the author of pp. 71–2 of the Materialist Theory, it seems to me; for the point there is that a being incapable of behavior, and hence incapable of having states apt for causing behavior (for it, at that time), might yet have mental states. Its states occupy the appropriate causal role not for it, but for others – in particular, for the man whose ner­ vous system was copied. Indeed, that example seems to me to parallel the example of the madman, except that there is a more wholesale failure of the states that normally



445.  To D.M. Armstrong, 19 June 1978

53

occupy the roles to occupy the roles in the special case. So if the quoted principles are essential to functionalism; and if you stand by that passage; and if you don’t explain occupancy of a causal role (or ‘aptness for causing’) in counterfactual terms (which is unlikely, given that you object to the behaviorist doing something parallel), then that’s how you differ from a functionalist. 4)  I would call it a type-type theory if a certain sort of pain was identified (in the case of humans) with a disjunctive property, the two disjuncts being quite unlike. But of course I don’t disbelieve in disjunctive properties. (Maybe you think I disbelieve in all properties, believing only in set-theoretic substitutes! Anyway, I don’t disbelieve in the disjunctive ones more than the others.) However, I think it would still be a typetype theory (or at least not a token-token theory – maybe ‘type-types’ would be best) if you said that pain was (for humans) identical with a disjunction of two very different sorts of brain-processes, and then went on to say that a disjunction like that is not a property in the same sense that a single sort of brain process is, but only is a property in some secondary sense. I don’t know what the charge of ‘secondariness’ means – see #2 – and that’s why I think it wouldn’t make any difference to your position if you threw in such a charge. All of this has more to do with our differing views on universals than with our views on mind, I presume. 5 )  I’ve added a reference to ‘The Causal Theory of Mind’2 and referred to you as ‘D.M. Armstrong’ throughout. 6 )  Our ‘causal role’ analysis, if indeed it is meant as an analysis – or rather, a scheme for analyses – certainly commits us to non-rigidity. A possible alternative but related theory, which I’ve never liked, would work in two steps: ‘pain’ is introduced into the language as a rigid designator of whatever it is that ‘the occupant of such-and-such role’ designates non-rigidly. Now we have a rigid designator of we know not what, but that seems possible. Our identities are then necessary but not a priori. Our ig­nor­ ance of them amounts to ignorance about some very common words of our own language. I don’t object to this theory because of the semantic notions it employs, but do object to it on the simpler ground that it has no place for Martian pain. 7 )  I think people aren’t so wrong to think that ‘x feels pain’ entails ‘x is aware of pain’, which in turn entails ‘x is aware of feeling pain’. I think there’s an ambiguity in ‘x is aware of pain’; it sometimes means no more than ‘x is in pain’ or ‘x has pain’ and sometimes means more than that – means something involving beliefs gained by inner sense. In fact, I think this same ambiguity is pervasive: it’s in ‘X is aware of pain’, ‘X feels pain’, and ‘X is conscious of pain’. It’s a shell game. If someone argues ‘X is in   (Armstrong 1977). Reprinted in The Nature of Mind (Armstrong 1981, 16–31).

2

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Philosophical Letters of David K. Lewis

pain, therefore X feels pain, therefore X is aware (or conscious) of pain, therefore X’s pain causes X to get the information that he’s in pain’. I’m sure that there’s a fallacy of equivocation somewhere, but it’s not at all clear where. Each step considered by itself seems acceptable – correct under some legitimate disambiguation. I’m afraid it’s clear at last that our planned visit must be called off. Steffi’s father is no better, but he is holding his own better than we thought likely. We are needed here to look after him; he can and does live at home much of the time, but he sometimes needs more looking after than friends coming to visit him can provide, and an alternation of stretches at home and stretches staying with us seems right for the time being. Whatever happens, we can’t postpone the visit to October–November 1978 as I once thought possible; Steffi has a job here at Princeton, which will keep her here from mid-September. It’s a one-year fill-in job with no future, so not really ­satisfactory. But as unsatisfactory jobs go it’s a very good one – some such jobs, including her last one, involve a very heavy teaching load for very bad pay. Also, her last job was 40 miles from home; this one is one mile. Jack Smart hopes that my ANU fellowship can be revived for 1980. (He and I prefer not to try for 1979, since he’ll be away then.) That would be very good, and I hope it works. I hope we’ll see you before long somewhere, though, whatever comes of ANU. Do you have any plans for travel here? Yours, David Lewis

446.  To Patricia Kitcher, 8 August 1978 [Princeton, NJ] Dear Pat, Thanks for your comments. Let me answer some of them. Why is ‘pain’ thought to be non-rigid? Is it just the confusion about contingent identity? Of course some who are completely free of that confusion – Kripke, notably – have a powerful intuition that it’s rigid. I don’t see that this is a suitable thing to have intuitions about; rather it’s a thing to be settled by theory. Let the theory that looks best on other grounds say whether it’s rigid. As David Armstrong said in his letter of comment on the paper: it’s a ‘spoils to the victor’ question.1

  Letter from D.M. Armstrong to David Lewis, 13 April 1978.

1



447.  To George Bealer, 4 February 1979

55

We can characterize some other phenomena than pain a priori, can’t we? Couldn’t we give an a priori, analytic characterization of thunder and lightning as the typical occupants of a pair of (correlative) roles? (It’s then a posteriori to characterize the phenomena that in fact occupy those roles.) Admittedly there’s no guarantee of success, but no harm trying! I agree that common sense psychology isn’t a finished theory, but it doesn’t have to be very finished (or entirely right) to do the trick. If functional analyses render common sense explicit, why don’t they strike average people as obviously correct? This looks like the paradox of analysis; therefore it’s suspect, because there are such things as unobviously correct analyses. Delta-epsilon definitions of continuity might be an example; and you could prob­ ably cook up examples (or find them in a puzzle book) involving kinship relations. [. . .]

447.  To George Bealer, 4 February 1979 Princeton University Princeton, NJ Dear Professor Bealer, Thank you for your paper ‘An Inconsistency in Functionalism’,1 which I’ve just read with interest. It looks to me as if the main question to consider is this: what is it for a definition of a T-term to be adequate? Let’s consider the simplest possible case: just one T-term, and that a name rather than a predicate. I imagine an astronomer trying to explain the perturbations of Mercury by means of a theory in which his new, undefined term ‘Vulcan’ (he could have used a predicate ‘is-Vulcan’ instead) appears, surrounded by old vocabulary. He says: ‘Vulcan is a small planet, closer to the sun than Mercury, . . .’. Thus his theory has the form: T(v) And accordingly I offer my ‘functional’ definition of the T-term: v = ℩xT( x ) (Or if you’d rather steer clear of any special theory of descriptions "x( x= v º "y(T(y) º y =x )

  (Bealer 1978).

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which is something closer to your ‘Lewis constant’ of page 343. There are problems with your formulation which I needn’t go into in detail; suffice it to say that Ti***(x, y) ought to mean that x bears to y a relation that stands at the ith place in an n-tuple that uniquely realizes the theory, and your formulation doesn’t say that.) Is it so that definiendum v and definiens ℩xT( x ) are provably equivalent given the theory T(v)? And is it so that definiendum and definiens are materially equivalent under any model of the theory? In other words, is the inference T( v )\ v = ℩xT(x) valid in either a proof- or a model-theoretic sense? Of course not, unless T has certain special properties (which, let us say, it doesn’t). That makes my definition inadequate by both of the two standards you propose, if I’ve understood you correctly. So what? Why do you think that a definition of a theoretical term is correct only if it follows, in some sense, from the introducing theory? What does that have to do with the natural test for a definition: that definiendum and definiens must be alike in sense? The def­ in­ition should follow from all that has been said, implicitly or explicitly, to fix the sense of the theoretical terms. But on my view (1) the theorist implicitly commits himself to more than T(v), and (2) not all the strength of T(v) is relevant to fixing the sense. I discuss this on page 439 of ‘How to Define Theoretical Terms’. So, as I see it, to demand as you seem to that an adequate definition must follow from (the postulate of) the term-introducing theory is to beg the question against my proposal. On another matter: I am well aware that our mental terms are not newly ­introduced. See my discussion of the matter on pages 256–7 of ‘Psychophysical and Theoretical Identifications’. Sincerely, David Lewis cc: Paul Benacerraf

448.  To Colin McGinn, 10 February 1979 [Princeton, NJ] Dear Colin McGinn, Thank you for the paper on functionalism and phenomenalism.1 I do have a few comments. I’ll start with some trivia.   ‘Functionalism and Phenomenalism: A Critical Note’ (McGinn 1980).

1



448.  To Colin McGinn, 10 February 1979

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Page 2: ‘His version of functionalism . . .’ It’s far from clear to me whether my view is a version of functionalism according to the most common use of the term. If functionalism includes the denial of identities between mental states and brain states – and this has been denied, very emphatically, by some of those who are universally called ‘functionalists’, e.g. Putnam – then I’m the opposite of a functionalist. Page 2: ‘the claim that mental terms are theoretical terms’. I don’t think I use, or would want to defend, the idea that some terms are ‘theoretical’ simpliciter. What I use is the notion of terms newly introduced by such-and-such theory – and mental terms certainly are not now, if they ever were, newly introduced. My thesis is that they’re semantically like terms newly introduced by a theory. You more or less correct this on page 5 (except that the myth isn’t that mental terms were theoretically introduced, but rather that their present semantic character is as it would be if they had very recently been theoretically introduced) but not before saying that virtually any term can be treated as theoretical in Lewis’s sense, which doesn’t seem right. Page 2: ‘the denotations of the T-terms (sc. mental states and events)’. Not events, unless by that you mean kinds of events rather than particular events. On my formulation, the T-terms denote universals: pain, not the particular pain I felt last night. Page 2: ‘none but expressions for behaviour and topic neutral talk . . .’ And expressions for stimuli. Now a couple of bigger comments. Page 4: ‘definitionally eliminate physical object talk’. Yes, from the primitive vocabulary. But you’d still have expressions that denoted physical objects: ‘that which, together with certain other things, occupies such-and-such causal role with respect to our experience’ will according to the ‘phenomenalist’ theory – and will simpliciter – denote a physical object, perhaps my typewriter. So I don’t see that you’ve eliminated physical object talk in the sense that serious phenomenalists intended, and I don’t recognise the theory as anything very close to traditional phenomenalism. Likewise if I definitionally eliminate mental talk from our primi­ tive vocabulary, I don’t therefore eliminate mental object talk. I don’t eliminate reference to, or quantificational commitment to, entities which (whatever else they also may be) are supposed to be mental states. So I don’t see that I’ve eliminated mental talk in the sense that serious behaviourists intended, and I don’t recognise the theory as anything very close to traditional behaviourism. It’s true that behaviourists and phenomenalists were out to define away certain parts of our language, but it’s also true that they were out to express disbelief (or agnosticism) about certain sorts of entities.

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There’s a common confusion in some philosophy of science books about Ramsey’s method of eliminating theoretical terms. Scheffler’s textbook has a section titled ‘Eliminative Fictionalism: Ramseyan Form’!2 That is, the use of Ramsey’s method of eliminating theoretical terms is supposed to be part of a program of showing that the portions of scientific theory that used those terms are not meaningful and true. That is, Ramsey’s method is supposed to be part of a program analogous to traditional behaviourism or phenomenalism. There’s a sort of association of ideas between elimination of primitive vocabulary and elimination of ontological and other claims expressed in that vocabulary. I think this is all wrong. Ramsey’s method is a way of eliminating the vocabulary without eliminating the commitments. See the paragraph on page 428 of my ‘How to Define Theoretical Terms’ in which I disparage both the notion of a ‘theoretical entity’ and the plan of dispensing with these entities. See also the discussion of Ramsey sentences in Smart, Between Science and Philosophy – Smart imagines Ramsey sentences used in the service of ‘macro-phenomenalism’ and rightly complains that they ‘cut no metaphysical ice’!3 You don’t, I think, commit yourself in any explicit way to this confusion; but your use of ‘behaviourism’ and ‘phenomenalism’ for theories which in no way deny that there are mental states and physical objects seems to me perhaps a descendant of this confusion. Footnote 7: ‘I was always taught that [circularity] was a defect in a definition’. It depends on what the definition is meant to accomplish. Whenever you’re producing a batch of definitions to show that certain vocabulary can be eliminated in virtue of certain other vocabulary, circularity is a defect – it blocks the proof of eliminability. In particular, you can’t be circular if you’ve undertaken to eliminate vocabulary somebody doesn’t understand in favor of vocabulary he does. So far, so good. But circularity in a system of definitions doesn’t cast doubt on their truth; or indeed their necessary truth; or indeed their power to illuminate the concepts that appear as definienda, provided that ‘illuminate’ needn’t mean ‘eliminate’. Each of necessity and possibility is definable from the other. That’s an important necessary truth about necessity and possibility, which you’d better know if you want to understand the pair of them. This interdefinability gives you the means to eliminate either from your primitive vocabulary in favor of the other – you have a choice. It doesn’t give you a way to eliminate both at once. If nothing short of the elimination of both at once would satisfy you, you can complain of circularity (in case anybody claimed that the two definitions would help you – which is unlikely). But if you grant that you

  The Anatomy of Inquiry: Philosophical Studies in the Theory of Science (Scheffler 1963, 203–22).   (Smart 1968, 147).

2 3



448.  To Colin McGinn, 10 February 1979

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have the concepts of necessity and possibility, and merely want to know something about them, the definitional circle is something well worth knowing.

to me just false. I think it’s consistent to say (a) the mental vocabulary is definable from, hence eliminable in favor of, the physical; (b) likewise the physical vocabulary is definable from, hence eliminable in favor of, the mental; but (c) the two vocabularies aren’t simultaneously eliminable – as you say, there wouldn’t be enough left to define them! If the two functionalisms were put forward to cure the plight of someone who claimed to understand neither the mental nor the physical vocabulary, the cure would of course fail. But if the two functionalisms were put forward to assist someone who already had both the mental vocabulary and the physical one – as in fact we do – and sought a better understanding of the necessary truths involving the relations of those vocabularies, then they might succeed. (They might – I don’t wish to say that ‘functionalist phenomenalism’ isn’t inconsistent with ‘functionalist behaviorism’ on some other grounds than you’ve mentioned. Nor do I want to say that it gives the correct account of the meanings of physical terms, though I think it’s at least not an absurd view.) If both right, the two functionalisms would give us a choice of eliminations. Given such a choice, some might choose one way and some the other. Others, like me, would see no particular need to eliminate either vocabulary, but would be interested to know that we had the choice. Only those who wanted to eliminate the lot would be disappointed. I think some philosophers have the idea that definitions need not just be true, and necessarily true, but also ought to conform to some hierarchy of more and less basic concepts: a good definition must define the less basic in terms of the more basic, not vice versa. I don’t buy this at all. Within a given system of definitions, indeed, some concepts come before others. But I don’t believe in some notion of ‘more basic’ that doesn’t just mean ‘more basic in such-and-such system of def­in­ itions’ but also can be used to object that a definition of A from B and a definition of B from A can’t both be good, because it can’t be that each of A and B is more basic than the other. They can both be good, if necessarily true, but what they’re both good for isn’t the simultaneous elimination of A and B. Yours,

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449.  To Robert C. Stalnaker, 8 March 1979 [Princeton, NJ] Dear Bob, I don’t have any good reason to think you’re hard up for reading matter, but I’ve sent you a couple of batches anyway. One is the De Se paper, revised.1 Mostly it’s just rewriting, but there are im­port­ ant changes in two sections. One is the section on de re belief; the new theory is superficially very different, but might be almost equivalent to the previous one under suitable definitions of the new notion ‘relation of acquaintance’ and the old 4-place counterpart relation in terms of one another. The other importantly changed section is the ‘Haecceitism doesn’t help’ section. It’s that which I’m mostly writing about. I wish we’d had a chance to continue the discussion we started at Rich’s house, though that wasn’t a very good occasion for it. According to the imaginary Haecceitist, we have this set-up:

W and V are qualitative duplicates differing by a permutation of individuals. T’s are tallest mountains, C’s are coldest mountains. A and D have a common haecceity, as do B and C (indicated by dotted lines). The subject we’re interested in is A; let’s assume we can distinguish him, qua subject, from D. I say: granted this set-up, let’s stipulate that A knows exactly which is his world – W, not V – and hence knows every prop­ os­ition true there. He can still not know whether he’s on the tallest mountain by not knowing whether he’s A or B. V and its inhabitants don’t enter into it – he knows he’s not one of them.  ‘Attitudes De Dicto and De Se’ (Lewis 1979a).

1



449.  To Robert C. Stalnaker, 8 March 1979

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The Haecceitist thinks that can’t be it: if A doesn’t know whether he’s on the tallest mountain, he must not know whether he’s A or D, hence I can’t really mean it when I stipulate that he knows exactly which is his world. Haecceitist: A must not know the proposition expressed by his utterance of ‘I am on the tallest mountain’, else he’d know whether he’s on the tallest mountain. I (taught by you) reply: he knows that proposition, but still doesn’t know whether he’s on the tallest mountain; for he doesn’t know whether he’s A, in whose mouth that sentence expresses a proposition true at W, or whether he’s B, in whose mouth that sentence expresses a proposition false at W. So far, so good; and that’s as far as I go in the paper. At Rich’s, you said: what about the diagonal proposition? Isn’t that the thing to look at when it’s an open question which proposition the sentence expresses (in the ordinary way of expressing)? And there the conversation broke off. OK, what about the diagonal proposition? If we assume that different possibilities must live in different worlds, and that the relevant possibilities for A are being on the tallest mountain versus being on the coldest mountain, the relevant prop­os­ ition­al concept will assign to W the proposition that A = D is on the tallest mountain, and will assign to V the proposition that A = D is on the tallest mountain. It’s a constant concept, which for either worlds yield the proposition already considered, one true at W and false at V. But what did we diagonalize for if it’s a constant concept? And why disregard my stipulation that the possibility of being D is excluded? And why ignore the possibility of being B, which is not excluded by A’s knowledge that his world is W? The right way to diagonalize, given my stipulations, is to take the relevant possibilities as the possibility of being A and the possibility of being B – two possibilities in a single world. The diagonal is true in the first possibility if the proposition expressed according to that possibility is true at the world of the first possibility; the diagonal is true in the second possibility if the proposition expressed according to that possibility is true at the world of the second possibility. The world of the possibility is W in either case. The proposition expressed in the first possibility, that A = D is on the tallest mountain, is true at W. The proposition expressed in the second possibility, that B = C is on the tallest mountain, is false at W. So the diagonal is true in the first possibility, false in the second. It’s true for A and false for B. And sure enough, knowing the diagonal would tell A whether he’s A or B, where in the world W he is. But what kind of thing can be true in one but not another of two possibilities in a single world? For one but not another of the inhabitants of that world? Not a proposition, by which I stipulate that I mean a set of worlds! What divides the inhabitants of a single world is a property, not a proposition. So: knowing the diagonal would help A to know where he is. But the diagonal isn’t a proposition. And it’s not so

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for the Haecceitist, any more than it is for me, that all knowledge is propositional. And that’s my point. Now maybe there’s a verbal difference: the Haecceitist means by ‘world’ what Quine means by ‘centred world’, or what I mean by ‘possibility within a world’ or simply ‘inhabitant of a world’. Then the Haecceitist agrees with me in all but ter­min­ ology. But if so, where does the Haecceitism enter into it? I surely do disagree with Haecceitists on other things than this matter of terminology! Sorry – I’ve been arguing not with you, but with a figment of my imagination suggested by something you started to say and didn’t finish. I think it’s unlikely that you’d have gone on to say what the figment did. But, be that as it may, I’d be interested to have your reactions now to all of this, if you have time. The other batch of stuff I’ve sent is a paper by Angelika Kratzer on counterfactuals, plus a note comparing her semantics with partial ordering semantics (it’s equivalent to a version thereof).2 I’d have sent this before except that I thought my note wouldn’t make sense without her paper, and I wanted her permission to send you that. The note breaks off abruptly when it gets to the question of completeness for partial ordering semantics. I haven’t had time to work on that for several weeks, but hope to get back to it soon. The only line of attack I have is your splitting suggestion; I want to try that out in detail. Angelika’s semantics is more interesting than it seemed to me at first. Briefly, you have a premise set, depending partly on the conversational situation and partly on the facts of the case. A counterfactual is true if every maximal consistent subset of premises-plus-antecedent implies the consequent. (There’s a fancier formulation to avoid the limit assumption – in her set-up, the assumption that there is a maximal consistent set – but the intuition comes across better the way I said it.) The gimmick is that the premise set isn’t logically closed. So you can package the information in equivalent ways that will have different effects on what it’s easy and difficult to discard. Like this: if I have premises A, B, C, D, it’s an easy matter to drop A. If I have B & A, C & A, D & A instead, dropping A is an extreme step.3 That seems to me interesting, but a bit gimmicky. However, it will work – that is, it will work if any sort of ordering semantics in a wide range will work. Hope you’re enjoying the Center!4 Yours,

  Related to ‘Ordering Semantics and Premise Semantics for Counterfactuals’ (Lewis 1981c).   In the right margin a handwritten note by Lewis reads: ‘Everything else goes too’. 4   Center for Advanced Study in the Behavioral Sciences, Stanford, CA. 2 3



450.  To J.J.C. Smart, 23 March 1979

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450.  To J.J.C. Smart, 23 March 1979 [Princeton, NJ] Dear Jack, Many thanks for your Davidson paper.1 I like it very much, but I do have one suggestion for change. On page 12, ‘Lewis holds that indeterminacy in [radical interpretation] is largely analogous to the indetermination of theory by evidence . . .’. Of course, anything is somehow analogous to anything else, but on the most natural way of taking this, I don’t think it’s right. When evidence underdetermines theory, I take it there is a genuine factual question, with a right answer and a wrong one, and no way to find out. (An example might be the hypothesis of circular time versus ­repetition, supposing that we had evidence that one or the other was true.) There are two different cases alike with respect to the total evidence, different in some other respect. But I don’t think there are any two cases alike with respect to everything physical (in a suitably broad sense, including the physics of astral bodies if such there be) and differing in some other respect: mental, semantic, or whatever. At least: not if either one of the two cases is at all like what happens in actuality. As I put it in the paper, ‘[the physical description] determines all the rest to the extent that anything does – . . . where determination by [physical facts] leaves off, there indeterminacy begins. . . . there cannot possibly be two Karls exactly alike [physically] but differing somehow with respect to [attitudes or meanings]’.2 That’s what minimal materialism is. The corresponding attitude to theory and evidence is that when two theories are indistinguishable with respect to the total available evidence – they make exactly the same observational predictions, in some sense – then they aren’t really different. There’s no difference between a world where one holds and a world where the other holds; they are literally equivalent descriptions. And that view about theories and evidence is a hangover of verificationism that I definitely do not hold. I think there might be, and probably are, perfectly good questions of fact that cannot possibly be settled by any amount of evidence; hence theories which are observationally equivalent but not equivalent in the sense of holding at exactly the same worlds. To the extent that the physical description leaves any mental or semantic indeterminacy, I think that indeterminacy is not too worrying. I do think there is some of this unworrying indeterminacy. When I mentioned ‘the “unsharp analyticity” of some so-called definitions in physics’,3 I meant that as an example of genuine but unworrying indeterminacy. This isn’t indeterminacy of theory by evidence; evidence   ‘Davidson’s Minimal Materialism’ (Smart 1985).   ‘Radical Interpretation’ (Lewis 1974, 334).    3  (Lewis 1974, 343).

1 2

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doesn’t enter into it. It’s semantic indeterminacy, given the physical description of the subject in question; though the semantics in question is that of the language of physics, that’s merely the choice of example. ‘He thinks that any additional indeterminacy’ – i.e. the sort that would be ­worrying – ‘can be eliminated, or if it cannot be eliminated, this will only convince him that he has not found all the constraints . . .’. I think it can be eliminated – the question is whether it can under the constraints I listed, or only under a list /that/ included other constraints I should have mentioned but didn’t. I was wondering whether you’ll be at the Oberlin conference in April. Both of us will be there. I’ll be performing, giving a paper ‘Attitudes De Dicto and De Se’ about the so-called propositional attitudes which I claim aren’t that at all. (Or rather, some beliefs and desires can’t be taken as propositional, none need be, so if we want a uniform treatment it can’t be propositional.) I forget whether I sent you a preliminary version of that; at any rate, I’ll send you the current version and a couple of other things as well. We’re off to Monash at the beginning of June. I hope we’ll be able to stop briefly in San Francisco and see you then, but it’s quite uncertain. One possibility is that we’ll have to travel separately. I should arrive as soon as possible in June; Steffi needn’t, will have a lot of year-end grading, and can save a significant amount if she takes a budget flight in which she names the week and Air New Zealand names the day! I hope we’ll know soon. We’re looking forward very much to the winter in Australia – to Monash itself, and even more to the chance to travel and see more of the country. This time, we’re definitely planning to go to Perth, flying one way and taking the train the other. We’ll also probably buy a used car to get out in the bush in Victoria on our own. (It might make sense, depending on insurance, registration, etc. to leave it unsold in storage somewhere for use in 1980!) One worry about Monash: do they tolerate carnivores? Singer will be talking in New York next month, but probably I can’t go to hear him. [. . .] I hope you’re enjoying the Stanford Center. In principle I like the idea of going there, and maybe someday we will. But whenever there’s a chance, it always seems preferable to go to England. Also I’m a bit scared of a situation where conditions are so perfect for working that I have absolutely no excuse if I don’t! I suppose I am glad that it was the philosophy section and not the railway section that got flooded. The railway collection is probably more unique and irreplaceable. And I’ve never been convinced that philosophy is more than a hobby that people are willing to pay me for. See you soon, I hope. Have you any plans for coming east before we leave? Yours,



451.  To J.J.C. Smart, 11 April 1979

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451.  To J.J.C. Smart, 11 April 1979 [Princeton, NJ] Dear Jack, I take your point about not swanning around too much. I’m going to three conferences on three successive weekends – Texas, South Carolina, Oberlin – and that’s just too much. Each one considered by itself seemed a good idea at the time I accepted it, but I didn’t really notice how much of my time over a few weeks they were going to wipe out! Oberlin is the last, this coming weekend. After that I may have a day at home once in a while, and time to do some real work – for instance, time to read several very interesting-seeming letters Bob Stalnaker has sent me about conditionals and partial orders. I should also be done at about the same time with most of my work for the year as Director of Graduate studies; and with the job of trying to prove to the Department that we ought to make a tenured appointment in philosophy of physics. (Not much chance of that coming off, but I think I’ve at least done a good job of making the case.) Bad luck: we can’t afford our stopover in San Francisco on the way to Monash. It raises the fare greatly, given the rules for budget fares. Partly it puts the trans­con­ tin­en­tal part on regular fare instead of cheap fare; and partly it puts the Pacific part on  June rates instead of May rates. If only we could leave a day or too sooner it might be done; but we’re already stretching things rather badly. Steffi’s end of term papers aren’t due until 28 May and we leave – and she must have them graded – on the afternoon of 30 May! So it’s beginning to seem that I was wrong to be so sure we’d see you at some point during your visit here. Ah well – 1980’s not so far off. But it’s too bad. I’m a bit bothered even by the revised paragraph in your 27 March letter. It suggests that I think there’s no indeterminacy at all. Let me suggest something like this. Lewis holds that any ineliminable indeterminacy in such a solution is limited in scope, and not too worrying philosophically. He thinks that any more radical indeterminacy, which must be distinguished from the indetermination of theory by evidence such as we get in physics, can be eliminated under suitable constraints on translation. The only question is whether it can be eliminated under the constraints on radical interpretation that he has listed, or whether it can be eliminated only by finding further constraints (10 p. 343).1

1   The reference in parentheses is to ‘Radical Interpretation’ (Lewis 1974, 343). See also (Smart 1985, 181).

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The harmless indeterminacy seems to me to be the sort of thing we believed in long before Quine and Davidson: vagueness, open texture, indecision about which parts of physics are definitional and which empirical; and on the mental side, the sort of confused half-beliefs and half-desires characteristic of neurosis and indeed common in all of us. Yours,

452.  To Robert C. Stalnaker, 28 May 1979 Princeton University Princeton, NJ Dear Bob, I’m afraid I never answered your question whether it was OK to cite the De Se paper.1 Sorry! Yes, it is OK. I haven’t yet heard from Phil. Review whether they’ve accepted it, but you could cite it as a talk at the 1979 Oberlin Colloquium. Harper seems to be using you as a go-between to the present editors of Phil. Review, so I will too – see enclosed. We’re off to Australia the day after tomorrow – at last. Smart managed to reschedule our cancelled ’78 visit to ANU for ’80, but in the meanwhile I’d told Frank Jackson how disappointed we were, so he cooked up a visit to Monash. (New university in the suburbs of Melbourne.) Address until 20 August: Department of Philosophy, Monash University, Clayton, Victoria 3168, Australia. I hope to get back to partial orders, Pollock functions, and all that, and to read your letters more carefully than I have so far. I’ve also got some stuff from Hans Kemp and Frank Veltman to read. Veltman apparently has an axiomatization for something like the Kratzer semantics (which shouldn’t be called that, as it’s equally his – premise semantics, maybe) directly.2 I was assuming that playing by whim meant handing the decision over to unconscious processes which (1) weren’t random to any great degree, and (2) couldn’t be figured out in advance by thought experiments, tickles in the tastebuds, search for saliences, etc. I was also assuming (3) that not only is it virtually certain that the players will play alike, but also this is so because they are very much alike, which means that not only C(success) but also C(success/whim) is high (in view of (1)). I think (2) is   (Lewis 1979a).   See ‘Ordering Semantics and Premise Semantics for Counterfactuals’ (Lewis 1981c).

1 2



452.  To Robert C. Stalnaker, 28 May 1979

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fair because it looks like making the problem harder for causal decision theory. But (1) and (3) may not be fair – I’m helping myself to something Hunter and Richter didn’t give me, and maybe the problem without (1) and (3) would be worse. To the extent that knowledge must be explained as a behavioral capacity or disposition (and of course I’m inclined to agree with this) it’s indeed phony to stipulate that someone knows which of two qualitative duplicates (in duplicate worlds) he is. So if there are duplicate worlds, worlds may be doubly wrong as maximal objects of knowledge: too small (in that they divide duplicates) as well as too big. The last stop short of omniscience is: am I A, B, C, or D? Omniscience, to the extent that makes sense, is: I’m A at W or D at V. But if that’s it, Haecceitism still doesn’t help propositional objects. That last stop was from: I’m in one of these two worlds, but where in them? to I’m in one of these two worlds, and whichever one I’m in, I’m on the tallest mountain in it. No further proposition is believed. It seems to me that if you reject the stipulation that they know they’re at W, it ought to be because it’s impossible to know whether they’re at W; impossible not because they can’t find out, but because there’s no such functionally specified state as knowing-you’re-at-W as opposed to knowing-you’re-at-W-or-V. The Haecceitist was supposed to be claiming that to know exactly which world you’re in is to know everything. It seems to me that you’ve defended that only as a vacuous conditional. Given that there are duplicate worlds, you couldn’t know exactly which one you were in. So if you did you’d know everything, you’d know nothing, you’d fly over the moon . . . What if we start by saying that propositions are objects of attitudes, worlds are maximally specific propositions? (And you do say such things, of course.) Then I have to agree: if you know your world you know everything; you have all possible knowledge de se; so worlds have something about your identity built into them. But I say these ‘worlds’ aren’t what I call worlds. They’re centered worlds, world-bound individuals (preferably stages), maximally specific properties, something like that; perhaps with a correction to allow for the impossibility of knowing which of two indistinguishable duplicates you are, if there are such duplicates. And I don’t see how Haecceitism enters into it. If Haecceitism just means that each centered world has a definite center, so that to know which (centered) world is yours is to know who in the world you are, then I’m a Haecceitist; the whole affair is a terminological variant of what I’ve thought all along. But I thought Haecceitism was something more dubious than that. And if it is, it still seems to me that it’s independent of my claim that the maximally specific objects of belief aren’t centerless worlds, or propositions understood as sets of centerless worlds. When you met Lingens, you self-ascribed meeting Lingens; you self-ascribed being such that you could truly say ‘You are Rudolf Lingens’; so you said it; he

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self-ascribed being addressed by someone in a position to truly say ‘You are Rudolf Lingens’; so he self-ascribed being Lingens. Nice of you, but must you go around wrecking good examples? Whether that’s ‘direct’ or not seems to me to depend on whether there was any more direct way it could have been done, and I don’t see that there was. I think what happened isn’t much different from what would have happened if you’d said to him: ‘Ha! At last I’ve found Rudolf Lingens!’ There you ex­pli­ cit­ly self-ascribe a property; he figures out what property you self-ascribe, trusts you, and also figures out that you have that property iff he’s Rudolf Lingens (he being the one and only person you’ve just found). In short, I rather like the idea that the diagonal content of a sentence in context is a self-ascribed property, and is closely related to expression of belief. This leaves a place for horizontal, propositional content as well, of course; both as part of an account of how diagonal content is determined and as a kind of content which gets picked up by demonstratives. Yours, David

453.  To Frank Jackson, 22 June 1979 [Melbourne, Australia] Frank As you expected, no surprises for me in ‘On Property Identity’,1 and no significant disagreements. Some comments by way of expansion, and maybe strategy for persuading people. But I like the paper very much as is. Page 9, ‘participle notation’. I’m not sure, but aren’t they gerunds rather than participles? I thought the adjectival ‘running’ in Running dogs pant Fido is running was a present participle, but the property-denoting noun ‘running’ in Running makes dogs pant and likewise ‘being too hot’ in Being too hot makes dogs pant   (Jackson 1982b).

1



453.  To Frank Jackson, 22 June 1979

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was a gerund. But I’m years stale on this. Page 2, bottom. Even the orthodox misunderstandings of the traditional view aren’t so bad as to be quite parallel with the daft view you here deny. The parallel would be ìterms ü (1) Property identities are true iff the í ý that flank the identity symbol are predicates î þ synonymous; (2) Material-thing identities are true iff the terms that flank the identity symbol have the same spatiotemporal location. The absurd view is (2). But if you make (1) perfectly parallel by filling in ‘terms’ you get something even worse than orthodoxy; the orthodox say that the relevant synonymies are predicate synonymies, even if they sometimes forget. If instead you fill in ‘predicates’ in (1), you respect the orthodox claim that it’s predicate-synonymies that matter; but you damage the parallel, and also you ascribe to orthodoxy the notion that an identity symbol flanked by predicates is a well-formed sentence. Either way, the version of (1) that parallels (2) is sub-orthodox. So this argument seemed a bit aimed at a straw man rather than your real opponents. Page 9, introduction of the P(-) functor; top of 10 on predicates in language; lower down on 9, equivalence of the P-notation and the participle/gerund-notation. Obvious objection: it’s a contingent matter what property a predicate ascribes; so ‘P (“is red”)’ is not equivalent to, but only contingently denotes the same as, ‘the property of being red’. The objection has two versions, both of which you can easily meet. Version 1: language is conventional; ‘red’ might have meant what ‘blue’ actually does; then P ‘is red’ would have been the property of being blue. Your reply: ‘predicate’ means what might also be called ‘predicate cum interpretation’, or ‘predicate-asinterpreted in-such-and-such language’. It’s not, as in some usages, just a string of letters or phonemes open to various interpretations. Version 2, the more interesting version: it’s open to say that ‘has the colour of ripe tomatoes’ ascribes the property of being red, and in general that ‘has the property that has 2nd-order property F’ ascribes whatever property it is that actually has F. Reply: that’s not what you mean by ‘ascribe’. I think you might grant that it’s a legitimate use of ‘ascribe’, not necessarily a mistake. But if so, your explanation of the P-notation is ambiguous. So is it better to stick to, or at least start with, the participle/gerund-notation? Trouble is, that may be ambiguous too. See next comment. I don’t know what to do against someone determined to misunderstand. I would say that F-ing, or P( F ), belongs at every world w, to just those things that satisfy F or the corresponding open sentence at w; but that drags in a lot of unpopular baggage that you’d best not be stuck with in this paper, even if you like it yourself which I’m not sure you do.

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Page 12, numbered line (5) – same goes for many other places. I think (5) is ambiguous.2 What you mean by it is false. But I think it can mean something true, and I think this true reading may be one source of the confusions you’re gunning for. Two alternative analyses of the true reading, but I’m not sure there’s any real difference between the two. First analysis: the true reading has a wide-scope, de re, occurrence of the description: (5A)  The colour property common to ripe tomatoes is such that: the property of being red = the property of having it. Second analysis: there’s a hidden actualization or rigidization, à la Kaplan, Stalnaker, Davies-Humberstone. (5B)  The property of being red = the property of having (Kaplan) ìDthat [the colour property common to ripe tomatoes] ü ï ï (Stalnaker) í† [" " " " " " " " "] ý ïthe colour property that actually is common to ripe tomatoes ï (D&H) î þ Suppose (5) can have the true, wide-scope, first analysis 5(A). No worries: (5A) isn’t an identity, if by that we mean the identity symbol flanked by closed terms. Then it’s  no counterexample to ( Prop = ).3 Then the ambiguity of the participle/gerundnotation is like this: on the narrow-scope reading, ‘the property of having the ­colour property common to ripe tomatoes’ is a decent closed term, rigidly denoting a property which isn’t the property of being red; on the wide-scope reading it’s an ‘incomplete symbol’, not of any semantic category, without any semantic value in isolation; or it’s a non-term that attaches to a predicate to make a sentence; anyway, it amounts to the colour property common to ripe tomatoes is such that: . . . (the property of having) it . . . The second analysis of the true reading of (5), (5B) with some sort of rigidization, is more bother. (5B) – which exists to cause trouble whether or not you favour it as a reading of (5) – is an identity, ‘=’ flanked by closed terms. It’s true. It has the form ‘P(a ) = P( b )’ , or ‘a -ing is b -ing’, where the predicates are (a ) is red ( b ) has Dthat [the colour property common to ripe tomatoes] 2   ‘(5) (The property of) being red = (the property of) having the colour property common to ripe tomatoes’ (Jackson 1982b, 296). 3  ‘ ( Prop = ) P( x ) = P( y ) º x is synonymous with y’ (Jackson 1982b, 294).



453.  To Frank Jackson, 22 June 1979

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. . .   (other versions) You’re OK if a and b are synonymous. Are they? They’re necessarily equivalent (‘superficially necessarily equivalent’ in the jargon of Evans and D&H), but no better. I think you have two alternative moves. Safe but a bit of a retreat: you could say that synonymy in ( Prop = ) means no more than (superficial) necessary equivalence; (a ) and ( b ), though not intuitively synonymous, are synonymous in the sense relevant to ( Prop = ). More daring: you could say that ( Prop = ) is meant for predicates of ordinary language, ( b ) as Kaplan etc. interpret it is nothing of the sort, hence P(a ) = P(b ) is no counterexample. That is, you could reject the whole fancy 2-dimensional semantics. I think you might get away with that. Mostly the 2-D semantics provides neat ex­plan­ ations of things that could also be explained in other ways. E.g. instead of taking ‘actually’ in the 2-D way, you could explain it as a surface manifestation (‘Dthat’ and ‘†’ didn’t look like ordinary language in the first place). Here the A-elimination the­ orem of Davies and Humberstone would help, provided it extends to sufficiently rich languages. Does it? Hard to say: more contexts from which you have to be able to eliminate ‘A’, but more resources to do it with! Counterexamples to ( Prop = ) with rigidization are the thing to beat, once you have the dumb confusions beaten. The fashionable view of temperature, i.e. Kripke formalized in the way that best fits what he says, would have it that the identity of temperature and mean K.E.  is just such a counterexample and provided the A-eliminations don’t look hideously miscellaneous and artificial. Does ( Prop = ) apply to languages with the A-operator? Let F be a 2nd-order predicate, G a 1st-order predicate, P a 1st-order property-variable. Suppose G-ing = ℩P AF( P ) as a matter of deeply contingent fact. Certainly G-ing = having G-ing. By substitutivity of rigid designators of the same property, G-ing = having ℩PAF( P ). But G doesn’t seem synonymous with ‘has ℩PAF( P ) ’. Reply: nevertheless, G is superficially necessarily equivalent to ‘has ℩PAF(P)’, and if that’s what you mean by synonymy, ( Prop = ) applies even when you have an A-operator. G isn’t F A-equivalent or F □ -equivalent to ‘has ℩PAF( P )’ so I guess that languages with A are counterexamples to ( Prop = ) with certain natural ‘deep’ conceptions of synonymy. Likewise languages with the A-operator buried in various predicates: suppose F □ "x (Hx iff x has ℩PAF(P)), then G-ing = H-ing; but G and H are synonymous only in the sense of superficially necessary equivalence, not in the sense of F A or F □-equivalence. (Ugh. Enough of that. I have very mixed feelings about 2-D semantics. It’s ingenious, it’s intuitive at the start – but suddenly it lands you in distinctions too subtle to be believed, and there’s no proof I know of that it’s the only way to do anything!)

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Page 4, bottom, the disjunctive characterization of criteria of identity. Good! But underplayed. Maybe that’s good strategy here – don’t fight orthodoxy on too many fronts at once. I think the notion of ‘criterion of identity’ is a bit of a disaster, since it covers two different sorts of principles which haven’t much in common. Some ‘criteria of identity’ amount to requirements of discernibility. They have the form: no two K’s are indiscernible in such-and-such respect. E.g. No two sets are coextensive No two properties are necessarily coextensive No two material things are at exactly the same spatiotemporal location No two events have exactly the same causes and effects Others amount to unity relations (Perry). They have the quite different form: two K-parts (or K-instances) (these parts (or instances) not themselves being K’s) are parts (or instances) of a single K iff they stand in such-and-such relation. E.g. Two railway wagons are parts of a single train if they stand in the relation: coupled-t* (where * means ‘ancestral’). Two person-stages are parts of a single person iff they are related by a suitable relation of mental continuity and connectedness. Two lines are instances of the same spatial direction iff they are parallel. Two word-tokens are instances of the same type iff they are equiform. Unity relations may or may not be specifiable using functors; it depends on whether we have any assurance that a K-part (or instance) is never a part (or instance) of two different K’s. If we have such an assurance, we can put the thing in your form with functors: The K of which x is a part (or instance) = The K of which y is a part (or instance) iff x and y stand in such-and-such relation. But if not, not. Even if K’s overlap, we can still have criteria of identity – unity relations – for them. Often the concept of K yields a requirement of indiscernibility; often a unity relation. Seldom both. I don’t see any good reason to think that for any kind K, there must be one or the other (not counting trivial ones). It’s only if you lump the two different things together as ‘criteria of identity’ that it begins to seem plausible that you can expect one, and that you need one, for any kind K whatever.



454.  To Donald Nute, 20 August 1979

73

454.  To Donald Nute, 20 August 1979 [Melbourne, Australia] Dear Don, Thank you for the paper;1 I look forward to reading it when I return to Princeton next month. (To save on forwarding and baggage weight, I’ve asked that only letters be forwarded.) I can’t say that I’m having a pleasant and productive summer; but I’m having an extremely satisfactory winter, which is still better. Turning to your comments on the de se paper (now forthcoming in the Phil. Review).2 (1) I agree with you that the subject that self-ascribes properties is ‘ephemeral’: not the whole of a continuant person, but a more or less momentary time-slice. The case of the insomniac wondering what time it is, Section VII, is supposed to establish that. I didn’t want to mention it right away, lest I be talking about too much all at once. But I mean it to hold in general, not just that case. I suppose the ephemeral subject could be taken as a continuant-time pair, but I prefer to take it simply as a temporal part of the continuant person. I don’t think I need to accompany this with any thesis about the ephemeral reference of ‘I’, however, and I think that would be a bit implausible. (2) On epistemological self-access. Certainly we have special ways of finding out about ourselves; but this concerns the causal role of self-ascriptions, not the objects thereof. I do want to steer clear of any sort of special and mysterious selfconcept. (Other than the relational one: identity. To self-ascribe X is to self-ascribe identity with something that has X – see final two paragraphs.) Given any nonrelation self-concept S, be it special and mysterious or not, that which is S also has X. That reduces self-ascription to propositional belief, which we know from the case of the two gods not to be possible in all cases. And it trivialises the self-ascription of S itself. (3) I’ve run across people who thought that ‘proposition’ was the word for objects of thought, whatever those might turn out to be. But I think they didn’t mean it, since I think also they presupposed that whatever propositions were, they weren’t properties! I don’t know the history of the word ‘proposition’, but I do think there’s a fair contemporary currency for the meaning ‘set of worlds’ especially in intensional logic. But if you want entities with indexicality to be objects of belief, it seems to me that you can do it easily enough: take functions from contexts (or features of contexts) to propositions. If you also want them to have syntactic structure, that can be done in a similar way. The so-called ‘meanings’ in my ‘General Semantics’ are the sort of thing I have in mind: they are abstractions from sentences that still have both   ‘A Probabilistic Causal Calculus: Conflicting Conceptions’ (Fetzer and Nute 1980).  ‘Attitudes De Dicto and De Se’ (Lewis 1979a).

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indexicality and syntactic structure, though they don’t have the transformational grammar or the vocabulary of any particular language. The news of the N-scale Southern sounds good. I have an idea that I’ve seen one or more articles in the magazines about the sort of high-ended pulp-wood flatcars you need. Remind me in a month or two (after the beginning of term rush is over) and I’ll see if I can hunt up any useful articles. Yours, David Lewis

455.  To Frank Jackson, 31 August 1979 [Melbourne, Australia] Frank Notes on ‘A Note on Physicalism and Heat’1 Page 3: (1) is not a statement of property identity.2 Maybe not quite, but it’s close. Maybe it’s a statement of magnitude identity, where a magnitude (which we often call a ‘property’) is like an ordinary property except that it comes in degrees. Maybe it’s a relation to numbers. Or else (1) is a quantified property identity: (1ʹ) ∀x Heat to degree x = M.K.E. to degree x Or since the units might be different (1ʺ) ∃y > 0 ∀x Heat to degree x = M.K.E. to degree yx. Don’t dash off to (2), which as you say is a false property identity.3 What we want is (1ʹʹʹ) Heat =df The magnitude that Heat-presents = M.K.E. Or (overlooking the different units) (1ʹʹʹʹ) ∀x (Heat to degree x =df the property that Heat-presents to degree x = M.K.E. to degree x). Page 6. How much is the ‘being the victor’ example supposed to prove?4 This much is  OK: We’d be in a pickle without a reasonable supply of rigid designators for  (Jackson 1980b).   2  (1) Heat = molecular K.E. (Jackson 1980b, 28).   (2) Having heat = having molecular K.E. (Jackson 1980b, 28). 4   The example is that Caesar in the actual world has the property of being the victor of Pompey, and in other worlds Pompey wins and Caesar lacks that very same property. 1 3



455.  To Frank Jackson, 31 August 1979

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­ roperties. But I get a hint – only that, and it may go away when I read on – that p or­din­ary property-designators should all be rigid. Of course you’ve not yet made a case for that. Note that even if ‘heat’ is non-rigid, as indeed I believe, still it can contribute to the similarity of two things at two worlds that they have the same amount of heat – even if that’s so because the one at world w1 has the amount of MKE that heatpresents at world w1 to degree x and the other at world w2 has the amount of caloric fluid that heat-presents at world2 to degree x. Their shared property is: having whatever it is that at its world heat-presents to degree x. [. . .] Page 9 on two attitudes to take. Here’s a third. (Or maybe it’s just a different formulation of the second.) The basic intuition in question is right, needs no explaining away, but you’ve misrepresented it. Page 9: the one and only possibility vs. the number of logical possibilities. This way of putting it – and likewise SK’s ‘metaphysical/epistemic possibility’ – encourages a misunderstanding. (At least I hope it’s a misunderstanding and not what you intend – but I’m pretty confident.) That is that there are different kinds of possibility, worlds or cases or . . . possible in one but not the other of two contrasted senses. That may be so, but it’s irrelevant to what you’re saying. The idea is that you have one and the same range of possibilities; none of them are properly described as differing with respect to whether heat is MKE, but many differing w.r.t. what it is that heat-presents. Page 10. The next page confirms that you have this right, but I still think that your  first way of saying it – especially when associated with what Kripke says – encourages misunderstanding. [. . .] Page 10, what Kripke finds unpalatable. He finds a consequence of it worse than ‘unpalatable’, and rightly so. When I broke my foot, I could tell that some property I then had was pain-presenting, and accordingly that it was the one called ‘pain’, but I couldn’t tell what property it was. So on the rigidity hypothesis, I couldn’t tell that I was in pain. But I could. [. . .] General comment. I think one might be a kind of physicalist that is analytic enough to meet your objections, non-analytic enough to meet the objection that the analyses produced can’t be what we generally mean. I’m that kind of physicalist about c­ olours, though not about heat or pain. I write the rigidization operator as (‘reggad’). Different people have their different definitions of ‘red’:

Philosophical Letters of David K. Lewis

76 For Fred, red =df For Ned, red =df For Ed, red =df 23/4/1935. For Ted, red =df etc.

the colour of pillar boxes the colour of blood the colour of the sample chip Ed was shown at 6:42pm, the colour of the people’s flag

In view of the facts about pillar boxes, the people’s flag, etc., it is true on each of these definitions that

(*)  □(red = the property of selectively reflecting or emitting light in the vicinity of such-and-such wavelength) So outside the ‘fixedly’ contexts – which don’t turn up so very often – the difference in their definitions won’t matter, and indeed won’t be detectable. So no harm done if the definitions differ; no harm done if Ed forgets his def­in­ ition and adopts a new one in terms of the people’s flag; no harm done if Ned forgets his and never bothers to adopt a new one; no harm done if there never was any fact to make it determinate which was the definition in the case of Jed, who first heard the word by learning that the color of beetroot = red = the colour of cherries. In short: the rigidized topic-neutral definitions of ‘red’ are miscellaneous, evanescent, indeterminate, and unimportant. A philosopher who proposed one of them as telling what we all mean by ‘red’ would be the laughing-stock of the profession: Fred never heard of the people’s flag, in Ted’s country the pillar boxes (which aren’t called that) are blue, . . . . So we get the idea that there’s no definition at all. But in that case, how is it possible – as it is – to make the discovery (*)? Or should I say: the discoveries (*)? I actually think the rigidized topic-neutral definitions of ‘red’ look different from the ones shown. A lot of it is the colour I spontaneously call ‘red’ (which can’t be adopted until one has undergone the training, but can be adopted then) or the colour Mum calls ‘red’ the colour most people hereabouts call ‘red’ The definitions can’t all borrow from other people, but a lot of them can.



456.  To Robert C. Stalnaker, 10 September 1979

77

(No hurry, sea mail fine, but could you please mail me a photocopy of this? Thanks. Maybe I’ll write a paper about it someday.)5

456.  To Robert C. Stalnaker, 10 September 1979 [Wellington, New Zealand] Dear Bob, John Bigelow showed me your ‘Semantics for Belief’1 (if you sent me one, it’s waiting at Princeton – to save postage and luggage weight I asked them to forward letters only). I liked it very much. I hadn’t been clear before that your propositional contents weren’t delivered by the semantic rules, though in hindsight there are various things you’ve said that make better sense that way. When you told me at Albany that you and Kaplan were doing different things, I thought you meant just that his ‘circumstances of evaluation’ were more than just worlds. Sorry! I’m afraid it’s too late to correct ‘Index, Context & Content’.2 On the two gods, my reply is doubtless predictable. Zeus thinks tentatively ‘I’m Zeus’ and wonders if that’s true. Under H’ism, his thought-token determines a (constant) concept and thence diagonally (as well as horizontally) a contingently true proposition. Zeus knows that proposition. He knows, of the thought-token which in fact is his, that it’s true. The trouble is that he doesn’t know that the thought-token is his. That’s very extraordinary; a theory that assumes that there’s no problem knowing which thoughts are one’s own will be safe almost always, but not this time. Still, I don’t see that the story is incoherent. At least it needs more argument – maybe you could make a case that Zeus realizes common-sense psychology so badly as not to have thoughts at all. Armstrong has noted that according to me, Zeus believes of himself, de re, that he is Zeus. True, but not good enough, as witness the pants-on-fire man. In a rewrite, could you credit the perhaps-incoherent case to Lewis-if-he-werea-Haecceitist, not Lewis simpliciter? What you discuss is the H’ist version, which I don’t really believe in. It’s true, of course, that if not knowing your thoughts for your own is incoherent, that hits the non-H’ist version too.

  See ‘Naming the Colours’ (Lewis 1997b).

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 (Stalnaker 1987).   2  (Lewis 1980a).

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Also, the question of H’ism isn’t the issue of whether there are qualitatively indiscernible worlds. On the latter question I have no views (since I think of the worlds as concrete). What I don’t believe in are indiscernible worlds that differ by a permutation of individuals, in virtue of H’istic linkages independent of the lines of similarity. Yours, David

457.  To Frank Jackson, 17 September 1979 [Princeton, NJ] Dear Frank, Home safe and sound, and busy starting the year. It turns out that a great deal of mail wasn’t forwarded at all – rightly not, I’m glad not to have had it at Monash but it’s a lot to handle now. Bruce is much the same, which is a relief. What made all the difference between a really nasty flight home and a tolerable one was that during our stop in Los Angeles we got away from the airport long enough for a nice dinner at a Mexican restaurant and a walk. While in Wellington I finished a new and (I hope) final draft of ‘Veridical Hallucination. . .’.1 I’ll send it along when it’s typed – which may not be for a while given the beginning-of-term rush. I thought of a way to modify the analysis to make it come out as you wish in the censor case; though I’ve decided that I really don’t want to make the modification, and prefer to insist that the censor case isn’t really seeing. The censor case (I think we were calling it something else) goes like this. The scene before my eyes is S, and S is causing visual experience E by the standard process (or by the non-standard process of a prosthetic eye in good working order). The ­censor wants to see to it that I have E no matter what the scene. In fact he is idle, since no intervention is needed. But if the scene were anything but S, the censor would intervene, stopping the standard (or non-standard) process and producing E by other means. So my visual experience does not depend at all on the scene before my eyes. I think, but you and Lloyd didn’t, that that’s enough to make the case not by seeing, despite its close resemblance to cases of seeing. Here is the analysis I think you should adopt – mine, but with counterfactual dependencen (for some n) where I require plain counterfactual dependence, or in   ‘Veridical Hallucination and Prosthetic Vision’ (Lewis 1980d).

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457.  To Frank Jackson, 17 September 1979

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other words dependence0. I can best show you what I mean diagrammatically. S’s are scenes, E’s are experiences, I’s are intermediates.

Counterfactual dependencen of the E’s on the S’s obtains iff (1) there exist I’s to provide the appropriate pattern of counterfactuals as shown, and (2) counterfactual dependencem of the E’s on the S’s does not obtain for any m < n . Since the counterfactual isn’t transitive, we can indeed have such cases. The simplest version of the censor case is one in which we have a suitable pattern of counterfactual dependence1, but no dependence0; so the suggested change would make it qualify. (Other versions would have patterns of dependencen for higher n.) To see that we have dependence1, let the causal chain from scene to ex­peri­ ence look like this:

(arrow pointing toward the future). X is the last stage that the censor monitors; so if S . . . X are such that he predicts E, he won’t intervene; and he wouldn’t intervene whatever happened later because if the causal chain were to swerve off toward a different experience after S . . . X had happened, it would be too late then for intervention. (As usual, the counterfactuals are non-backtracking.) Y is the first stage at which the censor would cut in if the chain were heading toward the wrong experience. There must, it seems to me, be a gap between X and Y and we pick any intermediate I in that gap. (There must? What if the censor acts instantaneously? What if we have a non-dense causal chain with causation across time gaps in which nothing happens? All I can say is that those suppositions make the case even more peculiar than it is already and maybe you needn’t trust any intuition you might have about it.) So I say that if there’d been a different scene instead of S, there would have been a correspondingly different intermediate instead of I; the censor would indeed intervene in that case, but only later at Y-time, after the alternative to I already had taken place. And I say that if there had been a different intermediate instead of I, there would have been a correspondingly different experience instead of E. For in that case there still would have been S . . . X, and so the censor wouldn’t have intervened. (No back-tracking!)

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As I say, this is not my theory; my theory is that dependence0 is required and the censor example isn’t seeing. But it’s the minimal change in my theory to fit your intuitions, and it isn’t disjunctive in a bad way. Two sources: (1) it’s something like the ‘differential explanation’ used in Christopher Peacocke’s treatment of the same problem; ‘Deviant Causal Chains’ in Midwest Studies in Philosophy, IV (1979).2 (2) It imitates my usual treatment of pre-emption as intransitivity of causal dependence. Thanks for the comment on probabilistic explanation. I haven’t much to say. Counting the chance-lowering factor as a cause still strikes me as counterintuitive – very much so – but counting it as part of the complete causal explanation doesn’t. However, leaving it out still doesn’t seem so bad either. At one stage, I thought of just stipulating that if e belongs to a causal history, then so does the chance that e is a realization of, if such there be. That brings in anything that the chance causally depends on, including things that lowered it, but without the bad consequence that what lowers the chance of e is a cause of e. (I wouldn’t say that the chance causes its own realization, only that it belongs to the causal history.) But that makes particular chances be occurrences, and if so they’re occurrences that raise puzzles about their distinctness from other occurrences. Is the chance an occurrence distinct from the various occurrences in virtue of which it has the value it does? Maybe (especially if supervenience of chances is false) but I’d rather not be stuck with that. I’ve got a tentative schedule for next year. Leave 31 May, after our meeting to decide what to do with grad. students not making satisfactory progress, and before the high season fares come in. I realise that the fares work a bit differently every year, though. Quick stop in Auckland and immediately on to Wellington, getting there maybe 2 June. Fly to Melbourne 17 June; stay with you, as planned. Fly to Hobart 25 June; 2½ weekdays for the University and a weekend for a little sightseeing. Return to Melbourne 30 June; pick up car and drive to Canberra 1 July. How would that suit you? All’s well at home. Bruce is in good shape, the housesitters were extraordinarily conscientious, the recent storms did no significant damage, and department affairs include less trouble than often. We returned to beautiful weather – just a bit warm for me, though, 70’s. Greetings from both of us to Morag and the girls, and to people in the ­department. Yours, P.S. Tim Oakley’s supposed to be here but I haven’t seen him yet. Peter Singer’s giving a paper next month.

  (Peacocke 1979a).

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458.  To Adam Morton, 8 February 1980

81

458.  To Adam Morton, 8 February 1980 [Princeton, NJ] Dear Adam, I’m interested in reading anything of yours, and in particular anything on the  topics you list. I never promise letters of comment. Sometimes I write them ­anyway. I think Harrison’s ‘meing’ might be the same as my ‘self-ascribing’.1 If so, the reason it doesn’t take a propositional complement is that it takes a property complement instead. You can sometimes extract the appropriate property, not in any very nice or uniform way, from the pseudo-propositional ‘that’-clause. Your examples could be written: Ù

Pooh meed x (they were x’s own footprints). Ù Pooh meed x (x is Tigger and x made the footprints). Right, meing (if it is self-ascription) isn’t the same as belief de re of x, where I’m x. Meing is one, but not the only, way to believe de re of oneself. Kaplan’s pants-on-fire man believes de re of himself that his pants are on fire; he believes it of himself under a suitable description, viz. ‘the one I’m staring at’, which is a relation of acquaintance he bears to himself. But he doesn’t believe it of himself under another suitable description, viz. ‘the one identical to me’. That is, he self-ascribes (correctly) the property of staring at someone whose pants are on fire; he doesn’t self-ascribe the property he also has of being someone whose pants are on fire (or more simply, of having pants on fire). Will you be in Bristol at the end of March? We’ll be chasing around on Britrail passes (itinerary unpredictable because the model railway exhibitions are unpredictable) and might try to find you if we’re in that part of the country. Yours,

  Andrew Harrison, then colleague of Morton’s at the University of Bristol.

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459.  To Jerry A. Fodor, 4 April 1980 Princeton University Princeton, NJ Dear Jerry, There’s a thesis dear to my heart which runs as follows. De re attributions of belief are all very well – they’re common among our ordinary belief sentences, they make sense (though maybe they’re a bit imprecise), and so on. But if you want to characterize somebody’s beliefs with a view to explaining his behaviour and the rest of his mental life, you never need them. (Or maybe if you need them, it’s only out of  ignorance; you’d rather explain by citing the de dicto content, if only you knew enough.) The psychological aspect of belief is all de dicto, or better de se; de re attributions mix information about this psychological aspect with information about the subject’s relations with the outer world. I hear you’ve argued something of the sort in print. I’d be very grateful for a reference or offprint, if so.1 Yours, David

460.  To Frank Jackson, 24 April 1980 Princeton University Princeton, NJ Dear Frank, It really does seem that the date on your unanswered letter about the censor is 12 October 1979! How can that be? As soon as it came I made up my mind to get to it in a few days (as soon as my work as bureaucrat in charge of graduate studies let up) and I’ve stuck firmly to that resolve ever since. Here’s your proposal if I have it right. We have a suitable indirect dependence of the experience E1, . . . on the scenes S1, . . . (suitable to make it so that the subject sees, at least if there also is matching and the partitions are sufficiently rich) if for some true C we have   ‘Methodological Solipsism Considered as a Research Strategy in Cognitive Psychology’ (Fodor 1980).

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460.  To Frank Jackson, 24 April 1980

83

S1⁄C S1C⁄E1 S2⁄¬C S2C⁄E2 S3⁄¬C S3C⁄E3 . . . In the censor case, C’s is the censor’s inactivity. And I certainly grant you that if one has the intuition that the man with the censor still sees (and I admit to having the inclination, though I suppress it) then this fits the intuition. But I say that this will be satisfied in cases where there is intuitively no kind of dependence and no ­seeing. Let S1 be the actual scene, and suppose we have one of my cases of veridical hallucination – or it might be accidental with no causal role at all for the external scene – with S1⁄E1 S2⁄E1 S3⁄E1 . . . Take C as the conjunction of biconditionals: S1 º E1 & S2 º E2 & … . Then C obtains; wouldn’t obtain if S2 or . . . were the scene; and together with any Si strictly (hence counterfactually) implies that the corresponding Ei. (If you say that you have to not have S1C ⥽ E1, S2C ⥽ E2, . . . , I think I can provide that by a cheap trick.) So your next move is to put a condition on what sort of thing C can be. Maybe you say it must be the sort of thing that can be a causal factor? Spring is ending, and it’s getting too hot. Fortunately winter is only 5 weeks (and 10,000 miles or so) away. See you soon! We arrive in Melbourne Tuesday 17 June, 19:30 pm, on TE 185 from Christchurch – I hope with all baggage this time. Probably off to Hobart 8:55 am (ugh), Wednesday 25 June, TN 571, but that’s not yet confirmed. Many thanks for all the things from the Bellarine (sp?) Railway. We missed it, though we did stop briefly at their old location in Geelong, and if time permits it would be very nice to go there.

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Greetings from Steffi; and to Morag and the girls. Yours, David PS [. . .]

461.  To John Bigelow, 17 July 1980 [Canberra, Australia] Dear John, Many thanks for your proof-checking. I did fix those (i)’s and (ii)’s between the draft you saw and the final one – and I bloody fixed them wrong, being distracted by the peculiarities of an unfamiliar typewriter! So they’re still wrong on the manuscript as it went to the JPL. Many thanks also for your comments on ‘VH&PV’,1 which I read along with your Brisbane paper (of which I’d seen a draft before, whether the same or not I can’t tell). Some comments. Necessity or sufficiency? More than sufficiency, less than necessity and sufficiency both. Think of it this way. I’m trying to fill in the blank to get an analytic truth of the form: Scene causes matching visual experience ⊃ (subject sees ≡ ------------------------)

and what I put in for ------, if we set aside the rich content condition and the problem about seeing in the dark, is the condition, Condition 1, that there is a suitable pattern of counterfactual dependence. So the thesis is, with obvious abbreviations, □(Causation ⊃ (Seeing ≡ CFD)).

So I claim that causation and CFD are sufficient for seeing; and I’d be vulnerable to counterexamples against sufficiency in which there are causation and CFD but no seeing. I don’t claim that anything is necessary for seeing simpliciter, but do claim that CFD is necessary for seeing given causation. So I’d be vulnerable to counterexamples against (conditional) necessity in which there are causation and seeing but no CFD. The censor example, if accepted as a case of seeing, would be such a counterexample against (conditional) necessity in which there are causation and seeing but no CFD.   ‘Veridical Hallucination and Prosthetic Vision’ (Lewis 1980d).

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461.  To John Bigelow, 17 July 1980

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The censor example, if accepted as a case of seeing, would be such a counterexample against conditional necessity. The pesky light meter, if accepted as a case of nonseeing, would be a counterexample against sufficiency. The pesky light meter. I claim that the victim does see the Mona Lisa when the pesky light meter fires the electrode. The case poses two issues in combination. They don’t worry me separately (and I don’t think they worry you separately, or you’d have raised objections based on simpler cases) so I don’t see why they should worry us in combination. The first issue is what I’ll call the problem of the narrow escape. The actual scene causes matching visual experience as part of a suitable pattern of counterfactual dependence, but a suitable pattern needn’t be a perfect pattern, and there are other scenes which would have failed to cause matching visual experience. So far, no threat; that’s the lesson of the examples of the laser beam and the hypnotic suggestion. The new feature, however, is that the actual scene is in some sense not far from one of the scenes that would have failed to cause matching visual experience. That’s the narrow escape. Luckily it was the Mona Lisa before you – not the Mona Lisa hung upside down, or the Mona Lisa with a large spider crawling over it, or another painting with a similar distribution of light and dark patches, or . . ., all scenes which would have turned on the electrodes and produced non-matching visual experience. But why worry? The mere possibility of scenes which would cause non-matching visual experience doesn’t stop you from seeing; the scene you were actually in wasn’t one of those ones, though it may have come dangerously close to one; so you saw, though you narrowly escaped not seeing. Put it another way. You can discriminate the scene before you from plenty of others. Not from all, indeed not from some of those contrary to the content of your experience. But perfect powers of discrimination – infallible, I mean, rather than perfect in sensitivity – aren’t required. The second issue is what I’ll call the problem of the varying mechanism. Suppose one sort of processing is best for one sort of scene, another for another – edge-detection in the city, point-by-point color measurement for the bush, or something. One sort of prosthetic eye has an all-purpose mechanism, designed as some sort of compromise, and uses it all the time. Another has two special-purpose mech­ an­isms and switches to the one that’s best for the task at hand. Who cares, so long as the device gives you matching visual experience across the range. Still seeing. Now suppose it’s one mechanism for almost the whole range, the other for a small part of the range. Still OK. Now suppose it’s one mechanism for all but the scene S, another for the scene S. Still OK. Now suppose this is not so for reasons of efficient design but by accident. Still OK. Once you accept that the standard process isn’t needed, why balk at the end and say that the process must be like the standard one at least in not

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varying from case to case? (What if the standard one turned out to vary from case to case?) The pesky light meter has the problem of the narrow escape and the problem of the varying mechanism combined. I’m not sure which aspect worries you. Is it the combination of the two problems? If they don’t matter singly why do they matter together? Chris Peacocke seems to worry about the problem of the varying mech­an­ ism – that I take to be the point of what he calls the ‘redwood case’ (if I remember his examples properly).2 Your solution in the 9 July letter, on the other hand, seems aimed at the narrow escape problem. If I thought a solution were needed, I might like something like that – it’s all part of the elucidation of what is a suitable pattern of counterfactual dependence, and that’s the main thing. But if I understand the proposal in the 9 July letter, it seems to me to have a problem. So I’d rather have no solution to the pesky light meter case – that is, I’d rather count it as seeing than doctor the theory so it isn’t. The proposal is that if scene S causes matching visual experience E as part of a suitable pattern of counterfactual dependence (in my original sense) that still isn’t seeing if there are too many alternative scenes Sʹ, Sʺ, . . . that would cause E although E doesn’t at all match them. (‘Too many’ not in number but in range of variety, presumably.) Now consider the hypnotic suggestion case. The guy isn’t on Mars, there are no Martians anywhere, the hypnotic suggestion (a partial censor) is just sitting there quietly, and he’s seeing normally or so it seems. But part of the scene is a nice black cat. In fact he’s getting just the experience he’d have if there were a Martian and the suggestion were doing its stuff. In fact just the experience he’d have if there were one of the sinister shiny black Martians, if there were one of the slimy green tentacle Martians, if there were one of the cute chubby pink furry Martians, . . . (and so on as long as need be to make the alternative causes of E sufficiently numerous and varied). Your solution says that this man, as well as the man with the pesky light meter, doesn’t see. I think both conclusions are wrong, but the conclusion about the man with the hypnotic suggestion, no Martians, and the cat is more clearly wrong. Probably you can doctor the solution to distinguish the cases. Counterfactual dependence and causation. A nice point, and I was certainly a bit confused when I wrote the first paragraph of section IX. The analysis elsewhere is untouched; but the paragraph says about counterfactual dependence of big partitions what really applies to counterfactual dependence of occurs/doesn’t partitions for single occurrences. What seems right is that it is redundant to say that the scene causes, or would cause, the visual experience provided that the fact that the scene is within the ‘large class’ mentioned on page 19 is counterfactually independent of  See Holistic Explanation: Action, Space, Interpretation (Peacocke 1979b, ch. 2).

2



462.  To Steven E. Boër and William G. Lycan, 23 July 1980

87

whether it is or isn’t any of the scenes in the class. That is, there has to be no counterfactual ¬S⁄Sʹ, where S is a scene in the large class and Sʹ is a scene outside such that Sʹ⁄ Eʹ where Eʹ badly fails to match Sʹ. I think the article has gone to the printer, but maybe Farrell (or is it now Ellis?) will let me add a footnote in proof. Thanks. See you soon. Regards from Steffi. Yours,

462.  To Steven E. Boër and William G. Lycan, 23 July 1980 Australian National University Canberra, Australia Dear Steve and Bill, At home I have a heap of pre- and offprints people send me. Everything that comes goes in, and things come out on the principle of quickest first. One thing that makes it not quick to take something out is that I know it’s going to be interesting and I know I’m going to want to write the author a letter. That’s why I’ve taken so damn long getting around to ‘Who, Me?’1 Sorry! I think my main disagreement is with the handwritten heading ‘an attempt at resistance!’ So far as I’m concerned, I think that’s wrong. We disagree less than I think you think, if at all. You think belief de se is belief de re about oneself, but not all belief de re about oneself is belief de se. I agree. You grant that there’s a psychological difference between belief de se and other belief de re about oneself; it’s the ‘first-personish’ sort of belief de re about oneself. So, despite what’s said about ‘glopping’, you’ve got the concept of belief de se. Perhaps what made it seem hard was that you supposed it had to be irreducible to belief de re plus some special feature. My irreducibility thesis is that belief de se is irreducible to belief de dicto, where belief de dicto is belief with a propositional object and a proposition is a set of worlds. Whatever you believe on that question, you don’t dispute my irreducibility thesis in the paper; for what you mean by de dicto is different. The issue reappears in your terms in the following guise. If Ralph accepts some dictum (in your sense, i.e. a sentence) of the form ‘F(a)’ where a is referential, does that mean that Ralph believes the proposition that holds at exactly those worlds where the object denoted by ‘a’ has the property expressed by ‘F’? I’d say not. I think Kripke’s puzzle about belief yields one   (Boër and Lycan 1980).

1

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proof of this, but there are others – consider the case where the property expressed by ‘F’ is contrary to the essence of the referent of ‘a’, yet Ralph accepts the dictum ‘F(a)’ and doesn’t therefore believe the proposition that holds at no worlds. For instance, suppose Saul is right about essences; Ralph reckons this modern scientistic stuff about sperms and eggs is balderdash and the truth of the matter is that we’re brought by storks; Ralph thus accepts the dictum ‘Saul came from no sperm and egg whatsoever’; Ralph does not believe the proposition that holds just at those worlds where the referent of ‘Saul’ has the property expressed by ‘comes from no sperm and egg whatsoever’, i.e. the empty proposition. I think the point could still be made with the aid of more wishy-washy views on essentialism e.g. my own views. So I don’t think I hold any irreducibility thesis that you reject, either about irreducibility of de se to de re or about irreducibility of de se to de dicto in your sense. What we may disagree about is opposite to that. I hold a reducibility thesis that you don’t contest, but that you probably don’t believe since you don’t help yourself to the the­ or­et­ic­al simplification it offers. That is, I hold that the rest of the de re, and the de dicto in your sense and in mine, are reducible to de se. You say: the de se is nothing but a special kind of de re. I say: right, but that special kind of de re is worth singling out because all the rest can be reduced to it. It really can do what de dicto (in my sense) belief was falsely thought to do: it can provide a rich enough system of objects to characterise any system of beliefs whatever. Two caveats. (1) All this is done without consideration of problems about failure of logical omniscience. (2) I’m talking about characterising the strictly psychological aspect of belief, the part in the head; I’m not talking about providing a system of objects rich enough to characterise both the state of the head and its relations to the external world. I question whether that should be done by providing a system of objects at all; though it certainly can be done that way, as it is by Perry. I hope you agree that the theses that de se is reducible to de re and that de re is reducible to de se are compatible. I mean them simply as theses about definability, and I take it that de re and de se are interdefinable, like necessity and possibility. I don’t mean that de se is more basic, more ‘at bottom’, conceptually prior, or whatnot; I try not to have any of those concepts, certainly not to put forward theses involving them! Yours, David PS Beware of using this address. I’ll be here until the AAP at the end of August, but as you know the mail is very slow. The worst case I know (not counting strikes) is 23 days from Princeton to Tim Oakley at La Trobe, first class air mail. Where do they get the special slow airplanes? I’ll be back in Princeton 13 September, though probably not well supplied with time to write letters about philosophy!



463.  To Brian Ellis, 24 July 1980

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463.  To Brian Ellis, 24 July 1980 Australian National University Canberra, Australia Dear Brian, Many thanks for your letter and the draft on de se attitudes and truth-bearers.1 Comments. First a small point. ‘To believe something is not to stand in a relationship of believing to an object of belief’. (Page 1) My first thought was that this was not my view: the self-ascribed properties are the objects of belief. However, I take it that your point isn’t that there aren’t objects of belief; but rather that the believer’s relation to them isn’t appropriately called ‘believing’ since it’s abuse of language to say ‘Brian believes to be editor’ or the like. If that’s the point, I agree. (Though it’s rather special to the case of ‘believing’; ‘Brian expects to be editor’ and ‘Brian wants to be editor’ are fine, and there the infinitive denoting the property which I take as the object of the attitude is indeed the grammatical object of the verb.) Or maybe – I seem to recall this from discussion last year – you think the two points are connected: unless the relation to the property is happily called ‘believing’ – which it isn’t – then the property shouldn’t be called an ‘object of belief’. If so I disagree, but it’s an unimportant matter of terminology. What matters is that for me, as for the propositional object position, beliefs are characterized by a relation of the believer to abstract entities. On truth-bearers and relata of logical relationships,2 I take a pluralist line. I’m willing to call all sorts of different things true – sometimes true relative to something or other, sometimes plain true. Sentence types (regarded as uninterpreted strings) are true under an interpretation, in a context; sentence tokens are plain true, iff the type produced is true under the prevailing interpretation in the context in which it was produced; propositions are true at worlds that belong to them, or true simpliciter iff this world belongs to them; properties are true of things that have them; thingproperty pairs are true iff the thing in the pair has the property in the pair; beliefstates (type or token) that can be characterized by propositional objects are true, at a world or simpliciter, iff their objects are; belief states generally, whether characterizable by propositional objects generally or irreducibly de se, are true for a believer if they are self-ascriptions of a property which that believer has; . . . We can run chains of definitions through these different kinds of truth in various directions. As for which   Untitled manuscript on Lewis’s ‘Attitudes De Dicto and De Se’ (unpublished) 5pgs.   In this manuscript Ellis argued that, if Lewis’s analysis of beliefs de se and de dicto is correct, then ‘beliefs become the bearers of truth, and hence the primary subject matter of logic. For the bearers of truth, whatever they may be, are surely the relata of logical relationships’ (Ellis, untitled manuscript, p. 3). See also Rational Belief Systems (Ellis 1979, ch. 2). 1 2

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is fundamental, I leave that to those who understand what it’s supposed to mean for one concept to be more fundamental than another. So I haven’t the slightest objection to taking beliefs (particular states, which I take to be what you have in mind) as truth-bearers and relata of logical relationships; but I don’t see them as having any exclusive claim on the role. I do think that we’d better not have propositions for our only truth-bearers and logical relata, on pain of leaving out some of the truths and some of the logical relations. Just as my belief that I’m not Hume isn’t a propositional belief, so the truth that I’m not Hume isn’t a propositional truth. It’s a matter of my having the property of not being Hume. Properties will do as a rich enough supply of truth-bearers, though of course I don’t mean to give them an exclusive claim. I want to push the analogy between properties and propositions. Propositions are sets of worlds; properties are sets of anything. Propositions are true at worlds that belong to them; properties are true of things of any sort that belong to them. (I admit there’s a bit of abuse of ordinary language at that point.) Propositional belief is ascription of propositions to one’s world; de se belief is ascription of properties to oneself. Propositions come out as a kind of property: they are properties that belong to nothing but worlds. The proposition that cyanoacrylate is soluble in acetone is the same thing as the property of being a world where cyanoacrylate is soluble in acetone, since both are the set of all worlds where cyanoacrylate is soluble in acetone. Proposition A implies proposition B if any world that belongs to A belongs to B; property A implies property B if anything (possible or actual) that belongs to A belongs to B. A conjunction of propositions is their intersection so is a conjunction of properties. And so on. *** I’m glad to hear the added note can be managed. By all means keep John Bigelow informed. Most likely we’ll see you in early August, when Steffi will be giving a paper at La Trobe and I’ll be giving a paper on counterfactuals (equivalence of my sort of ordering semantics, somewhat generalized, to Angelika Kratzer’s theory) at Monash.3 I’ll be going also to hear Mark Johnston on ‘The Self’ at Melbourne Uni., which I gather will have to do with the de se and all that. Yours, David

  ‘Ordering Semantics and Premise Semantics for Counterfactuals’ (Lewis 1981c).

3



464.  To John Bigelow, 20 August 1980

91

464.  To John Bigelow, 20 August 1980 Australian National University Canberra, Australia Dear John, Many thanks for your paper on vision.1 It makes the case for the augmentation quite nicely. I’m undecided about it – I value the simplicity of the original theory, but I grant that you have some intuitions (which I share) on your side. I’m not sure you can make your case on the strength of intuitions that certain cases definitely are or aren’t seeing. However, as you said at lunch and might say in the paper, there’s another kind of intuitive evidence: one borderline case might at least seem closer to a clear case of seeing than any another, although they satisfy the requirements of my ori­ gin­al theory to exactly the same extent. I like your strategy of starting with the alternative experiences rather than alternative scenes; I rather wish I’d done it that way. Let me suggest that you do away with the p’s and q’s and treat your reader to a more mnemonic notation, or even English! In this letter I’ll use v1, . . . as you do; O for ‘occurs’; M for ‘matches’; s as a variable over possible scenes. Then your q1 becomes O(v1) and your p1 becomes $s(sMv1 ). Why bother to display the quantificational structure? You’ll see. Let me ask you whether you intended the v’s to be mutually exclusive. If they’re maximally specific descriptions of visual experience, they must be; that’s probably your intention. But if they characterize experience by content then maybe they overlap, unless they’re made maximally specific by including a ‘that’s all’ clause. I mean that my experience now might have all the content of my experience a moment ago, and more besides. A moment ago I had v1, and now I have v2. But am I still having v1 as well, seeing that its content is wholly included in the content of my present ­experience? I both expect and advise you to answer: no. But I suggest that you make that explicit. You presuppose that at least some of the v’s have rich content, and that many of them appear (that is, their p’s and q’s appear) in the battery of counterfactuals. I suggest you make both things explicit, lest your conditions, and your reformulation of mine, be trivially satisfied by someone nearly blind. I think the rich content requirement on the actual v ought to be an optional extra for the augmented version just as for the original version, so that you can agree that in some sense we don’t see in the dark.

  John Bigelow. 1980. ‘Lewis on Vision’ (unpublished).

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While I’m on at you to be more explicit, let me suggest that you say what you clearly intend: that not all the p’s need appear as antecedents in the batteries of counterfactuals. The subscript and ellipsis notation has some tendency to suggest the opposite. What you describe as my theory isn’t quite. I’m not one to get especially hot and bothered over it, but still I suggest some changes. Two trivia, two points that matter more. (1) You might mention that I have the optional rich content requirement. (2) You might mention that you’re talking about the purely counterfactual and only implicitly causal version which I committed myself to in Section IX, rather than the explicitly causal version (which I wrongly thought equivalent to it) from the rest of the paper. (3) Now for more interesting points. Your counterfactuals in formulating my theory have a quantificational structure: (B) $s(sMv i )⁄O(v i ). Mine, if I followed your good plan of starting with the v’s, would be (L-) "s(sMv i ⊃ (O( s )⁄ O( v i ))).

(Or roughly so; but the next point makes a further change.) The difference is that your formulation does, and mine doesn’t, make seeing depend on questions of the form: if there were to be some one of the scenes matching vi, which one would (which ones might) it be? You may want these questions to be relevant more than I  do; at any rate on my theory in its simplified, purely counterfactual Section IX ­version, they’re not. (4) If you stick with the (B) counterfactuals, this point may or may not apply; if you switch to the (L-) form or something like it, at least in formulating my theory if not your own, then it does. I say, in specifying a suitable pattern: ‘There is a large class of alternative possible scenes . . . such that . . . any scene in the large class would cause visual experience closely matching that scene. . .’. You need to take the restricted class, rather than all scenes, in view of the laser beam and hypnotic suggestion ex­amples. OK; if we don’t require that the battery contain something for each and every v, aren’t we covered? Somewhat; not quite. Example: the Invisible Deceiver. For every vi, the scenes s such that sMvi divide into those with and without the I.D. in them.2 Since he’s invisible, he can be present without affecting the match. No scene with the I.D. would produce matching experience; every scene without the I.D. would. Hence 2  There is a short, mostly unreadable handwritten marginal remark intended to be inserted as a ­parenthetical qualification at the end of this sentence: ‘(so each ’.



465.  To Robert C. Stalnaker, 14 November 1980

93

no quantified counterfactual of the form (L-) is true. My conditions are satisfied, assuming the I.D. isn’t actually present. So no battery of (L-)’s will quite formulate my view. Nor will a battery of (B)’s – not only for the reason already given, but also because of what happens if too many counterfactuals of the form $s(sMv i )⁄the I.D. is present hold. (Come to think of it, maybe this is the reason already given, restated.) So I think the way to go is to have a variable C ranging over classes of scenes, and restrict the  quantifiers of the quantified counterfactual by turning each (L-) into the ­corresponding (L) "s Î C( sMv i ⊃ (O( s )⁄O( v i )).

Then you put a condition on C: it includes a wide variety of scenes, i.e. it includes scenes that match plenty of different v’s. Call this condition: Big(C). Then you precede the battery by an initial quantifier: $C(Big(C)&……(battery of(L)’s)…………..) I don’t see how you can state my theory without doing something like this; I’ll leave it to you to decide if a similar device would be wanted for your theory, but I think it might. See you; maybe Melbourne early in September between one train and the next, maybe La Trobe next year, maybe . . .? Best to all, Yours, David On rereading this letter I see that I’ve concentrated on quite minor points and omitted to say that I very much like the paper!

465.  To Robert C. Stalnaker, 14 November 1980 Princeton University Princeton, NJ Dear Bob, Between the draft you just sent me and a paper I wrote a few months ago, I think I understand the line you take on the two gods etc. much better than I did before. Let me tell it my way, and invite you to say if I’ve got it right.

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The story begins with Hintikka’s idea of ‘cross-identification by acquaintance’ – e.g. perceptual cross-identification, but generalized to apply also to more indirect relations of acquaintance, e.g. the relation the subject bears to someone he’s heard about by name. If we cross-identify by acquaintance we identify (regard as literally identical? regard as counterparts? place on the same trans-world heir line? – never mind) inhabitants of different worlds who are alike in their relations of acquaintance to the subject, even if different in their origins, famous deeds, natural-kind membership and all those things that are as important in other sorts of cross-identification. In my paper ‘Individuation by Acquaintance and by Stipulation’,1 which ­unfortunately isn’t copyable in its present state, I argued that cross-identification by acquaintance requires prior cross-identification of the subject, which cannot be either by acquaintance or by description. The problem is solved if we take the alternative possibilities not as possible worlds but as possible individuals situated in worlds. Then we cross-identify across alternative possibilities – not alternative worlds! – by identifying things which are alike in their relations to the individuals which are the possibilities in question. Equivalently, we center the worlds, thereby cross-identifying the subject by theft instead of toil. We cross-identify by acquaintance by identifying things alike in their relations of acquaintance to the centers of their worlds. Given the centering, we get the cross-identification by acquaintance. This involves pseudo-haecceitism. We have different possibilities without qualitative differences of worlds. But it’s OK – we don’t have bad haecceitism, nonqualitative ways for worlds to differ. Instead we have different possibilities but not different worlds: different individuals in one world, different centerings of one world. Now some people, for instance Mark Johnston in a recent talk in Melbourne, have said that my irreducibly de se self-ascriptions can be analyzed by quantifying into belief using cross-identification by acquaintance: ∃x(x is the editor & the editor believes that (x is a millionaire)) or something similar, where the style of quantifier or whatnot tells us to cross-identify by acquaintance. Under a suitable resolution of vagueness,* I think this is right. But does it get around the need for centering, or for the distinction between possibilities and possible worlds, which I claim is needed to handle de se belief? – No, the cross-identification by acquaintance itself requires them, since you can’t cross-identify by acquaintance without first cross-identifying the subject. Now, I see you as standing the connection between centering and cross-­ identification by acquaintance on its head. (By which I don’t necessarily mean that

  (Lewis 1983a).   Namely, one that makes the self-acquaintance one has by being oneself always outweigh the selfacquaintance one has e.g. by seeing oneself. 1 *



465.  To Robert C. Stalnaker, 14 November 1980

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you have it the wrong way up – I lack the concept of conceptual priority – but just that you have it the other way up from me.) I said: given the centering, we get the cross-identification by acquaintance. You say: given the cross-identification by acquaintance we get the centering. That is, we don’t need to build in the centering; we read it off from the cross-identifications. Suppose given the worlds, including perhaps different worlds that are qualitative duplicates. And suppose given the cross-identifications which, when we are done, we will regard as cross-identifications by acquaintance for a certain subject. At this stage we’re not in a position to call them that; for we can’t say that they work by identifying things alike in their relation to the subject since we’ve yet to find the subject. (It’s enough to find him at one world, we thereby find him at all, or all where he is. For we have the cross-identification of the subject, along with the cross-identification by acquaintance of various other things.) Now we can find the subject: he’s the one such that cross-identified things are alike in their relations of acquaintance to him. Take the case of twin prisoners in duplicate dungeons. We have two qualitative duplicate worlds, and we have lines of cross-identification (red), and we have relations of acquaintance (blue).2

We can tell that the subject is in the lower dungeon in world 1, and in the upper dungeon in world 2: his relations of acquaintance set up lines of cross-identification between prisoners, dungeons, and cats, whereas the other guy’s don’t. Now complicate matters by switching to the case of the gods, so that each is acquainted with everything. We now get fissions and fusions of the lines of cross-identification, since there are two different ways for a god to be acquainted with something. (So we’d 2   All three solid lines from the prisoner, cat, and dungeon in world 1 to the prisoner, cat, and dungeon in world 2 were coloured red. The relations of acquaintance that were coloured blue are the little arrows inside each dungeon that originate from each prisoner.

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­better not say the identifications involve literal identity. But even without crossworld identity, there’s still the part of haecceitism that says there are non-qualitative differences of worlds relevant to cross-identification.) You’ll notice that I’ve included some thought-tokens to be among the things for the gods to be acquainted with, and I’ve provided for a special kind of acquaintance with one’s own thought-tokens, alongside the acquaintance that a god has with everything in his world. I’m going to leave out the blue arrows for the relations of acquaintance by divine, perspectiveless omnipercipience; the cross-identifications they give rise to are shown in dotted red, and agree with cross-identification by description, and don’t do anything to help us find the subject. But I will draw blue arrows for the relations of acquaintance that each god bears to himself and to his thoughts, and solid red lines for the corresponding lines of cross-identification by acquaintance. (The solid red lines fiss and fuse with the dotted red ones.) Now we can find the subject: He’s the god on the tallest mountain at world 1 and the god on the coldest mountain at world 2.3

Now if my telling of your position is right, what of its merits? First, if you insist on identifying possibilities with worlds, then you are identifying by acquaintance across worlds, in which case I think you have to have the haecceitistic differences between duplicate worlds. Anyway, you have to have them just because you want to say that

3   The solid and dotted lines that extend across both worlds were coloured red. The little arrows that turn back to the respective god or thought-token were coloured blue.



466.  To Sydney Shoemaker, 2 December 1980

97

the gods’ ignorance is after all ignorance of which of the duplicate worlds they’re in. But maybe the haecceitistic differences aren’t so bad for a moderate realist as for me – certainly this is so in the case of Bob Adams’s sort of moderate realism. Second, I think that once you see how easy it is to get back and forth between cross-identification by acquaintance and centering, you should find it no more and no less objectionable to build one into your system of worlds as given than the other. Third, I think the cross-identification you rely on is by acquaintance. So I think you’ve really given me my point. You give an account of de se belief by building in extra structure into the system of worlds that serves to mark the subject, albeit in a roundabout way. This structure isn’t built in once and for all; it’s different in the treatment of your beliefs and of mine, since your cross-identifications by acquaintance are different from mine. (Put both sets of red lines in all along, and you still can’t find the subject.) So it’s the sort of built-in feature that you meant to reject, being subjective or in­dex­ ic­al or egocentric or whatever you want to call it. Further, your choice of extra structure is such as to stick you with haecceitism instead of pseudo-haecceitism, but that may be no problem given the rest of your position. Yours,  David cc: Mark Johnston

466.  To Sydney Shoemaker, 2 December 1980 [Princeton, NJ] Dear Sydney, Many thanks for your ‘Varieties . . .’1 which I’ve read with much interest and liked. No comment on CTP and CTP-functionalism, except that I’m very interested and would like to have clearer views. I’ve been recently thinking about related matters in connection with David Armstrong’s proposals about necessary connection, over which he and I have had a running argument. Until lately, I thought all there was to the problem of universals was the question a Quine student would naturally have in mind: what do we quantify over when we seemingly quantify over universals? (To which I remain content with the answer: sets of possibilia.) There’s more to it, but I’m unclear how to formulate the more. Enough. Let me comment on the parts of ‘Varieties . . .’ having to do with me.

  ‘Some Varieties of Functionalism’ (Shoemaker 1981).

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Page 11: ‘Lewis does not say much about what constitutes a “population” and what constitutes membership in a population’. Second things first: a population is a set and membership is membership. (Maybe it’s a set of partly unactualized possibilia, but that’s still just a set.) But which sets count? I deliberately don’t say much – one of my points is that it’s indeterminate, we haven’t made up our minds when we didn’t have to. Make puzzle cases – humanoid freak Martians, or humans born of Martian parents – and I’ll say there’s no fact of the matter: either population has a claim to be considered the reference population, and that’s all there is to it. Then also it’s indeterminate whether the freak is in pain, if the freak is in a state that occupies the role for one candidate reference population and not for the other! Page 12: Yes. Make a place for mad pain in the only way a materialist can (I think), and the price you pay is that pain comes out non-intrinsic. ‘A creature could fail to be in pain despite being physically indistinguishable from a creature which is in pain’ due to differences in other members of the respective reference populations. This is surely the most counterintuitive part of my view, but I think making no place for mad pain or making a place for it at the expense of materialism would be even worse. I take comfort from the thought that all sorts of things turn out to be less intrinsic than they seem, according to other views I hold. (It cuts two ways – so much the worse for those of other views, maybe.) In particular, how about normal pains? Or better, how about pain in a unique being, for whom the only available reference population is a set of which he is the sole member? Then at least the question is whether he’s in a state that occupies the appropriate causal role for him. But that’s a question about the causal relations of his states; causal relations depend on the laws of nature; laws are at least regularities, whatever else they must also be; regularities are subject to counterexamples anywhere in the universe. So it seems that whether my sprained ankle is giving me pain right now (or better, whether the unique being’s ankle is giving him pain) is at least partly a matter of the global patterns in virtue of which the laws, and hence local causal relations, are as they are. So either I’d better change my mind radically about laws and causation, or I’d better not set much store by intuitions about what’s intrinsic. Incidentally, you don’t need the Martian freak to make the point that given my provision for mad pain, pain comes out non-intrinsic. I would think of it first as the point that I and my unactualized counterpart might be physically indistinguishable, yet one in pain and one not, because of differences in our human worldmates. (Still, I suppose this example is only open to an extreme modal realist.) ‘. . . a view which it ought to be difficult for a materialist to stomach’ seems a little misleading. The materialist has no special brief for things being intrinsic. A dualist thinks physical duplicates might differ in their pain because physical differences



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aren’t the only differences; a materialist of my sort might think it because intrinsic physical differences aren’t the only physical differences. Agreeing with a dualist thesis for non-dualist reasons doesn’t give away any materialism. I think the point comes perfectly clear later in the paragraph, but the quoted line seems to point in the wrong direction. Page 12. ‘But this . . . is ambiguous’. I definitely meant core realizations all along. Page 13. ‘But now the question is, why should we allow that the madman has . . . pain?’ I didn’t mean to argue the point. I imagined myself arguing with the dualist who appeals to intuition that mad pain is possible, where the kind of mad pain in question is to be so mad that it does not at all occupy the causal role of pain, not even when the causal role is given all the necessary qualifications – made a cluster, stripped of more superficial causes and effects, made probabilistic, and whatever else is needful. And I imagined myself reluctantly admitting that I shared this intuition to some extent, and casting about for a way of accommodating it. If the intuition isn’t there, or needn’t be respected, so much the better for materialism – then a more straightforward functionalism will serve. And indeed I don’t respect the whole of the intuition the dualist appeals to – there can be mad pain (thoroughly mad) and it is intrinsic – so I can’t go on all the way taking the line: yes, I have those intuitions too, but they don’t support your view over mine. Incidentally, what do you think of the view that the madman is in pain in a ‘special’, ‘attenuated’, ‘peculiar’, or otherwise stigmatized sense; whereas one who is a typical member of a (uniquely) appropriate reference population, and who has a state occupying the role of pain in his own case, is in pain in a ‘principal’, ‘standard’, ‘full-blooded’, . . . sense? I find it hard to deny that the madman is in pain in some sense; but I wouldn’t mind calling the sense in which the madman is in pain various rude names, if I knew better what those rude names meant. (This, I think, is David Armstrong’s inclination.) One can then say that pain in the ‘principal’ sense is intrinsic; or at least that it doesn’t fail to be intrinsic in the way that anything causal does. Page 17. If I’m a functionalist (question of terminology, not lack of self-knowledge!) then I’m an analytic one. The platitudes themselves aren’t exactly analytic – not to evade, let me just say they’re synthetic – but something in their vicinity, a sort of doctored version of them, is analytic. Let’s add the complications step by step. (First approximation) Each and every one of the platitudes is analytic. (Second approximation) The only possible way for the platitudes to be false is  for them to be unrealized and for the mental terms to be denotationless. So a ­conditional whose antecedent says that there are such states as pain, . . ., and whose consequent is the conjunction of platitudes is analytic.

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(Third approximation) As above, except that it isn’t a conjunction but a cluster – a disjunction of conjunctions each of which contains most of the platitudes. That is, there’s an analytic truth to the effect that unless there are no such states as pain, . . ., most of the platitudes are true. (Fourth approximation) As above, except that we draw on theories of verisimilitude – which theories are a bit underdeveloped, I admit – to make a consequent fancier than just a cluster: a consequent that will be true iff enough of the platitudes are close enough to the truth. More simply: iff common sense psychology as a whole is close to the truth. Let common sense psychology be theory T; let T* be a theory which is plain true iff T is close to the truth. It’s analytic that unless there are no such states as pain, . . ., then T* holds. (Fifth (and final?)) Since we haven’t given precise sense to our words, it’s in­de­ter­min­ ate just what is and isn’t analytic. Every resolution of the indeterminacy makes some conditional of the form just considered come out analytic, but maybe different resolutions make different versions come out analytic. The difference might be partly a difference in what gets included in T in the first place, but mostly a difference in exactly how we pass from T to T*. Yours,

467.  To Laurence Nemirow, 20 February 1981 [Princeton, NJ] Dear Professor Nemirow, Last year I lectured at various places in Australia and New Zealand about Tom Nagel’s bat, and I was about to begin writing a paper called ‘Knowing What It’s Like’, when I read your review1 of Mortal Questions and wondered whether I had anything to add to what you’d already said. The line I was taking went this way. A materialist would do best to concede that no amount of knowledge of the behavior and behavioral dispositions of the bat, no amount of knowledge of the causal roles and physical realisations of the bat’s inner states, no amount of similar knowledge about other bats, . . . no amount of any kind of information the materialist believes in would en­able one to know what it’s like to be a bat. But the materialist needn’t concede that this goes to show that he still lacks some kind of nonphysical information. Rather, it goes   ‘Review of Thomas Nagel’s Mortal Questions’ (Nemirow 1980).

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to show that knowing what it’s like is only partly a matter of possessing information; partly it’s a matter of being able to imagine, and partly it’s a matter (this part I’m not sure of) of having been in the bat’s states oneself. (Cf. knowing Lloyd George. Father can’t know L.G., it’s too late. No amount of biographical information will help. So what he needs is some special sort of nonbiographical information?) We tend to run the informational part, the ability, and the past experience together as a single state of ‘knowing what it’s like’ because ordinarily they go together, but it remains possible to fail to know what it’s like without lacking any of the informational part. All this seems very much the same line I read in your review. Therefore, two requests. (1) Is your thesis2 available through University Microfilms? If so, can you tell me a price and order number? (2) I’d very much like to see any papers of yours on this or related matters, either thesis-descended ones or later ones. Many thanks for any help you can give me. Sincerely, David Lewis

468.  To D.M. Armstrong, 11 June 1981 La Trobe University Melbourne, Australia Dear David, This letter is a reply to points 4 and 5 in your comments on Jackson, Pargetter, and Prior, ‘Functionalism . . .’1 – since I’m in pretty complete agreement with JPP, I suppose I owe you a reply as much as they do! I don’t think there should be any great mystery about why we think that nonrigid designation of properties makes for a distinction between such-and-such property and (what we may call) the property of having such-and-such property. For instance, if the sky is blue and all trees are 20 meters high and C-firing is the state that occupies the pain-role in all earthly creatures, then blue = the colour of the sky ≠ having the colour of the sky; height of 20 meters = the height of trees ≠ having the height of trees; C-firing = pain ≠ having pain.   Functionalism and the Subjective Quality of Experience (Nemirow 1979).

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  ‘Functionalism and Type-Type Identity Theories’ (Jackson, Pargetter, and Prior 1982).

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But we think this because we believe something you reject. Your objection should be to this premise of ours, not to the use we make of it in arriving at distinctions like those above. The premise, of course, is that properties are far more abundant than you think they are. I know from what JPP wrote that they agree on some version of the abundance premise, though I don’t know quite how far they’re prepared to go. I  myself go quite far: as a class-nominalist about what properties are (though not about what analytical purposes they can serve!) I think that properties are as abundant as classes, and classes are very abundant indeed. Let me state the abundance premise vaguely, failing to tell you what I mean by the word ‘condition’. Abundance: for any condition C, there exists a property P such that, for anything x at any possible world w, x has P at w iff x satisfies condition C at w. (Perhaps some or all of JPP would prefer modality to this quantification over worlds; it doesn’t matter.) Some conditions are expressed by predicate phrases; the gerunds of such phrases denote properties; and we can write down the following semantic rule for gerunds. Gerund Rule: if predicate phrase Φ expresses condition C, then the gerund Φing rigidly designates the property P such that, for anything x at any possible world w, x has P at w iff x satisfies condition C at w. The Gerund Rule is quite natural given Abundance; quite unreasonable without. We would expect you to object to it as follows. ‘Some predicate phrases, perhaps most, express conditions such that no one property is necessarily shared by exactly the things satisfying the condition. That is, in some of most cases the part of the Gerund Rule beginning with the words “the property P such that” is an improper definite description, hence denotationless. So your Gerund Rule makes some or most gerunds denotationless – which surely isn’t right. Hence as a denier of Abundance, I need a substitute for the Gerund Rule’. Perhaps I part company with JPP slightly over the Gerund Rule. They write as if they take it entirely for granted. (Since it would be foolish to accept it, still less take it for granted, if they rejected Abundance, I have inferred that they accept Abundance in some sufficiently strong version.) I think of it as a semi-technical regimentation of ordinary English, one which fits usage but may not be the only semantic rule for gerunds that would fit usage. I think you could find a substitute rule for gerunds that would fit ordinary usage about as well as ours. Be that as it may, the distinctions between pain and having pain, etc., depend on the Gerund Rule. If you reject the Gerund Rule, as someone might on linguistic grounds and as you ought to on metaphysical grounds, these distinctions go away.



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Or rather, our way of expressing them goes away, though more long-winded ways are still possible. Consider a possible world where the sky is red and a certain apple also is red. At that world, ‘the colour of the sky’ non-rigidly designates red, just as at our world it non-rigidly designates blue. (Let’s not worry about the risk that the colours themselves aren’t genuine properties on your view – switch examples if need be.) So the apple under the red sky satisfies at its world the condition expressed by ‘has the ­colour of the sky’. By the Gerund Rule, therefore, this otherworldly apple has the property rigidly designated by ‘having the colour of the sky’. But it does not have the property non-rigidly designated by ‘the colour of the sky’, for that is blue. (I mean, of course, the property non-rigidly designated at this world by ‘the colour of the sky’; we are still here, after all, and haven’t taken a trip to the world we were talking about.) So the properties designated (at this world) by ‘the colour of the sky’ and ‘having the colour of the sky’ aren’t the same, since this otherworldly apple has one but not the other. (Perhaps my allies would prefer to put this in a modal or counterfactual way – again it doesn’t matter.) No similar counterexample to identity would have been forthcoming if we’d started with a rigid designator of a property, say ‘sphericality’. (Again, switch examples if need be.) For anything x at any possible world w, x has the property actually (and rigidly) designated by ‘sphericality’ iff x satisfies, at w, the condition expressed by ‘has sphericality’. So the property designated by ‘having sphericality’ according to the Gerund Rule is the same as the property designated by ‘sphericality’ itself. (Here I’ve taken for granted something else that’s controversial: namely, that no two properties are necessarily coextensive. Actually, I took that for granted some while ago, when I started writing descriptions of the form ‘the property P such that for anything x at any world w, x has P at w iff . . .’, since if there were distinct ne­ces­sar­ ily coextensive properties, such definitions would sometimes or always come out improper. I wonder whether I’m on safe ground in saying that JPP join me in accepting this premise. Something you told me last week suggested that Pargetter might distinguish sphericality from having sphericality, though the two are necessarily coextensive; in which case Pargetter couldn’t accept the Gerund Rule as I formulated it, though he might accept one enough like it to give the same account of why the colour of the sky ≠ having the colour of the sky, and so on.) The end of your point 5 raises a question about intensional logic. Let us use ‘C’ as a free variable ranging over properties, ‘A’ as a non-rigid designator of a certain property, ‘B’ as a rigid designator of the very same property. We say: having B = B = A ≠ having A. So are we to conclude that a certain property, the one designated rigidly

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and non-rigidly by ‘B’ and ‘A’ respectively, satisfies the formula: having C = C = C ≠ having C? Or that it satisfies both of the formulas: having C = C and C ≠ having C? No. The inference from . . .A. . . to the conclusion that the thing designated by A satisfies . . .C. . . is fallacious when the formula is modal and A is non-rigid. The inference from pain ≠ having pain to the conclusion that a certain property, namely the one designated by ‘pain’, satisfies the formula C ≠ having C is an instance of this fallacy. So is the inference from the number of planets was recently discovered to be nine to the conclusion that some number satisfies the formula n was recently discovered to be nine. In modal contexts, it’s fallacious to apply the ordinary quantifier rules to non-rigid designators. A gerund, as we claim, is a modal context, as you can see by examining the Gerund Rule; though this will be controversial, since if on linguistic or metaphysical grounds you prefer a substitute Gerund Rule, that may very well not be a rule that makes gerunds be modal contexts. Yours, David cc: JPP

469.  To Max Cresswell and Arnim von Stechow, 17 June 1981 La Trobe University Melbourne, Australia Dear Arnim and Max, (Max: I don’t have a full address for Arnim, so could you please send on his copy of this – thanks.) Thank you for the draft on de re belief,1 which just arrived. I certainly like the main idea; however, I’d like to be clearer on its relation to Bob Stalnaker’s ideas, which I also liked as an approach to mathematical ignorance and error. I’ve looked especially at Appendix 2, and I’m afraid I think you’ve misunderstood me. If I ‘give the impression that de re belief is unlike de se belief and can be reduced to propositional belief’ that’s unfortunate, for that’s not at all what I think. (And not what I thought when I wrote ‘Attitudes . . .’2 – I’ve not changed my mind.) Here’s my position, as I hope it is expressed in ‘Attitudes . . .’.

 ‘De Re Belief Generalized’ (Cresswell and von Stechow 1982).  ‘Attitudes De Dicto and De Se’ (1979a).

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(1) De se belief is like de re belief, in that de se is a special case of de re. (2) De se belief cannot, in general, be reduced to propositional belief (in my sense of ‘propositional’, which is the same as yours: belief for which the objects can be taken as sets of worlds). (3) Hence at least some de re belief cannot be reduced to propositional belief; there is no general reduction of de re to propositional. (4) What there is, however, and what is presented in ‘Attitudes . . .’, is a general reduction of de re to de se. The general case (de re) reduces to its special case (de se). (5) Not just a few exceptional cases of de re belief, but rather the majority of cases (believing of Ortcutt that he’s a spy, having glimpsed him in suspicious circumstances) involve irreducibly de se belief. Suppose we set out, as you and I all do, to analyze de re belief as belief under a ‘suitable description’. Let’s stick to linguistic descriptions, as it helps me in making the point that follows, though we agree that this won’t do in the end. Descriptions might be non-egocentric, like ‘the shortest spy’, ‘the philosopher who has most often crossed the equator’, ‘the politician whom people call “Piggy” ’. Other descriptions might be egocentric, like ‘the person I’m now watching’, ‘the person I am’, ‘the person I’ve heard of/ person I’m now in a position to refer to/source of the mental representation I’ve filed/. . . under the name “Piggy Muldoon” ’. Non-egocentric descriptions correspond to properties, egocentric descriptions correspond to relations. Thus ‘the shortest spy’ corresponds to the property that belongs, at any world w, to the shortest of the spies that inhabit w; whereas ‘the person I’m now watching’ corresponds to the relation that obtains, at any world w, between any pair of inhabitants of w (take them as momentary) of which the first watches the second. So we can trade in our linguistic descriptions on properties or relations, and then introduce further properties or relations that don’t correspond to linguistic descriptions. Fine; but for ease of ex­pos­ ition, let’s stick to linguistic descriptions. When I ascribe a property to someone under a non-egocentric description, my belief may be regarded as propositional. I believe of Fred, under the description ‘the shortest spy’, that he’s crafty. (Not a case of de re belief yet, since the description isn’t suitable, but that’s beside my point.) Then Fred is the shortest spy, and I believe the proposition comprising just those worlds w such that the shortest spy of w is crafty. When I ascribe a property to someone under an egocentric description, my belief cannot in general be regarded as propositional. It sometimes must (and always can) be regarded as self-ascription of a property. I believe of Fred, under the description ‘the person I’m not watching’, that he’s crafty. (This time the description is suitable, and it is a case of de re belief.) Then Fred is the person I’m now watching; and I believe that the person I’m now watching is crafty, or in other words I self-ascribe the property of watching someone crafty (and no-one else).

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I believe of myself, under the egocentric description ‘the person I am’, that my pants are on fire. The description is doubly suitable. It’s a case of de re belief; and it’s a case of the special kind of de re belief that is de se self-ascription of the very same property that’s ascribed de re. (As opposed to the previous case, in which the property ascribed to myself de re wasn’t the same as the property ascribed to myself de se.) Then I am the person that I am (that’s easy!); and I believe that the person I am has pants on fire, or in other words I self-ascribe the property of being someone with pants on fire, or in other words I self-ascribe having pants on fire. ‘Suitable descriptions’, we agree, always or mostly have to do with the believer’s epistemic access to the thing described. If so, suitable descriptions will always or mostly be egocentric. They will have the form: the one that I am in epistemic rapport with in such-and-such way. So the typical case of belief de re will be a case of ascribing a property to someone under an egocentric description involving a channel of epi­ stem­ic access. In other words, taking the postponed step of trading in linguistic descriptions for properties or relations, the typical case will be one in which the description is a relation, not a property. This is the crucial point: if we analyze de re belief in terms of belief under a suitable description, then when the description becomes egocentric, the analysans becomes de se. Or, in the non-linguistic improved version, when the description is taken as a relation rather than a property, the analysans becomes de se. Something of a form which, at first, looks like a reduction of de re to de dicto turns out to be a reduction to de se instead. In ‘Attitudes . . .’, this happens on 538–9. The preliminary version on 538 has it that description Z is a property it is objected that this requires the subject’s belief to be propositional; so on 539 we get a final version in which the description Z is taken as a relation, and instead of believing a proposition (as in the preliminary version) the subject self-ascribes the property of bearing relation Z uniquely to something which has [the ascribed] property. ‘Now for belief de re . . .’ and it turns out that the suitable description of the relation Z is to be a relation of acquaintance (539). There should have been a conspicuous announcement: here the project turns into a reduction to de se, rather than a reduction to de dicto. So – what does all this say about your draft? Mostly, the effect is confined to Appendix 2. You grant the irreducibility of de se; agreed. You take it that de se and de re stand and fall together, so far as reducibility to de dicto goes; agreed, contrary to the impression I gave. You think the view that ‘de se belief is basic in a way in which [de se (presumably)] belief is not’ is unsupported; agreed, more or less, since I think de re and de se are interdefinable, and I don’t understand issues about which is more basic of two interdefinable notions. You offer to eliminate the need for self-ascribed properties as irreducible objects of belief. Not agreed; de se belief and de re belief about oneself both involve properties ascribed to oneself, and to get rid of self-ascribed



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properties you’d have to reduce de re, including the special case of de se, to prop­os­ ition­al. I never claim to accomplish this; you seem to claim it, but retract the claim on page 26, lines 3–5. Also ‘admits’ on page 25, line 10, is out of place, since what is ‘admitted’ isn’t damaging – it would be highly damaging if I claimed that de re is reducible to de dicto but de se isn’t, but as I don’t claim that, saying what I do makes no problem. Earlier, page 6, you’ve said that you offer an account of de re belief in terms of the relation of doxastic alternativeness. That means a reduction to de dicto, to prop­os­ ition­al belief. This is a belief-under-a-suitable-description account. You briefly say, middle of page 6, that the suitable description might be a relation, but you don’t follow this alternative up. I say: (1) in most or all cases, it had better be a relation. If you try to have ξ always be a property – a non-egocentric description – things won’t come out right. But (2) if you do let ξ be a relation, what you get no longer is an account of de re belief in terms of propositional belief, doxastic alternative worlds. (Doxastic alternatives, yes. But not doxastic alternative worlds. Your doxastic alternatives are the possible (in some cases, actual) individual you might, given your beliefs, be. Mutatis mutandis, the structure of Hintikka’s story carries over. The content of your system of beliefs is given by your set of doxastic alternatives. A set (of things of the right sort, viz. possible individuals) is an object of your belief iff all your doxastic alternatives belong to it – such a set being one of your self-ascribed properties.) As for (1) above, why do I say that suitable descriptions had better be relations often and maybe always? Well, consider the substitutes you offer, namely such properties as: the property of being the thing which Arnim is looking at. (Page 6, names changed.) Well, consider this. Arnim is looking at Max. Max has the property of being the thing which Arnim is looking at. Arnim believes the proposition that Arnim looks only at logicians; Arnim has taken the notion that Arnim is a peculiarly single-minded scholar. (Arnim also believes that Arnim never fails to look at one and only one person.) So Arnim believes the proposition that the thing which Arnim is looking at is a logician. So Arnim believes of Max, under the description ‘the thing that Arnim is looking at’, that he is a logician. So if that is a suitable description (suitable property, as you have it) Arnim believes de re of Max that he’s a logician. But it needn’t be so. Arnim, alas, has gone around the bend. He thinks he spends all his time in the company of famous statesmen, and never has met or heard of any logicians. (He thinks: how different am I, who never look at logicians, from that poor scholar Arnim, who never looks at anything else!) Arnim, of course, thinks that he himself is not Arnim. He thinks: ‘this man I am looking at is no logician, but is the New Zealand minister for railways’, thus having a false de re belief about Max under the description ‘this man I am now looking at’. Then I say it is not so that Arnim

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believes de re of Max that he is a logician, though the conditions you gave are satisfied. In short, the non-egocentric description ‘the one Arnim is looking at’ is unsuitable for de re belief (even when Arnim is the subject); what you need is the egocentric ‘the one I am looking at’. When Arnim believes that he himself is Arnim, as well he might, the difference won’t matter: if he believes that the one Arnim is looking at is a logician, he’ll also believe that the one he himself is looking at is a logician, so he’ll have the de re belief of Max that he’s a logician. But it’s only a matter of good fortune that Arnim does believe that he himself is Arnim, it might not be so. Yours, David cc: Bigelow PS I’ve talked to John Bigelow a bit about this and about your paper, though by your instructions I’ve not made him a copy or shown it to him. May I? We are both interested in the question whether your treatment does indeed avoid the need for a hierarchy of BELIEVEs, and don’t quite see how it does.

470.  To Kim Sterelny and Frank Jackson, 22 June 1981 [Melbourne, Australia] Kim & Frank Some comments on Kim’s comments on ‘Ep. Qualia’.1 p1. ‘in terms of information’ ≠ ‘linguistically’. Expressive limitations of language aren’t relevant. Suppose someone is in pain iff the number of C-firings per second in him is the Gödel number of a true sentence of the language of physics, whatever that is. (No anatomical limit on possible rate of C-firing.) Can’t be finitely said in the language of physics that I’m in pain That’s a lousy supposition, but it isn’t nonphysicalistic! Physical information still settles whether someone is in pain. I’d say that physicalism is something like the thesis: no differences without physical differences. Maybe ‘physical difference’ is to be explained linguistically – though I’m not convinced of that – but this still doesn’t restrict information to what’s expressible in any particular language.

  ‘Epiphenomenal Qualia’ (Jackson 1982a).

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p2-mid. The freak should have the Nagelian meaning throughout; and the ­physicalism he’s refuting should be not ontological physicalism but informational physicalism, as above. pp 3–6, Reply #1. I don’t get this. I like the reply that Fred has no information that the physicists lack, rather he has extra capacities. But that doesn’t mean scepticism about colours. There are colours, there is colour information; blind physicists have it all, Fred has no more, maybe he has less; the special thing Fred has is a capacity. pp 3–6, Reply #3. If #1 is modified as above, then #3 is compatible with #1 and we should buy both. pp 3–6, Reply #2. Can this reply be redone if, as I believe, knowledge is not a relation to sentences or anything with sentence-like structure? p7 middle. I agree with Kim that there’s a puzzle here. In this world Fred has C-firings, physicalism is true, C-firings play the role of pain, Fred is in pain. In another world there are extra nonphysical whatnots, everything physical is just the same, physicalism is false, the whatnots stop the C-firings from playing the role of pain, Fred is not in pain. So a physical duplicate of Fred, in a physically duplicate world, might lack pain – might even lack mental life altogether. But it’s not that he lacks something nonphysical that we have; vice versa, he has whatnots that we lack. As a physicalist, I still find all this OK. Here’s the point: if my physical duplicate and I differ mentally, phys­ ic­alism is false for one of us. One of us has features additional to those of his physical replica. But why should I be the one? Why not him? The freak says: because I have the qualia, and they’re the additional feature. But we shouldn’t buy that. So my loose formulation of physicalism ‘No differences without physical ­differences’ isn’t right. It’s a formulation of noncontingent physicalism. How do we fix it? ‘No differences between physicalistic worlds without physical differences’ – true, necessary but silent about what sort of world ours is, so not a formulation of physicalism. It tells you that whenever two worlds differ without physical difference, then one of them is nonphysicalistic. But it doesn’t say which one. ‘Our world is such that there’s no difference between it and any physicalistic world without physicalistic differences’. True, but the idea obviously can’t be made into a definition of ‘physicalistic world’. ‘Our world is such that whenever it and another world differ without physical difference, that other world is more inclusive than ours. It has (duplicates of) everything our world has, and more besides’. I don’t like this. Does it have to be extra things that make the other world nonphysicalistic? And on my view of properties (classes of

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possibilia) there’s no sense in which one world contains more properties than another. Not even: in which a world contains a property. Believing in Armo-style universals would be good for me here. (They needn’t replace my abundant classes of possibilia; I tentatively admit that I need something beyond the resources I’ve got. But is it ontology of universals I need? Or are there other remedies that would do as well? (Related thing I’ve been worrying about. Physics discovers a ‘new property’ of elementary particles: charm, or what have you. Some actual and possible particles have it, those in class C, the rest lack it. What’s the news? I already thought there was a property common to all and only the particles in class C! Properties are cheap.) (What a long comment on a short comment) p10. The epiphenomenalist can have qualia making a difference to qualia all over the place. He can say that a belief has a qualia-part and a physically ­efficacious part. Where Kim says ‘beliefs are causally efficacious’ he should add ‘in the physical world’ to make his point stick. p11. If Kim grants that an intuition could be overturned, he should grant that it’s possible for it to be false but not overturned (unless he’s some kind of verificationist). So if you can’t possibly confirm any theory that there are epiphenomena, that doesn’t mean there aren’t. Anyway, Frank qua freak probably thinks it’s well confirmed for each of us that there are qualia, and the part about their being powerless is getting gradually confirmed by the success of qualia-free physics. pp. 14–16, heading #1. The freak can say that beliefs, in the full sense, have an epiphenomenal part and a physical part. The physical part is what has physical effects, e.g. in behaviour. But someone who had just the physical part wouldn’t believe anything. The epiphenomenal part of a belief depends partly on the physical part, partly on previous qualia. The epiphenomenal part of my belief that I saw something red yesterday would have been different, and the belief as a whole would not have been a belief in the qualia that it is in fact a belief in, had my qualia yesterday been different. Then the freak’s belief in qualia does (in part) depend causally on those qualia. Given this line of defence, I think what Kim says works only against a pretty half-hearted freakery, one that gives beliefs away completely to the opposition. Still, it remains that the epiphenomenalist freak must admit that the philosophical words from his mouth and pen depend not at all on the qualia whereof he speaks. That seems to me pretty bad. He may indeed hope that his words will stimulate (the epiphenomenal part of) belief in qualia in those who hear them, but that



470.  To Kim Sterelny and Frank Jackson, 22 June 1981

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hope – at least the epiphenomenal part of it, which is the only part produced by qualia – does nothing to cause the words. Here is another argument, based on Kim’s, that epiphenomenalist freakery must not be too half-hearted. Yesterday’s qualia are remembered today. According to the freakish line as I’ve imagined it, today’s mental epiphenomena depend on yesterday’s, they aren’t fully determined by today’s physically efficacious states. But I spent some of last night in dreamless sleep. So what are the links in the causal chain from yesterday’s epiphenomena to today’s? Not physical states, by physical inertness of the epiphenomena. Not conscious epiphenomenal states, by lack of consciousness in the night. Either (1) the epiphenomenal causal order has causation over time gaps, causal discontinuity, or (2) it consists not only of conscious states. (I’m not sure either horn is terribly damaging to the freak, however.) To go with Kim’s arguments that the freak had better embrace interactionism, here’s an argument that he’d better not. (Besides the main, but futuristic argument from the triumph of physical science.) Suppose qualia were causally efficacious. Then we could get a handle on them, describe them, by their causal powers. But now the knowledge argument can be turned against the interactionist freak; for now there is a way to give information about qualia to one who hasn’t had them, yet he still won’t know what it’s like! Countermove: qualia have causal powers in the physical world; up to a point they can be described by speaking of their powers, but beyond that point they can’t be. When Fred tells us that red-1 produces qualia with such-and-such causal powers in the physical world, e.g. the power to produce the physically efficacious part of beliefs about qualia, even the blind can learn from his teachings; but they can’t learn what it’s like to see red-1 (and not confuse it with red-2) since he hasn’t said exactly which qualia it produces. Reply: now we go round again, with the efficacious aspect of qualia adjoined to the physical – something the knowledge of which can never tell us what an ex­peri­ ence is like – and the inefficacious aspect of qualia just as epiphenomenal as ever. We might as well have said at the start that the qualia were defined as the inefficacious, epiphenomenal, residue of all we needed to have knowledge of to know what an experience is like. There’s been a delaying move, after which the objections to ­epiphenomenalism come into their own.

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471.  To Max Cresswell, 11 August 1981 La Trobe University Melbourne, Australia Dear Max, Thank you for your replies to my letter of comment on your de re paper with Arnim.1 My difficulty in getting clear about the relation to Stalnaker isn’t due to any unclarity in what you say; it’s part of my general difficulty in getting clear about belief sentences. What Stalnaker does is superficially different from other alternatives that appeal to me, and I’m unclear whether (as he seems to think) there is any more-than-superficial difference. Alternativeness isn’t between worlds because there are differences of belief which could be captured by difference of alternatives and couldn’t be captured by difference of alternative worlds. You and I might agree perfectly about what the world is like (and suspend judgment about the same questions) and so have exactly the same belief-worlds, but differ as we do about our respective places in the world. Our irreducibly de se difference of belief would then be captured by difference of ­doxastic alternatives only if the alternatives are possible individuals. For instance, if we’re not mistaken about anything, I am one of my doxastic alternatives but not one of yours, and vice versa. There’s a presupposition here which some would reject: that the point of assigning doxastic alternatives is to capture the whole content of belief in a narrowly psychological sense, including the irreducibly de se part. I can’t see clearly what to say about suitable descriptions and the case of Arnim and Max. My original thought was that any treatment along the lines you suggest, including the use of relational descriptions as in your letter, would succeed in re­du­ cing de re, including de se, to de dicto, contra the fact that there can be differences of de se belief without differences of de dicto belief, e.g. between you and me in the example above. But now I think that’s too quick: maybe what you could do successfully is reduce de re to de dicto + suitability, where the suitability is, as you insist, for a given subject. That would lead me to think that your suitability itself is a de se notion, but I don’t see why that couldn’t be so. If that suspicion is right, my only remaining objection would be that it’s so much neater to put the de se element in more explicitly, in the alternatives rather than

 ‘De Re Belief Generalized’ (Cresswell and von Stechow 1982).

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472.  To Arnim von Stechow, 18 October 1981

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the suitability. But I’m prepared to learn that there’s a great range of different ways it could be put in. The Maitland near Newcastle is indeed the right one. I, and probably Steffi, would like to join you for a visit to the South Maitland Railway if at all possible. We much enjoyed it two years ago – preserved lines are fine, but it’s different to see steam earning its living hauling coal trains. We might just manage without a car, but it would be much easier with, especially if we want to watch trains in the countryside as well as standing around the shed. Most of the activity on the SMR is in the morning, and fortunately it looks as if most of the better stuff at the AAP is after 2:00. See you soon! Yours, David

472.  To Arnim von Stechow, 18 October 1981 Princeton University Princeton, NJ Dear Arnim, Thank you very much for your ‘Reflections . . .’. I have a few comments. Concerning Section 3. You define the H-relation from the L-relation like this – (5) wHxwʹ iff {z: z lives in wʹ} ∈ {y: xLy} or, in words: iff every inhabitant of world wʹ is one of x’s doxastic alternatives. That is a hard condition to meet unless x’s belief is entirely propositional. For instance, if x believes that there are kings but he isn’t one himself, no world wʹ will satisfy the ­condition. I would be inclined to define H differently. (5*) wHxwʹ iff {z: z lives in wʹ} overlaps {y: xLy} or, in words: iff some one of x’s doxastic alternatives lives in wʹ. That is to say, that it is compatible with x’s beliefs that wʹ might be the world where he lives. In that case, Hx can be used in Hintikka’s way to capture part – the propositional part, or better the part consisting of propositional properties – of x’s belief system, and my only complaint will be that this is not the whole of his belief system. Concerning Section 4. Suppose I were forced to work within a haecceitistic framework. I think I might try to have a single alternativeness relation which relates individual-world pairs to other individual-world pairs. This would be a sort of

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­combined L-relation and H-relation; we wouldn’t have a separate L and H.  In one direction we could say – y-in-v is an alternative of x-in-w iff, for all P, if x in w self-ascribes P then y in v has P and in the other – x in w self-ascribes P iff, for all y and v, if y-in-v is an alternative of x-in-w then y in v has P. (The alternativeness relation could be a four-place relation, or a two-place relation among pairs – of course it doesn’t matter.) That is, my plan would be to imitate my original scheme, only using individual-world pairs to simulate my original singleworld individuals. Note (*) on 14–15. I don’t quite understand this, and I wonder if it’s mistyped. Is the point that Arnim is Arnim might be given a logical form such that it’s true in w iff ArnimN has a unique counterpart in w? Note (**) on 14–17. I think the revised definition is no longer an acceptable definition of maximally informative belief, though I have no objection to it as a step toward a definition of knowing who one is (in a very stringent sense). For suppose my doxastic alternatives are me and some of my counterparts (at most one per world) and are also counterparts of each other. Then, by the definition, my belief is max­ imal­ly informative. But it could become still more informative if the set of alternatives were further reduced. For instance, so-called maximally informative belief does not rule out agnosticism – some of the alternatives might live in worlds with gods, some in worlds without. Concerning multiply de re belief, pages 16–17. Would it be equivalent to use the original singly de re belief, and apply it to n+1-tuples as follows – x ascribes to the property Q (where Q is the property of being an n+1-tuple of an n-ary relation and n things which it relates) iff, for some R (a) R puts x into cognitive contact with , (b) x bears R uniquely to , and (c) x self-ascribes bearing R uniquely to something that has Q.

The question amounts to this: is it safe to assume that cognitive contact with the ’tuple is analyzable into term-wise cognitive contact with its terms? Concerning the ‘I’ in ‘Who am I?’, page 28. I seem to remember a hideously obscure paper by G.E.M.  Anscombe,1 and perhaps another by Anselm Müller,   ‘The First Person’ (Anscombe 1975).

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473.  To Ian Hacking, 12 February 1982

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a­ rguing in general that ‘I’ is not a referring expression. I’m afraid I haven’t much notion how to find them. I don’t think they concentrated on the ‘I’ of ‘Who am I?’, which does seem to be one case, at least, in which their thesis looks right! Yours, David cc: Max

473.  To Ian Hacking, 12 February 1982 [Princeton, NJ] Dear Ian, I much enjoyed your microscope paper;1 thank you. Yes; my views on perception are consistent with yours on seeing with microscopes. But perhaps they’re more than just consistent; I wonder if I’m committed to counting some cases of seeing with microscopes as seeing, or perhaps even all cases. I say that if the scene before the eyes causes matching visual experiences as part  of a suitable pattern of counterfactual dependence, one sees; if the scene before the eyes causes matching visual experiences without the suitable pattern of dependence, one doesn’t see. I don’t care whether the causal mechanism is standard, or even whether it’s standard enough to involve light. The microscopic scene before the eyes causes visual experience, sure enough; and the pattern of counterfactual dependence is OK. The question that remains concerns whether the experience matches the scene. The experience matches iff its content is true. Its content is the same as the content of the belief it tends to give rise to without benefit of features of the prior state of the subject that aren’t widely shared. (I don’t want it to be part of the content of Holmes’ visual experience that the stranger on the street is an unemployed phil­ oso­pher homeward bound from the pawnshop.) So the question comes to this: does the microscope produce visual experience that would give rise to mainly true belief in a subject without special training or background information? If yes, I’m committed to saying that the subject sees. If yes on some reasonable resolution of the vagueness, I’m committed to saying that on some reasonable resolution, the subject sees – it’s not determinately not a case of seeing.

  ‘Do We See Through a Microscope?’ (Hacking 1981).

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If no, I’m not committed one way or the other. It’s either literally a case of seeing, or something closely analogous that we might well call seeing by a very natural metaphor. I don’t know how to argue about where literal truth gives out and very natural metaphor begins, if indeed there is such a case; hence my official neutrality about the case. I’m convinced that the visual experience I get when I use a jeweler’s loupe is matching: it would give a naïve subject largely correct beliefs. I don’t know whether the loupe deserves to be called a microscope, though it is strong enough to show me things I can’t see at all without it. I do indeed think it helps that I manipulate things under the loupe; but I think the experience produced is familiar enough that I’d expect it to produce mostly true beliefs even in a passive spectator. I have very little experience with real microscopes, so I just can’t tell how much of what I say about the loupe carries over. Yours,

474.  To Kendall Walton, 25 March 1982 [Princeton, NJ] Dear Ken, Today I was talking to Ted Adelson, a psychologist at RCA1 (I think he asked you a question having to do with using fiber optics to scramble a picture) about ‘Veridical Hallucinations . . .’2 and especially about your reservations against the case where somebody else’s beliefs enter into the causal mechanism from scene to ex­peri­ ence. His reaction to that was interesting, and I think may have some force against you. Let me paraphrase very freely – if I misrepresent what he thinks, he has the opportunity to tell us. You, and others, say: it doesn’t seem like seeing if the causal chain goes by way of the beliefs of some intelligent creature; as I said it in VH&PV, ‘it sees better if the prosthetic eye contains no parts which can be regarded as having wills of their own and cooperating because they want to’. Reply, first step. What if the actual, standard mechanism turns out to have intelligent believers partway through (or throughout!) the causal chain? You dare not say we never see!   RCA Laboratories, David Sarnoff Research Center, Princeton, NJ.   ‘Veridical Hallucination and Prosthetic Vision’ (Lewis 1980d).

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474.  To Kendall Walton, 25 March 1982

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Will you say that intelligence at intermediate stages disqualifies a non-standard mechanism, but not the standard mechanism? – pretty ad hoc. Reply, second step. The actual, standard mechanism does turn out to go through intelligent believers. The eye isn’t a TV camera. A fair bit of processing goes on before a signal gets beyond the eye. And in this processing the eye makes assumptions, relies on its beliefs about the world; it arrives at beliefs about the scene before it on the basis of the retinal stimulation and its presuppositions about what’s likely to go on, and its output gives these inferred conclusions. To this the protest is inevitable: all that is suggestive metaphor, not literal truth. There are indeed analogies between what the ‘intelligent eye’ does and what a real believer does in drawing conclusions from current information and background presuppositions. But the eye doesn’t believe things the way we believe things! What’s literally true when the eye presupposes X is just that it processes in ways that serve the eye’s function only so long as X is the case. Reply, third step. Sure, the eye doesn’t believe in the way people believe. Call it analogical/literal if you find that clear enough to be worth saying. (And it may well be clear enough.) But what we have here is a difference of degree only. The belief-anddesire schema fits different things to different degrees. It’s well nigh indispensable for us, pretty good for cats, some good for a fancy automated air defence system or the intelligent eye, not much good at all for rocks. The appropriateness of ascribing beliefs, or the literalness of the truth of such ascriptions, comes in a continuum of gradations. So normal vision is not entirely transparent, if transparency requires that the chain not go through intelligent believers. I suppose this is not terribly bad news – let it be that transparency is a matter of degree, let it be that the intelligence of the eye makes normal vision imperfectly transparent, still it remains that normal (or photographic) vision is a lot more transparent than ‘vision’ mediated by a helpful painter! OK; no counter to that other than the one you’ve already rejected, viz. that it seems like seeing to me even in very clear cases of the chain passing through an intelligent believer. Yours, David Lewis cc: Edward Adelson

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475.  To Philip Kitcher and Patricia Kitcher, 3 April 1982 Princeton University Princeton, NJ Dear Philip and Pat, A little while after I saw you at Swarthmore, we had Herbert Simon visiting the Department for two weeks, giving a great many lectures and seminars on many things. He’s a dire philosopher – a hard-shell positivist, and a master of the art of looking under the light instead of where you dropped the wallet – but on AI and other scientific matters he’s very interesting indeed. On the whole, well worth the vast amount of time he took up. He gave one lecture on sociobiology and all that – good popular science, good sense, I don’t think anything very new. In the course of it, he said something that fits into what we were talking about at Swarthmore: evolution is a depth-first search. I asked Paul Oppenheimer, a graduate student with a background in AI, what that meant. If I understand, the answer is as follows. Many problems can be regarded as tree searches through trees much too big to be surveyed fully. There are many first moves to try, each followed by many second moves, each. . . . Some sequences of moves are winners. You can’t tell ahead of time how long a winning sequence will be, though maybe there’s something about a not-yet-winning sequence that tells you how promising it is – how likely to turn out to be an initial segment of a winner. You can see very easily how theorem-proving fits the picture, but lots of other things do too. A breadth-first search tries everything a little bit; if no winner, tries everything a little bit more (I guess it remembers what it got the first time round, or else it has to do the first round over); if still no winners, tries everything a little bit more, . . . . A real grasshopper-mind; but undogmatic, willing to try anything some ratbag suggests. If there’s a winner, it will find it in the end. But it will waste a lot of time on the way. And it will need a lot of memory, and memory that can manage a very miscellaneous record of fresh starts, if it’s going to avoid repeating itself. When you do a completeness proof in logic, often you include what amounts to a demonstration that a breadth-first search will eventually find a proof if there is one – and of course you don’t care how long ‘eventually’ might be. A depth-first search is the opposite. It stubbornly pursues any line that seems promising, on and on, until it peters out decisively. Only then does it give up and try something else. If there are lots of seductive dead ends around, it may never find the winners – even if there are very easy winners around that it could very easily have found if it had been less stubborn, winners that the breadth-firster found ages ago. But if it’s lucky, it’s very lucky. If it latched onto the right line, it finds a winner very



475.  To Philip Kitcher and Patricia Kitcher, 3 April 1982

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fast. Science as Kuhn describes it is a depth-firster, and I’d like to think that our present science is a lucky depth-firster. Of course, there must be ways to mix and compromise the two strategies. There ought to be vast amounts of operations research dealing with the question which sort of search is the better bet, given various assumptions about the problem tree. It’s pretty obvious that you can’t say that one kind or other is the better bet always. I’d love to find a discussion of the problem that is accepted by experts as sound and that is readable by non-experts. Ideally, I’d like one that I could assign to be read along with Kuhn, and also Martin Gardner, Fads and Fallacies in the Name of Science,1 which is at once a survey of the range of crackpot science and an exemplar of the refusal to consider it seriously that I’d like to see defended, in an upperclass phil­ oso­phy of science course. It would seem that science has set itself up, at least to some extent, as a depthfirst searcher through the tree of research strategies guided by hypotheses. It might very well have done so for reasons having to do with the vanity or power-hunger of the individual scientists. Or it might have done so because, in some inchoate way, scientists realized that they were facing the sort of problem tree that responds better to depth-first search. Or they believed that, truly or otherwise, reasonably or otherwise. Or some mixture. Or perhaps the depth-first customs were set up for the discreditable reasons, but might be sustained and justified by more creditable ones. Suppose that it’s reasonable to think that the problem tree is one for which depth-first science is the best bet. (Whether or not that’s the reason scientists behave as they do.) That would give me what I wanted: a justification for ignoring – in particular, for excluding from curricula – those myriads of ‘dissident scientists’ who don’t have the political clout to force (some of) us to study and criticize their works. It’s all very well for you to say to the creos what you do: you don’t get your ideas taught in our schools because your arguments have been examined with some care – here, read all about it – and found wanting. But my nightmare is that the next gang of ‘dissident scientists’ come along, and the next, and the next, . . . and the creos themselves with their new 1983-model arguments, and . . . and each time we have to study their works with care to earn the right not to have their stuff taught in the schools! I can think of things I’d rather study. Even if the burden of examining ‘dissidents’ is given to a few volunteers like yourself, so that the scientific community as a whole is more open-minded than most of the individual scientists are, it’s still a dismal prospect. If that’s what our academic ideals call for – and it is, I’m afraid – is that a reason to spend our lives reading claptrap, or is that a reason to reconsider our ideals?

  (Gardner 1957).

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Do you know anything I might do well to read along the lines I’ve been s­ uggesting? As previous remarks may have hinted, I’m no very wide reader, even of non-claptrap. Yours, David cc: Benacerraf, Oppenheimer, Mahoney

476.  To Thomas McKay, 24 April 1982 [Princeton, NJ] Dear Tom, Thank you for your letter and paper.1 I don’t think we disagree much. In ­particular, I quite agree that we commonly ascribe content of belief in a broadly ­psychological way, so that content is jointly determined by narrowly psychological states and relations to things outside. And when we do, even an excellent logician like Pierre can – through misinformation, not error – find himself correctly assigned contradictory belief-contents. I took it that charity required us to construe Kripke as setting aside this broad content in part by his very insistence on (3), and in part by his explicit setting aside of de re belief.2 I think that most cases of broad content are just cases of de re belief more or less as usually conceived, and as analyzed in my ‘. . . De Se’ paper.3 I stare at Bruce; I selfascribe staring at something furry; staring at is a relation of acquaintance. Thereby I ascribe furriness to Bruce, believe de re of Bruce that he’s furry, have a belief of which the broad content is the ‘singular proposition’ that Bruce is furry, which perhaps should be taken as the ordered pair of Bruce and furriness. And that makes true, in an ordinary sense and perhaps in the only ordinary sense, a belief sentence: ‘David believes that Bruce is furry’. The content is broad: had it been cat Pittoronyx instead of Bruce, even if my narrow state had been the same, the broad content (so far as this episode goes – of course I’m acquainted with Bruce in other ways) would have been that Pittoronyx is furry.

1   Presumably, ‘On Proper Names in Belief Ascriptions’ (McKay 1981). See also ‘De Re and De Se Belief’ (McKay 1988). 2   (3) is ‘He cannot be convicted of inconsistency; to do so would be incorrect’ (Letter from Thomas McKay to David Lewis, 16 March 1982). 3  ‘Attitudes De Dicto and De Se’ (Lewis 1979a).



476.  To Thomas McKay, 24 April 1982

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Complications: (1) I’ve suppressed uniqueness conditions. (2) Being a relation of acquaintance is a vague matter, and a matter of degree. (3) Sometimes the above story has to be replaced by something more roundabout. I believe nothing de re of Fred’s liver, which is hidden from my sight; but I believe de re of Fred that he has an inflamed liver; so I have a belief with the broad content that Fred’s liver is inflamed. I believe nothing de re of Santa, who doesn’t exist; but I believe de re of ‘Santa’ that it names a present-bringer; so I have a belief with the broad content that Santa brings presents. The ‘Père Noël’ example suggests that I can have a belief de re of a word through being acquainted with the connected word of another language – I think I can accept this. So the broad content-de re isn’t a simple equation, but I think it’s close to right. I’m glad you believe in ‘the narrow psychology associated with belief’. But why don’t you call it also belief? Doing so wouldn’t force you to confuse it with the r­ elation of believer to broad content. Here, if anywhere, is the main real difference between us. I’m happy with broad content of belief, but I want narrow content as well. Maybe I want a dualism of belief-content; but I think not, since I think I can regard both as special cases of some undifferentiated notion. Ordinary belief sentences typically give broad content, as I think we agree. But not always. ‘Pierre believes that the city he has heard of / he thinks of / he is in a pos­ ition to refer to as “London” is ugly’ is a belief sentence giving narrow content.4 I want my narrow content for two reasons. (1) I think I know how to use it – I know in a rough way, as you’ve seen – in explaining the broad content, hence it’s a step on the way to an account of belief-content generally. (2) I think it lends itself to functional characterization in a way that belief-content generally doesn’t. Note that narrow content isn’t supposed to be de dicto, either in the sense that it’s an especially linguistic matter or in the sense that it can be characterized by propos­itions in the sense of sets of worlds. Against the first: narrow content for dogs, narrow content for my beliefs involving tunes or faces that I can’t describe. Against the second: egocentric narrow content, as when Pierre believes that the city he has heard of as ‘Londres’ is pretty. I’d characterize narrow content in the Hintikka way – possibilities admitted and excluded – but take the possibilities as egocentric ones, as possible individuals. That’s the same as what I say in ‘. . . De Se’ that the narrow objects are self-ascribed properties. Pierre’s narrow content has to do with the London-role – rather, with two London-roles – more directly than with London. But with broad content it’s as you say: his beliefs are straightforwardly about London.

  The insertion with slashes is in the original and is not an editorial amendment.

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Concerning the paper: I have little to disagree with, except that the narrow psych­ology associated with belief – whether or not it has its own narrow content – might deserve more of a part in the play. Also, one minor thing: I’m more sceptical than you seem to be about clear-cut lines between literal use and implicature, standard use and non-standard. It’s not that I object to where you draw the lines, I wonder whether there’s anything to make any placement of those lines uniquely right. I share your hope for a suitable topical conference. Yours, David Lewis

477.  To Terence Horgan, 22 March 1983 [Princeton, NJ] Dear Terry, I enclose two things titled ‘Knowing What It’s Like’.1 The short one appears as a postscript to my ‘Mad Pain and Martian Pain’, reprinted in my Philosophical Papers, Vol 1 (Oxford, 1983). The long one will be what Graham was referring to. But it is not, repeat not, an ‘unpublished paper’, and I’m distressed to have it thus referred to. It’s the (abbreviated) text of a public lecture to a non-specialist audience. I have no intention of publishing it, apart from the bit that’s in the postscript to ‘MP&MP’. The principal reason for not making a paper of it, or allowing others to treat it as a paper, is that I was scooped by Larry Nemirow: he was there first (in his Stanford dissertation) and I must respect his priority. A public lecture makes no claim to originality, a paper does. The matter is especially important now that Nemirow has left the profession and gone to law school; he could all too easily be forgotten. Yours, David Lewis PS You did send me ‘Functionalism . . .’ before – thanks.2 I agree with you, of course, that my way with the inverted-spectrum objections conflicts with the thesis that experiences are intrinsic. I agree that this consequence is unwelcome, but I think it quite tolerable. One reason to tolerate it is that if I’m right about other things, lots of   An early version of ‘What Experience Teaches’ (Lewis 1990).   ‘Functionalism, Qualia, and the Inverted Spectrum’ (Horgan 1984a).

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478.  To Frank Jackson and Valina Rainer, 29 March 1983

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things are less intrinsic than we think. That is, the price of mistrusting intuitions of intrinsicness is a price I’ve paid already. For instance, you might think that the occupancy of causal roles by brain states in the case of a particular person was intrinsic. Not so: causation somehow involves laws, whether via counterfactuals with laws held mostly fixed, or whether via D-N assumptions. But laws are at least regularities, whatever else they are too. And ­regularities are cosmic, not intrinsic to the person in question. So a functionalist already should think experiences are extrinsic, whatever he may do about inverted spectra! Unless (like Armstrong) he goes in for some very unHumean line on laws and causation. I enclose another postscript from Papers in which I deny (with regret) that it is entirely intrinsic what mental states (qua mental states) one is in.

478.  To Frank Jackson and Valina Rainer, 29 March 1983 Princeton University Princeton, NJ Dear Frank and Valina, This is in reply to Frank’s letter of 17 March, concerning what I might say now in answer to Hartry Field’s postscript to ‘Mental Representation’.1 I attach a copy of my November 1977 letter to Hartry, which is what his ‘David Lewis has informed me’ refers to.2 I don’t like the question ‘whether belief is fine-grained or coarse grained’. (I evidently liked it better in 1977.) So I don’t like either of your proposed things for me to say: (A) It’s an a posteriori question whether belief is fine- or coarse-grained, and a question open enough that neither answer should be taken as a premise in considering whether there are mental representations or in considering whether our usual ways of talking about belief presuppose that there are; (B) Belief for language-users is fine-grained, belief for animals is coarse-grained. There are belief states; these states are not, in their nature, fine- or coarsegrained. They do not consist of external relations to fine- or coarse-grained pro­posi­ tions in abstract heaven! Rather, they probably consist of patterns of synaptic interconnection. We characterize these states by indexing them with content, much as we characterize states of molecular motion by indexing them with numbers. In  (Field 1978).   2  Letter 441. To Hartry Field, 13 November 1977.

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either case, the detour through the scheme of indexing facilitates generalization about the causes and effects of the states. In either case, we may have more than one fruitful way to do the indexing. One system of content-indexing assigns coarse-grained propositions (or better, properties); and does so in a narrowly psychological way, on the basis of the functional roles of the belief states being characterized. (Not, alas, an intrinsic way: first, because of the counterpart for belief of ‘mad pain’; second, because functional roles are a matter of causal relations, hence of counterfactuals in which laws tend to be held fixed, hence of laws, hence of cosmic regularities fitting into systems.) Another system (or several systems jumbled together) assigns fine-grained propositions, and does so in such a way that the fine-grainedness makes a difference; and does so in a broadly psychological way, so that narrow-psychological duplicates get assigned different fine-grained content. It is this second system (mixture of systems?) that is encoded in the belief sentences of ordinary language. I don’t want to reject the second system. In that sense, I accept fine-grained belief, even for animals. I believe, controversially, (1) that the first system, plus nonpsychological information about the subject’s relations of acquaintance with surrounding things, provides as complete a characterization as the second system can; (2) the main relevance of language to the analysis of belief – as opposed to its relevance to the mechanisms whereby the functional roles of belief states probably get realized – is as a source of relations of acquaintance that we can bear to remote things; (3) that the best order of analysis is to start with the first system, and go on to the second via – in large part, but not entirely – something like the treatment of de re belief at the end of my de se paper; (4) that the contents of embedded clauses in ordinary-language belief sentences are a far cry from the contents that best serve to index belief states in a way that codifies their functional roles. There’s certainly some truth in your offering (B). Language-users have vastly increased opportunities for de re beliefs about things not in their immediate surroundings, because that can get into relations of acquaintance with such things by linguistic means. Hence they have vastly increased opportunities to get into the predicaments described by ordinary-language belief sentences for which interchange of logical equivalents, or of synonymous names, fails. But I hope that these predicaments also could be described, fully, in terms of coarse-grained, narrowly psychological content, plus relations of acquaintance. For instance, Fred, a language-user, self-ascribes the (coarse-grained) property of being ‘Cicero’-acquainted (uniquely) with a wise man, and also the property of being ‘Tully’-acquainted (uniquely) with a fool. ‘Cicero’-acquaintance is, roughly, the relation one bears to the causal source of one’s tokens of ‘Cicero’; ‘Tully’-acquaintance likewise. This makes it true (on one, but not the only, resolution of ambiguity) that



479.  To Terence Horgan, 16 April 1983

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Fred believes that Cicero is a wise man, whereas Tully is a fool; and also (on one, but not the only resolution) that Fred does not believe that Tully is a wise man, or that Cicero is a fool. Yet ‘Cicero’ and ‘Tully’ are synonymous names; or if not, I could repeat the example with a clear case of synonymy, as when Ed believes that the hill is covered with gorse but not that it’s covered with furze. An animal couldn’t get into a like predicament, being unable to be ‘Cicero’- or ‘Tully’-acquainted with things. Max Cresswell and Arnim von Stechow have a fancy theory of ordinarylanguage belief sentences along the sort of lines here sketched; Bigelow probably has copies of their stuff, especially a book manuscript by Max. Yours, David cc: Field

479.  To Terence Horgan, 16 April 1983 [Princeton, NJ] Dear Terry, Thank you for your response to Jackson.1 One request: could you please cite my ‘New Work . . .’ as: Australasian Journal of Philosophy 61 (1983).2 Maybe I can give you page numbers by the time you get the proofs for yours – I don’t know. As I understand Frank’s argument, there’s no equivocation: ‘physical information’ means ‘explicitly physical information’ throughout. (It’s a little hard for me to apply your distinction, given that I think of information in terms of elimination of possibilities, rather than sentences; but I think that’s it.) Mary has complete explicitly physical information beforehand; of the possibilities that remain open at that point, none differs physically from another (or else there is only one open). Or, in a more down to earth version, none differs physically from another in any way relevant to what happens when she learns what colour is like. Yet when she learns she allegedly does eliminate some possibilities; then the eliminated possibilities differ in a nonphysical way from actuality; contra materialism. I see the argument as targeted directly against materialism as a supervenience thesis. Equivocation or no, what should be said to the hypothesis that when Mary learns what it’s like, her accomplishment is to pick up a new piece of ‘ontologically   ‘Jackson on Physical Information and Qualia’ (Horgan 1984b).   ‘New Work for a Theory of Universals’ (Lewis 1983b).

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physical information’ – which is to say, she becomes able to predicate the same old physical properties of the same old physical things in a new way, viz. by the use of an indexical to refer to a certain physical property? First, I say that if this is the only sense in which she gains information, then you’re right that this gaining of information doesn’t meet Frank’s needs. Second, I don’t like to call this a gaining of information at all, since it doesn’t seem to eliminate previously open possibilities. Third, it does at least seem true that the thing you describe happens she can refer indexically to the state she’s in and to properties of that state, as she couldn’t before, so she has a new way to truly predicate physical properties of phys­ ic­al things. Finally, and most important, this seems to understate what has happened. For it likens Mary’s accomplishment in coming to know what it’s like to my accomplishment: today, for the first time in my life, I came to be able to refer to 16 April 1983 as ‘today’. Thus I now have a new bit of ‘ontologically physical information’ that I can express by saying ‘today it’s rainy in Princeton’; no amount of lessons beforehand could have given me anything better than ‘on 16 April 1983 it’s rainy in Princeton’. Big deal – Mary’s puzzling accomplishment seems to have been something more than that! Thus I think I’m more in agreement with what you say in the 26 March letter than with the note. Yours, cc: Jackson

480.  To Ted Ziolkowski, 24 May 1983 [Princeton, NJ] Dear Ted, Thank you for the copy of C.L. Hardin, ‘Pseudoscience’.1 I liked it, but with a reservation: it seems inconclusive. The conclusion that I believe to be warranted by what he says, and to be correct, is that while it’s risky to ignore unorthodox science (and the risk cannot be eliminated by means of some easy test to detect bad science without taking the time to examine it closely), nevertheless this risk may be worth

  (Hardin 1983).

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481.  To Terence Horgan, 11 July 1983

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taking, on balance, if the great majority of unorthodox science is ‘garbage’ but to find out which is the garbage takes ‘careful detective work’. If you knew for certain that ten diamond rings were thrown in the garbage in New York every day, and you wanted a diamond ring, that wouldn’t be reason enough to sort through the garbage – there might be easier ways to get a diamond ring. Compare the sorry state of philosophy: we’re always eager to listen to someone who offers to revolutionise philosophy, with the result that one proposal after another goes out of fashion without very thorough examination – only to be revived another year. We could scarcely tell the natural scientists that they’d be better off if they followed our example! I looked Hardin up in our records. He took his Ph.D.  in 1958, and went to Syracuse in 1959. I take it that he’s done little since; that would explain both why he’s still an associate professor and why I didn’t know of him though I know most of the Syracuse department. Yours, David Lewis

481.  To Terence Horgan, 11 July 1983 Princeton University Princeton, NJ Dear Terry, Thank you for the new supervenience paper.1 I like it, and I agree with your main point that the constraints whereby the whole truth about a world supervenes on its microphysics can only be matters of meaning. If supervenience formulations are in fashion because they hold out the hope of reductive analysis without analyticity, that’s a false hope; though if they shift attention from meaning-constraints that can be captured in short, discoverable analytic sentences to ones that can’t be so ­captured, that’s fine. What you say about semantic indeterminacy on page 13 seemed to me perhaps not quite right. It’s not that I disagree with what you actually say; but there’s at least a suggestion that serious semantic indeterminacy would get in the way of supervenience. I think not. If there’s serious indeterminacy, we can still have supervenience; it’s

  ‘Supervenience and Cosmic Hermeneutics’ (Horgan 1984c).

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just that what supervenes will be ranges of indeterminacy, rather than determinate semantic values. If two worlds are microphysical duplicates, it may be indeterminate in both whether Fred is bad, or whether his complicated neurotic relationship to his mother is love; but it will be indeterminate to precisely the same extent and in ­precisely the same way in both the worlds. Your account of my ‘New Work . . .’ on 18ff. might give the impression that I definitely believe in universals. A parenthetical sentence inserted into the top line of page 20, to say that I remain neutral between (i) and (ii), would be welcome. Yes; I meant my ‘principle of generativity’ to be roughly the same point as Davidson’s objection to unlearnable languages. Only I didn’t want to stick too closely to Davidson’s ideas of how a language has to work to be finitely specifiable; for instance, it seems to me that a language can have an uncountable lexicon and still be learnable (if not practically usable). Take the language just like written English except that for any positive real number r, a black disk with radius r serves as a name denoting r. There – you’ve just learned one! Admittedly, it’s a bit hard to write or read it . . . Your footnote 3. I think a world where human experiences had some alien natural property would be irrelevant to materialism. You make it seem more relevant by stipulating that the alien property, and also some natural property that ex­peri­ ences actually have, are called ‘qualitative characters of experiences’. But I doubt that you’re entitled to that stipulation. Also, I’m afraid I didn’t see how the characterization on page 34 was meant to get around the problem – is the different ‘qualitative character’ supposed to not be alien because it shows up within the core? Why should it? Yours, David P.S. Cite ‘New Work’ as Australasian Journal of Philosophy 61(1983). Issue after next, or maybe next issue.

482.  To Carolyn McMullen, 17 November 1983 [Princeton, NJ] Dear Carolyn, I’ve looked at your pp. 12–18, and accompanying footnotes.1 I didn’t see any significant problems about interpretation of my views – I’m not sure what David   From a draft of ‘ “Knowing What It’s Like” and the Essential Indexical’ (McMullen 1985).

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482.  To Carolyn McMullen, 17 November 1983

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Lumsden might have had in mind. I do have a collection of trivia, and a comment not on a matter of interpretation. [. . .] Page 17, line 15. (Slightly less trivial.) When you believe de re you self-ascribe a property: namely, a property of being acquainted in such-and-such way with something that is so-and-so. Self-ascribe staring at something furry while staring at cat Bruce, and that’s one way for you to believe de re of Bruce that he’s furry. But I don’t think it’s a good idea to call the property you self-ascribe an ‘object of belief de re’. For one thing, because in my terminology at least ‘objects’ are things used to index narrowly psychological states, and belief de re is not narrowly psychological except in special cases; that is a reason to avoid talking of objects of de re belief at all. (But alas, my terminology has ended up idiosyncratic at just this point. When people saw that they couldn’t in general both make objects of belief index narrow psychological states and make objects of belief correspond to the ‘that’-clauses in ordinary belief sentences, they often went for the latter and let the former go, which in my opinion is the less useful choice.) Also, if you must have things you call ‘objects of de re beliefs’, I think a better choice might be the pair of the property you ascribe to the thing you’re acquainted with and the thing to which you ascribe that property. Thus instead of Staring at something furry. That has the advantage that believing de re with the same object captures a fairly ordinary sense of agreement. You stare at Bruce, someone else strokes him while blindfolded; the two of you agree that Bruce is furry, you both ascribe furriness de re to Bruce, but you ascribe different properties to yourselves. Your continuation of the paragraph is another example of the same thing. Dunbar and Cranshaw self-ascribe different properties (being MT-acquainted with the author of HF, being SC-acquainted with the author of HF); as I put it in slightly regimented terminology, they fail to ‘believe alike’; but they ascribe the same property to the same thing in their different ways, so they agree in ascribing that property to that thing, so (in this respect) they agree in their de re believing. If you’re going to introduce entities which are de re beliefs, or which you call ‘objects’ of de re beliefs – and I don’t think that’s something you have to do – I think it would be a good idea to do so in such a way that they have the same one. That is: index the half-psychological half-external states of de re belief in a way that links up with ordinary-language belief sentences, and with our ordinary notion of agreeing (≠ my ‘believing alike’). But all this is terminological recommendation, it seems to me, not doctrine. I don’t think there’s any definite pre-theoretical notion of ‘same de re belief’ waiting to be captured. I think the way we answer questions ‘do they believe the same thing’ is pretty flexible, and we’ll go along with different ways depending on what has ­conversational point, or what meshes with the usage of our conversational partners of the moment.

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(Sorry – long discussion on a very minor point!) I did want to say something a bit more substantive. Horgan said, and I agreed, that when Mary escapes, she can for the first time refer to colors in a new way; and, what goes with that, she can then for the first time self-ascribe properties such as the property of seeing green. And when you self-ascribe new properties, isn’t that (on my own telling) getting new information? I think not. That’s the point of the date example. Yesterday I self-ascribed being on the day before 17 November, so today I self-ascribe being on 17 November; new self-ascribed property, no real discovery. (OK, so there was a moment when I discovered from the clock or the daylight that midnight was passed. That’s a discovery of sorts, but not the relevant one.) There’s a kind of self-ascribing of new properties that happens by discovery, and there’s a kind that happens by more up-dating of properties your past self self-ascribed. ( John Perry has written on this somewhere, in his barely pre-situationist days. I’m not sure where. Midwest? Pacific ΦQ?) Now it seems to me that you accept the distinction between new self-ascription by discovery and by up-dating, but you join Horgan in thinking Mary’s case is the second. That’s the point of your analogy at the bottom of p. 15. Well, it might be. But not necessarily so. Our problem was: what happens to Mary that no amount of previous lessons could have accomplished. And Mary’s previous lessons could very well have given her the information that the very first thing that would happen when she escaped would be that she would see green. And hence that the very first thing would be that she would have the property: being able to refer to seeing green by ‘my present experience’ or just ‘this’. And hence that the very first thing would be that she would have the property: being able to say truly ‘this is seeing green’. But if she self-ascribed beforehand such properties as ‘being just about to see green’, ‘being just about to be in a position to truly say “this is seeing green” ’ – and she could have self-ascribed those beforehand on the basis of lessons – then when she starts to self-ascribe seeing green, etc., that does seem to be up-dating. The thing about discovery or realization, as in your example, is the failure of fit between selfascription of P now and self-ascription of being just about to have P just before. *** That was meant to be all, but as I read on, I thought to make a further comment. It begins as a comment on what you say about my theory at the bottom of 17. Sure, the varying descriptions are doing the work. But how can they do the work given propositional objects? For the descriptions in question have to be (always, or almost always) egocentric, relational: the one I am, the thing I’m saying, the one I’ve heard of as ‘Fitzwilliam’. Vary the descriptions all you like; make them pictorial or perceptual as well as linguistic; fine. But if the descriptions are egocentric, how do you plug them into a proposition unless the proposition also thereby becomes



483.  To Paul Teller, 21 November 1983

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egocentric – which is to say, becomes a property rather than a proposition in your official sense? If, for instance, your idea of a noise ‘consists in the fact that /you/ can locate it with respect to /your/self’ etc., how can thought involving such an idea be ‘correlated 1-1 with propositions’? I should think, rather, with egocentric pro­posi­ tions, in other words properties. Yours, David Lewis

483.  To Paul Teller, 21 November 1983 [Princeton, NJ] Dear Paul, Thank you for the further bit of draft about noncontingent materialism.1 No worries about misrepresentation. No worries about intuition massage as opposed to arguments. I don’t understand the difference between an alien physical property and an alien non-physical property. I tend to take ‘physical’ as making reference to physics more or less as we know it; which makes it hard for any alien property to be physical. (Though maybe you could play on analogies: the physical-by-analogy properties are few-valued magnitudes of fundamental particles that enter into force laws, . . ..) On the other hand, you might say that a property is physical in a more abstract sense if it must be recognised by any comprehensive and systematic account of the causal order; but then it’s hard not to be physical. My idea was that Materialism claims that physics more or less as is is correct and exhaustive; surely that’s contingent for surely there might have been a radically different ‘physics’ (or, if ‘physics’ is tied to physics-as-is, a radically different physicssubstitute). A different thesis is that some theory in the style of physics – a highly microreducing theory, with resources to milk a lot out of a very few, very powerful, very simple laws – is correct and exhaustive. That’s different, but still seems contingent. Yours,

1   Presumably in connection with ‘The Poor Man’s Guide to Supervenience and Determination’ (Teller 1984).

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484.  To David Austin, 19 March 1984 Princeton University Princeton, NJ Dear David Austin, Last things first. In ‘Naming and Necessity’, fn. 13,1 Kripke barely mentions that ‘it would be interesting to compare’ me with Wheeler-Everett. Brian Skyrms does a bit of comparing in ‘Possible Worlds, Physics and Metaphysics’, Φ Studies 1976, 323 ff.; he says that because the wave function has different decompositions (into the eigenvectors of different observables) Everett shouldn’t really be called a manyworlds theory. John Leslie has written extensively, in many places, about manyworlds cosmologies and the anthropic principle. He is aware of the question whether my kind of many worlds would suit his purposes, but I don’t know if he has written about it. He recently sent me a quote from Sciama favoring an ‘extreme form of the anthropic principle’ which ‘invokes the existence of all conceivable logically selfconsistent universes’. It’s in Some Strangeness in the Proportion, ed. by Harry Woolf (Addison Wesley, 1980); I haven’t hunted it up. Sciama is a distinguished cosmologist; he may or may not have heard of modal realist philosophy. That’s all I can come up with. My ‘New Work’ is irrelevant to your problem; nevertheless I’m sending a copy. I’m sending along something else that might be a bit more relevant, though mainly its relevance consists in repeating things from the de se paper.2 It connects with the second objection and reply in my Pierre paper, pp. 287–8.3 On most things, Stalnaker is absolutely lucid; but I too don’t understand the line he takes in ‘Indexical Belief’4 though I too have corresponded with him about it at length. I agree with you that the essence of the spot is irrelevant to Smith’s psychology, unless it be an essence-by-acquaintance for Smith. I see the matter this way. There are two relations of acquaintance: R and L (having to do with seeing through the right and left eyes). The narrowly psychological part of the story concerns egocentric, de se content. (I simplify by forgetting that Smith consists of many different stages; really it’s the stages that do the self-ascribing.) In the first part of the experiment, Smith selfascribes being R-acquainted with a red thing, and with nothing else. In the second part, he goes on self-ascribing that, but he then also self-ascribes being L-acquainted with a red thing and nothing else. That’s the change in his belief and knowledge when   ‘Naming and Necessity’ (Kripke 1972).    2 ‘Attitudes De Dicto and De Se’ (Lewis 1979a).   ‘What Puzzling Pierre Does Not Believe’ (Lewis 1981d).    4  (Stalnaker 1981).

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484.  To David Austin, 19 March 1984

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he opens the left eye. He does not self-ascribe being R-acquainted and L-acquainted with the same thing. But nor does he self-ascribe being R-acquainted and L-acquainted with different things. Now we widen our attention and take account of non-psychological facts. In the first part, he is in fact uniquely R-acquainted with the spot; thus he believes and knows, de re, of the spot, that it is red. In the second part, he is also uniquely L-acquainted with the same spot; which provides a second sufficient condition for the same conclusion, namely that he believes and knows, de re, of the spot, that it is red. Now for a bit of ordinary language. The same combinations of narrow content plus acquaintance that suffice to make it true that be believes and knows, de re, of the spot, that it is red (in other words that he ascribes redness to the spot) also suffice to make true the ordinary language sentence ‘He believes (and knows) that the spot is red’. In the first part of the experiment we have one, and in the second part two, truth-making combinations for that sentence. The sentence has an embedded clause: ‘the spot is red’. The subject of this clause denotes the spot, the predicate expresses redness; so this clause has a semantic relation to the ordered pair of the spot and redness; and thereby also it has a semantic relation to the set of all worlds where something with the essence of the spot is red; that is, it has a semantic relation to two different things that might be called the ‘singular proposition’ that the spot is red. So Smith has this relation, at least, to the singular proposition. His narrow psychological state plus his acquaintanceships jointly make true a belief-and-knowledge sentence with an embedded clause that cor­res­ ponds in a certain way to the singular proposition. Big deal! I don’t terribly mind if somebody wants to say, on this basis, that Smith believes and knows the singular proposition; but I insist that the singular proposition that in this roundabout sense he believes and knows is not at all the same thing as the narrowly psychological contents that are functionally characterized, that motivate his action, that more or less obey canons of rationality, that will be consistent if he’s as good a logician as Pierre . . . . Narrowly psychological content is linked only in a roundabout way to embedded clauses of true ordinary language belief sentences. So you can connect ‘objects of belief’ to one or to the other; but not to both at once, at least not without serious equivocation. Say what you like, but personally I prefer to say ‘objects’ to mean the things that are tightly connected to narrow psychology, and loosely connected to clauses in belief sentences, not the things that are vice versa. That way, singular pro­ posi­tions are no good as ‘objects’. Indeed propositions generally aren’t much good, unless by propositions you mean egocentric propositions – better known as properties. But if you go the other way, you can have your propositions and your singular propositions as objects – but then objects haven’t a lot to do with belief as a psychological phenomenon.

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(In the above, I may have given the impression that I hold a general theory of the semantics of ordinary belief sentences, which I was applying. Not so; the subject is a mess. But at least sometimes it’s clear what makes a belief sentence true, whatever other truth-makers that sentence might have had; and that’s all I was using.) Your Smith thinks in words. Maybe mine does too; maybe not. I don’t see why it matters. I would think that ‘this’ and ‘that’, as used in Smith’s inner speech, are equivalent in context to (something like) the definite descriptions you mention; you deny it; but I don’t see why that matters. There’s no reason why the proposition expressed by his inner sentence has to fit either the narrow content of his belief, or the proposition expressed (in any sense) by the embedded clause of the belief sentence. Yours, David Lewis

485.  To David Brooks, 13 July 1986 Prospect Avenue Princeton, NJ Dear David, Long ago you sent me a draft paper on functionalism.1 It sank into the to-beread heap, and it’s stayed there a shamefully long time. I’m being punished for writing too much – the time I’d like to have for reading and writing must go instead to proof reading and index-making. Today I finally read it, liked it, and mostly agreed with it. I especially liked the part about more and less abstract blueprints. I thought that was going to be the basis of the reply to Block’s problem about chauvinism with respect to the inputs and outputs: state folk psychology abstractly – organs of locomotion, not legs or wheels; nearby-object-detectors, not eyes or sonars; manipulators, not hands or tentacles – and it’ll apply to all manner of extraterrestrials, yet not to the economy of Brazil, so steering between the errors of chauvinism and liberalism. But then you veered off, if I understand you; rather than going that way, you’d do the Ramsey sentence over again for different concrete blueprints, not once and for all for an abstract blueprint. Have I got this right? We have a disagreement about total-state functionalism – Turing machine functionalism, minus the special way a Turing machine handles its memory. You   A reply to Ned Block’s ‘Troubles with Functionalism’ (presumably it was never published).

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486.  To Reinaldo Elugardo, 2 May 1988

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think it’s the next thing to behaviourism; I think the causal relations of the total states give us a grip enough to raise the question whether the Martian works the same way we do. (I’m prepared to defy Block’s chauvinist intuitions about homunculus head, whereas you retreat and hold the line further back. I say hh does work the way we do, therefore does have mental states.) I think an a priori functionalist had better use fairly total states, at least in the department of belief; because folk psychology hasn’t anything very decisive and plausible to say about how the belief system splits into many smaller states. It splits somehow, no doubt; but folk psychology gives no good guidance on how, so we’d best look for realizations of the folk psych of total belief states. Yours, David

486.  To Reinaldo Elugardo, 2 May 1988 [Princeton, NJ] Dear Professor Elugardo, How does an inner brain state determine content given by a class of doxastic alternatives? First, it determines more: a system of belief and desire. Roughly, the belief part is given by the doxastic alternatives; the desire part is given by an ordering of alternatives as more or less preferred. (Better, belief and desire should both be matters of degree, as in decision theory.) Behavior fits a system B + D of belief and desire iff it serves the desires D according to the beliefs B. Your inner state fits B + D insofar as that state tends to cause behavior that fits B + D. Roughly, what makes it true that B + D is the content of s is that s fits B + D, and doesn’t fit any eligible alternative better. (Complications: (1) what the brain state tends to cause may differ from what it causes in your case – for you might be paralyzed, wired up wrong, or something. (2) Eligible alternatives are those in which content is not some sort of gruesome gerrymander. Goodness of fit may trade off with eligibility, to some extent.) Your example. According to me, you get only indirectly to such content as that London is a city. In the first place, the assignment that best fits your inner state s will give you a class B of doxastic alternatives, all of which have you standing in a certain relation of acquaintance R to a city; and in the second place, you actually stand in relation R to London. (R might, but needn’t, involve the name ‘London’.) It’s unlikely, however, that London itself is common to all the doxastic alternatives in 1

  Cf. ‘Lewis’s Puzzle About Singular Belief-Attribution’ (Elugardo 1987).

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class B (better: it’s unlikely that descriptive counterparts of our London are common to all these alternatives). All your doxastic alternatives are like you in being acquainted in a certain way with cities, but they’re not all like you in being acquainted with London (or its counterparts). Your second question. Right you are – if you had no idea what a doxastic alternative was or what a (narrowly) believed proposition was, making the connection between the two wouldn’t help. In introducing the notion of doxastic alternative (PoW, 29) I introduce the less familiar notion with the aid of the more familiar one. But if we want to proceed from the ground up in deriving content from the causal role of the brain state, of course it does no good to run around the circle from representation in terms of a set of propositions to representation in terms of doxastic alternative and back again. Instead we must do what’s sketched in the first paragraph of this letter, and in PoW, 36–40. See also ‘Radical Interpretation’, in my Philosophical Papers, Vol. I; and pages 373ff of ‘New Work for a Theory of Universals’, Australasian Journal of Philosophy 1983. Sincerely, David Lewis

487.  To Frank Jackson, 14 June 1988 [Princeton, NJ] Dear Frank, When I sent you the draft of ‘What Experience Teaches’1 I said we might have a minor terminological disagreement in connection with (1) knowing what it’s like to taste Vegemite under the description ‘tasting Vegemite’ – i.e. having the ability to imagine, etc., the taste while knowing (egocentric-propositionally) that it is the taste of Vegemite that one is then imagining; and (2) knowing what it’s like to taste Vegemite simpliciter – i.e. just having the ability to imagine, etc., the taste. In your letter to Nemirow of January 1982, you said in effect that we ought to take something like (1), rather than (2), as our analysis of ‘knowing what it’s like to taste   ‘What Experience Teaches’ (Lewis 1990).

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Vegemite’. (That wasn’t it exactly, and to the extent that what you really said differs, I don’t understand why.) In the draft, I compromised. I said that we have both (1) and (2) on offer, I still prefer (2) as our analysis of knowing what it’s like, but it matters little which one is our official choice. Now I think there’s a little more to it than that. There’s a not-very-formidable challenge to you. We can have, and can distinguish, (1) and (2). You too should have, and distinguish, something corresponding to (1) and something corresponding to (2). Do you? – Well, probably yes. (1J) corresponds to (1), and I suggest that (2J) cor­ res­ponds, or near enough, to (2). I waive my complaint that ‘phenomenal character’ might refer not to the special subject matter of phenomenal information but to something materialists believe in. (1J) knowing what it’s like to taste Vegemite under the description ‘tasting Vegemite’ – i.e. knowing that the experience produced by tasting Vegemite has such-and-such (nameless) phenomenal character. and (2J) knowing what it’s like to taste Vegemite simpliciter – i.e. knowing what it’s like to taste Vegemite under the trivial description ‘the experience I’m now imagining (or remembering, or having)’ – i.e. knowing that the experience I’m now imagining (or . . .) has a such-and-such phenomenal character. I thought a little about other candidates to be your counterpart to (2). (3J) knowing that there is some possible experience with such-and-such ­phenomenal character. The trouble with (3J) is that what’s known is noncontingent. (4J) knowing de re, of the experience of tasting Vegemite, that it has such-andsuch phenomenal character – i.e., being such that for some relation of acquaintance R, one knows oneself to stand in R uniquely to an experience with such-and-such phenomenal character, and in fact stands in R uniquely to the experience of tasting Vegemite. The trouble with (4J) is that the only likely candidate for R seems to be the relation of imagining (or…), so why not just offer (2J) and have done with it? Yours, David Lewis cc: Laurence Nemirow [. . .]

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488.  To Simon Blackburn, 17 June 1988 [Princeton, NJ] Dear Simon, A long-delayed letter about ‘Losing Your Mind . . .’.1 (At last it’s vacation!) The main issue of the paper is one that I recognise as important, but also I consider quite selfcontained. Where state-name S (‘pain’, ‘unlockedness’) is associated with functional role R, we have the realizer state: the state that actually (in a certain case or class of cases) occupies role R (or near enough). And we have the role state: the state such that, necessarily and for all x, x is in it iff there is some state X such that x is in X and X occupies role R in x’s case. (NB: role state ≠ role.) Metaphysical common ground is that physics coun­ten­ ances both realizer and role states. It allows them both; it even has the wherewithal to describe them both, whether or not it often bothers to. (Physics can talk about the motion of macroscopic bodies, it can talk of causation, it can quantify over states, so it can talk of states qua occupants of functional roles. Physics can; whether or not somebody’s favourite formalization of quantum electrodynamics can is another question. Cf. your good remark about the lay misunderstanding, page 17.) Semantic common ground is that x is in S iff x is in some state that occupies role R in x’s case. But that leaves open whether ‘S’ denotes the realizer state (in so-and-so case) or the role state. Which is it? If you think ‘S’ denotes the realizer state, then you have to say that although there is indeed a state common to all actual or possible individuals who are in S, yet strange to say this state is not S itself (the realizer state in so-and-so case) but rather is a different state associated with ‘S’ (the role state). Counterintuitive, but you can live with it. Whereas if you think ‘S’ denotes the role state, then you have to say either that a highly disjunctive and extrinsic property causes the effects that S is reckoned to cause; or else that, although there is indeed a state that causes the effects that S is reckoned to cause, yet strange to say this state is not S itself (the role state) but rather is a different state associated with ‘S’ (the realizer state in so-and-so case). Counterintuitive, either way, but you can live with it. For consolation, tell yourself that even if S itself doesn’t do the causing, still it certainly does enter into the causal explaining. Can you bend intuition that far? I’m not a total neutralist. Myself, I do find that bending intuition about having S in common is quite a lot easier than bending intuition about S itself doing the causing. (Which in turn I find easier than counting disjunctive and extrinsic states as extra causes.) So I’m not in full agreement with Jackson and Pettit, forthcoming in your mag, who seem to take the choice between realizer and role states as altogether optional. But I think I am in full agreement with them about what the issue is, and about how very much the two options have in common – everything, so far as the metaphysics goes; quite a lot even in the semantics – and therefore about how little else can possibly depend   ‘Losing Your Mind: Physics, Identity, and Folk Burglar Prevention’ (Blackburn 1991).

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489.  To William G. Lycan, 24 June 1988

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on which you choose. For one thing, I can’t see how one alternative could be any more or any less associated with a Tractarian vision than the other. For another, I can’t see how one could put you on the road to San Diego any more or any less than the other. Indeed, you yourself say a lot of things against San Diego that work regardless of whether S is the realizer state or the role state. --Now some minor comments. [. . .] --Enough. I hope all this is some help, despite coming so late. I’m off in a couple of weeks to NZ, Australia, then NZ again. Steffi will join me for three weeks of it. I’ll be in Britain briefly in September – not clear whether I can stop by Oxford. [. . .] Yours, c: Frank Jackson

489.  To William G. Lycan, 24 June 1988 [Princeton, NJ] Dear Bill, Replay1 could be set in branching time, but for the reason you say it shouldn’t be just the main stem and branches from that. There ought to be branches off the branches. How can I draw it on this word processor?

  Replay is a novel by Ken Grimwood (1986).

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The rule seems to be that when a replayer arrives, the world branches; and everyone in it branches continuously; except that in the new branch – I mean, the one later in the arriving replayer’s personal time – the new branch of the replayer undergoes a mind transplant. In this simplified story, Pamela and Winston have met, and found out about the phenomenon of replaying, already in their first life, say at point A. Their first life ends at B. The next thing Winston knows, he’s at point C in a new branch, the one heading off to the right. Since C is a branch point with Winston as the arriver, everyone in the world except Winston branches continuously, including Pamela. So Winston goes and hunts up the new branch of young Pamela, not a replayer and not acquainted with him, at point D. After a while Pamela the replayer arrives at point E. Since E is a branch point with Pamela as the arriver, everyone in the world except Pamela branches continuously, including Winston. Now in the far right branch, for instance at F, Winston the replayer and Pamela the replayer are reunited. Winston remembers C, A, B, C, D, E, F in that order; Pamela remembers C, A, B, E, F in that order, but not D.  In Pamela-at-F’s personal history, Pamela-at-B immediately precedes Pamela-at-E, and Pamela-at-D isn’t included at all. So far, so good, but what about the branch with X on it? I posit it for the sake of a simple rule about what happens when a replayer arrives; but it doesn’t have to be there. (The rule could have distinguished what happens at arrivals on the main stem, like C, and what happens at arrivals on branches, like E.) And no such branch ever gets described in the book – it couldn’t be, so long as the order of the book matches Winston’s personal time order and the order of the book doesn’t itself branch. On the branch through X, Winston the replayer finds that Pamela never does ‘wake up’ as a replayer, never does recognise him, and Winston copes somehow or other with the disappointment. You could wonder: why does Pamela the replayer arrive off on the branch at E? Why not on a new branch off the main stem at G like this



489.  To William G. Lycan, 24 June 1988

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so that just as Winston the replayer at X finds himself stuck with an ‘unawakened’ Pamela, so Pamela the replayer at Y finds herself stuck with an ‘unawakened’ Winston, and never do they get together with A in the personal histories of both? Why the first picture rather than the second? Well, that’s just how it is – after all, the book never explains anything. Or is it? Again, you can have a simpler rule if you’re willing to believe that more goes on in the world of the book than the book tells you about. Suppose that a replayer arrives in new branches off all the branches that there are at  arrival time; then we combine the two previous pictures to get two different ar­rivals of Pamela the replayer, one in a branch off the main stem at G, one in a branch off the branch at E. The Pamela the replayer in the branch off the branch at E meets Winston the replayer and they live happily for some while after, at F. Whereas the Pamela the replayer in the branch off the main stem at G has to be content with ‘unawakened’ Winston.

Hey, this is a lot more fun than finishing three papers and three evaluation ­letters before I fly south eight days from now, right? [. . .] I’ll hold onto this letter until I can enclose the late-June draft of ‘What Experience Teaches’. It’s quite a bit different from the May draft you saw. It’s meant to be final enough that you can hand it in to Blackwell as part of the book manuscript, but I may want to change it some more after reading it around in NZ and at the Rus. Soc. I’ll try to be restrained about further changes. Would you prefer them one at a time as I think of them, or all in a batch at some later time?

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Phenomenal individuals? Me? We’re speaking of ‘Individuation by Acquaintance & by Stipulation’, I take it? No, as someone once said, ‘I argue that we would do better to take the individuals in question to be nonactual physical objects rather than actual phenomenal ones’. Macbeth’s dagger isn’t any more phenomenal than the Lapp knife hanging on my living room wall. It’s just elsewhere, off in some other world. (Better: they are in other worlds. But let that pass.) Even if experience, or some part or aspect of it, has some special properties that are the subject matter of phenomenal information, it wouldn’t be something like Macbeth’s dagger that has these properties. But I agree there was some short-changing going on in the section on the subject matter of phenomenal information. By the time you get this letter and the draft, I shall have done some rewriting there. I didn’t intend to question that it’s fair, by the qualia freak’s own lights, to say e.g. that phenomenal information concerns certain introspectible, intrinsic properties of experience, or of phenomenal individuals. But when he gives his description ----- of the subject matter of phenomenal information, he shouldn’t expect us to agree that if there’s such a thing as information about -----, then there’s such a thing as phenomenal information. For in most cases we ought to reply that ‘-----’ denotes something such that information about it is not ineffable phenomenal information, but rather is information that can be taught to the inex­peri­ enced. For instance we ought not to concede to freaks that only they believe there’s something it’s like to be a bat, we should insist that we too believe that there’s something it’s like to be a bat, and we mean by this exactly that the bat has experiences, and we never denied that there were experiences, but experiences are not the subject matter of ineffable phenomenal information. I’ve got rather pissed off about people, for instance some I heard lately in Iceland – that turned out to be the Nordic pluros’ meeting, near enough – who say: ‘Oh well, materialism is all very well as an account of mere experience, but it entirely overlooks the fact of schmexperience’ – where schmexperience turns out to be just the same thing as experience except that materialism about it is false. Only they don’t say ‘schmexperience’ – they say ‘what it’s like’ or ‘how it feels’ or ‘phenomenal character’ etcetera ad infinitum. I take your point that in a certain sense there’s something it’s like to be an order of fries, but mostly what that would mean to the people who like talking about ‘what it’s like’ would be that the fries have experiences – no more, no less. Thank you for ‘What is the “Subjectivity” . . .’.2 I hadn’t seen it, and read it with interest. Is it for Mind and Cognition? I don’t know about Frank’s reply mentioned in  footnote 32 – where will it come forth? M&C, maybe? You and I have one big

  ‘What Is the “Subjectivity” of the Mental?’ (Lycan 1990).

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490.  To Laurence Nemirow, 4 October 1988

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­ isagreement in the background: modal de se narrow content occupies the place in d my scheme of things that the functional roles of expressions of the language of thought occupy in yours. (What place? That of a more nearly intrinsic whatnot that underlies, but doesn’t single-handedly determine, which properties the believer ascribes to which objects.) Of course I have disagreements with ‘What is the “Subjectivity” . . .’ that trace back to this background disagreement, but I think I have no others. See you in February. So far, still no need for a wild card, but thanks very much for offering. Yours,

490.  To Laurence Nemirow, 4 October 1988 [Princeton, NJ] Dear Larry, I think you can truly say ‘Fred knows the experience of tasting Vegemite’, ‘Fred remembers the experience . . .’, ‘Fred has not forgotten the experience . . .’ if he tasted vegemite once, retains the imaginative abilities he then gained, but no longer remembers the occasion. There’s at least a hint that he remembers the occasion, but I think no more. So I don’t think you have conclusive trouble for the identity treatment on which in general: what E is like = the experience one has when E = E itself, when E is already an experience. But I do have to grant you that there’s a noticeable difference in shade of meaning between what I count as two equivalents: ‘knows E’ etc. carry more suggestion of remembering the occasion than ‘knows what E is like’ etc. Too bad; but not yet a conclusive problem for the identity treatment. Equivalents can ­differ in implicature. I’m happy to say – and say as an uncontroversial truth, not as a deliverance of some sort of theory – that if vegemite tastes just like marmite, then the experience of tasting vegemite and the experience of tasting marmite are identical. (And no funny business on ‘identical’.) Or rather, that’s what I say once it’s settled that ‘experience’ is  being used in its narrow, purely psychological sense; and it was the purely ­psychological sense I intended in putting forward the identity: what E is like = the experience one has when E. Insofar as I balk at saying the experience of tasting vegemite and the experience of tasting marmite are the same, I think it’s because of interference from a not-purelypsychological sense of ‘experience’ in which the ‘experience’ may be the whole

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­episode – or rather, type of episode – rather than just its inner part; so that even if we have a single narrow psychological experience E, E-produced-by-marmite counts as a different broad ‘experience’ from E-produced-by-vegemite. I think it’s a near thing, but we still disagree. I doubt that it would be helpful to our readers to discuss this disagreement more thoroughly in either of our papers. Sufficient to note that it’s there, as I’ve done. Yours, c: Lycan

491.  To Ned Block, 2 June 1989 [Princeton, NJ] Dear Ned, Thank you for your papers, which I’ve now read with interest. Comments could not be short, so let me beg off. But let me steer you to a couple of my papers – not very new, but newly published [. . .] – which are relevant to the epiphenomenalism business. They are ‘Causal Explanation’ and ‘Events’ (best read in that order) both in my Philosophical Papers, Volume II (OUP, 1986). Key thing to bear in mind: I don’t have any one notion that corresponds to your notion of ‘causally efficacious property’. There are A) properties, ascriptions of which afford some information or other about how something was caused. And there are B) properties such that events which are essentially havings of them are causes. The property of having the first of a ’tuple of properties that jointly realise some theory, for instance, would be A) but not B). Sorry – that’s cryptic. The long story can’t be made but only just so short. And anyway I’m far from sure that it solves the whole of the problem. (I’m especially bothered about causation by colours.) But maybe it helps. See you in Swansea? Yours, David Lewis



492.  To David Velleman, 4 October 1989

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492.  To David Velleman, 4 October 1989 [Princeton, NJ] Dear David, I’m sorry we didn’t get a chance on Monday to talk about ‘Are We Free to Break the Laws?’1 [. . .] I’ve now read ‘Physicalist Theories of Color’.2 It was interesting but difficult – especially since I kept trying to classify my own view in the pigeonholes offered and found I didn’t quite seem to fit. I’ve written nothing about color except one footnote (in ‘Psychophysical and Theoretical Identifications’)3 and some letters to people. I hope to write a paper about color someday;4 and I’m afraid that I’d practically have to write that paper in order to comment properly on ‘Physicalist Theories. . .’. So I won’t – sorry. Briefly, I want a chromophysical identity theory that parallels as closely as possible the version of psychophysical identity theory that Armstrong and I hold. (It would be like Armstrong on mental states and hence unlike Armstrong on color.) Names of colors and color-experiences would be interdefined in terms of causal role; the concept of red would be the concept of a property, we know not what, that satisfies such-and-such conditions. It’s OK if it turns out that red is different properties in different cases – and very likely it does turn out that way. A cluster of examples of red would enter into the concept of red and into the propositional content of visual ex­peri­ence. Accordingly the concept and the content might differ a little from one of us to the next – some people nowadays come from places where the fire engines are yellow – but I think we can live with that. Rigidification would be a sometime thing, as usual: the description that defines a color-name should be taken as rigidified when what’s said makes better sense that way, but not rigidified once and for all. Colors are similar when they’re easily mistaken for one another, or when they’re connected by a shortish chain of colors each easily mistaken for the next. No a priori guarantee that easily mistaken colors are similar in any other way. And maybe they’re not: e.g. the spectral colors at opposite ends of the spectrum are easily mistaken. Yours, c: Paul Boghossian

  ‘Are We Free to Break the Laws?’ (Lewis 1981a).    2  (Boghossian and Velleman 1991).  (Lewis 1972a).   4  Cf. ‘Naming the Colours’ (Lewis 1997b).

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493.  To Frank Jackson and Philip Pettit, 27 December 1989 [Princeton, NJ] Dear Frank and Philip, A reply on behalf of the identity response to the paragraph beginning ‘We think this reply evades . . .’, page 5 of ‘Causation. . .’.1 When I explain your behaviour by citing your belief, I am explaining it in terms of something I know about you. Yes. I am saying, in part, that there is some internal property, I know not what, which is causally relevant to your behaviour. This existential statement is something I know about you, even if I don’t know what the truth-making instance of it is. What makes it more than a declaration that your action is not a random occurrence is that there’s more in the scope of the quantifier than we’ve yet seen: I say there is some internal property which is causally relevant to your behaviour and occupies such-and-such role. In giving information about how something got caused, I can say more or I can say less. How much I say depends on how much I know, and also on how much I want to tell you. Sometimes, but not in this case, I can name a causally relevant property: the effect was caused by F. Sometimes, but not in this case, I can give a short disjunction: the effect was caused by F or by G or by H. And sometimes I can give an existential quantification: the effect was caused by some property X such that ---X---. As it might be: by some property X that occupies such-and-such functional role. A mere disjunctive or existential statement about how something was caused is an incomplete causal explanation. Yes. But every causal explanation is incomplete (short of a full account of the infinite causal history of the explanandum event). ‘As I don’t know about the nature of your internal states, it can only be the functional role which I am citing as causally relevant’. No. I’m ascribing the ‘secondorder’ property: having some internal state which occupies such-and-such role. But I don’t say that it did the causing. Rather, by ascribing it, I make my existential statement about what sort of unknown ‘first-order’ inner state did the causing. When you speak of ‘citing’ or ‘invoking’ a property in a causal explanation, and you ask what is the property cited or invoked, I think that’s where you go wrong. You want the property invoked to meet two conditions at once: (1) I know what property it is, and (2) it does the causing. (And if one property had to meet both conditions, yes, we’d better find a way to claim that the second-order property does the causing.) But I say that two properties are both, in different senses, invoked. One is invoked in   ‘Causation and the Philosophy of Mind’ ( Jackson and Pettit 1990).

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494.  To Philip Pettit, 13 February 1990

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the sense that it is ascribed; that one meets (1). The other is invoked in the sense that it is the truth-making instance of my existential quantification; that one meets (2). [. . .] See you soon! If at all possible I’ll meet the plane: CO 12, Newark, 6:54am, 16 January. Yours,

494.  To Philip Pettit, 13 February 1990 [Princeton, NJ] Dear Philip, The second-order property P2 is the property such that (1) we know what property it is, and (2ʹ) it is causally relevant, not in the sense that it does the causing itself, but only in a ‘programming’ sense. And this second-order property is, in one good sense, ‘invoked’ and ‘ascribed’ when I explain your behaviour by citing your belief. So far, so good. But if someone thinks the ‘programming’ sense of causal relevance is in­ad­ equate for genuine causal explanation, then it’s time for the identity response. It is impossible to have P2 without also having some first-order property P1, presumably an internal physiological state, that occupies the role and does the causing; so an ascription of P2 ipso facto ‘invokes’ and ‘ascribes’ – albeit by an indefinite rather than a definite description – some such P1. P1 is causally relevant in a more direct way than P2. Needn’t choose – you have both. All this is neutral about whether it’s P2 or P1 that’s identified with the belief property. Whichever it is, when we ascribe the belief we invoke both P2 and P1. The identity thesis is an optional extra to the identity response! It’s not needed in order to defend ‘an explanation in terms of belief is a causal explanation; it tells us how the behaviour was caused’. But it is needed if, like me, you want to say something simpler: not just that belief-explanations are causal explanations, but that beliefs cause behaviour. What am I supposed to be committed to in the case of the metal ladder? ‘The  opacity explanation ought to work on your account’. Why? Consider three properties of the ladder. P2a The property of having some first-order property that makes it conduct electricity;

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P2b The property of having some first-order property that makes it opaque; P1 The property of having loose electrons. Unbeknownst to me, the ladder has P2a and P2b in virtue of having P1. I can explain the electrocution by mentioning P2a explicitly, and thereby indirectly invoking the unknown basis P1. Does it follow that I could have explained the electrocution just as well by mentioning P2b explicitly? I don’t see why. Mentioning P2a does, mentioning P2b doesn’t, fit into an incomplete story about how the death was caused. [. . .] Yours, c: Frank

495.  To Carol Rovane, 9 October 1990 [Princeton, NJ] Dear Professor Rovane, I’m writing about your paper ‘Branching Self-Consciousness’.1 I liked it; I found myself in full agreement with almost all of it, and in particular with the main point that if branching were unexpected or unwanted, the very fact of branching would make it hard for the two branches to continue one’s present projects and fulfill one’s present intentions. (The trouble with branching wouldn’t just be a matter of comical inconveniences, as I suppose I thought before.) But right at the end I came to something I didn’t understand: you say you’ve ‘offered an account that concedes nothing to an untenable metaphysics about the nature of self-consciousness and personal identity such as that of Descartes, Nagel, Chisholm, Lewis, etc.’. Who, me? The only Lewis you’d previously mentioned? You see, I’d have thought I was in full agreement with you about the metaphysics of the matter, and I’d have thought that I had precious little in common with the rest of the gang of four. I see myself as granting all that Parfit ever wanted. I’m a reductionist, I agree that what mainly matters in survival is some sort of psychological relation, I agree that it may come in branching form or in significantly diminished degree. The only disagreement with you (and Parfit) that I can spot is on a mere point of terminology, not metaphysics. As you know, I say that if we define persons as maximal aggregates interrelated by the appropriate psychological relation, then the   (Rovane 1990).

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496.  To Carol Rovane, 26 December 1990

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peculiar happenings in the puzzle cases should be described not as cases of survival without personal identity, but rather as cases where persons overlap, or where ­certain things are persons to a significantly diminished degree. I doubt if this can be what you had in mind, since it’s a pretty superficial disagreement and since my line in no way allies me with D, N, and C. So I suspect a misunderstanding, either on my part or on yours. Shall we see if we can sort it out? What was the untenable metaphysics you had in mind? Thanks, Sincerely, David Lewis

496.  To Carol Rovane, 26 December 1990 [Princeton, NJ] Dear Professor Rovane, Thank you for your very helpful letter. Before we get down to business: yes, I was surprised to be included in the gang of four. But not indignant. On your first point: for me, it’s always meant to be the stages who do the ­self-ascribing. To be sure, ‘Attitudes De Dicto and De Se’ starts out ignoring time for the sake of simplicity, but that’s soon set right. You think of your future self like this: ‘I-now stand in suitable relations to a future stage which does so-and-so’ or equivalently ‘I-now am part of a suitably interrelated aggregate of stages, and a future part of that aggregate does so-and-so’. That’s still de se thought (or you could call it de se et nunc) but the ‘se’ in question is the present stage – not the aggregate, still less the future stage. (I’ll go on calling a suitably interrelated aggregate of stages a ‘continuant person’. But this has turned out to be a bad choice of terminology, because people who don’t believe in stages sometimes grab the word ‘continuant’ for the thing which, as they think, exists wholly at each of many times.) Branching complicates the story, as you say. See ‘Two Minds with But a Single Thought’ (in my Philosophical Papers, Volume I, pp. 73–76) for some discussion. This is where my reductionism about personal identity and my position about attitudes de se come together, though only very briefly. What I say there will come as no surprise to you – you’ve got it worked out in the letter. If I want to survive, and I anticipate branching, then it’s my present stage, shared between two overlapping continuants, that’s doing the wanting de se. If so, the stage presumably doesn’t want the property

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because it knows there is no such unique continuant. It can want the property

(2) being such that some continuant of which it is a stage survives

or it can want the property

(3) being such that every continuant of which it is a stage survives

or both. I think my present stage, if it anticipated branching, would care little for (3) and very much want (2). I argue that even now, when I don’t anticipate branching, my present stage still wants (2), as well as wanting (1) and maybe (3); but this assumes what you question, that unanticipated branching would give my present stage most of what it wants in wanting survival. Note that (2) can be equivalently given as (2ʹ) being suitably related to some future stage. Properties (1) and (3) also can be equivalently rewritten in terms of relations of stages, but it’s harder. Identity, I said, is a relation of acquaintance par excellence that every stage bears to itself. It is not, of course, a relation that the stage bears to the continuant of which it is part; the stage is identical to only one small part of the continuant. (The stage normally does bear other relations of acquaintance to earlier, though not later, stages of the continuant it’s part of.) A relation of acquaintance I bear to someone is a relation such that ‘there is extensive causal dependence of my states upon his, and this causal dependence is of a sort apt for the reliable transmission of information’. So in saying that identity is a relation of acquaintance, I mean that there is extensive causal dependence of the states of a stage upon other states of that same stage, and that this causal dependence is of a sort apt for the reliable transmission of information. For instance many of my present beliefs about my immediate surroundings (and hence my relational properties, e.g. the property of facing a green screen) depend on what’s true about my present surroundings, and this dependence is of a sort apt for the reliable transmission of information. Likewise my present beliefs about the arrangement of my limbs depend upon the arrangement of my limbs; my present beliefs about my present thoughts depend upon my present thoughts; etc. Not as a matter of necessity, of course; but as a matter of the sorts of causal dependence that actually go on in the world. I daresay the rest of the gang of four may have had something more remarkable in mind under the heading of ‘self-acquaintance’, something to which you’re rightly allergic. But what I had in mind was just this multifarious pattern of causal dependence. Do you question that, in this sense, we (that is, our stages) have plenty of self-acquaintance?



496.  To Carol Rovane, 26 December 1990

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(Mark Johnston questioned it, at least when the stages are taken to be in­stant­ an­eous rather than just short. He pointed out that there’s a slight time lag, so my present beliefs about the arrangement of my limbs, for instance, depend not on the present arrangement of my limbs but on the arrangement of my limbs a split second ago. Point taken; but I don’t see that it makes much difference.) I do think that the pronoun ‘I’ normally refers to a continuant: the continuant (presupposing there’s a unique such continuant) of which I-now am a stage. (When there isn’t a unique such continuant, the normal ‘I’ comes to be like an improper definite description – I think that makes it not denotationless but ambiguous, and the ambiguity may or may not matter.) But I think usage is easy-going. Nobody – well, nobody who believes in stages in the first place – should make heavy weather over a stage referring to itself as ‘I’. Still, I’ll try to stick to ‘I-now’ as the first-person pronoun for stages. Stages are subjects of attitudes, according to me. Are continuant persons also subjects of attitudes? – Sure, in a derivative sense: my attitudes are the attitudes of my various stages, my attitudes now are the attitudes of I-now. Likewise, persons (as well as stages) are objects of attitudes: when my present stage thinks ‘I-now am writing on the afternoon of 26/12/90’, not only does it self-ascribe writing; it also thereby ascribes to the whole of me, under the relation of part to whole, the property of ­having a stage on the afternoon of 26/12/90 that is writing. I agree with you that we have extensive self-conceptions. We wouldn’t amount to much as agents, or even as passive spectators, unless we – that is, our stages – selfascribed being in space and time, being parts of suitably interrelated aggregates, engaging in causal transactions with our near spatiotemporal surroundings, and thereby less directly with our more distant surroundings. Among the temporal surroundings of a stage, I include the earlier and later stages of the same continuant person. Life wouldn’t be at all the same for a stage that didn’t self-ascribe being part of a continuant person, and bearing all the right causal and other relations to the other parts. Such a peculiar stage would indeed miss out on all sorts of ‘distinctive features and capacities’ of person-stages; and the person of which it was a stage (if there were one) would likewise miss out on all sorts of distinctive features and capacities of persons. Do we also need ‘direct self-acquaintance’? Surely we need what I call selfacquaintance: a pattern of causal dependence whereby a stage reliably self-ascribes a lot of the intrinsic and relational properties that it has. But I think you mean something else. I’m not clear what this something else would be; but if I knew, I well might agree that we don’t need it. I think we agree that all you want to say could probably be expressed within the framework of my analysis of de se attitudes. ‘But not happily expressed’? Well, it does

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sound clumsy and unfamiliar when it’s said my way! (Though one can get used to it, I’ve found.) I suppose that between a familiar lingo that breaks down in bizarre cases, and a clumsy and unfamiliar lingo that copes with bizarre cases, there’s at least some reason to go for the latter. After all, nobody says I have to talk that way all the time! One advantage of being the kind of reductionist who claims equivalence is that I don’t have to choose. I have both, and can choose the lingo that best suits the occasion. Again, thanks very much for your letter. (I’ll re-read your JΦ article1 in the light of it, but I haven’t yet.) Yours, David Lewis

497.  To Daniel Dennett, 21 January 1991 [Princeton, NJ] Dear Dan, I have a phone message that says you want to know whether I, in ‘General Semantics’, invented mentalese. I don’t think so. Did I use the term ‘mentalese’ at all in ‘General Semantics’?1 I don’t recall it, nor do I spot it on a quick look through. A term I did use, and I think I did coin, is ‘Markerese’: a language consisting of Jerry Katz’s ‘semantic markers’. I also use ‘Semantic Markerese’ in ‘Languages and Language’,2 written before ‘General Semantics’ (for a conference in 1968) but published later. I think I use ‘mentalese’ somewhere, but I can’t say where. I don’t recall ­coining it. Now a question for you. Who first said ‘folk psychology’? (You?) When, where? I recently read someone who said it was a recent coinage, and was pejorative from the start. I don’t believe that – I think it goes back to at least the early 70’s, and wasn’t pejorative until Paul  C.  tried to make it so. I came close, but didn’t quite use the phrase: ‘common-sense psychology – folk science rather than professional science, but a theory nonetheless’ (in ‘Psychophysical and Theoretical Identifications’, AJΦ 1972; written for a conference in 1968). Yours, David Lewis   ‘The Epistemology of First-Person Reference’ (Rovane 1987).

1

 (Lewis 1970a).   2  (Lewis 1975b).

1



498.  To W.L. Craig, 21 January 1991

153

498.  To W.L. Craig, 21 January 1991 [Princeton, NJ] Dear Dr. Craig, I’m one of those who thinks of time as a fourth dimension, and who thinks of us as aggregates of temporal parts. The subject who self-ascribes properties is a momentary self, and may self-ascribe, among other things, a location in time. This is de se belief or, in fortunate cases, de se knowledge. Whether propositions are tenseless, and whether there are ‘non-propositional de se facts’, seem to be terminological issues only; and terminological issues which can’t be settled in any authoritative way, because philosophical usage isn’t uniform enough. My own ‘official’ choice of terminology is one in which propositions are sets of worlds, and facts are true propositions; and in this terminology, of course, de se knowledge is non-propositional and non-factual. But if somebody wants to adopt a different terminology, I don’t protest. So, for instance, what I call a ‘self-ascribed property’ could instead be called an ‘egocentric, tensed proposition’: true relative to individual, time, and world. (Or, more simply, true relative to a world-bound momentary self.) And a true one of these egocentric, tensed propositions could be called an ‘egocentric, tensed fact’; its facthood, like its truth, would of course be relative to individual, time and world. In this terminology, the objects of de se attitudes are egocentric, tensed propositions; and the objects of de se knowledge are egocentric, tensed facts. Or there might be a mixed terminology, in which ‘proposition’ is used (my way) for the non-egocentric, non-tensed entities, but ‘fact’ is used (the other way) for the egocentric, tensed ones – or rather, for those of them that are true. In this mixed terminology, you’d say (in the words of your letter) that there are ‘non-propositional de se facts about things, which are apprehended in knowledge de se’. I find the mixed terminology clumsy, but not otherwise objectionable. Anyway, talk whatever lingo you like, I would agree that there’s nothing minddependent or subjective about it. Sincerely, David Lewis

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499.  To Jerry A. Fodor, 6 March 1991 [Princeton, NJ] Dear Jerry, I’ve read your ‘David Lewis: Holism and The Inextricability Thesis’.1 Or shall I say I’ve tried to read it – I fear it doesn’t exhibit your accustomed clarity, and there’s a good deal of it that I don’t think I understood very well. I’m sorry. Most of the chapter is about the failure of an argument from something called the ‘inextricability thesis’ to something called ‘meaning holism’. The first is the claim that ‘the conditions for content attribution necessarily inherit the conditions for belief attribution’ (page 65) and the second is ‘roughly . . . the doctrine that only whole languages, or whole theories, really have meanings, so that the meanings of smaller units . . . are merely derivative’ (page 64). I don’t understand either thesis; nor do they strike me as things I’d be likely to believe if I did understand them (especially the second). I’m sure I’ve nowhere asserted either one, still less argued for the second from the first. But then, you never quite say I did, right? The chapter title seems to promise a discussion of Lewis on holism and the inextricability thesis, but once we get beyond page 64, it’s never very clear when you’re talking about what Lewis does say, when you’re talking about what you think Lewis might say, and when you’re ­talking about what someone nameless might say. The first four pages really are about my paper, but I regret to say they’re rather  badly distorted. One problem concerns my alleged behaviorism. ‘Radical Interpretation’ is indeed too behavioristic in various ways; but certainly it doesn’t throw out all the physical facts except ‘behaviors under physical descriptions’: don’t forget the role of Karl’s history of evidence. Of course what you say (page 61) is that I appeal ‘primarily’ to behaviors under physical descriptions; who knows what that ‘primarily’ means; so you’re not committed to anything definite, a fortiori not to anything definitely false; but certainly there’s a misleading suggestion. A worse problem is that you conflate my ‘Principle of Charity’ with Davidson’s – or rather, with Davidson’s most sloganistic formulations, which he readily retracts under pressure. My Principle does not involve maximising truth; it does make a place for disliking the experience of pinpricks, and for being mostly right about what’s before one’s open eyes; and the platitudes that are parts of it do come out contingent. (‘Utterly contingent’? – Can’t say, what’s the difference between utter and less-than-utter contingency?) Yours, David Lewis 1   Holism: A Shopper’s Guide (Fodor and Lepore 1992, ch. 4: David Lewis: Meaning Holism and the Primacy of Belief). It is stated therein that Lewis does not endorse the primacy thesis, formerly labelled the in­ex­tric­ abil­ity thesis (Fodor and Lepore 1992, 114).



500.  To Earl Conee, 17 September 1991

155

500.  To Earl Conee, 17 September 1991 [Princeton, NJ] Dear Earl, Thank you for your paper.1 I think I have very little disagreement with it. The question I wanted to answer was: what is the lasting change produced in Mary when she has novel experiences and comes to know what those experiences are like? Answer: she gains imaginative abilities, and such abilities normally are retained afterward. And to this I think you don’t object. But your question is: if somehow she didn’t gain these abilities, and in fact didn’t undergo any lasting change as a result of her novel experience, couldn’t we still say that she knew what the experience was like at least while it was still going on? OK by me. It’s a queer case, I’m not sure it’s quite determinate what we ought to say, but I certainly don’t think you’re determinately wrong! There’s a question about just what you’re supposing. Is it that (1) she never gains any sort of imaginative ability? Or is it that (2) she does, temporarily, but her new-found ability to imagine the novel experience ends just when the novel ex­peri­ ence ends? I know your case is meant to be (1), and needs to be (1) in order to make your point that she knows what it’s like without benefit of imaginative ability. What I’m a little unsure of is whether (1) and (2) really differ. On a naïve does-or-would-ifshe-wanted analysis of ability, plus a naïve analysis of imagining E as having some E-like experience, it’s automatic that she has the ability to imagine E whenever she has E. (What so E-like as E itself?) I don’t think I believe either of those ‘naïve’ ana­ lyses; what I’m not sure of is how much difference it would make if they were corrected. My guess is that (1) and (2) would indeed come out as different suppositions, so you’d be OK. I agree with you that whether there’s room for a sceptical doubt about other minds is (what Armstrong calls) a spoils-to-the-victor question. Given the rest of what we disagree about, Frank and I should indeed disagree about that as well. But it’s not likely that at this point we’ll find some intuition so decisive to all concerned that it can be the premise that leads to agreement about all the rest. I found one small disagreement with you toward the end. The experience of tasting vegemite is, in fact, the firing of V-fibers; Mary was already well acquainted with the firing of V-fibers not only through book learning but also through many experiments she performed on V-fibers in the lab, stimulating them (in other people) and recording their firing patterns. So how can we say she gained acquaintance with   ‘Phenomenal Knowledge’ (Conee 1994).

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Philosophical Letters of David K. Lewis

156

V-firing for the first time when she first tasted vegemite? – We can agree that what she had already wasn’t the right sort of acquaintance; the question is how to spell that out. Your idea is that her lab acquaintance with F-firing doesn’t count because it wasn’t the most direct acquaintance with V-firing that’s humanly possible, but what she got when she tasted vegemite was the most direct acquaintance with V-firing that’s humanly possible. Now consider ultrasound: dogs can hear it, we can’t. The most direct acquaintance with ultrasound that’s humanly possible is lab acquaintance, like Mary’s lab acquaintance with V-firing. So it looks as if you’ll say that Mary in the lab isn’t yet acquainted with V-firing, but is acquainted with ultrasound (another thing she has experimented with). But wait: is it technically feasible to transplant dog’s ears (complete with all required neural circuitry) into a human? Is it nomologically possible? Is it compatible with the essence of humanity to have working dog’s ears? If yes, you’ll say that Mary’s lab acquaintance with ultrasound isn’t after all the most direct that’s humanly possible, so it doesn’t after all count as acquaintance. But I think that, whatever we do or don’t want to say about whether lab acquaintance with ultrasound should count as acquaintance, the answer shouldn’t depend upon far-fetched questions about the sense in which it is and isn’t humanly possible to have dog’s ears! It seems to me that an ana­ lysis that makes those questions relevant has got to be on slightly the wrong track. Paul Teller sent me a draft about five years ago which says some, but only some, of the same things you do. I don’t know if he ever published it. If I were you I’d check the Philosopher’s Index, and maybe compare notes with Paul (now at U.C. Davis) to see if a citation is called for.2 Yours, David Lewis c: Jackson, Nemirow

501.  To J.J.C. Smart, 4 October 1991 Princeton University Princeton, NJ Dear Jack, Thank you for your note on ‘looks red’1 which I’ve read with great interest and half-agreement. I fully agree with you that we should not begin with ‘looks red’ and   ‘Subjectivity and Knowing What It’s Like’ (Teller 1992).

2

  ‘ “Looks Red” and Dangerous Talk’ (Smart 1995).

1



501.  To J.J.C. Smart, 4 October 1991

157

then explain ‘is red’ in terms of it. But I do not agree with you that ‘ “looking red” should come at the end of the story, not at the beginning’. I think both notions should enter together at the beginning of the story, neither one preceding the other. It’s an old story by now, on which I think you and I agree pretty completely, that folk psychology is a theory which introduces several theoretical terms all at once; and that these terms should be taken to denote the occupants of roles set forth in that theory; and that these roles are interrelated. Thus part of the belief-role is to join with desire in causing behaviour, while part of the desire-role is to join with belief in causing behaviour. Folk-psychological names for occupants of roles are therefore interdefined. The roles set forth in folk psychology are occupied, not perfectly perhaps but near enough; and in all probability the occupants of the roles are certain physical states, e.g. certain patterns of nerve firings; and that is how these physical states deserve the folk-psychological names. Well, I’d like to extend that account in exactly the same style. I say that folk psychology is really a bit more than just psychology. It’s a combined theory, folk psychology-cum-psychophysics. It specifies causal roles for the colours (surface properties of opaque things, in the main case) and it specifies causal roles for the colour-experiences (states of the person). These roles are interrelated, much as the definitive roles of belief and desire are; and the names for occupants of the roles are thereby interdefined. Part of the definitive role for a colour, and part of the definitive role for the corresponding colour-experience, is that the former typically causes the latter (at least on a cloudy day in Scotland). Of course, there’s more to the roles than that. Another part of the role of the colours is to be fairly permanent properties of most of the things that have them, and also to be correlated to some extent with other differences between kinds of things. (Roses are red, violets are blue.) Part of the role of colour-experiences is to give rise to beliefs about identity over time of the things before one’s eyes. Thus the whole of what folk psychology-cum-psychophysics says about the colours and the colour-experiences together will explain, among other things, the discriminatory responses whereby we sort and classify and reidentify things by colour. A colour-name denotes the occupant, or the near-enough occupant, of a role set forth in folk theory; and so does a colour-experience name. But the roles are enough entangled that there’s no question of defining a colourname without simultaneously defining the corresponding colour-experience-name, or vice versa. That’s the idea. Matters get complicated in two different ways, but I think, contrary to the opinion of many, that neither sort of complication forces us to abandon the account I just gave. One complication is that nature turns out to hold some big surprises. If nature had worked as we might naively have guessed, there would have been just one

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­surface property to occupy each colour-role; and that property would have been highly natural, non-disjunctive, and intrinsic. Notoriously, that’s far from the truth. I think that means that we turn out to have no perfect occupants of the roles, no perfect deservers of the colour-names; and we have a good deal of choice between rival imperfect near-enough deservers of the names. (I think it’s a bit wild to say we don’t even have near-enough deservers, so that science teaches that Essendon doesn’t after all wear red and black!) The main business of philosophy of colour nowadays seems to be the choice between rival imperfect but near-enough deservers of the colour-names. Shall we say that a given colour turns out to be a ‘hellish disjunctive and ­idiosyncratic’ physical property of surfaces? Or a unified dispositional property? Or not one property but many which give rise to the same colour-experience, so that prussian blue is a different property in different cases? Shall we say that prussian blue turns out to be, to some extent, a relational rather than an intrinsic property? Or that there’s no intrinsic property prussian blue simpliciter, but rather there is one intrinsic property that occupies the prussian-bluefor-MacGregor-tomorrow role (if Angus and MacGregor differ in their neural wiring, or if today is cloudy and tomorrow is clear)? Or just that there’s much more colour illusion about than we usually think? I suspect that these questions have no very clear-cut answers; and I suspect that the case of specific shades of colour may go differently from the case of red, green, blue, and yellow. Anyway, I think it’s a bit backward to try to sort out problems about the imperfect deserving of colour-names here in the real world without first getting quite clear about what it would have taken to deserve the names perfectly in a nice surprise-free world where our folk theory was exactly right. The other complication concerns unactualized possibilities. It has nothing to do with the complexities of the real world, so let’s ignore those and pretend that each colour-role is indeed occupied once and for all by one intrinsic and non-disjunctive natural property, and likewise each colour-experience-role is occupied by one pattern of nerve firing. It remains contingent, though, which properties occupy which causal roles. (It may be not only contingent but also temporary. So instead of ex­amples about other worlds that are different all along, we can have examples about worlds that start out like ours but then undergo great changes. Let that pass.) It seems (1) that things might have been red and green exactly as they are here, but it might have been leaves that were red and blood that was green. It seems (2) that things might have been red and green exactly as they are here, blood red and leaves green, and so on; but that, owing to a difference in the nervous system, looking red and looking green might have been quite different patterns of nerve-firing than they



501.  To J.J.C. Smart, 4 October 1991

159

actually are. On the other hand it seems (3) that things might have looked red and looked green, just as they actually do, but some quite different surface property of  blood might have made blood look red, and so might have been the colour red; and likewise some different surface property of leaves might have made leaves look green. When we have a name for an occupant of a theoretically defined role, it might be a ‘rigidified’ name for the actual occupant of that role; and it might continue to name that same thing even when we discuss a world where that thing doesn’t occupy the role. On the other hand it might be a non-rigid name which, relative to any given world, names the thing that occupies the role in that world. (You can restate this if you like in terms of a treatment of modality more to your liking. Further, I still think, pace Kripke, that rigidification can be equivalently restated in terms of wide scope. But I’ll carry on in the way I’m used to.) Each of the examples above can perfectly well be handled by making an appropriate assumption about which of the colour-names and colour-experience-names are and are not rigidified. But the assumptions to handle the different examples will turn out to conflict. For instance, (1) and (2) demand rigidification of ‘red’ and ‘green’; (2) forbids rigidification of ‘looks red’ and ‘looks green’; and yet (3) demands rigidification of ‘looks red’ and ‘looks green’ and forbids rigidification of ‘red’ and ‘green’! Some will say that if I can’t arrive at a consistent hypothesis, once and for all, about what’s rigidified and what isn’t, then the whole approach collapses. And if so, what can we put in its place? Elimination of the colours? – That’s crazy. Fixing the non-rigid reference of colour-names and colour-experience-names both in terms of qualia which we can name rigidly by direct acquaintance? – I want to avoid that as much as you do. Rigid naming of colours by ostension of their instances? – That mightn’t be bad in the nice surprise-free world we’re imagining, but I think it wouldn’t carry over at all easily to the real world of hellish disjunctiveness and idiosyncrasy, not to mention relativity to perceiver and surroundings and lighting. But I think the right response is much less radical and exciting, and has more to do with the semantics and pragmatics of ordinary language than with the phil­oso­ phy of colour. I think the lesson to learn is that rigidification comes and goes with the pragmatic wind, according to the rule that the right way to take what’s said is the way that makes the message make sense. The question whether colour-names are rigidified or not shouldn’t be taken as a philosophical issue with arguments pro and con; the answer should be that sometimes they are and sometimes they aren’t. In conversation, we play along with our interlocutor; when he rigidifies, we join him; but if he’s a philosopher purporting to prove to us that a designator is, once and for all, rigid, then our playing along can mislead us quite badly.

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As you’ve surely guessed, this is a paper I’ve meant to write for a long, long time; this letter amounts to a very preliminary draft.2 Maybe I’ll do it properly as my main project for my sabbatical in 1993. Yours, David c: Armstrong, Campbell, Jackson, Johnston, Pargetter, Pettit

502.  To Ned Block, 26 January 1993 [Princeton, NJ] Dear Ned, Chauvinism? I don’t think I need be worried. The extent of my ‘chauvinism’ is that an alien without a foot can’t kick anything; and so can’t have any state that (in its case) is apt for causing kicking. The same is true of all too many humans, e.g. victims of land mines. Likewise you and I lack tails, and so can’t have any state which (in our case) is apt for causing tail-chasing. But I don’t see that these disabilities, by themselves, do very much to limit the applicability human folk psychology to wheeled aliens and human amputees, or to limit the applicability of cat psychology to us. I’m no perfectionist about terms defined by theoretical roles; most, maybe all, folkpsychological terms can apply well enough to an imperfect realizer of human folk psychology and of the humanoid anatomy presupposed thereby. Even if differences of anatomy might make some few bits of human folk psychology inapplicable to the wheeled alien, there’d be plenty left. I can even grant that the wheeled alien, if suitably deceived about its own ­anatomy, could intend to kick a ball; just as I, if deceived, could intend to chase my tail. For I don’t think that intending to kick is just a matter of being in a state apt for causing kicking. (I’d be a bit wary of going over to something in terms of ‘effector organs’ for fear of making the theory insufficiently folksy. But maybe I needn’t worry too much, since I don’t in any case require the folk to master the jargon whereby we might expound what they tacitly believe.) Mary. Know-how isn’t a red herring, but neither is it the heart of the matter. The heart of the matter is that whatever may be happening, anyway Mary is not eliminating genuine possibilities left open by her perfect knowledge of physics. What is   ‘Naming the Colours’ (Lewis 1997b).

2



503.  To Michael McDermott, 8 April 1993

161

­ appening is less important than what isn’t. Still, it has some importance, because h after all something is happening that’s easily mistaken for the elimination of hithertoopen possibilities, and of course we want to know what that something is. No harm done, however, if that something turns out to be a bundle of several different things happening together, different ones of which have been mentioned by different philo­ sophers. But I’d still say that gaining know-how is at very least an important part of the bundle. Secondary qualities. This paper was originally subject to a 3K word limit, which Guttenplan has kindly allowed me to stretch to about 13K. So you’ll understand why I’m reluctant to expand the discussion still further. What would be good to do is to cite my paper ‘Naming the Colours’, but unfortunately that has yet to be written. However I enclose a copy of a letter1 which tells the story in summary form. (Not for citation, of course.) Recopying. Okay; but the copies must carry the ‘please don’t recopy’ note at the top. When do you want them? If you can wait, there will at some point be a version improved at the one point I’m seriously unhappy with: the discussion of necessity a posteriori, which almost everyone says is too technical. Yours,

503.  To Michael McDermott, 8 April 1993 Melbourne, Australia Dear Michael, I enclose a copy of a letter to the philosophy editor at Blackwell and a copy of a near final draft of ‘Reduction of Mind’.1 Parts that differ from the version you saw are pages 4–5 on necessity a posteriori, pages 17–18 on concepts. I think of myself as identifying wide with de re ascriptions, yes. But often the res is a property: waterhood, in Putnam’s Twin-Earth story. That leads to ambiguity in applying the de re/de dicto distinction. ‘Oscar believes of waterhood that instances of it fall from clouds’ is de re in the  sense that we can substitute for ‘waterhood’ salva veritate a non-synonymous term that refers to the very same property. However we cannot substitute a term that refers to a different but contingently coextensive property – and some people might   Letter 501. To J.J.C. Smart, 4 October 1991.

1

  (Lewis 1994b).

1

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therefore say that there’s a sense in which it’s de dicto. The fact that we learned the de re/de dicto jargon from a man who didn’t believe in properties helps us to be unsure how to apply it in such a case. I stipulate that Strawman does indeed say that the meaning of a word of the language of thought is just the reference. After all, he’s my character – and he’s meant to exemplify a position in its simplest and most unrefined form. If I wanted to subject Strawman’s position to piecemeal reform rather than replacement, I would indeed suggest adding other dimensions of meaning. Whether the inference from the premise People who believe x and p are thereby typically caused to believe q to the conclusion that x is the conditional ‘if p then q’ is an instance of constitutive rationality depends, I suppose, on whether we should characterise conditionals by means of truth-conditional analysis or whether it’s better to characterise them in terms of the psychological role of conditional beliefs. What I had mostly in mind under the heading of constitutive rationality wasn’t so much deductive logic as the fit between actions and belief and desire. Yes, this does sound like Davidson – though without his irrealism and without his emphasis on the interpreter. But still more, it should sound like decision theory, and the project of recovering subjective probabilities and utilities from the agent’s dispositions to choose between gambles. That was the common source for Davidson and for me. I’ll see you in June. Yours, David

504.  To Michael Smith, 1 August 1993 Melbourne, Australia Dear Michael, Thank you for the paper on conceptual analysis and colour. I’ve read it and I like it, but doubt it. Someday – when I’m here again next winter? – I mean to write on colour. But other projects have kept jumping the queue. What I’ve written (apart from brief mentions in ‘Psychophysical & Theoretical Identifications’ and ‘Reduction of Mind’) is mainly in one or more letters to Jack from the early 70’s.1 (If Jack doesn’t   Letters 422, 423, 427, 429, and 430 to J.J.C. Smart.

1



504.  To Michael Smith, 1 August 1993

163

mind, and if he can find them without bother or you ask me to find them in Princeton after I get home in September, I’d be glad to have you see them. I think of my position on colour as basically unchanged since then, but maybe years of small changes have added up to more total change than I know.) Philosophical comments follow, and I’d be glad if you could make copies for interested colleagues, especially Jack, Frank and Philip; and others as you see fit. But first a couple of private and trivial ones. [. . .] Yours, David David Lewis 1 August 1993 Comments on Smith, ‘Conceptual Analysis’ 1) I’d agree that your ‘non-reductive analyses’ – or non-analyses, I’d call them – will do as premises to generate the platitudes, and also as premises for identification of colours with reflectance properties, and also as premises for specifications of the reference of colour names. So what more could I want? – specification of the sense of colour names; and, thereby, explanation of why the colour names have the reference they do. All very traditional. 2) For this purpose, I take for granted that we have to solve, not dodge, the permutation problem. More on that later. 3) Have we an alternative to analyses as a means of explaining why the colour names have the reference they do? Ostensive teachings, did you say? – But I say that’s not an alternative. It yields analyses. Peculiar ones – parochial, I’ll call them – available only to one or a few members of the linguistic community and only temporarily. Also, de se and tensed. But of the proper non-circular form. Assume ‘colour’ has been defined ahead of time. Assume we know what it means to ‘demonstrate’ a colour: you draw my attention to a salient instance of it. ‘Green = the colour just now demonstrated to me by someone while saying “that’s green” ’ is an analysis available to the learner, though it’s a very parochial analysis. 4) Or rather, there’s the corresponding permutation-stopping clause in what you call a ‘Lewis-style analysis’. (I might prefer to name it for Ramsey and Carnap, thinking that my own tinkering is but a small part of the story. Let’s compromise and abbreviate: ‘RCL’.) 5) Actually, I favour a combined RCL analysis of colours and colour experiences simultaneously (and other secondary qualities and other mental states besides) based

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on folk psychology including folk psycho-physics, plus permutation-stopping clauses. Of course the expansion by itself doesn’t stop the permutation problem. 6) I didn’t long remember when or by whom or with what samples I was taught the colours. (I vividly remember my disgust at being taught them all over again in school at age six, long after I’d learned them the first time.) But by that time I had many other permutation-stoppers available to me, still parochial but less so. I didn’t have the poms’ favourite – ‘Red is the colour of pillar-boxes’ – but I did have ‘Dark green is the colour of mailboxes’ (they were repainted blue only some years later), ‘Red is the colour of fire engines’, etc., etc. I also had others that were de se and involved my own verbal dispositions: ‘Red is the colour which, together with a question about the colour of something and lack of motivation to be unhelpful, would tend to elicit from me and others hereabouts the spontaneous reply “It’s red” ’. 7) I had far more than enough of these permutation-stoppers to solve the permutation problem. The colour solid is a fairly rigid structure, given shape in terms of simi­ lar­ity distance. These distances are measured by the number of steps of easy confusability that take you from one colour to another. (I can confuse a very dark blue with black, or with a lighter blue; I can confuse the lighter blue with a still lighter blue; . . . From black to sky-blue might be less than ten steps of easy confusability. From anywhere to anywhere might be under twenty.) Folk psychophysics tells us, in a rough and ready way, about these distances. Further, the light and dark poles of the colour solid should be easy to specify, given the connection between black and the lack of that whereby we see. So to nail down the whole colour solid will take very few nails – very likely just one. ì we ü 8) If í ý have far more than enough permutation-stoppers, why bother to îI þ ìour ü make up í ý mind which one(s) to take as the officially chosen one(s)? It’s îmy þ harmless to leave it undecided which facts about colour are to count as analytic, which not. We have versions of colour language that differ in sense but not reference of the colour terms, and we don’t bother which one is to be picked out as the official version. Countless platitudes will be not-definitely-not analytic. They will seem open to challenge and revision, almost as if there was no analyticity there at all. Only if you try to imagine them all going at once will any suspicion of incoherence arise. 9) On top of all this, we might have a Kratzer effect: those candidates for analyticity that we especially focus our attention on might, temporarily, become definitely not analytic. That would do still more to render invisible the diffuse and indeterminate analyticity of the many available permutation-stoppers.



504.  To Michael Smith, 1 August 1993

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Kratzer’s idea was originally meant for boundary vagueness. She starts with the usual supervaluationist line: we are undecided between many different resolutions of vagueness, a.k.a. ‘classical valuations’. What’s true on all is determinately true; what’s false on all is determinately false; what’s true on some and false on others suffers a truth-value gap. So it’s determinately true (because true on each resolution) that somewhere there’s a border between short and tall. (Or two boundaries between short and middling, middling and tall; but let’s keep it simple.) But it’s indeterminate whether the boundary comes at 1,894 meters, because some admissible resolution put it there but others put it elsewhere. Further, it’s a context-dependent matter just which resolutions of vagueness are admissible. So far standard supervaluationism as background. Now for Kratzer’s new twist. Consider a special context: one in which we’re focusing on the question whether the tall-short boundary comes right at 1,894 meters. In that context, she says, the resolution that puts the boundary just there becomes inadmissible. So likewise with other locations of the boundary. (It’s important that we cannot focus on all the different locations all at once.) Thanks to this contextual effect it turns out that wherever we look the boundary is determinately not there but elsewhere! Where else remains indeterminate, of course. 10) I’ve been leaving out the fact that the analytic permutation-stoppers are parochial. Let’s return to that, dropping for now the semantic indecision. Let’s suppose by way of idealization that English-speakers divide into subcommunities that make different official and determinate choices about which permutation-stoppers are analytic. So the colour-names have different senses, but the same reference, in different subcommunities. A typical member of one subcommunity knows that the sense varies and the reference doesn’t; knows what the senses are in his own subcommunity and some but not all of the others. 11) Now put together both halves of my picture, the semantic indecision and the parochiality. Any one subcommunity has not its determinate official choice but its range of indecision. The ranges of indecision differ from one subcommunity to the next, but with a lot of overlap. Each knows that the overall situation is as I’ve described – plenty of parochiality and indecision about the sense of the colour-names, but no resulting variation or indeterminacy of reference. Nobody knows the whole picture in detail. No pom knows whether ‘Red is the colour of pillar-boxes’ is or is not one of the permutation-stoppers that’s not-determinately-not analytic for the Kiwis, etc., etc. 12) Would this messy situation do any harm? Not much! There’d be trouble only on those rare occasions when we ask, e.g., what colour beets would have been if they’d been the colour that unripe apples actually are.

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13) And on those rare occasions, we can still keep out of trouble by judicious rigidification. Here Kripke gave us a bum steer. He taught us that we could have a dispute between two philosophical views: the view that name N is an unrigidified description once and for all, versus the view that N is once and for all a rigidified description. No decision once and for all about whether the colour-names are rigidified, and no decision once and for all about whether the colour-experience-names are rigidified, will together fit everything we want to say. I forget the details, but look in old papers by Michael Bradley and by Keith Campbell. Solution: names aren’t rigidified or unrigidified once and for all. Rigidification comes and goes with the pragmatic wind, governed by the rule that the right interpretation is the one that makes the message make sense. We were wiser when we spoke not of rigidification but of wide-scoping. (And I say pace Kripke, that the two ways of putting it are equivalent descriptions.) Nobody would ever have expected a scope ambiguity to be settled once and for all! 14) So we could live comfortably with parochial analyticity, even if it’s on top of semantic indecision about what’s analytic. That said, I’m not sure we have to. (At least not for the language of the grown-ups, as opposed to the learners.) For it’s common knowledge that a few permutation-stoppers are available throughout the entire linguistic community. ‘A few’ means four, but that’s enough. Maybe more than enough. Not pillar-boxes, not fire engines, not chicks; but how about – The red of blood? The green of most leaves when well watered? The blue of the cloudless, smokeless, midday sky? The yellow of the sun? 15) A different kind of permutation-stopper and a better candidate for determinate analyticity than any I’ve yet mentioned would be an irregularity in the colour solid – an irregularity that’s common knowledge. I can only think of one, but maybe one is all we need. Namely There is no such thing as dark yellow, so dark it’s almost black. The trouble is that I expect an objection: ‘there is so, and we call it “brown” ’. I believe that experts like Hardin know of good reasons why brown should not be considered dark yellow, but I don’t really know what those reasons are. What’s more, the folk don’t know (or do they? Are the reasons something that could be elicited Meno-fashion?) But I want my permutation-stoppers to be analytic or not-determinately-not because they’re part of folk psychophysics and hence common knowledge. [. . .]



505.  To Michael McDermott, 2 August 1993

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505.  To Michael McDermott, 2 August 1993 [Melbourne, Australia] Dear Michael, A belated – I apologise – reply to parts of your 3 May letter. Tom believes that the one he himself is ‘Cicero’-acquainted with denounced the one he himself is ‘Catiline’-acquainted with. That’s narrow, and accordingly it’s equally true of twinTom. And I think that’s one thing, though not the most likely thing, for someone to mean who says ‘Tom believes that Cicero denounced Catiline’. But a more likely thing to mean would be the conjunction of ‘Tom believes the one he himself is “Cicero”-acquainted with . . .’ (etc. as before) with further conjuncts to the effect that the one Tom is ‘Cicero’-acquainted with is Cicero; and likewise for Catiline. That’s wide, not narrow, thanks to the extra conjuncts; the names aren’t purely referential, thanks to their quotational appearances in all three conjuncts; and it doesn’t fit my formula for the de re reading. The de re reading is still a third, somewhat less likely(?), thing for the original sentence to mean. ‘We are invited to agree that Twoscar believes that XYZ falls from clouds’ (and that Oscar believes that H2O does). Invited by Strawman, and by Putnam, I meant. Maybe the particular judgements of what’s rational given just such-and-such beliefs and desires aren’t part of folk psychology; but the principles underlying those judgements are. I think of folk psychology as predicting behaviour by a two-step procedure. First it introduces a (descriptive!) distinction between rational or ir­ration­al, or (better) between more and less rational; second, it predicts a certain modicum of rationality. Compare the way thermodynamics first introduces the distinction between entropy-reducing and entropy-increasing processes, then predicts that it will mostly be the latter that happen. Yours, David [. . .]

506.  To Ned Block, 3 January 1994 [Princeton, NJ] Dear Ned, Some conceivable space aliens are more alien, some are less. Some may be so unlike us that human folk psychology gets no foothold – the roles of the alien’s states

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are by no stretch of imagination even remotely analogous to the roles that figure in human folk psychology. At some point, chauvinism becomes the right response. Where that point comes is doubtless a vague matter. And besides, you’re giving me very underdescribed cases. And besides, even if human folk psychology and veryalien alien psychology in full and explicit detail, it would still take work to spot the analogies whereby a state of the aliens might come out as a very imperfect occupant of a human-folk-psychological role. So I’m not about to start drawing hard-and-fast lines with any confidence! That said, I’ll guess that chauvinism comes out right for the gaseous beings of your old letter; for the plant-like beings of your new letter; and for the economy of Bolivia. The thing I’m most confident of is comparative: your plantlike or gaseous beings have no obvious advantage over the economy of Bolivia when it comes to being near-enough realizers of human folk psychology. I don’t know, and folk psychology doesn’t know, what would happen if a wheeled alien thought he had feet and he wanted to kick a ball; or if you thought you had wheels and you wanted to burn rubber; or if you thought you were a cat and you wanted to chase your tail. Offhand, I guess nothing much at all would happen, at least nothing much by way of vigorous motion. In general and within limits and subject to exceptions, desires and intentions to perform basic actions are apt to cause movements that would be those actions. These cases of anatomical delusion are among the exceptions. But I can’t just say that some particular case of a human wanting to chase his tail is exceptional; every case of a human wanting to chase his tail is exceptional, since none is apt for causing tail-chasing. What makes a state of humans be the desire to chase one’s tail, despite the fact that the central part of the role is missing in every case? I suppose it might be in part a matter of some sort of similarity to other states of desire to perform basic actions; and in part a bunch of surviving less-central parts of the role – e.g. connections with other desires and with perceptual expectations. (A convinced language-of-thoughter would have an easier time with this question than I do. He says we have the general role of the desire-box, and we have mentalese words for ‘I’, ‘shall’, ‘chase’, ‘my’, and ‘tail’.) If a child of human parents is an exact duplicate of a normal Martian, I say he’s a Martian, not a human. Sure, I’d give pedigree some weight in deciding what species a freak belongs to, but calling this guy human takes pedigree far too far. Yours,



507.  To Myles Burnyeat and Peter de Marneffe, 25 March 1994

169

507.  To Myles Burnyeat and Peter de Marneffe, 25 March 1994 [Princeton, NJ] Dear Myles and Peter, At one point in the discussion last time you were in a vigorous disagreement somewhat as follows. Peter thought it possible to be angry at something that hadn’t knowingly wronged you, that couldn’t have done, and that you knew perfectly well couldn’t have done. (The word processor that accidentally erased the only copy of your laboriously written paper, say.) Myles granted that we might call your state anger in loose daily speech; but thought that if we did, we’d lose the distinctive intentional content of anger and be left with nothing better than a word for a nondescript state of being somehow hot and bothered. I agree with Peter about what we sometimes want to say, and I think it perfectly proper to say such things. I agree with Myles about not wanting to lose the distinctive intentional content of anger. But I think I can have it both ways. Remember Kendall Walton’s example.1 You’re at the movies. The deadly green slime is endangering the hero, now it’s coming toward you as you sit there watching it . . . . You fear the green slime. How can this be? Fear isn’t just a state of being somehow hot and bothered; it requires a distinctive intentional content. Fear is an attitude toward something taken to be dangerous (to you especially, or anyway to someone). But you know it’s just a movie. Nobody’s really in danger from deadly green slime. Not the hero, who doesn’t even exist. Not the actor who plays the hero. Not you. Not anybody. Walton’s solution: the distinctive content is still there, except that belief is replaced by make-believe. You fear the slime that you make believe is endangering the hero and you. Likewise, when the word processor eats your paper, nothing is easier than to make believe that it did so out of malice, knowing full well what an injury to you that would be. You can go on to make believe that if you bash the machine, or scream curses at it, it will suffer, and it will know why it deserves to suffer. (What’s difficult is to refrain from such make-believe.) Then the distinctive content of anger is all there, except that belief is replaced by make-believe. That’s how you can be angry at a machine. I think it’s common to be angry at machines (or stones, or animals, or ­people who harm us unknowingly, or . . .) in just this way. Walton says that a state just like fear except that belief is replaced by makebelieve isn’t really fear; he calls it ‘quasi-fear’. He might likewise speak of ‘quasianger’. I have some inclination to disagree; but also some inclination to think there’s no settled semantic fact of the matter. That matters little. Either way, the distinctive   ‘Fearing Fictions’ (Walton 1978).

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content (apprehension of danger; desire to revenge a wrong) is still essential to what’s going on. We have something much more specific than just a word for a nondescript hot-and-bothered state. Yours, David c: Dick Moran

508.  To David J. Chalmers, 11 June 1994 San Francisco, CA Dear Dave, I’ve now read Toward a Theory of Consciousness.1 I’m impressed but unconvinced. As you say, purely ‘psychological’ versions of mental concepts are widely available. More widely, even, than you say. My first philosophy of mind paper, in 1966, was not about mental states generally but about experiences in the psychological sense;2 I enclose a new paper3 about qualia in the psychological sense; maybe there could be a sequel about the psychological sense of ‘phenomenal’; . . . As I understand your definition, I’m a zombie iff (1) the psychological versions of the mental concepts apply to me fully and normally, and (2) that’s the whole story of my mental life. Then do I think a zombie is logically possible? Too right I think so – in fact, I think I am a zombie. (In your official sense, never mind Hollywood.) This is not to say that I have no experiences: in the purely psychological sense, of course I do. Likewise my experiences do of course have qualia (in the psychological sense), I am of course conscious of them (in the psychological sense), there is of course something it is like to be me (given by the experiences I have in the psychological sense), and so on, and so on. Nothing is lacking. Well almost nothing. In the ‘Should a Materialist . . .’ paper, I claim to spot a way in which qualia in the psychological sense fall short of what friends of qualia might want. While reading you, I kept a lookout for avowals of the ‘Identification Thesis’; I found nothing fully explicit, but a couple of brief passages did strongly suggest it. Do you hold the Identification Thesis? If so, does that suffice to bear the full burden of distinguishing your position from mine? – as it must, if you let me get away with insisting that I do have experiences, conscious ones, with qualia, . . .

 (Chalmers 1993).   2  ‘An Argument for the Identity Theory’ (Lewis 1966a).   ‘Should a Materialist Believe in Qualia?’ (Lewis 1995).

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508.  To David J. Chalmers, 11 June 1994

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Thinking as I do that zombies are not just logically possible but actual – and why should I be special? – do I also grant the logical possibility of non-zombies such as you take yourself to be? Well, certainly there could be some extra properties that supervene nomically but not logically upon the psychological goings-on. (Or even upon the physical realization thereof.) The part I have trouble granting is that these interesting extra properties would have anything to do with experience, qualia, consciousness, etc. (Except by supervening upon experience, etc.) If experience (in the psychological sense) fully deserves the name ‘experience’, it’s not clear to me how anything else could deserve to share the name. ***** Assuming your position for the sake of the argument, I want to ask what you say about memory of qualia. You look at a patch of nasty brownish-green, you look away, and unfortunately you still remember what it looked like. Your memory ex­peri­ence has a quale of its own, presumably closely related to the quale of the ex­peri­ence remembered. The quale of the memory experience supervenes nomically upon the psychological memory experience, just as the previous quale you remember did upon the psychological perceptual experience. The psychological perceptual experience caused the psychological memory experience. Suppose instead that you’d been a zombie all your life up through the time you had the psychological perceptual experience. And suppose the antidote for zombie poison was administered in the short interval between the psychological perceptual experience and the psychological memory experience. Then I take it the quale of the memory experience would be just the same, though there’d be no previous quale to be remembered – right? In that case, your memory would be deceiving you – the previous quale you ostensibly remembered would not exist. Return to the normal case, as you suppose it to be. The previous quale did exist, but seemingly it plays no part in causing the quale of the memory experience. Or at least this much is clear: the quale of the memory experience doesn’t depend on the previous quale, since it would have been no different if the previous quale had been missing. Now is it a genuine case of memory? I wasn’t terribly bothered by the paradox of phenomenal judgement – or rather, I wasn’t inclined to claim it triumphantly as a reductio against you – because I’m not committed to a causal theory of knowledge. (For views about knowledge, see the other enclosed paper.) But I am committed to a causal theory of memory, and I don’t believe you’d be remembering a quale if that quale had played no part in causing (the principal component of) your memory of it! Reductio? I don’t think so. There’s a possible way out (which I think I owe to a conversation with Frank Jackson) and I wondered if you’d want to take it. It appeals to overdetermination. How would it be if the quale of the memory experience were redundantly

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caused both by the psychological memory experience and by the previous quale of the perceptual experience? Would that be enough causation of the memory by the thing remembered to fulfil the demands of a causal theory of memory? – Maybe, I’m not sure. Anyway, if there were redundant causation in this way, then in the normal case the phenomenal component of the memory would be appropriately – if redundantly – caused by the thing remembered; whereas in the case of the ex-zombie the ostensible memory would be bogus, which I guess is the answer you’d want. ***** Last small comment. I was reading Toward . . . while on my way from Princeton to Melbourne via, among other places, Denver, the mile-high city. My sister there told me that a colleague of hers rides a unicycle. Yours, David Lewis [. . .]

509.  To Georges Rey, 28 July 1994 Melbourne, Australia Dear Georges, Thank you for the two papers,1 which I’ve now read. I liked them, especially liking the idea that the colour sensations of a victim of recent spectrum inversion would be imperfect occupants of ordinary functional roles and hence imperfect deservers of the corresponding names. I had two further comments. I’ve always thought it a significant merit of the view that mental states are inner states (presumably physical, presumably neural) characterized in terms of their occupation of a functional role that this view straightforwardly acknowledges the possibility of inversions. The occupant of so-and-so role in me is not the occupant of that same role in you, rather it is the occupant of some different role in you. (Likewise for the occupation of roles in me-today and me-yesterday, if we overlook the tem­por­ ary imperfection.) This is an advantage over behaviourism, as you say. But also it is an advantage over Putnam’s sort of functionalism – what used to be unambiguously called ‘functionalism’ – on which the mental state is the ‘role state’: the state of being in some inner state or other that occupies the role, the state common to those in whom the role is occupied by different realizers.   ‘Sensational Sentences Switched’ (Rey 1992); ‘Wittgenstein, Computationalism, and Qualia’ (Rey 1994).

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509.  To Georges Rey, 28 July 1994

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Doubtless life is like a teapot. Doubtless a clever analogizer, with a taste for such riddles, could come up with some analogy or other. But the existence of some or other analogy – as opposed to some particular analogy that might be offered – is uninformative. It’s just another instance of the general truth that if you look hard enough, anything is analogous to anything. Doubtless, likewise, mental representation is analogous to language, and thought is analogous to computation . . . I applaud the disclaimer in footnote 4 of the ‘. . . Switched’ paper.2 Without it, computationalism would be altogether too speculative. With it, computationalism is a much safer bet. But is it so safe as to be contentless? Probably not. But I’m not al­together clear what is and what isn’t being disclaimed. In ‘Reduction of Mind’ I tried to find a thesis of language-of-thoughtism that wasn’t strong enough to be silly, wasn’t weak enough to be just life-is-like-a-teapot, and so was worth being agnostic about. I hope the thesis you favour (as a hypothesis) is much the same as the one I was declaring agnosticism about. But I’m not sure. When you mention a ‘LOT symbol corresponding to “I” ’ so that LOT seems to have a subject-predicate structure that goes beyond thinking that a belief-system divides into many beliefs in much the way that an encyclopedia (but not an atlas) divides into many sentences. Turning to your letter, I see that it raises the same question I mentioned earlier of the Putnam-style functionalism that identifies mental states with role states versus the theory I prefer that identifies mental states with the occupants of the roles. Under Putnam-style functionalism, knowing that something is going on in me that occupies such-and-such role would count as knowing the essence of my mental state. Under my view not. But (in addition to other drawbacks) this makes identifying the essence of the quale of tasting Vegemite altogether too easy – you don’t even have to taste Vegemite to identify. So there’s no joy there for Kripke, and for such of the folk he follows (or leads). Yours, David

  (Rey 1992).

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510.  To David J. Chalmers, 8 August 1994 University of Melbourne Melbourne, Australia Dear Dave, A belated reply (sorry!) to your 17 June letter. 1) The Identification Thesis is trouble for a materialist who identifies mental states with ‘realizer states’ – occupants of causal roles – because we don’t identify the occupants of the roles (we don’t know whether they’re patterns of neural firings or janglings of (miniature) beer cans) just by introspection. It isn’t trouble for a dualist, because he can afford to deny that the mental states have any structure that’s hidden from introspection. And as you say, it isn’t trouble for a materialist who identifies mental states with ‘role states’: higher-order states of being in some realized state or other, states common to those of us who fire our neurons and those of us who jangle our beer cans. Maybe we do normally identify our role states. The trouble with rolestate identity theories lies elsewhere: the role state is not itself a suitable occupant of a causal role – too disjunctive! – whereas the mental state is the occupant of a causal role. You’re right that I share the view that not much hangs on the choice between role state and realizer-state identity theories. But more than nothing does. Is it the mental state itself that occupies the role? (Role state materialism says: no, it’s the realizer that does.) Is it the mental state itself that we identify? (Realizer-state materialism says: no, but maybe we can at least identify the role state.) Maybe that makes the choice even more of a toss-up than I thought when I wrote ‘Reduction of Mind’. And, either way, a materialist had better disown something at least somewhat intuitive. No state both occupies the role and gets identified. -- 2) Could the fundamental intrinsic properties be swapped? Is there a world where the property that in actuality plays the nomological role of mass and thereby deserves the name ‘mass’ plays instead the role of positive charge and deserves the name ‘charge’? Yes, I think I’m committed to this by my (slightly qualified) combinatorialism about possible worlds: On the Plurality of Worlds, §1.8. Or at least I would be so committed by the extended principle in the next-to-last paragraph of PoW §1.8; and I find that principle attractive, and I don’t see why it couldn’t be restated to dodge the objection I make that it sacrifices neutrality between theories of properties. See you in October. Yours, David



511.  To Christopher S. Hill, 4 October 1994

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511.  To Christopher S. Hill, 4 October 1994 [Princeton, NJ] Dear Prof. Hill, Thank you for your book and offprint.1 Here’s my paper for Notre Dame, also forthcoming in the AJP.2 You’ll find that it’s business at the same old stand. My line about qualia hasn’t really changed; it’s just that I’ve found a way to concede a small point to the opposition. The opposition will – and should! – find the concession too small to matter. Bob Adams has, in effect, said so to me privately; and will pre­sum­ ably say so publicly at Notre Dame. Comments on your review of Seager.3 (1) Besides Seager, the views he supports have found another ‘eloquent new champion’. He’s your neighbour, post-doc in phil­ oso­phy at Washington University, St. Louis: David Chalmers. Watch out for him – especially for something called the ‘argument from fading and dancing qualia’.4 (2) What if Mary doesn’t gain any lasting abilities? – Gaining transient abilities is good enough. And if she doesn’t gain even transient abilities? – Then I’m not so sure she does find out what it’s like. And if she doesn’t gain even transient abilities and yet she does find out what it’s like? – Then the finding out what it’s like just consists in introspective awareness of the experience. So I don’t oppose the defence you offer, but I’d keep it as a third line of defence, not clearly needed. (3) I think that what Frank Jackson and I both had in mind in saying that Mary had full physical information was clearly the first of the two alternative in­ter­pret­ ations you mention. And I wouldn’t have thought that Frank said anything that pointed toward the second interpretation. Sure, Mary does gain access to the old facts through new channels. That’s common ground. But I wouldn’t have thought anybody had this confused with what Frank thinks also happens to her. Yours, David Lewis

1   Sensations: A Defense of Type Materialism (Hill 1991); ‘Critical Notice: The Metaphysics of Consciousness by William Seager’ (Hill 1994). 2   ‘Should a Materialist Believe in Qualia?’ (Lewis 1995).    3  (Hill 1994). 4   ‘Absent Qualia, Fading Qualia, Dancing Qualia’ (Chalmers 1995).

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512.  To Robert Adams, 21 October 1994 [Princeton, NJ] Dear Bob, Thank you for your good comments. It’s really nice when philosophers who disagree as much as we do about the main issue can agree so well – perfectly, I think – about the shape of the disagreement! It does mean we won’t have much by way of argy-bargy to offer at Notre Dame. On one point, we may agree better than you think. I know that the phrase ‘folk psychology’ can have a pejorative flavour – but not when I use it. I say folk psych­ ology is not primitive, except in the sense that it’s been around a long time. I say it  would be neither feasible nor desirable to replace it by scientific psychology. Piecemeal reforms in the light of scientific psychology, maybe – to be considered on their merits. Revolution, no. I might have some proprietary rights to the phrase. I didn’t quite introduce it, but I came close. I used to say ‘commonsense psychology’. That had a pleasant Moorean ring to it, but it had the drawback of being seven syllables long. And I wrote: Think of commonsense psychology as a term-introducing scientific theory, though one invented long before there was any such institution as professional science . . . Imagine our ancestors first speaking only of external things, stimuli, and responses . . . until some genius invented the theory of mental states . . . But that did not happen. Our commonsense psychology was never a newly invented term-introducing scientific theory – not even of prehistoric folk-science . . . (‘Psychophysical and Theoretical Identifications’, Australasian JΦ, 1972) It wasn’t much later that the phrase ‘folk psychology’ started turning up, e.g. in writings of Paul Churchland. I haven’t a clue whether there was influence from me or whether it was independent invention. At first it was pejorative in just the way you say. But it had the advantage of brevity. And besides, I think the best tactic for dealing with an epithet is to take it over and wear it proudly, rather than resist it. [. . .] So I, and others, took it up. I’m sure that in some circles, in Australia at least, ‘folk psychology’ has by now entirely lost any pejorative flavour – if anything, it’s a somewhat positive term. But I may well overestimate how far those circles reach.



513.  To Frank Jackson, 27 October 1994

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I enclose some snippets from a recent survey paper to give you further samples of how I think of folk psychology.1 Yours, David Lewis

513.  To Frank Jackson, 27 October 1994 [Princeton, NJ] Dear Frank, Thank you for your colour draft.1 I like it, and mostly agree. A few comments. I wondered where a contingent identification of colours with reflectancetriples would fit in. A reflectance is a sort of disposition, but the disposition is a ­disposition to differentially reflect light, not a disposition to cause experiences. Or is it? Is the reflectance a disposition? Or is it the base, a primary quality apt for causing differential reflection? (Is it then disjunctive, or is it different properties in different cases?) Or is it both – as in DMA’s theory of dispositions? I didn’t buy your case for taking transitory colour as basic, and I thought this was an unnecessary dispute with the folk. Further, I thought it unmotivated to go different ways on (1) whether the tomato is red when in the dark and (2) whether the tomato is red when in the light but unobserved. I’d rather say that red is the causal basis that disposes things to look red when both the light and the observer are present. It is a reflectance-triple (or the causal basis thereof, or a not-too-messy region in the space of reflectance-triples, or in the space of causal bases thereof) that (a) is apt for causing differential reflection of light, when there is light, and (b) is thereby also apt for causing things to look red, when there are both light and observer (and both the light and the observer are ­suitably normal). Further, I thought that if you did start with transitory colours, it might be not good to say that a standing colour is the transitory colour the object would have in normal circumstances. Can’t I say that a photosensitive compound is white in the dark, but would instantly turn pink in the light?

  From ‘Reduction of Mind’ (Lewis 1994b).

1

  ‘The Primary Quality View of Color’ (Jackson 1996).

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Or (if normal circumstances did include being observed, which I take it for you they don’t), can’t I say that Mark’s shy chameleon is now white, but would instantly blush pink if observed? I’m a bit inclined to think it a factual question whether red is a natural kind. Case 1. The things that look red are thoroughly miscellaneous, and they cause experience of redness in thoroughly miscellaneous ways. Then red isn’t a natural kind, and none the worse for that. Case 2. Those things aren’t at all mis­cel­lan­ eous. Then red is a natural kind. Case 3. Almost all the things that look red aren’t at all miscellaneous; but some few are quite unlike the rest, and cause experience of redness in quite a different way. Then maybe red is a natural kind, and some few of the red-lookers aren’t really red. I somewhat want to say this. But I’d more want to fall in with what others around me wanted to say, and I find it hard to guess what they’d want to say. Maybe they too, like me, would be easily led one way or the other, and have no determinate linguistic dispositions in advance of the case arising. Trivia, both on page 16. Last line: double ‘as’. Second line of Section 6: I first misread this as having the clause ‘That I insisted’ as subject of the sentence. --Ernie Sosa’s letter suggested a collection of recent papers. But if the plan goes further, I will indeed ask if it might include some of my older papers that were left out of Papers I and II. ‘Psychophysical and Theoretical Identifications’ was left out because of overlap with ‘An Argument for the Identity Theory’ and ‘How to Define Theoretical Terms’. Michaelis suggested including ‘Index, Context, and Content’. As yet I still haven’t written Ernie along the lines I mentioned to you. I thought I’d see if I could have a preliminary talk first with Stephan Chambers at Blackwell, and if he says – as I expect him to – that Blackwell doesn’t do collections of reprinted papers, that will be one less issue I’ll have to take up with Ernie and CUP. Yours,



514.  To David J. Chalmers, 30 November 1994

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514.  To David J. Chalmers, 30 November 1994 [Princeton, NJ] Dear David, In your 1 November letter, you say that the only thing that you might take issue with (in my reply to Cresswell) is that you would not classify a de se belief as de re. I take issue, in turn, with your way of saying what I’m doing. But I think these two issues together will boil down to much less than one issue – that is to say, I hope we may find ourselves in better agreement here than you thought. As you know, I’m agnostic about whether there are such things as beliefs – little snippets, many of which together add up to a belief system. The snippet hypothesis may or may not be a good hypothesis, but I don’t want to read it into folk psychology and I want to say as much as I possibly can without presupposing it. A fortiori, I don’t want to be in the business of classifying these hypothetical snippets as de re, de dicto, or de se. (Oh, I don’t mind speaking in a rough-and-ready way of de re beliefs, etc., but I consider that way of speaking a bit misleading and I want to drop it at the first sign of trouble.) Rather, there are different kinds of belief-attribution; different ways of saying things about Fred that are made true or false at least partly in virtue of Fred’s belief system. Four things I may say about Fred that are made true at least partly in virtue of his belief system are these. I say them first in ordinary English; then in regimented language (in case (1), in two equivalent versions), and finally, in cases (2) and (4), in what I take to be the correctly analysed equivalent. ( 1) He believes that he himself is studying law. (1r) He self-ascribes de se the property: studying law. (1rʹ) He self-ascribes de se the property: being identical uniquely to someone who is studying law. ( 2) He believes of Fred that he’s studying law. (2r) He ascribes de re to Fred the property: studying law. (2a) There is a relation R such that (i) he bears R uniquely to Fred, (ii) he self-ascribes the property: bearing R uniquely to someone who is studying law, and (iii) R is a relation of acquaintance. ( 3) He believes that he himself has heard under the name ‘Hahvad’ of the top law school, and of nothing else. (3r) He self-ascribes de se the property: having heard under the name ‘Hahvad’ uniquely of the top law school.

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(4) He believes of Harvard that it’s the top law school. (4r) He ascribes de re to Harvard the property: being the top law school. (4a) There is a relation R such that (i) he R bears uniquely to Harvard, (ii) he selfascribes the property: bearing R uniquely to the top law school, and (iii) R is a relation of acquaintance. (2) is true in part because (1) is; in part because Fred is identical to Fred (which is so necessarily); in part because identity is (necessarily) a relation of acquaintance. So (1) implies (2). Likewise, (4) is true in part because (3) is; in part because Harvard is what he’s heard of under the name ‘Hahvad’ (which is so contingently); in part because having heard of something under the name ‘Hahvad’ is (necessarily?) a relation of acquaintance. So (3), together with at least one contingent auxiliary premise not about Fred’s belief system, implies (4). Fred’s belief system makes (2) true because it is such as to make (1) true; it does its part in making (4) true because it is such as to make (3) true. That’s my story about the relation between the de se attribution (1) and the de re attribution (2); and it’s an instance of the general story illustrated by (3) and (4); but (1) and (2) are a rather ­special instance because of the necessity of the relation of acquaintance that Fred bears to the res. Belief-snippets are not getting classified; belief-attributions are getting classified; but the de se attribution (1) still isn’t getting conflated with the de re attribution (2). *** If I were classifying de se beliefs as de re, you could equally say that I classify de dicto beliefs both as de se and as de re! For here are some more attributions made true by Fred’s belief system. ( 5) He believes that lawyers get rich. (5r) He believes de dicto the proposition: lawyers get rich. ( 6) He believes that he himself lives in a world where lawyers get rich. (6r) He self-ascribes de se the property: living in a world where lawyers get rich. ( 7) He believes of the world he lives in that it’s a world where lawyers get rich. (7r) He ascribes de re to the world he lives in the property: being a world where ­lawyers get rich. (7a) There is a relation R such that (i) he R bears uniquely to the world he lives in, (ii) he self-ascribes the property: bearing R uniquely to a world where lawyers get rich, and (iii) R is a relation of acquaintance.



515.  To David J. Chalmers, 2 December 1994

181

(5) and (6) I take to be equivalent. (7) is true in part because (6) is; and in part because Fred bears the living-in relation uniquely to the world he lives in (necessary – but controversial); and in part because living in is (necessarily) a relation of acquaintance. So (6) implies (7). Again, belief-snippets are not getting classified; belief-attributions are getting classified; but the de dicto attribution (5), the de se attribution (6), and the de  re attribution (7) aren’t getting conflated. For (5) relates Fred to a proposition; (6) relates him to a property; (7) relates him to a pair of a thing and a property (a different property). That said, what becomes of the wording you objected to in my reply to Max? Sure enough, it isn’t entirely defensible! What happened was that I started off talking of various classifications of beliefs when I was presenting the trap to beware of, but didn’t drop it afterward when I began speaking for myself. Even if I’d been speaking clearly of attributions, I shouldn’t have said ‘it isn’t de dicto so it’s de re’; but I still should have said – though not for that reason – that it implies a de re attribution. And when I said that de re beliefs obtain partly in virtue of relationships of acquaintance, what I should have said was that de re belief-attributions are true partly in virtue of relationships of acquaintance. I think those two corrections would set it right. Yours, David Lewis

515.  To David J. Chalmers, 2 December 1994 as from: Princeton University Princeton, NJ [location unknown] Dear David, Today I’m writing, belatedly, about the second matter you took up in your 19 October letter. You asked what I said to someone who is enough of a materialist to say – b1  the pattern of instantiation of phenomenal properties supervenes, with metaphysical necessity, upon the pattern of instantiation of physical ­properties, but b2 this involves no necessary connection between distinct existences, and no violation of recombination; because b3 the phenomenal properties are identical to some high-level physical ­properties;

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and who yet is enough of a qualia freak to say a Mary gains phenomenal knowledge that is not derivable a priori from the physical knowledge she had beforehand. What Mary knew beforehand was that when she got out and saw her first ripe tomato, her experience (take this in the ‘psychological’ sense applicable even to zombies) would have high-level physical property P. What she didn’t know beforehand and couldn’t derive a priori from what she did know was that it would have phenomenal property Q. Yet P = Q. How can this be? Since P = Q, we needn’t confuse ­ourselves by giving this one property two different names. What she did know beforehand was that her experience would have property P.  What she didn’t, and couldn’t, know beforehand was that her experience would have property P. This looks hopeless. To make it less hopeless – or at least less obviously hopeless – make a distinction thus. c1: P qua physical is such that Mary knew beforehand that her experience would have it; but c2: P qua phenomenal is such that Mary couldn’t know beforehand that her experience would have it. I don’t understand c1 and c2. Can the position you have in mind explain them in such a way that they come out consistent? – I don’t say that can’t be done. But I haven’t a clue how to do it. How, in general, might the insertion of ‘qua’-phrases resolve a contradiction about what Mary knew? – Two ways, but I fear neither applies to the case at hand. The first is that she might be a compartmentalized doublethinker. She knew in one mental compartment but not in the other, and the two ‘qua’-phrases point somehow to the two compartments. Not applicable: when we say she couldn’t derive knowledge a priori, we mean that better thinking wouldn’t help, yet better thinking would bring down the walls between mental compartments. The second way is that she might be in the position of Pierre. What Pierre does and doesn’t know de re about London may be relative to restrictions upon the relations of acquaintance* we’re considering. p1 For some R, Pierre bears R uniquely to London, Pierre knows de se that he bears R uniquely to an ugly city, and R is a relation of acquaintance of kind K1, but p2 Not: For some R, . . . [as before] . . . and R is a relation of acquaintance of kind K2.   aka ‘modes of presentation’, ‘noemata’, . . .

*



516.  To William G. Lycan, 18 December 1994

183

Then the ‘qua’-phrases might point somehow to the different restrictions upon relations of acquaintance. – OK in the abstract, but I don’t at all see how to apply this to the case at hand. And those are the only ways I know for ‘qua’-phrases to resolve the contradiction. I have another comment on the position. I don’t see how P could be a phenomenal property (= quale) in the full sense of the word (= perfect occupant of the role and deserver of the name) unless Mary could know the essence of P just by having an experience that has P, without drawing upon all her prior knowledge of physics. And if P is a higher order physical property, its essence is presumably captured by its def­ in­ition in terms of simpler physical properties and there’s no way Mary would know that definition just by having the experience (though she would know it by drawing on her knowledge of physics). Yours, David

516.  To William G. Lycan, 18 December 1994 [Princeton, NJ] Dear Bill, What you say happens to Mary when she gets out and sees red seems to me very like what happens to Larry in this new story: When shut in his room, Larry has all the textbooks, encyclopedias, etc. he could possibly use; and also a collection of samples of all manner of colours, smells, and flavours. What he doesn’t have is a German teacher. Now suppose it’s true – as countless students will tell you it is – that German is so hard a language that it’s humanly impossible to teach yourself German. You absolutely have to have a teacher. So when Larry eventually gets out – only a few short years later, in fact – he is finally able to say to himself: Schweine fliegen nicht! That thought was unavailable to him so long as he was shut up in his German-free room. Of course, he hasn’t ruled out any formerly open possibilities – he knew all along that pigs didn’t fly. But he can now rule out a case that is metaphysically impossible, though unobviously so: namely, the case that Schweine fliegen, aber pigs don’t fly. Before getting out, he was unable to rule out this impossible case.

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When Larry learns German, does he think a new thought? Come to know a hitherto unknown truth? Gain new information? Rule out a new not-obviously-impossible case? – OK, say what you like. You’re not wrong if you say he does, anyhow you’re not unambiguously wrong. Let’s be easy-going about criteria of identity for thoughts, for truths, for information, for cases, etc. Let’s not pretend we’ve decided questions of individuation that it would have served no purpose to decide. But however you care to describe what happens to Larry, this much is clear: it is not one little bit like what the qualia-freaks think has happened to Mary! Yours, David Lewis c: Frank Jackson, David Chalmers, Laurence Nemirow

517.  To Jamie Dreier, 2 January 1995 [Princeton, NJ] Dear Jamie, I like your problem about wanting to have never existed. I put off answering your letter in hopes I might be able to talk to you about it at the Boston APA. But if you were there I didn’t spot you. I have no full solution to offer you. Certainly I agree that wanting to have never existed is possible. I’m not sure I’m fully convinced by your example of the utilitarian fanatic – do his desires really follow where utilitarian argument leads? – but I’m more convinced by the example of a suicidal depressive: what he most wants is never to have lived at all, immediate death is only second-best. There had better be some place in our account of desire for wanting the impossible. Can’t some want the 4-colour conjecture to be true, others want it to be false? – Then either the some or the others want the impossible. One could even want what’s impossible by truth-functional logic alone. On his logic final, Duntz marked [pigs fly iff ducks quack] iff [(pigs fly and ducks don’t quack) or (ducks quack and pigs don’t fly)] as true, and he wants his answer to have been correct. The best account I know of how to believe the impossible is Stalnaker’s, in Inquiry and elsewhere, though I admit that sometimes it looks too artificial for comfort. (In other cases it seems intuitively just right.) I suppose it could be adapted to



518.  To D.M. Armstrong, 25 October 1995

185

wanting the impossible. I think I should say that wanting de se never to have existed is wanting the impossible, I should say that it’s possible to want the impossible, and I  should hope that the case of wanting never to have existed falls into line with other cases. My other comment is that your problem is not just a problem about desire de se. Mightn’t our depressive (or maybe some Buddhists about whom I know very little) wish de dicto that there had been nothing at all? Really nothing – not even unpolluted vacuum, not even ‘abstract entities’, not even unactualized possibilities, . . . . The world as he wishes that it had been is a nonexistent world – which is nonsense. Yours, David Lewis

518.  To D.M. Armstrong, 25 October 1995 [Princeton, NJ] Dear David, Thank you for your letter about my colour paper.1 (1) For the property of circularity, the counterpart of D2 seems OK. The counterpart of D1 might be OK as a truth, but seems perverse as a definition, when we could instead define a circle as the locus of points equidistant from some central point, and circularity as the property of being a circle. (Or sometimes having a boundary which is a circle.) If some equally straightforward definition of ‘red’ were avail­ able as a matter of common knowledge, it would be equally preferable to D1 as a definition; but in the case of ‘red’, no such preferable definition is available. The phrases ‘primary quality’ and ‘secondary quality’ never appear in my paper, and I think it best to steer clear of them. I’m inclined to agree with you that the distinction came from theorizing; and further, that the theorizing it came from was to some extent infected with false anti-materialist presuppositions. Since I hold a chromophysical identity theory, does that mean that I think colours are primary rather than secondary? Or both at once? Or do I think that some, or maybe all, secondary qualities are not primary, but are nevertheless physical and mind-independent? Or what? No way to say it seems clearly right! Further, I think the problem of definitional circularity for colours and colour experiences may be less of a problem for some of the other (customarily so-called)   ‘Naming the Colours’ (Lewis 1997b).

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secondary qualities. It’s hard to find really widespread common knowledge about red things that goes beyond the knowledge that they typically cause experience of red; but I do think it’s common knowledge that sugar, honey, and ripe fruit are sweet; that a sulphurous smell is the smell of burning sulphur; and so on, not for all the tastes and smells and sounds, but for quite a lot of them. So if I’d tried to write not about colours but about secondary qualities generally, I’d have had to be much more careful about when there’s a circularity problem and a lack of more-than-merelyexistential common knowledge, and when there isn’t. Experience of red is usually, but not always, veridical perception of something red. When it isn’t that, at least it’s usually ostensible perception of something red. But maybe not always: in cases where experience is obviously illusory, and there’s not even the slightest inclination to acquire any belief about what’s before the eyes, I’m not sure there’s even ostensible perception of something red. (2) OK: the self-identity of a property, in these cases a structural property that can be named either in terms of its structure or by a short name, is necessary. The occupancy of a causal role by that property is contingent. Thus an identity sentence which names the property on one side by a nonrigid designator defined in terms of occupancy of a role, and on the other side by a structural specification, is contingent. All this is an old story. The remaining question is whether ‘red’ and ‘experience of red’ are rigid or not. I take Kripke’s argument on pages 150–2 of Naming and Necessity to be a decisive reductio against the supposition that such names as ‘pain’, ‘red’, and ‘experience of red’ are rigid designators of physical properties. He thinks they’re obviously rigid, hence he concludes that they’re not designators of physical properties; whereas I think they’re designators of physical properties, hence – pace Kripke’s very emphatic in­tu­ itions – not rigid. That fits the hypothesis that they’re names definable in terms of occupancy of causal roles (the hypothesis we agree on for ‘pain’ but not for ‘red’); in which case we get contingent identities as a consequence of the contingency of which properties occupy which roles. Anyway, whether one uses it his way or mine, here’s Kripke’s reductio. (1) If these names are designators of physical properties, some chromophysical or psychophysical identities involving these names are true. (2) But, as everyone agrees, no such identities can be known a priori. (3) If the names are rigid designators, then the identities are necessary but a posteriori. How is that possible? (4) Only in the way Kripke describes previously: we fix the reference rigidly upon something without knowing what we’re fixing it upon. We don’t know which of two indistinguishable possibilities (‘epistemic situations’) we’re in, in one of them we fix the reference ri­gid­ly upon one thing, in the other of them we fix the reference rigidly upon something else. (5) But in the present cases, the two allegedly indistinguishable pos­si­bil­ities



518.  To D.M. Armstrong, 25 October 1995

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would differ because pain in one was replaced by something else in the other; or because experience of red in one was replaced by something else in the other. Note that in saying this, I rely on our supposition for reductio that ‘pain’ or ‘red’ or ‘ex­peri­ ence of red’ is a rigid designator. (6) But two possibilities that differed by any such replacement would not be indistinguishable. (7) This completes the reductio, and refutes the supposition that the names are rigid designators of physical properties. (8) We’re left with a choice between the hypothesis that the names are nonrigid designators of physical properties (my choice, and yours too in the case of ‘pain’); the hypothesis that they are rigid designators of nonphysical properties (Kripke’s choice); and the hypothesis that they are nonrigid designators of nonphysical ­properties. One qualification. I think the reductio refutes the supposition that these names are always rigid designators of physical properties. It may not refute the supposition that they can sometimes be used rigidly, so long as they are not being used rigidly in the crucial step (5) of the argument. (3) I think your distinction between ‘standing colour’ and ‘transient colour’ is another piece of theorizing – and again, it’s theorizing that is to some extent infected with false presuppositions. This time, the false presuppositions are underestimates of our ability to compensate for differences in the illumination. Be that as it may, by ‘colour’ I always mean standing colour. If there are transient colours, rightly so-called despite the false presuppositions under which the notion was introduced, then indeed it may well be that we’re under no illusions about those. I think you misunderstand the term ‘reflectance spectrum’. The reflectance, at a given wavelength, of a surface is the fraction of incident light at that wavelength that would get reflected – not the amount of light at that wavelength that gets reflected. So (except when light produces some sort of chemical change in the surface) the re­flect­ ance spectrum of a surface does not vary with changes of illumination; and phrases like ‘actually emitted reflectance’ don’t make sense. In fact, a surface in complete darkness normally has exactly the same reflectance spectrum – exactly the same dispositions to reflect various fractions of light at various wavelengths – that it would have when illuminated. (4) John Cooper tells me that Aristotle applied ‘homeomerous’ to substances; Goodman applied ‘dissective’ to predicates; so neither term is quite right to apply to properties. But there’s a precedent for me to follow: David Hilbert talks about colours being imperfectly dissective.2 (5) It would be an illusion if there seemed to be a big blue dome up there, but to me it doesn’t seem that way.   Color and Color Perception (Hilbert 1987, 29–42).

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(6) Right: the standing colour is the disposition to reflect a certain fraction of the incident light at any given wavelength. But in standard terminology, the re­flect­ ance value (at that wavelength) is the disposition, not the manifestation of it. (7) I think the folk can talk equally happily about resemblances among colours or resemblances among colour experiences. So I don’t think this happy talk is any evidence about which ought to come first. Where should we start? What won’t work – or rather, it might work, but we have no a priori reason to assume it will – is to say that similar colours are similar qua microstructures, or that similar colour experiences are similar qua neural firing patterns. So I say: the only safe starting point is that simi­ lar colours are hard to tell apart. And then I say that the experiences are causally closer to the tellings-apart than the colours are. So when I begin with tellings-apart and I work back along the causal chain, I arrive at the colour experiences before I arrive at the colours themselves. (8) Ballygunnion isn’t in the index to the Times Atlas, and I don’t know the story about it. Ballybunnion is in County Kerry, near Listowel and near the mouth of the Shannon, and it is a small village – the smallest size that shows up in the Atlas at all. Its claim to fame is as the terminus of the Listowel and Ballybunnion monorail. (9) Any story about familiar exemplars will need to talk mainly about the colours rather than the experiences, because coloured things are more permanent and more practically accessible to public examination than experiences are. And, even though the common knowledge turns out to be interestingly imperfect, the line I take is still one on which colours are named by reference to familiar exemplars. -----[. . .]

519.  To Philip Kitcher, 2 January 1998 Princeton University Princeton, NJ Dear Philip, It was very good to see you in Philadelphia. Sorry we missed Pat. But maybe in New York . . . [. . .]



519.  To Philip Kitcher, 2 January 1998

189

I’ve been re-reading ‘Unity of Science as a Working Hypothesis’1 to see if I could find anything to disagree with. I think the answer is: I don’t disagree outright with theses that Oppenheim and Putnam assert, but some of the presuppositions in the background strike me as alien. I keep not knowing what O & P mean by ‘can be micro-reduced’. Take chemistry and microphysics. (To make these be ‘adjacent levels’, let it be the microphysics of nuclei and electrons, not of fundamental particles generally.) Can chemistry be reduced to microphysics? Well, I take it to be highly probable – a good ‘working hypothesis’, to say the very least – that all chemical properties supervene on arrangements of microphysical properties, and that all chemical laws are entailed by microphysical laws. I also think that it’s a reasonable expectation, in this case, that we can discover the physical definition of any chemical property we’re likely ever to introduce a term for. (Supervenience covers the case of infinitely complex definability, but I doubt if that’s to be expected in the case of chemical properties.) I also think that it’s not a reasonable expectation that we’ll deduce very many chemical laws from the microphysical laws that entail them – mathematical intractability will stop us. Do I  believe in micro-reducibility in this case? I’d offhand say yes, but I can’t guess whether I mean what O & P mean – to what extent are they betting on humanly ­feasible derivations? Likewise for the other pairs of ‘adjacent levels’, except that sometimes the def­ in­ition­al part will be hard too. Sometimes, mind you, the term for a higher level will be vague. Or it will be egocentric – part of what it is to be a penguin, or a Plantagenet, is to be a terrestrial organism. And sometimes the properties will be extrinsic: another part of what it is for x to be a penguin, or a Plantagenet, is for x to be part of a microphysical structure extended through time and space, a structure that includes much more than x itself. But an extrinsic property can supervene on microphysics just as much as an intrinsic one can. So, no worries. (Would ‘electron in orbit around a proton’ defeat reductionism?) One alien presupposition is that all levels have their laws. I suppose that chemistry does, but beyond that I begin to doubt it. To the extent that there are biological, psychological, etc. laws, I take it to be reasonable to believe that they’re entailed by, but not feasibly derivable from, the laws of lower levels; but I don’t believe that the discovery of such laws has much to do with what goes on in the sciences of biology, psychology, etc. I think O & P think that if there weren’t any laws of biology, psych­ ology, etc., there couldn’t be explanations in those sciences; and then there couldn’t be inference to the best explanation. So another alien presupposition that pervades

  (Oppenheim and Putnam 1958).

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the article is the D-N model of explanation. If, as I think, explanation is information about how things are caused, then a science with no laws of its own can still do plenty of explaining, both in single cases and with appropriate degrees of generality. So am I part of this unanimous retreat from unity of science? I’d say not, though it’s true that I’m not happy with every word of O & P! Yours, David

520.  To David J. Chalmers, 5 January 1998 [Princeton, NJ] Dear Dave, Thank you for the ‘Materialism and the Metaphysics of Modality Draft’.1 I liked it, but I’m not entirely comfortable. It raises issues that I don’t have sufficiently well under control. The trouble is that I want to say that there’s some sense in which I can conceive of impossibilities. How best to say it? – Maybe it’s conceiving, sure enough, but not the kind of conceiving that’s the test of possibility. Or maybe it’s make-believe conceiving; or maybe it’s an illusion of conceiving. I think I can ‘conceive(?)’ of –  Graham Priest’s stories of true contradictions, –  The necessary existence of God, – Each of two alternative answers to some open question in math, both the true answer and the false one, – Each of two alternative answers to some open question in metaphysics of modality – say, whether there are proper-class-many worlds – both the true answer and the false one. I (increasingly) favour an expansive notion of possibility; yet not so expansive that all these things I can ‘conceive(?)’ are genuine possibilities. But if I admit that there are conceivable impossibilities, how do I resist the idea that some of what I took for genu­ine possibilities (because of their conceivability) are really among the conceivable impossibilities? I most certainly want to resist it, just as you do, but I’m not sure how. What’s needed is a clear distinction between the genuine conceiving that establishes

  ‘Materialism and the Metaphysics of Modality’ (Chalmers 1999).

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521.  To David J. Chalmers, 29 January 1998

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possibility and the bogus ‘conceiving’ illustrated in my list above. But that’s what I don’t know how to provide. (I think maybe the safest term is just ‘possibilities’. All three adjectives – ‘logical’, ‘conceptual’, ‘metaphysical’ – can mislead.) May I share your draft with a graduate student who is much taken with Loar’s position? The argy-bargy about which commentator got you right or wrong is beside the point, but I’d like him to read the paper as a rejoinder to Type B materialism. (Needs a catchier name!) I enclose a few papers. One of them is related to the final footnote of your book.2 Yours, David Lewis

521.  To David J. Chalmers, 29 January 1998 [Princeton, NJ] Dear Dave, When I read Graham Priest’s short story ‘Richard’s Box’1 (in which a friend looking through Richard Sylvan’s belongings after his death finds that he’d owned a box which was empty and had something in it) I know what to imagine, and somehow I’m able to imagine it. Or anyway I’m no less able to imagine it than to imagine some things that are allegedly actual, such as the experience of seeming to see r­ eddish green. I’m glad to agree that this is a ‘purely formal act of conceiving, and not one that even seems to deliver a world’. But I fear it seems that way exactly because I already know that such a world isn’t possible. Yes, I have a grip on the notion of an a priori statement, just as I have a grip on the notions of possibility and necessity. But I fear these notions are not far enough apart to shed much light on each other – since I think, as I think you do too, that an a priori statement is just one that diagonally expresses the necessary proposition. So I  think your ‘innocent’ notion of conceivability is innocent indeed, but unhelpful. The tight little circle of notions is too tight. The best hope (only hope?) for getting a handle on conceptual (= ‘metaphysical’, = ‘logical’) possibility from far enough away to be informative seems to me to be via   ‘How Many Lives Has Schrödinger’s Cat?’ (Lewis 2004).

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  ‘Sylvan’s Box: A Short Story and Ten Morals’ (Priest 1997).

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principles of recombination. The trouble is that it’s controversial just what these principles should say, partly because a strong enough principle of recombination is going to presuppose one or another controversial theory of properties. Indeed, cases where different versions of recombination disagree are prominent among the cases where I can, in some sense, conceive of something without knowing whether it’s really possible. Should recombination say that all monadic intrinsic fundamental properties are compatible? Could there be an elementary particle that’s both positively and negatively charged? ---------------Everettism owes us an answer to the question: why should expectation (over branches in all of which I’m alive) be proportional to squared amplitude? (In terms of Everett’s original paper: when he showed that frequencies would match the predictions of quantum mechanics except on a set of branches of negligible amplitude, why was that any reason to expect frequencies to match the predictions of quantum mechanics?) I haven’t a clue what that answer might be. But either there is one or there isn’t. If there isn’t, I lose all interest in Everett. If there is, then the prospect that some of my eternal lives, with a very small share of the total amplitude, are less horrific than the rest is small comfort indeed. ‘Comatose with an occasional dream’ branches wouldn’t be so bad; I was supposing that the great majority (going by amplitude) would be far worse than that. Yours, David Lewis

522.  To Philip Kitcher, 13 February 1998 [Princeton, NJ] Dear Philip, [. . .] Thanks for your comments about disunity of science. But the picture I have of what’s happened to classical genetics must be different from yours in a way I can’t quite make out from your letter. I think of it as a case where the old theory was partly scrapped, partly reduced. There was a theoretical role associated with the term ‘gene’. It turned out there were no very good occupants of the role and deservers of the name, but there were some poorish occupants. In such a case I say it’s a matter of semantic indecision whether the poorish occupant of the role should get the name.



522.  To Philip Kitcher, 13 February 1998

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The best among the poorish deservers of the name turns out to be a minimal segment of DNA bounded by ‘stop reading’ codons. (This has a name which I could probably look up if I had your book in my office instead of at home.) Each of these minimal segments is a necessary condition, and sometimes a member of a jointly sufficient set of conditions, for production of a certain protein. (Well, almost ­necessary and sufficient; disregard highly improbable accidents.) We could say that one of these minimal segments is a gene for the property of producing such-andsuch protein. But classical geneticists thought there were genes for other kinds of properties, for instance anatomical properties. The magpies of New South Wales have black backs and the magpies of Victoria have white backs because the NSW magpies have the black-back gene instead of the white-back gene. However, there is in all probability no single minimal segment that causes black-backedness. Anatomical, etc., properties are probably caused by a whole lot of minimal segments working together. The cases where classical genetics works well are cases where either (1) all but one of the relevant minimal segments are pretty much constant throughout the population, or (2) all the relevant minimal segments are very close together on the DNA, or (3) the two previous cases are combined. Since these conditions are matters of degree, the successful applicability of classical genetics is a matter of degree. Do I have the scientific story right? I gather, not quite; because you speak of lawlike generalizations about genes that are not entailed by microphysical laws. And you speak of explanations in genetics that are extended but not completely absorbed into molecular explanations. Now, I take it you meant ‘true generalizations’ and ­‘correct explanations’; and I take it you meant ‘not entailed by microphysical laws together with initial conditions having to do with the structure of the organisms and their DNA’; and I take it you didn’t just mean ‘not completely absorbed into molecular explanations known today’; and I take it you didn’t just mean that in easy cases, it’s easier to think classically and not worry our heads about the underlying molecular explanation. Unless I’m right about what you did and didn’t mean, there’s nothing here that ought to bother Putnam and Oppenheim, or me. What you seem to be saying is that sometimes classical genetics works and molecular genetics explain why it works; and not just because the details are as yet unknown. Rather: sometimes classical genetics works when molecular genetics predicts that it shouldn’t work! But even that’s not enough. Disunity of science is one thing, unsolved anomalies are another. To make a case for disunity, you’d need a reasonable expectation that unexplained successes of classical genetics will remain indefinitely as an unsolved problem. Sorry: I’m reading between your lines a lot, and I wonder if what I’ve made you out to be saying is anything like what you were really saying! Yours,

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523.  To Robert C. Stalnaker, 26 February 1998 [Princeton, NJ] Dear Bob, I found my old undergraduate paper, ‘The World Turned Upside Down’,1 that I mentioned to you at NYU. It’s probably from 1961: the year I returned from Oxford and switched my major from chemistry to philosophy. It’s an embarrassing museum of Oxbridge mannerisms: ‘We might be tempted to say ----- (but I’m not about to come clean about whether I do say it or I don’t)’. So I think I won’t show it to you after all. But I still think that underneath all the meandering and waffle was a good idea. It’s reported that people who wear inverting prisms eventually adapt; they’re no longer disoriented. Aside from the effect of an uncomfortable weight on the nose, the inverting glasses no longer make any difference to behaviour. We Rylean behaviourists and verificationists (as I then was) would offhand say that it’s a meaningless question whether the adapted subject still has an upsidedown visual field. If common folk think it does make sense, they’re bewitched by  the false idea that the visual field is a picture inside the head; but we know ­better. But maybe, after all, there’s an indirect way to make behaviouristic sense of the question. It certainly makes sense to say that the subject has undergone an episode of inversion; or that the subject has undergone two successive episodes of inversion; or any number. (Let the second inversion, the one that puts the light input back to normal, be done not by removing the heavy glasses, but by keeping them on and rearranging the prisms in such a way that the subject can’t tell any difference in the weight on his nose. Likewise for all subsequent inversions.) I considered saying that the ‘outward criterion’ for having an inverted visual field despite adaptation was just having undergone an odd number of inversions. I  rejected this, not because it begged the question whether adaptation undoes the inversion of the visual field, but because it seems frivolous ‘that events in the far past should be the criterion for how things look now. It can’t be that that’s all we mean!’ I considered saying that, no matter how good his adaptation was in other respects, the subject would still tell us that things seemed to be upside-down; his say-so would be our behavioural criterion. I noted that it was reported that adapted subjects sometimes didn’t say this; but that we could wonder what they 1   David Lewis Papers, C1520, Swarthmore College, Papers, Box B-000696 Folder 3, Princeton University Library.



524.  To David J. Chalmers, 1 May 1998

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meant by what they said. (I think I’ve since heard that adapted subjects have difficulty giving a  straight answer to the question whether things still seem to be upside-down.) I said: ‘we tend to be confident that if we put a man through a great number of inversions of his visual field in quick succession, so that he certainly could not have kept count of them, but so that he made a good adaptation every time, it would not unfit him to tell which state he ended up in. He would agree with the odd-and-even counter. (This would be an interesting thing to try out experimentally, if it has not been done yet.)’ (I now add: and if it were a morally permissible experiment to try, which doubtless it wouldn’t be.) ‘The objection is, then, that adaptation so perfect as to destroy this last behavioural criterion (being able to tell which state one is in) could never happen. This is a factual objection; and, although I find it plausible’ (now I’d be agnostic) ‘I don’t know if it is true. But if it is, it destroys the possibility of saying that the adaptation process is the reverse of the orientation process’. (Sic; I probably meant ‘the reverse of the disorientation process, i.e. of the inversion process’.) There you have it. Well, never mind the old-time behaviourism. But I still think the hypothetical case of someone who has undergone so many successive inversions as to lose count of whether the number is odd or even makes an interesting inter­ medi­ate between the intra-personal case and the inter-personal case. It would be nice to know if you can tell odd from even without keeping count. If not, I reckon that would somewhat reduce the weight that could be put on comparisons by memory in even the simple intra-personal case of one inversion followed by adaptation. Yours,

524.  To David J. Chalmers, 1 May 1998 [Princeton, NJ] Dear Dave, An a priori truth expresses, as its primary intension, the necessary proposition; it – that is its primary intension – is knowable independent of experience. Both fine! But too close together. When you say ‘knowable’ I understand that I’m invited to idealize by ignoring failures of rationality. Fine; I’m happy to go along. When I do, I operate with a modal conception of knowledge: proposition P is known iff every possible world is either one eliminated by the subject’s experience or else a P-world (or else a world that’s

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properly ignored in the present context, an ‘irrelevant alternative’). So of course the  necessary proposition is knowable independent of experience: all worlds are P-worlds, so all uneliminated (and unignored) worlds are P-worlds, independent of what worlds may be eliminated (or ignored). But these moves are so quick and easy that I don’t see that I’m getting any ­second handle on the knowability of an a priori truth. You’d better not just withdraw your invitation to idealize! Duntz, who’s just now flunking elementary logic, is in some natural sense ignorant of plenty of a priori truths; and in some natural sense he’s even unable to know them. To avoid saying that in Duntz’s case a priori truths are not knowable, and at the same time to avoid letting a priori knowledge collapse into necessity via the modal conception of know­ ledge, plainly what’s wanted is some half-way house in the idealization of knowledge (or of rationality). While I have no reason to insist that there couldn’t be any half-way house, neither do I have one to offer. I would very much like to think that belief in (primary) impossibilities is always due to irrational doublethink. But I have to admit that’s not credible in Graham Priest’s case. I don’t know what to say about Graham. But let that pass. Suppose he didn’t exist. – No, that’s not enough. Suppose he couldn’t exist. Under that supposition, a genuine possibility is one that can be believed to obtain without irrational doublethink. What means ‘irrational doublethink’? Well, I suppose it means somehow believing two propositions that couldn’t possibly be true together – in other words, that aren’t true together in any genuine possibility. It’s  happened again: a modal conception of rationality, so I’m still in the tight ­little circle. Can’t I have a less idealized conception of rationality? – Yes, I can and I do. But on that conception Graham is highly rational, so rational believability is not the test of possibility. ‘Unknowable’ truths about large cardinals are, if true, knowable under the modal conception of knowledge, and believed by any rational being under the modal conception of rationality. So they may be good evidence that there’s a half-way house. But evidence that there is one doesn’t help us find it. Yours, David Lewis



525.  To Terence Horgan, 28 May 1998

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525.  To Terence Horgan, 28 May 1998 Princeton University Princeton, NJ Dear Terry, Thank you for the copy of your paper for the protosociologists.1 (And for the one on transvaluationism.2 The manner of presentation raises eyebrows – and will surely raise more than eyebrows, say hackles or fists, in the case of some other­ readers – but I don’t see that I have any quarrel with the doctrine. Not if it’s compatible with iterated supervaluationism, anyway.) Let me describe some of the background and subsequent developments to the  ‘too disjunctive’ argument. I was following the lead of Prior, Pargetter, and Jackson, ‘Three Theses About Dispositions’, American Philosophical Quarterly 1982;3 and subsequent writings by permutations and subsets of the same three authors, up to and including Frank Jackson’s Locke Lectures, just published under the title From Metaphysics to Ethics.4 The same issue arises in at least three areas. (1) Dispositions. There are different microstructures that can dispose something to break when struck; in other words, different causal bases for fragility; in other words, different ways to be fragile. Do you want to say that when the fragile thing is struck and breaks, its fragility was a cause of it breaking? – Well, you might want to say that; but don’t you want even more to say that the microstructure was a cause, and also that fragility is what all fragile things have in common; and also that this is not a case of redundant causation? Best, on balance, then, to say that fragility was after all not a cause. (2) Functional states and their neural realizations. This is the case you talk about. (3) Colours. You’d want to say that the reflectance property caused the colour-experience; but not at the price of denying that the microstructural basis of the reflectance property caused the experience, and not at the cost of saying there’s redundant causation. So far, PP&J. I’m not sure I added anything, but if I did, it was only the idea that the reason why fragility, etc., are impotent might be that they’re disjunctive. Recently – more recently than anything cited in your paper – I’ve come to think there’s a way around the argument for impotence in all these cases, and indeed in the case of disjunctive properties generally. You’ll find it briefly mentioned (for the case of reflectance properties) in my ‘Naming the Colours’, AJP 1997, pp. 330–332. Here’s

    3   4   1 2

‘Multiple Reference, Multiple Realization, and the Reduction of Mind’ (Horgan 2001). ‘The Transvaluationist Conception of Vagueness’ (Horgan 1998). (Prior, Pargetter, and Jackson 1982). From Metaphysics to Ethics: A Defence of Conceptual Analysis (Jackson 1998).

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the idea. Let’s agree, pace PP&J, that the reflectance property (or the functional state, or the property of having some basis or other for a disposition to break, or in general the disjunctive property) does the causing. It’s also true (undeniably!) that the surface microstructure in the particular case (or the neural realization in the particular case, or the basis of the disposition in the particular case, or the actual disjunct) does the causing. But even though there are two different properties doing the causing, that doesn’t make it a case of redundant causation. That’s because, though there are two properties, there’s only one particular property-having. This one property-having is a having (maybe in two different senses) of the two different properties. About the same time, independently of me, David Robb defended what’s essentially the same solution in his paper ‘The Properties of Mental Causation’, Phil. Quarterly 1997, 178–194.5 Robb discusses the case of the functional state and its realizer in the particular case. The idea is again that there are two different properties, but there’s one single particular having which is a having of both the two properties. Robb thinks this having is a trope – I have no objection, but I might prefer to be a bit more neutral about what it is. You’ll also find some discussion of the topic in my ‘Finkish Dispositions’, Phil. Quarterly 1997,6 with only a parenthetical mention of the single-having solution on page 152. It seems to me that your solution is only a cosmetic solution to the aspect of the problem whereby we don’t want to say there’s redundant causation. Aren’t you granting that there is redundant causation, but saying that it’s conversationally in­appro­pri­ate to mention it? I’m not content: I think I can tell the difference between not wanting to say things because they’re false and not wanting to say things because they’re inappropriate. On ‘higher-order natural properties’ and reductionism: note that I’m happy to say that naturalness comes in degrees. If you’ll grant me that your higher-order nat­ ural properties aren’t perfectly natural, I’ll grant you that they’re fairly natural, being not too very far in definitional distance from the perfectly natural properties. Deal? Needless to say, these comments aren’t meant to urge any changes in your paper. Mostly I’m commenting on moves that happen outside the papers you’re ­writing about. (One place where I would urge a change is line 19, page 5, where there seems to be a missing word.) Yours, David Lewis c: Frank Jackson, David Robb  (Robb 1997).   6  (Lewis 1997a).

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526.  To John Heil, 8 June 1998

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526.  To John Heil, 8 June 1998 [Princeton, NJ] Dear John Heil, Thank you for your paper on multiple realizability.1 Yes, it is ‘in the same ballpark’ as what I’ve recently thought. The enclosed copy of a letter to Terry Horgan explains how I’d put the matter,2 and gives a reference. (Terry himself favours ‘levels’, in much the way you describe in the opening pages of your paper.) I take some properties more seriously than others. (Compare DMA’s increasingly prominent admission of ‘second-rate’ properties.) I don’t deny the existence of second-rate properties, but neither do I admit them to the basis upon which all else supervenes. Class nominalism is my theory of the second-rate properties. (I reject predicate nominalism not because it’s deflationary, but only because we don’t have enough predicates to go around.) As for the properties that I take most seriously – the few ‘basic’ or ‘fundamental’ or ‘perfectly natural’ properties – I’m neutral between at least three theories: (1) DMA’s theory that they’re immanent universals, (2) the theory that they’re classes of exactly resembling tropes, or (3) class nominalism with a primitive distinction between perfectly natural classes and less natural classes. The property of having some or other property which occupies the pain-role is second-rate, disjunctive, imperfectly natural – but other disjunctions, still more miscellaneous, are still less natural. And yet, in its second-rate way, this property does exist. (I do not think it ought to be called ‘pain’, but whether it exists is a different question from what name it deserves.) I’d like to say that havings of it cause paineffects; but I wouldn’t want to say that, if it meant I had to deny that havings of a much more specific property, the neural state that occupies the pain-role for me now, also cause pain-effects. I’ve lately come to think that the multiply-realized less natural property and the more natural realizer aren’t really in causal competition after all, because one and the same particular property-having might be a having of both properties. This particular property-having might be a trope, as in David Robb’s paper,3 or it might be some other appropriate sort of particular. Yours, David Lewis

  ‘Multiple Realizability’ (Heil 1999).    2  Letter 525. To Terence Horgan, 28 May 1998.   ‘The Properties of Mental Causation’ (Robb 1997).

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527.  To Allen P. Hazen, 6 August 1998 [Princeton, NJ] Dear Allen, Trams. Just before we left Melbourne, Steffi and I saw an Age article about the fate of the W-class trams. (I take it these are the newest of the round-ended trams, as seen on the City Circle.) None of them are now in service (except on the Circle); but they are to be reintroduced after modifications, if negotiations succeed with the union about what modifications there will be. Something is to be done about the fact that the fare-collecting gadget blocks the driver’s view in some directions; and maybe they will have pantographs. Kripke paper. Enclosed is the old Kripke paper1 I mentioned to you at George’s. After I came to Harvard as a graduate student in the fall of 1962, I found a copy of it in the departmental library. I imagine it was left-over reserve reading for some graduate seminar in some previous semester. Your guess is as good as mine about whether the hand-written marks and underlines are Saul’s or someone else’s. Most of it is Saul’s reply to Quine’s claim that quantified modal logic requires murky essentialistic distinctions. I must say that I find this unconvincing. What Saul accomplishes without benefit of MEDs is, in effect, to construct a socket into which whatever MEDs you may happen to have can be plugged. Yeah, yeah; but only after you have plugged something into that socket do you have a specific interpretation for the language of QML, as opposed to a range of possible interpretations. (This resembles something I think about paraconsistent logic. I’ve long thought that to make reasonable, as opposed to Priestly, use of this machinery, I need some way to make the murky distinction between blatantly impossible and subtly impos­ sible impossibilities. And I’m not given that distinction – I’m only given a socket into which it could be plugged if I had it.) What caught my attention as a graduate student was not the main part of Saul’s paper, but rather the brief discussion that starts at the middle of page 17.2 I thought: ‘OK – I know how I like to think about identity through time, and I like the analogy’ – and that’s how I came to write ‘Counterpart Theory and QML’.3 Naming the Colours. I have no objection in principle to the use of landmarks to define certain colour terms (enough that we can get the rest by triangulation from the landmark colours), provided that this can be done without going beyond the

  ‘Quantified Modality and Essentialism’. Recently published: (Kripke 2017).   That is, (Kripke 2017, 230–1). 3   Cf. Letter 121. To Dagfinn Føllesdal, 6 March 1966, Volume 1: Part 2: Modality. 1 2



527.  To Allen P. Hazen, 6 August 1998

201

knowledge of the folk, and provided it can be done without circularity. But I’m ­doubtful about both of these conditions. As to folk knowledge. I’ve always had a problem about unique green, and I suspect I’m not alone. You see. I was brought up to think of green as yellowish-blue, in the same way that orange is yellowish-red, or purple is reddish-blue. And it still seems that way to me! (Or at least it doesn’t seem clearly not that way.) So when I’m told that unique green is supposed to be not at all yellowish or bluish, that ex­plan­ ation seems to presuppose something about my phenomenology that isn’t clearly right (and sometimes even seems clearly wrong). As to circularity. Waiving the previous difficulty, unique green is supposed to be not at all yellowish or bluish. Yellowish? That means: in the direction of unique yellow. Unique yellow, I presume, is supposed to be not at all greenish or reddish. And so on. Maybe we could get as far as identifying the quadruple of unique hues but we still need something in folk psychophysics to say which of them is which. And then we’re back to the problem as I stated it in the paper: unique red is that one of the unique hues that’s close to the colour of the people’s flag – but wait, some of the folk never heard of the people’s flag. --Moorean inclinations differ from Quinean inclinations, I agree, but in practice and if we’re lucky, they can coexist peacefully. A Quinean can and should be conservative, as Quine himself is; and a Moorean can and should be cautious about ascribing Moorean status to just any offhand formulation of just any com­mon­sen­ sic­al opinion. It’s a Moorean fact that the sun rises; and what’s true is that the angle from horizon to sun increases. Isn’t that at least the principal part of the Moorean fact that the folk wanted to insist on? So weren’t they right all along? Well, not entirely right, not right in everything they thought about the motions of sun and earth; but anyway, more right than wrong in what they believed most confidently. I think that’s a typical example, and stories of the victories of science over ­common sense tend to be badly exaggerated. --I don’t see how the line I take is ‘empiricist’. It’s descriptivist, and in that respect reactionary; but that’s different. Maybe it’s true that having some sort of perceptual contact with the world is a prerequisite for having any descriptive concepts of anything. But that’s not a confident opinion of mine, and not a claim that appears in the paper. Be that as it may, I  definitely don’t think that having colour-sensations is a prerequisite for having a descriptive concept of colour-sensations.

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Consider the blind. I suppose that they – those of them who are well educated, anyway – have mastered folk psychophysics. For them, it’s a theory of discriminatory powers and inner states that they don’t themselves possess, but none the worse for that. (Study bats, and you too will have a theory of discriminatory powers and inner states that you don’t yourself possess.) A blind man who has mastered folk psychophysics has a descriptive concept of colour sensations; and, if he has the right little bit of extra information, he has a descriptive concept of the colour sensation that is produced in the sighted by beholding the people’s flag, and of the surface property that is apt for producing that colour sensation. (Granted, the blind man is missing one de se part of my own descriptive concept of red: he doesn’t say ‘it’s the property that produces in me the spontaneous judgement “that’s red” ’. (Of course, a monolingual Finn is also missing this de se part of my own descriptive concept.) But how much of a loss is that, if the blind man does know that red is what produces in sighted English-speakers the spontaneous judgement ‘that’s red’?) So I don’t think I subscribe to your first ‘basic empiricist tenet’; not, anyway, if it says that mastery of colour-sensation-concepts must be traced to actual coloursensations (had by the master of the concept). As for the assumption of simplicity of colour-sensations: I think what I assume is not so much that they are simple as that the folk are ignorant of whatever complexities there may be. Or at least they lack common knowledge of these complexities. Yours,

528.  To Delia Graff, 24 August 1998 [Princeton, NJ] Dear Delia, I think Dummett’s ‘very coarse observer’ is possible. I think so because I myself am a very coarse observer – or near enough. Not all the time, fortunately. I have a good left eye and a bad right eye. The trouble with my bad eye is called amblyopia, or ‘lazy eye’. What happens in early childhood is that, because of a tendency to crossed eyes, it’s hard to use both eyes together; the dominant eye does all the work; the other eye – or rather, its neural circuitry – remains undeveloped. In my case, vision in the bad eye is somewhere between 20/50 and 20/200; all it’s good for is to provide a rightward extension of peripheral vision.



529.  To Michael Tooley, 16 October 1998

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So that I can speak from experience about what it’s like to be a very coarse observer, I’ll change the example: not coloured clock hands, but a row of letters on a one-row eye chart. The letters are black, the row is illuminated, the room is otherwise dark. There are about five letters in the row. I’m looking with the bad eye, with a patch over the good eye. I can see that somewhere toward the right is a letter with verticals and horizontals: it could be an E, an F, an H, an L, a T, or maybe even a B, but I can’t tell which it is. And somewhere toward the right is a rounded letter: it could be a C, a G, an O, a Q, or maybe even a D, but again I can’t tell which it is. I cannot see whether the rounded letter is to the left or to the right of the vertical-and-horizontal letter, but they’re both right of center. It does not look as if the letters are superimposed; rather, it looks as if there’s one letter after another, left to right. It does not look as if the letters are at all blurred. It does not look as if the letters are fading in and out, or blinking. It does not look as if the letters are dancing or shimmering, or moving in any other way. In short, you couldn’t make a picture, either a still picture or a moving picture, that captures just the visual information I’m getting without putting in some further information that I’m not getting. If you assumed that how it seems must be representable by some picture, you’d have to conclude that how it seems is incoherent. The only way I know to represent the information I’m getting, no more and no less, is by a verbal description like the one I gave. A verbal description can be silent about some aspects of the ­situation in a way that a picture cannot. Two questions I leave open. (1) Is peripheral vision with the good eye the same way? (2) Is central vision of finely detailed textures with the good eye the same way? (Cf. the example of seeing a speckled hen and being unable to count the speckles.) Yours, c: Gil

529.  To Michael Tooley, 16 October 1998 [Princeton, NJ] Dear Michael, Thank you for your reply to Bealer.1 I almost entirely agree with it. But I have one quibble, which might perhaps lead to a slight simplification. 1  ‘Functional Concepts, Referentially Opaque Contexts, Causal Relations, and the Definition of Theoretical Terms’ (Tooley 2001).

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In the terms I’m most comfortable with, we have a functional role; we have P, the property which actually occupies that role; and we have the property Q of having some property or other which occupies just that role. P is some fairly natural property; Q is a highly disjunctive property, shared by those who have P in possible worlds where P occupies the role, those who have Pʹ in worlds where Pʹ occupies the role, and so on. It’s Q that corresponds to the ‘concept’ in your discussion. It’s Q, not P, that the introspector knows he has. You say, in effect, that it’s P, not Q, that causes behaviour. I disagree. I used to be persuaded by the impotence argument, due to Prior, Pargetter and Jackson. (It’s given sometimes in connection with functionally characterized mental states, sometimes in connection with dispositions, sometimes in connection with colours.) Surely P does the causing. (I agree.) But surely this is not a cause of redundant causation. (Again I agree.) So Q doesn’t do the causing. I say: no, P and Q both do the causing, yet not redundantly. After all, it’s really particular havings of properties – events? – that do the causing; one and the same particular having (just one, so there’s no redundancy) is in one sense a having of P and in another sense a having of Q. If you say that states of affairs are the particular havings, and states of affairs are individuated in such a way that one of them can’t be the having of two different properties, then I reply that either this is the wrong view about what the causal relata are or being caused (not jointly) by two different states of affairs need not be a case of redundant causation. In ‘Events’, Φ Papers II, I say some things about how an event could be essentially or accidentally a having of one or more properties. In ‘Naming the Colours’, AJP 1995, pp. 292–4, I state this one-having-two-properties line (for the case of re­flect­ ance properties and their microstructural bases). It was independently invented by David Robb, ΦQ 1997, 178–94. But Robb presents it in terms of a trope theory of properties – something on which I’d rather remain neutral. Yours, David Lewis c: L.A. Paul



530.  To Frank Jackson, 9 November 1998

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530.  To Frank Jackson, 9 November 1998 Princeton University Princeton, NJ Dear Frank, My short answer is that what you say in the footnote is literally true.1 A longer answer is that it may or may not be misleading, depending on what ‘notion . . . capturable in terms of sets of possible worlds’ is being contrasted with. To capture my favourite notion of content, on which (plus appropriate collateral information) I hope all other sorts of content supervene, remove two simplifications: (1) In place of ‘possible worlds’ put either ‘centered possible worlds’ or else ‘possible momentary individuals’. (2) In place of ‘set’ put ‘subjective probability distribution’. A notion more straightforwardly capturable in terms of sets of worlds is horizontal content, aka secondary intension, aka C-proposition. I think this has been much overrated, but nevertheless is a well-defined and not altogether useless notion. Maybe in describing the belief system of someone who is ignorant or mistaken about non-contingent matters we sometimes need a hyperintensional notion of content, something like Max Cresswell’s ‘structured meanings’. I’m not fully convinced of this; and I think that it’s anyway not the central notion of content. Yours, David

531.  To Daniel Dennett, 7 December 1998 [Princeton, NJ] Dear Dan, No worries – I do not suppose that the difference between amblyopia and ­normal vision is anything more than a difference of degree. I think of it this way: what’s obviously true of my visual experience with the bad eye has taught me to notice what’s less obviously true of my visual experience with the good eye. In the letter to my colleague that I sent you,1 I was indeed explicitly noncommittal about the case of normal vision. Not because I was unsure what to think; but   A footnote in ‘Non-Cognitivism, Normativity, Belief’ (Jackson 1999).

1

  Letter 528. To Delia Graff, 24 August 1998.

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only so as not to strain my colleague’s credulity beyond the needs of the point ­currently at issue. I have trouble experimenting with my peripheral vision because, when there’s something there to look at, I can’t stop it from attracting my central vision. CE p. 54 asks me to overcome the problem by being ‘careful’,2 but I don’t think I can resist just by trying. Is there another way to do the experiment? Yours, David Lewis

532.  To Frank Jackson, 6 August 1999 Princeton University Princeton, NJ Dear Frank, Thank you for ‘Locke-ing onto Content’.1 Little to disagree with! – But there is one small thing. Mostly this is a disagreement I have with Dave Chalmers; but your paper has just a little smidgin of the same problem. Agreed, we have two ‘components of content’. (I prefer Stalnaker’s terms, ‘diagonal’ and ‘horizontal’; but I suspect Dave’s ‘primary’ and ‘secondary’ have a better chance of becoming established, so let’s use those.) Dave likes to explain the difference by saying that subjunctives evoke the secondary intension, indicatives evoke the primary intension. That same suggestion seems to be the point of your parenthetical sentence just below the middle on page 22. Well, sometimes. But I think usage is more flexible than that. I have no ­trouble saying ‘If water had actually been XYZ . . .’ which, on Chalmers’s story, should be a contradictory supposition. (This example also illustrates another way in which I think usage is more flexible than it’s often made out to be. Do ‘actual’ and its cognates always function as rigidifiers? Or only sometimes?) If XYZ had been the only watery stuff of our acquaintance, what then? I’m equally happy to say ‘. . . then XYZ could have been water’ or ‘. . . then we wouldn’t be acquainted with water’, though of course not both together. I’m inclined to think that how we disambiguate has little to do with indicative versus subjunctive contexts, more to do with making the message make sense.   Consciousness Explained (Dennett 1991).

2

  (Jackson 2001).

1



533.  To Delia Graff, 14 October 1999

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(By the way, Jasper Reid (Princeton grad. student) and Neil Thomason have both done some polling of naïve subjects on what to say about XYZ. To Jasper’s ­distress and Neil’s delight, it seems that flexibility is quite common among those who haven’t been taught what they’re supposed to say.) Yours, David

533.  To Delia Graff, 14 October 1999 [Princeton, NJ] Delia I wrongly thought your paper on phenomenal continua1 was one I’d read before; it turned out that it was new to me. I found that it reminded me of a distinction I used very long ago, for a very different purpose; and restating some things you said in my old lingo helped me to overcome (to some degree) my initial reluctance to believe the line you were taking. A percept is, roughly, a proposition that’s true according to one’s perceptual experience. (No doubt it’s an ‘egocentric proposition’. No doubt it often cannot be expressed accurately in language.) Thus I have a percept of change when it seems to me that something is changing; whereas I have a change of percept when how it seems to me that things are at first is different from how it seems to me that things are later. There can be a percept of change without any change of percept. I mentioned the Waterfall Illusion; the illusion of quivering you mentioned is another example. There can be a change of percept without any percept of change. Watching the hour hand is one example: whether or not there’s COP without POC in every very short interval, it’s anyway undeniable that there’s COP over a 5-minute interval without a POC at any time in that 5 minutes. Other examples: a gestalt shift; suddenly noticing something that’s well, but not perfectly, camouflaged. In parallel fashion, we can distinguish difference of percept from percept of difference; or percept of homogeneity from homogeneity of percept; or percept of continuity from continuity of percept. It may be true that as I look at two regions an inch apart in the foot-long spectrum from red to yellow, I have no percept of difference. It doesn’t follow, though I well might carelessly think it did, that there’s no

  ‘Phenomenal Continua and the Sorites’ (Fara 2001).

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difference of percept. Looking at a one-inch-wide band of the spectrum (but without blanking off the surroundings) I might have a percept of homogeneity. It doesn’t follow, though I might carelessly think it did, that there’s no inhomogeneity in my several percepts of the parts of the band. I might have a percept of continuity, or anyway no percept of discontinuity, when I look at the whole spectrum. It doesn’t follow, though I might carelessly think it did, that my percepts vary continuously from one end of the spectrum to the other. This seemed to me a useful way of restating your doubts about the factual premises of the better arguments for non-transitivity. Do these restatements seem OK to you?

534.  To David J. Chalmers, 8 December 1999 Princeton University Princeton, NJ Dear Dave, I look forward to seeing you next month. Thank you for your invitation; but I think it’s already been arranged that we’re to stay with Al and Holly. Anyway, I leave this to you and your colleagues to settle. I’m afraid the only thing I have that might – stretching a point – suit the cognitive science group is the thing I’m giving as my main talk. I think there’s a perfectly good sense in which the truth of the story of Richard Sylvan’s box is conceivable. I can imagine it. Of course, I can’t imagine it without contradiction – since, after all, it is a story of contradiction. You asked: could I describe what it would be like to look in the box? Could I describe a movie of this story? Of course I could; and of course those descriptions would be contradictory too. I think there’s a perfectly good sense in which the truth of the story is inconceivable: I can’t imagine it without contradiction. Of course I can’t since, after all, it is a story of contradiction. If conceivability is to be a test of possibility, this second sense (call it the logical sense), and not the first (call it psychological) sense had better be what’s meant. But then the conceivability test can’t be used without circularity to answer the question whether contradictions are possible. It says that they’re not, simply because they’re contradictions. That’s the right answer, say I. I’m not at all open minded about the possibility of contradictions. I say they’re necessarily, certainly, and a priori false. But Graham



535.  To David J. Chalmers, 10 December 1999

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would say I’m being dogmatic, and I have to say he’s right. (All the better for dogmatism say I, dogmatically.) I have no good argument. In particular, it’s no good to argue that contradictions are impossible because they’re inconceivable. If that’s meant in the psychological sense, my premise is false; if it’s meant in the logical sense, my argument is flagrantly circular. Maybe all I’m saying is that the conceivability test doesn’t deliver something that you never said it did deliver, but that I would have liked it to deliver. (I never remember whether Graham’s view is that contradictions are possible; or whether it’s that they’re impossible but the real world may well be impossible. I’ve put this the first way; but it should be obvious what to change if you’d prefer the second.) To change the subject. Suppose we have a sentence containing, or a thought whose linguistic expression would contain, several descriptive names like ‘water’, ‘the meter’, ‘Julius’, . . . . We could rigidify everything in sight and obtain the secondary intension. Or we could leave them all unrigidified and obtain the primary intension. So far, so good. Is there any reason why we couldn’t rigidify some but not all of them and obtain a betwixt-and-between intension? Might an anaphoric reference like ‘what he said’ sometimes pick up a betwixt-and-between intension? Two bibliographical questions. (1) I’ve seen mention of ‘Components of Content’ as forthcoming in Mind.1 Has it forthcome? Will it? I couldn’t find it, but our departmental collection of journals is incomplete, and our main library is worse. (2) You’ve mentioned a paper which, judging by the title, I’m going to like, called something like ‘The Tyranny of Secondary Intensions’.2 Available? Yours, c: Graham Priest

535.  To David J. Chalmers, 10 December 1999 [Princeton, NJ] Dear Dave, On Thursday 9 December, things weren’t happening as I expected them to. In the course of the afternoon I suddenly realized: I’ve been thinking that today is tomorrow!   ‘The Components of Content’ (Chalmers 2002).   ‘The Tyranny of the Subjunctive’ (unpublished ms). Available at: http://consc.net/papers/tyranny.html.

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The primary intension of ‘today is tomorrow’ is, I take it, the egocentric prop­ os­ition that is true of any momentary self iff the day when it is located is identical to the day following the day when it is located. The secondary intension of ‘today is tomorrow’, if said – as it was – on 9 December is the proposition that 9 December is identical to 10 December. Confused I was; but not to the point of believing obviously false identities. No kind of content of my belief was given by either the primary or the secondary intension. Rather, it was given by the sort of betwixt-and-between intension suggested in my previous letter: a partially rigidified intension of ‘today is tomorrow’, if said on 9 December, which is the egocentric proposition that is true of any momentary self iff the day when it is located is identical to 10 December. In other words, I’d been selfascribing being on 10 December. Yours,

536.  To David J. Chalmers, 26 December 1999 [Princeton, NJ] Dear Dave, Enough said about conceivability and contradiction. I don’t think I had a systematically different way of thinking of primary and secondary intensions; I think I was treating them differently in different cases. And I think that lost something that might better have been kept. Start with the case of an unambiguously rigidified designator. (With the caveat that I’m not sure there are any such.) The designator, and likewise a sentence in which it appears, has a primary descriptive and a secondary objectual intension. It is not ambiguous between these, as Bob Stalnaker once thought. It primarily expresses one proposition and it secondarily expresses another. What are ambiguous, though, are singular terms purporting to denote ‘the’ content of such a sentence: ‘What Fred said’ and the like. So far, so good? In the case of an unambiguously unrigidified designator (if there are any such) we needn’t distinguish. The designator, and the sentence in which it appears, has a single all-purpose intension. (At least if we set aside the distinction between a function from centered and from uncentered worlds.) It doesn’t matter whether we call it primary, secondary, or (as you’d prefer) both.



537.  To David J. Chalmers, 14 January 2000

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But what if we have a designator that’s ambiguous between being rigidified and being unrigidified – the usual case, I take it, once we’ve unlearned the philosophical training that teaches us to always disambiguate one way or the other. I was thinking: if it’s disambiguated as non-rigid, it’s like the (supposed) case of an unambiguously non-rigid designator: there’s one all-purpose descriptive intension. Whereas if it’s disambiguated as rigid, there’s an objectual secondary intension. What gets lost on this way of thinking is that there’s also a descriptive primary intension, just as in the (supposed) case of an unambiguously rigid designator. Thinking of it that way, if we have two ambiguous designators, and one is ­disambiguated as non-rigid and the other as rigid, there’s a betwixt-and-between intension, part descriptive and part objectual. Now I take it that you’d think of the ambiguous case this way. On either disambiguation, we have the same descriptive primary intension. The two disambiguations give different secondary intensions. One gives a descriptive secondary intension, which is near enough the same as the primary intension – harmless duplication. The other gives an objectual secondary intension. And if there were two ambiguous designators in the sentence, we could get an intension which was betwixt and between – not betwixt and between primary and secondary, but rather a secondary intension which is part descriptive and part objectual. OK; that’s what I wanted, and I see the advantage of describing it in your terminology, namely that the primary intension never gets lost. As you may remember, I disagreed with you about whether the primary intension was always evoked by epistemic contexts, the secondary by subjunctives. I had in mind that we could say such things as ‘If Brunel had invented the zip, he would have been Julius’ or ‘Julius may have been someone I’ve heard of, but if so I don’t know whether he invented the zip or not’. But maybe there’s a different way to interpret this evidence: as displaying the rigid vs. non-rigid ambiguity of ‘Julius’. Yours,

537.  To David J. Chalmers, 14 January 2000 [Princeton, NJ] Dear Dave, I meant my sentence about Julius to be epistemic, and nevertheless to mean something true. Here it is with some stage-setting to favour the reading I had in mind.

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Philosophical Letters of David K. Lewis I’ve heard of Brunel; he was clever enough to invent the zip, but I don’t know whether he did or not. The same is true of Lavoisier; of Ben Franklin; of Darwin; and of several other people I’ve heard of. Julius may for all I know have been anyone of these several people. But each of them, including Julius if he’s one of them, is someone such that I don’t know whether he invented the zip or not. In short, Julius may have been someone I’ve heard of, but if so I don’t know whether he invented the zip or not.

The reading I have in mind could be regimented as It is epistemically possible for me that Julius is suchx that: (1) I’ve heard of x, and (2) I don’t know whether x invented the zip or not. So maybe what’s going on is that ‘Julius’ is descriptive, as you’d expect given the e­ pistemic modality; but the variable x (the pronoun ‘he’ in my original sentence) is objectual. In some other sentences, for instance Whoever Julius may be, I know that he invented the zip. a pronoun may pick up the primary intension of ‘Julius’; but my sentence doesn’t work that way. Yours,

538.  To Mark Johnston, 27 September 2000 [Princeton, NJ] Mark It seems to me that there are two different desiderata for a notion of an object of hallucination or of seeing. There’s no need to choose, only to distinguish. I’ve mostly taken an interest in the first of the two, but I have no objection to the second. The object-1 of hallucination or of seeing is an entity that characterizes just what is and isn’t true (of one) according to the experience one is having (and only according to that experience, unaided by background knowledge). Hallucination and seeing alike have as their objects-1 a sensible structural property: the (maximal) property that the subject has according to the experience. Conjunctivism is true insofar as it says that seeing consists of (1) being in a state characterized by a certain object-1, where (2) this state is caused by (or counterfactually depends on) the surrounding things in virtue of which one has the property which is that object-1. Hallucination consists in (1) being in a state characterized by a certain object-1 where



539.  To David J. Chalmers, 6 May 2001

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(2) one does not have the property which is that object-1, and accordingly one’s experience is otherwise caused than by surrounding things in virtue of which one has that property. The (primary) object(s)-2 of hallucination or of seeing is (are) what one is acquainted with by means of that hallucination or seeing. Hallucination and seeing have different objects-2. Insofar as hallucination or seeing are characterized by their objects-2, conjunctivism is false: there is no common object. It isn’t just a fact about the experience that it acquaints you with certain things; it’s a fact about the entire causal process that ends with that experience. Or, if you prefer, you can say that it is a fact about the experience, but it’s an extrinsic fact. Roughly, the object-2 of hal­lu­cin­ ation is the same as its object-1: a structural property. Roughly, the object-2 of seeing consists rather of the arrangement of things which together instantiate the structural property which is the object-1; or, if you like, of the state of affairs of those things instantiating that structural property. To see why those ways of putting it are only rough, start with the case of seeing. Not all the things that together instantiate the object-1 are things you’re visually acquainted with, for you yourself are one of those things. You may indeed be visually acquainted with, say, your hand, but not with your eyes. So somehow we have to carve out a large part, less than the whole, of the arrangement of things that jointly instantiate the structural property which is the object-1: the surrounding things without their center. In the case of hallucination we may likewise have to carve out a large part, less than the whole, of the structural property itself. Macbeth is acquainted with the structural property seemingly instantiated by the dagger, but not with the structural property seemingly instantiated by himself looking at the dagger. So I’ll give you everything you say about objects-2 if you don’t regard them as standing in competition with objects-1.

539.  To David J. Chalmers, 6 May 2001 Princeton University Princeton, NJ Dear Dave, I’ve read ‘The Nature of Epistemic Space’.1 I like it, and agree with it near enough completely, but I have three related suggestions.

  (Chalmers 2011).

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(1) The very first line, the title of section 1, might better be ‘ways things might be’ or ‘ways worlds might be’. Ways the world might be suggests that alternative possibilities are supposed to be described or thought of from the perspective of the actual world: for instance, by calling otherworldly H2O ‘water’ regardless of whether it’s the watery stuff of its own world. That’s the ‘subjunctive conception’, which is the last thing you want to evoke at this point! Note that ‘ways the world might be’ is Saul’s favourite phrase for possible worlds; whereas ‘ways things might be’ is mine and Frank’s, ‘states of affairs’ is Plantinga’s, ‘ways worlds could be’ is Forrest’s. (2) I believe, with two qualifications, that you think as I do that worlds are worlds, whether thought of subjunctively or epistemically. The difference is not in what they are, but in how they get described and what semantic and theoretical roles they’re playing. (First qualification: I’m ignoring centering. But I take it that a centered world is a world, whatever that is, plus a designated center. Second qualification: I’m ignoring the less idealized versions of epistemic possibility that you take up in your final section.) If you do think this, it would be well to do much more to make that clear to the reader. If you want to maintain neutrality on the question, it would be well to do more to make that clear. If, on the other hand, you really do want to distinguish epistemic from subjunctive possibilities not only as different ways that worlds may be regarded and described and put to use, but as different kinds of things, that needs an argument I don’t find. (3) Of course I agree with you that the tyranny of the subjunctive is vexingly widespread; but I think it’s an overstatement to suggest that it’s the generally received opinion. It has been resisted by various people in various ways since very soon after Naming and Necessity first appeared in 1972. And it has been widely ignored. Remember, there was a lot of talk of possible worlds before the subjunctive conception was ever heard of. I don’t just mean Leibniz; I’m thinking more of the scene I was part of at UCLA in the late 60’s, which traces back to Carnap in the early 60’s. A good deal of the use of possible worlds in those days was in connection with subjective probability – an epistemic matter if ever there was one! Many of the discussions from that time just continued and evolved without paying much heed to the subjunctive conception. It was widely, but not universally, agreed that one way to describe other worlds was by means of terms rigidified at the actual world; but it was not nearly so widely agreed that this was the best or the only way. The 2-D framework was used to minimize the impact of Kripke’s views as early as Stalnaker’s 1974 lectures at a summer linguistics institute; the 2-D framework itself dates from about 1969, and was in print by 1973. Yours, David

PART 5 Language

540.  To W.V. Quine, 9 February 1965 Kirkland St. Cambridge, MA Dear Professor Quine, The department has nominated me for a Woodrow Wilson Dissertation Fellowship, so I must suddenly produce plans for next year (contingent on passing my metaphysics prelim). I ought to return the form by the end of this week. So I must bother you during your leave. Please accept my apologies. I would be very grateful if you would permit me to name you as director for a thesis on tacit conventions of language. I would begin next summer, and I hope I would finish by September 1966. We have discussed the topic; I understood you to express favorable but non-committal interest. I would attempt to develop my account of linguistic regularities by tacit convention (as discussed in my ‘Meaning and Convention’ which you have seen. I enclose a copy in case it will help you decide). I would try to defend it against objections, and to show to what extent it serves to explain various sorts of analyticity or necessity. I might also apply it to Grice’s account of meaning or Austin’s account of illocutionary force; I might compare the way in which it asserts the essential publicity of language with the way in which Wittgenstein or Cavell asserts the same. (This is my original plan, without the modifications we discussed last spring for turning it into a thesis in philosophy of science so as to bypass my metaphysics prelim.) I must give some name to the Wilson Foundation at once. But I take it what I say to them now is not very binding. They require a prospectus by 15 March; when I have written it you may be in a better position to tell whether you want to direct my thesis. I have told the Wilson Foundation that I want to start in mid-July. I understand that the department might either arrange to give me a topical exam right after prelims or permit me to begin officially on the thesis in anticipation of the topical. If you tentatively agree to direct the thesis, to what extent would you be available for consultation between mid-July and the beginning of classes in the fall? And would you be willing to criticise one or two prospectus-drafts this spring? I apologise again for taking your time with this now. I had intended to leave it until you were back and my prelim was settled, but it seems that I might lose a lot of money that way. Thank you very much for your consideration. Sincerely yours, David K. Lewis enclosed:   ‘Meaning and Convention’ Return envelope

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541.  To W.V. Quine, 21 May 1965 Kirkland St. Cambridge, MA Dear Professor Quine, I have passed the metaphysics prelim, and I have been awarded the Dissertation Fellowship. Thank you again for your kind assistance during your leave. I have given Albritton three copies of a new version of the prospectus (enclosed). You will see that I have made most of the changes I considered, except for  bringing in Austin and Wittgenstein and elaborating on Bennett and Putnam. I have also revised the statement of the definition of convention (beginning of Section 2) to make it clearer which are the clauses of the definition and which are ex­plan­ ations thereof. It turns out that Wilson does not require me to take the topical before they start paying. Thus I suppose there’s no reason for asking the department to give the topical somehow during the summer. I understand that, because of the Wilson, Harvard is willing to pay summer school tuition for me this summer, so I may as well enroll for the sake of fringe ­benefits. (Cheap audits, use of various facilities, etc.) I could take a 300 course from you. TIME under your supervision, or TIME under supervision of somebody who’s teaching a regular course in the summer school (say, Mueller). I don’t care which, and I suppose it might make a difference of extra pay and/or inconvenience to you, so I  leave it up to you. In the first two cases, you have to sign and return one of the enclosed cards (no rush). I had hoped to get either Scheffler or White as second reader. They will both be away, but I take it that does not entirely exclude them. I suppose Dreben and Putnam are also possible. The overlap with Cavell’s work is quite small, and would be even if I talked about Austin along with Grice, and Wittgenstein along with Cavell himself. I’m not clear how the second reader is chosen. Should I leave it to you and the department, or should I look for somebody who would be willing? I shall be in Cambridge more or less all summer. I want to spend some time in June working on other things and reviewing things I’m supposed to know related to the thesis; and then I’ll plan to really start sometime in July, depending somewhat on when you get back. Yours,



542.  To W.V. Quine, 21 November 1966

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542.  To W.V. Quine, 21 November 1966 UCLA Los Angeles, CA Dear Professor Quine, Steffi and I are very grateful to you, Putnam, and Kalish for making it pos­ sible for me to get going again on the thesis: I have just mailed the necessary application forms and summaries to Peg. The thesis is in the hands of a typist who can probably be counted on to do a good job and take no more than about three weeks. Steffi and I will come to Cambridge the afternoon of Sunday, 18 December. Would it be satisfactory if I hand in the thesis in person on Monday;* and take an oral sometime early that week? Any time that would suit you and Putnam and the department would be fine with us.  Yours, David K. Lewis * PS: Under Christmas conditions I don’t think it would arrive any sooner by air mail; and also it would be less safe that way.

543.  To Thomas C. Schelling, 5 October 1967 UCLA Los Angeles, CA Dear Professor Schelling, This was my dissertation; and is to be a book about a year hence, under the new title Convention: A Philosophical Study.1 The idea, in a sentence, is that a convention may be defined as a regularity in conduct whereby members of some population repeatedly solve some recurring coordination problem. Strategy of Conflict2 figures prominently in the first chapter.

 (Lewis 1969).   2  (Schelling 1960).

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Philosophical Letters of David K. Lewis

I would very much appreciate any comments you might care to make. If you would like to skim the thing, you’ll find a section-by-section summary at the end of the introduction, pages 6–12. Please feel perfectly free to give me as little time as you like! I recognize the i­ mposition. Sincerely, David Lewis

544.  To W.V. Quine, 18 October 1967 UCLA Los Angeles, CA Dear Van, Let me tell you some new ideas I have for Convention. I’m thinking about it again after a year on other things, teaching a seminar on it, and revising. I plan to have the revised version to the H.U. Press in December. There are two things I think are seriously wrong with the thesis. 1) The theory of conventions of language has no visible connection with referential semantics. 2) I try to claim one can recognize sentences which are accepted in consequence of conventions of language, even without being able to say (for any non-trivial language) what the conventions of language are. Such sentences are the ones whose acceptance will survive any stimuli except stimuli producing a change in convention; and a change in convention is supposed to be recognizable even if one can’t say what the conventions were before and after. This is at best indirect, and the ‘paradox of conventional wisdom’ suggests it doesn’t work at all – sentences can be accepted in consequence of what is – intuitively – the wrong sort of convention. Well, so why not say that the content of the convention governing a language is a specification of the referential semantics of the language? That’s what Hilary ­suggested at the topical exam, I guess. That is, the convention will be the ordinary Tarski truth-definition for the language. Put that way, it obviously won’t work: a convention is supposed to be a regularity in behavior, and a truth-definition, by itself, doesn’t specify any regularity in anybody’s behavior, so it can’t be the content of a convention. But now I see that it can be part of a convention. Suppose the convention of a  language has two conjuncts: Ι) a recursive specification of truth-conditions for



545.  To W.V. Quine, 27 November 1967

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­certain expressions, ΙΙ) the regularity of only uttering sentences which meet those truth-conditions, so far as one is able. Conjunct Ι cannot be a convention, for it is not a regularity in behavior. Conjunct ΙΙ cannot be a convention, though it is a regularity in behavior; telling the truth is not one of several alternative regularities, any one of which would do fine provided we all conformed to it. But what about the conjunction of Ι and ΙΙ? That is a regularity in behavior, and it is conventional. We already know that not any consequence of a convention is a convention, so it’s perfectly OK for Ι and ΙΙ, separately, not to be conventions. If I’m right, I can say what the convention of a non-trivial language would look like; and referential semantics is connected with my theory in the best way possible, by being built into it. Yours, David Lewis

545.  To W.V. Quine, 27 November 1967 UCLA Los Angeles, CA Dear Van, I’d never say that persistent lying is the only alternative to persistent truth-telling. In one sense it is one of many alternatives; in another sense it is no alternative at all. Before I explain, let me give you my current account of conventions of language, streamlined since last letter but not deeply changed. A possible interpreted language (for short, language) L is an ordered pair in which Σ is a set of strings of sounds or marks (called sentences of L) and τ is a two-place relation between sentences of L and possible occasions of utterance. A sentence σ is called true-in-L on an occasion w iff Î τ.

For every language L there is a corresponding regularity of persistent truth-in-Ltelling. One such regularity is a population’s convention of language; the rest, for all the other languages, are the alternatives to the convention. An expression σ is true on an occasion w iff there is some language L such that 1) σ is true-in-L on w and 2) the regularity of persistent truth-in-L-telling is a convention prevailing at w.

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The regularity of persistent falsehood-in-L-telling is a possible convention, and an alternative to a convention of persistent truth-in-L-telling. However, it is no different from the regularity of persistent truth-in-Lʹ-telling, for suitably chosen Lʹ. The regularity of persistent falsehood-telling is not a possible convention, indeed not a possible regularity for a whole population. For a falsehood is a falsehood in the conventionally prevailing language; and for any language L, if people persistently told falsehoods-in-L, then L could not be the conventionally prevailing language. Complications: presumably Σ and τ ought to be somehow effective, not arbitrary sets. Also, what about non-indicative sentences, vagueness, ambiguity? I haven’t thought this through very well yet, or started writing it up for the book; I’ve been spending lots of time, more than I’d expected, cleaning up earlier parts that I had thought were in pretty good shape. I predict that by Christmas I’ll be done except for the writing of two or three sections – but these two or three sections will be hard to do. I fear I may not keep the schedule I gave Mrs Wilcox. We’ll be in Cambridge for the APA. Will you be there? Steffi has finished her first two of four prelims, and takes the other two – logic and history – next spring. She sends regards. Yours, David

546.  To John Winnie, 30 January 1968 UCLA Los Angeles, CA Dear Professor Winnie: A short note after reading the reprint,1 but before reading the newer paper on Carnap.2 Your non-uniqueness theorems are compatible with everything I want to do. Both my rejoinders are anticipated in your own paper: (1) I do not think it is realistic to have disjoint domains of theoretical and ­observational – I prefer to say pre-theoretical – entities to be the extensions of   ‘The Implicit Definition of Theoretical Terms’ (Winnie 1967).   ‘Theoretical Analyticity’ (Winnie 1970).

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547.  To Grover Maxwell, 20 February 1968

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t­ heoretical and pre-theoretical predicates. Even electrons are in the extension of all sorts of pre-theoretical predicates: ‘too small to see’, ‘particle of matter’, ‘colorless’, . . . (2) I would certainly claim that a scientific theory ought to be formulated in an intensional language, though the extensional approximation would do for many purposes. Among the pre-theoretical terms turning up (with fixed interpretations) in my Ramsey and Carnap sentences will be such things as ‘it is a law that’, ‘because’, ‘physical magnitude’, etc. So the program you have defeated is a more ambitious one than the one I am interested in. Many thanks for the papers. See you in March! Yours, David Lewis

547.  To Grover Maxwell, 20 February 1968 UCLA Los Angeles, CA Dear Mr. Maxwell, John Winnie sent me a copy of his BJF S paper1 right after I sent him my outline. I don’t think he has made a bad problem for unique realizations. In the first place, he takes the theory to be stated in a first-order, extensional language. So it won’t contain pre-theoretical terms like ‘it is a law that ___’ or ‘___ is a physical magnitude’, etc. I take it that these second-order or intensional terms in the statement of the theory have a lot to do with keeping down the number of realizations. In the second place, he requires the realizations to have disjoint theoretical and observational domains, to provide extensions for the theoretical and observational vocabulary. I don’t think either restriction ought to be accepted. So Winnie’s argument works only for a special class of theories. Let Tʹ be a reducing theory, T a theory to be reduced. Let the pre-theoretical vocabulary of T be part of the total vocabulary of Tʹ. Let s1 . . . sn be terms in the vocabulary of Tʹ – presumably not primitives of Tʹ, however. Let T(x1 . . . xn) be the Ramsey formula of T. Now consider the sentence

  (Winnie 1967).

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Philosophical Letters of David K. Lewis "x1… x n [ T(x1… x n )iff x1 = s1 &…& x n = sn ].

This is a sentence entirely in the vocabulary of Tʹ; so I see no reason why it should not be a theorem of Tʹ, unsupplemented by any correspondence laws containing the­or­ et­ic­al vocabulary of T. If such a sentence were a theorem of Tʹ, I would say that Tʹ had reduced T without the aid of any correspondence laws. Why couldn’t this happen? Of course maybe not any old theory Tʹ is capable of having theorems of this form – maybe it takes a theory which purports to be in some sense all-inclusive. And maybe not all reduction works this way; I only say that reduction without correspondence laws is possible, not that it’s the only kind of reduction. I’d be very interested in seeing what you’ve done on similar lines.2 I knew you had been taking a line something like mine, because Keith Gunderson’s immediate reaction to my outline was to say so. It seems now as if the Hawaii meeting will mostly be about the unique realizations of common-sense psychology – especially now that Fodor is coming! I look forward to meeting you then. Yours, David Lewis

548.  To J.J.C. Smart, 24 July 1968 UCLA Los Angeles, CA Dear Jack, Thanks for complaining about the many obscurities in the T-terms paper!1 It is hard, I agree; and I’m so close to it that I can’t easily see where it’s unnecessarily hard. The main thing, which comes up again and again: for convenience, the theory is formulated so that the T-terms are, grammatically, names. Do they have to be names of properties? No – they can be names of entities of any category you like. Names of properties, states, Quinian scattered particulars, ordinary particulars, sets, functions, relations-in-intension or in-extension, species, event-types, or what have you. (I’m not saying all the above are distinct categories – it doesn’t matter whether they are or not.) You might like it if they were all named sets – that’s OK as far as my   ‘Structural Realism and the Meaning of Theoretical Terms’ (Maxwell 1971).

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  ‘How to Define Theoretical Terms’ (Lewis 1970b).

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548.  To J.J.C. Smart, 24 July 1968

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subsequent construction is concerned, though I have some suspicion that a theory whose T-terms were names of sets might lack explanatory power unless it used some rather hairy O-terms. I would take ‘phlogiston’ as Quine proposes to take ‘water’ as purporting to name a scattered particular – but a scattered particular which doesn’t really exist, because phlogiston theory is unrealized. That is, in the actual world ‘phlogiston’ is denotationless; in other possible worlds ‘phlogiston’ names a certain scattered particular material object which is part of the unique realization of phlogiston theory in that world. ‘Phlogistonhood’, on the other hand, names a property, the property of being all or part of the abovementioned scattered particular; that property is unexemplified in the actual world, but is exemplified in those worlds in which there is some phlogiston. OK? If you have countenanced the possibility that τ might be denotationless, you have to restrict universal instantiation and existential generalization: ∀xFx doesn’t imply Fτ, and Fτ doesn’t imply ∃xFx. (So τ = τ is consistent with ∼∃x x = τ.) UI and EG need an auxiliary premise ∃x x = τ; everything else works normally. Second sentence on p. 13 says: if T is realized, but T is not uniquely realized, then nothing is τ1, nothing is τ2, etc. As you thought, p. 5 footnote 4 says that on Russell’s theory of descriptions there are no denotationless terms just because all terms except variables disappear in primitive notation. Sandra Peterson is a colleague of mine here, trained at Oxford and Princeton, does half Donald Davidson stuff, half ancient Φ. She named her dog after Carnap’s chosen individual. P. 19, line 13: yes, ‘definientia’, misspelt. P. 19, 13–15: Jeffrey’s method, adapted to the Frege-Carnap theory of descriptions, would automatically grind out this sort of counterexample when asked: is there any way for the postulate T to be true although T is multiply realized? ‘Resonance hybrid’ is a term from organic chemistry. Consider benzene – no, orthodichlorobenzene, to enable us to identify some of the atoms. When you try to assign valence bonds (electron pairs) you get two possible structures like so:

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(There are some others, but unimportant.) It turns out that the actual structure is a quantum mechanical superposition of these. It’s not that half the stuff is in one form, half in the other; it’s not that all six bonds are 1½ electron pairs; it’s not that the molecules oscillate between the structures. It’s said to be a resonance hybrid of the two structures. I think this is an extremely apt image for the relation of a natural language to its many alternative precise reconstructions.2 P. 24: yes, ‘explanadum’ misspelt. Example of reduction with derived bridge laws. How about the identification of genes with DNA? Didn’t the reduction take place when we learned both that DNA did what the genes were said to do and that nothing else did? P. 28, line 15: delete ‘consider’. And that’s the lot. Many thanks – I’ll look through the letter again when I come to work on the paper again, maybe next fall. Next main project: Keith Gunderson’s philosophy of language conference at the Minnesota center in August; I’ll be there the last week. Off to San Francisco tomorrow for an extended weekend; I’ll leave behind examinations to keep my students busy without me! Yours, David

549.  To Terence Parsons, 1 September 1968 UCLA Los Angeles, CA Dear Terry, I was delighted to get your draft on a semantics for English.1 So far I’ve looked into it only enough to see what was going on; that wasn’t hard, for I’ve been thinking along similar lines for about a year – since reading Davidson, Vermazen, and Stenius in Synthese last fall, I’ve thought that transformational grammars should be interpreted by referential semantics over all possible worlds. Whereas you are interested in working out an example, I have rather been interested in how the finished product fits into the rest of the philosophy of language. Here are these interpreted languages or grammars, hairy set-theoretic constructs out

 See Convention: A Philosophical Study (Lewis 1969, 201).

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  A Semantics for English (Parsons 1968).

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550.  To Terence Parsons, 26 September 1968

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of sounds or marks, possible worlds, and things in possible worlds. And here are these guys going around making sound or marks in order to influence each other’s thoughts and actions – a regular, convention-governed, rational human social activity. What’s the connection? What is it for a language or grammar, understood as you understand it, to be used by a certain human population? Roughly, my answer is this: the population has a convention to be truthful with respect to that language or grammar. It’s more like Stenius’s line than anything else around. This stuff is in my forthcoming book Convention (due maybe next March); I enclose copies of part of a recent version. It is also in a paper called ‘Languages and Language’ that I just read at Minnesota.2 I enclose the definition handout for that, and will send a copy of the paper itself as soon as I have it properly typed – well before the end of the month. You ought to find out about Richard Montague’s attempts to do semantically interpreted grammars for English. He has done a fragmentary example; his semantics, like yours, is a referential semantics over all possible worlds. However, he despises the transformationalists for some reason; so his syntax is like nothing you ever saw before. I think maybe it’s really equivalent to an Aspects-model grammar, but not obviously so. Montague’s stuff is now a hand-written draft called ‘English as a Formal Language’; it was given as a lecture somewhere this summer (Vancouver?).3 Yours,

550.  To Terence Parsons, 26 September 1968 UCLA Los Angeles, CA Dear Terry, I’ve still not studied your semantics of English in detail, but there’s one suggestion I want to make now: I think you ought to exploit the fact that (if I understand it properly) your base component is not merely a phrase-structure grammar. It is also something much more specialized, and much easier to work with in an elegant and simple way: an Ajdukiewicz categorial grammar. The original paper is K.  Ajdukiewicz, ‘Die Syntaktische Konnexität’, Studia Philosophica 1 (1935): 1–27. Two translations exist: a partial one by Geach in

 (Lewis 1975b).   3  (Montague 1970a).

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R. Metaphysics, 20 (1967): 635–647; another in Polish Logic 1920–1939, ed. by Storrs McCall (Oxford, 1967). Bar-Hillel and his gang took an interest in categorial grammars in the early 50’s – see several papers in Language and Information. Haim Gaifman proved that every phrase-structure grammar was equivalent to a cat­ egor­ial grammar; but not necessarily to a categorial grammar of the especially simple kind Ajdukiewicz described. Bar-Hillel lost interest when he decided that no categorial grammar by itself would ever do for a natural language; but so far as Gaifman knows, nobody ever tried using a categorial grammar as the base component of an Aspects-model transformational grammar. I believe that is in effect what you are doing. The thing works like this. I’ve put in the semantic part: the original thing is just syntax. I’ve left out Ajdukiewicz’s treatment of variable-binders, since it’s a mess and you’ve used Quine’s rearranging gadgets to get away from variable-binding (this is one of the main differences between you and Montague).  1) NOUN is a category; SENTENCE is a category; if Co, . . ., Cn are categories, so is Co/C1 . . . Cn. 2) A NOUN-intension is a function from worlds to individuals; a SENTENCE-intension is a function from worlds to truth-values; a Co/C1 . . . Cn-intension is a function from sequences of a C1-intension, . . ., a Cn-intension to a Co-intension.

3) If is a lexical entry (where C is a category and 𝜄 is a C-intension), then ξ is a constituent of category C, and 𝜄 is the intension of ξ.

4) If ξ is a constituent of category C0/C1 . . . Cn with intension 𝜄, and ξ1 is a constituent of category C1 with intension 𝜄1, . . ., and ξn is a constituent of category Cn with intension 𝜄n, then ˹ξ ξ1 . . . ξn˺ is a constituent of category C0 with intension 𝜄(𝜄1 . . . 𝜄n).

And there you have the entire compositional machinery of your language! It remains only to plug in a lexicon and to provide a transformational and orthographic or phonological (top) component to go above your bare component, and you have your whole semantically interpreted grammar with one further rule:

5) If ξ is a constituent of category SENTENCE and with intention 𝜄 and the top component maps ξ onto the expression σ, then σ is a sentence with the intension 𝜄.



550.  To Terence Parsons, 26 September 1968

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Of course, all the hard work now comes in designing the lexicon and the trans­ form­ations. But this makes a good division of labor, I should guess. (Incidentally, one thing to notice: the lexicon will contain many constituents that disappear in the transformational stage and don’t correspond to segments of any sentence. But that’s OK; it happens also in existing transformational grammars.) I turn now to your letter about my Minnesota paper.1 I now share your doubts about the facts objectively selecting the language of P. I’m rather confident that a convention of truthfulness in ℒ is a necessary condition for use of ℒ by P, if we throw out various abnormal cases which are enough like normal language-use so that they might be so-called. I’m much less confident that it’s a sufficient condition. This is because of an objection raised by Stephen Schiffer when he read the paper. Suppose we take a language ℒ that really is used in P, and we form an expansion in ℒʹ by adding to ℒ the sentence ‘Bleegity bleegity bleegity bleegity bleeg.’, with the truth condition that the moon is made of green cheese. Now is it really clear that there does not prevail in P a convention of truthfulness in ℒʹ? According to the definition, they are truthful in ℒʹ; and they expect each other to be, in the weak sense given on page 25. I regard this as a serious difficulty. One way to meet it would be to say that the language used by P is the most grammatical language in which there prevails in P a convention of truthfulness – but this would depend on evaluation of grammars. You are one of many to be disturbed by the claim that the convention binds the hearer, not the speaker, in the case of imperatives. But what’s wrong with it? I can’t give a short defense; a long defense, which will appear in the book, is to start by checking the plausibility of this and other claims when applied to certain simple signalling systems. Is it sufficient to say that your liars (either the deluded ones or your others) use a language individually, but that the population does not have the sort of organization which allows it to use a language – or do much of anything – collectively; and that a man uses a language individually if he is similar in sufficiently many sufficiently important respects to a normal member of a population which uses the language collectively? You are right to say that I don’t consider this sort of objection very ser­ ious­ly: my object is not so much to produce a watertight analysis of existing usage as to capture the essential features of the phenomenon – essential not in the technical sense, but rather in the sense: the important, key, central, features. However, I believe essence in the technical sense follows essence in the non-technical sense. I buy the line in Michael Slote, ‘The Theory of Important Criteria’, J.Φ. 63 (1966): 211–224.

  ‘Languages and Language’ (Lewis 1975b).

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The argument about moods and radicals in general imperatives may be a problem for me; I’m not sure. One might try this line:* a single lie falsifies the sentenceradical, so the command has been disobeyed. But normally – and by no means always – the interests which presumably give the command-recipient a reason to obey, but which were somehow overridden, also give him a reason to pseudo-obey – to act in a way which would have constituted continued obedience if only he hadn’t already lied. Very roughly: maybe the implied command to be truthful after lying once is a sort of conversational implicature of the command ‘O(t) – you lie at t’. I don’t, by the way, find an intuitive difference in obedience-conditions between ‘Never lie’ and ‘Make it the case that you never lie’. For both, I have some inclination to say there can be repeated disobediences; for both, I have a counter-inclination to say that repeated disobedience is a confused notion: the command is (timelessly) disobeyed or obeyed, and that’s that. On thinking in language: no comment. In a paper of this sort, I can’t expect to defend my position to philosophers of every persuasion; only to present the notion, and try to give an idea of roughly what you have to believe in if you want to seriously consider accepting it. (So also in the book, unfortunately.) Yours, David

551.  To George Lakoff, 27 September 1968 UCLA Los Angeles, CA Dear Professor Lakoff: Thank you very much for sending me your paper on counterparts and trans­ form­ation­al grammar.1 My apologies for delaying this long in commenting – I’ve been travelling most of the time since it arrived. I’m delighted to see that the idea of doing semantics by means of possible worlds is making headway not only among logicians but also among linguists. I think it’s important and right; and also it may contribute more common ground than exists at present between different schools of thought in philosophy of language. It’s rather a *   PS: This reminds me of the headaches in deontic logic about what ought to be done in response to something which oughtn’t to have been done.

  Counterparts, or the Problem of Reference in Transformational Grammar (Lakoff 1968).

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551.  To George Lakoff, 27 September 1968

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secondary issue whether you connect things in different worlds by identity or by counterpart relations; but of course I’d agree that for doing semantics of natural ­language – as for any other purpose – the method of counterpart relations is more flexible and general. I know of two philosophers who have recently been interested in semantic interpretation of grammars for English by means of denotational semantics over many possible worlds. If I understand your position from Barbara Partee’s accounts, it seems to me that there might be much in common between their ideas and yours. One is Richard Montague, here at UCLA; unfortunately, though his work overlaps that of the transformationalists, he has no interest in exploring the overlap but prefers to start from scratch. The other is Terry Parsons at the University of Illinois at Chicago Circle; he, unlike Montague, is concerned to work with an Aspects-model grammar. Montague and Parsons both have drafts of their work which I think they are willing to circulate. Now for comments in more detail. On page 6, please do something about the last sentence of the second paragraph. Most of the axioms that modal logicians have been assuming for years turn out to be true in counterpart theory; most of the axioms that modal logicians have been debating inconclusively for years turn out to be empirically ridiculous. None of the principles I attacked have been uncontroversially accepted, or anywhere near it. On page 4, the McCawley sentence is a delightful problem. Notice that the common phrase ‘If I were you . . .’ raises essentially the same issues. So does a tricky modal argument about personal identity in J. Shaffer, ‘Persons and Their Bodies’, Phil. Review 1966. I take it we can have two (or more?) different counterpart relations involved in the analysis of a single sentence. These are similarity relations. But the different counterpart relations come from different weightings of different respects of similarity or difference. (You might try to get hold of Jaakko Hintikka’s ‘The Logic of Perception’ (unpublished). Hintikka thinks he needs two different ways of hooking things up between worlds. He gets fouled up because he thinks they are somehow both identity; and he marks the difference, confusingly, by means of two styles of quantifiers.) So I’d analyze ‘If I were you, I’d do so-and-so’ like this: In any world in which there is something x which is my counterpart with respect to desires, beliefs, strategic habits, etc., and which is your counterpart with respect to the situation, problems, resources, etc. (and which is at least as close – similar – to the actual world as any other world containing such an x) x does so-and-so. I’d do the McCawley sentence like this: the world of my dreams contains two people x and y such that: x is my counterpart1, y is Bardot’s counterpart1, y is my counterpart2, and x kisses y.

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Page 5: you often speak of the world of someone’s dream, beliefs, etc. Surely there are very many worlds compatible with the content of a dream, a set of beliefs, or what-not, unless the dream or belief set is as exhaustively detailed as possible – which it will never be. Page 7: In (20),2 you use A as a predicate applying to a world; I think of it as applying to things in the actual world. But it isn’t important: it could be either or both. Or we could take the name as primitive. Page 7: I think the scope of ‘you think’ and ‘I think’ in (20) is too big. The clauses ‘a ≠ b’, ‘a will run against b’, etc. and the clauses ‘Cac’, ‘Cbc’, ‘c will win’ aren’t part of what you or I think; they’re part of the facts about what goes on in the worlds you or I think to be actual. So I’d use: (20ʹ)  (Ex) (Ey) (Ea) (Eb) (Ec) (Wx & Wy & Iax & Ibx & Icy & a is named Humphrey & b is named Nixon & x is the world of your beliefs & a ≠ b & a will run against b & b will run against a & [not (a will win) or not (b will win)] & y is the world of my beliefs & Cac & Cbc & c will win) or something similar, rather than your (20). Page 7: (22) and (23)3 shouldn’t be starred; they could mean ‘John wants to catch a certain particular fish and . . .’. Maybe the fish in question is that notorious tricky old bass that hangs out last six years pp. 155–6 on two ways to hunt lions, or to want a sloop. There is a much harder problem of the same kind in Geach, ‘Intentional Identity’, J. Phil. 1967: 627–632; Geach’s sentence can’t be handled in Quine’s way, so far as I know, but can be analyzed by counterparts. Pages 7–8: Can your points about intending be explained on the hypothesis that to intend to do something is, roughly, to both want and believe that you will do it? Page 9: Again, since one’s realizations or intentions determine not single worlds but enormous classes of worlds, I don’t know what to make of your R-relation. I should say something like this: the class of worlds in which my intentions are fulfilled (call them my intention-worlds) includes the class of worlds compatible with my beliefs (call them my belief-worlds). Any one of my belief-worlds is one of my 2   ‘(20) (Ex)(Ey)(Ea)(Eb)(Ec) (Wx & Wy & Iax & Ibx & Icy & a is named Humphrey & b is named Nixon & (you think (Ax & (a ≠ b) & (a will run against b) & (b will run against a) & [(not(a will win)) or (not(b will win))])) & (I think (Ay & Cac & Cbc & (c will win))))’ (Lakoff 1968, 7). 3   ‘(22) *John wants to catch a fish and he will eat it. (23) *John wants to catch a fish and Bill wants to eat it’ (Lakoff 1968, 7).



552.  To Terence Parsons, 15 October 1968

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intention-worlds, but normally not conversely. Thus where you have a special relation R between single worlds, I have familiar set-theoretic relations between sets of worlds. The idea that propositional attitudes determine classes of worlds is not mine; it goes back to Carnap’s idea that propositions are classes of models. The idea is prominent in Hintikka’s Knowledge and Belief, though he tries to reduce worlds to ­partial descriptions thereof. I’m one of those who shrink from impossible possible worlds; I don’t see how the contradictions in the impossible world can be prevented from yielding contradictions in what we want to say about what goes on in the world. But one approach would be this: think of a possible world as a maximal consistent set of sentences in some language; think of an impossible world as a maximal non-blatantly-inconsistent set of sentences. Yours, David Lewis

552.  To Terence Parsons, 15 October 1968 UCLA Los Angeles, CA Dear Terry, Yes; I had thought that your system was designed so that the formal language of I and the base component of II would be inter-translatable in some quite simple way. It is the formal language I thought of as supporting an Ajdukiewicz-type semantics. I would agree that a noun-phrase like ‘some pigs’ needn’t and shouldn’t be of the Ajdukiewicz category I called NOUN; rather, it should be of the category SENTENCE/(SENTENCE/NOUN). That is, it makes a sentence when put in front of something which makes a sentence when put in front of a NOUN. What I called NOUN in the letter might better have been called NAME. Then the quantifier itself is of the category (SENTENCE/(SENTENCE/NAME))/(SENTENCE/NAME). Lakoff sent me his paper, and I recently sent him a letter of comment, making many of the same points you did. In particular, I also said that the main thing was to do semantics by possible worlds and it was a secondary issue whether you want to have counterpart relations or inter-world identities; I said that the claim about modal axioms being empirically ridiculous was excessive; and I objected to his R-relation on the grounds that there will be big sets of belief-worlds, desire-worlds, and ­intention-worlds.

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I’m in disagreement, though, with your reason for saying maybe we can’t talk about ‘my (unique) desire-world’. You say it’s because I may have several in­com­pat­ ible desires; but if I had only one desire – say, for great wealth – I would have many desire-worlds: all those worlds in which I (or my counterpart) am very wealthy. I would want to handle the McCawley sentence, and the ordinary ‘If I were you . . .’ which raises similar difficulties, by means of two counterpart relations, obtained by weighting the importances of different respects of comparison differently. In the world(s) of my dream we find A kissing B; A is my counterpart1 and Bardot’s counterpart2, whereas B is my counterpart2. Your sentence (13*)1 I take to present a different difficulty: dreams, like stories, can be logically incoherent, hence not true in any world. I also disliked the Humphrey-Nixon example, on the grounds that there was a  confusing mixture of intentional operators with the explicit talk about possible worlds which is designed to translate them out. In particular, Lakoff shouldn’t have so much stuff in the scope of ‘you think’ and ‘I think’; he should just say ‘x is the (a) world of your beliefs’ and ‘y is the (a) world of my beliefs’. If you think of H and N as real predicates of Humphreyizing and Nixonizing, you can use them to do the interworld identification; but Lakoff’s predicates are not that, but only predicates concerning the name something goes by in its own world. Yours, David

553.  To Nelson Goodman, 13 October 1969 UCLA Los Angeles, CA Dear Professor Goodman: Thank you for your letter of comment on my paper ‘Analog and Digital’.1 I agree with you that the distinction between differentiated and non-differentiated representation is ‘clear and illuminating’; I only think my differentiated analog ex­amples show that the ordinary analog/digital distinction is a different distinction – one that I hope also is clear and illuminating. 1   ‘(13*) I dreamed that there was a sultan of Arabia, that he was one of his own concubines, and that he danced for him’ (Letter from Terence Parsons to George Lakoff, 10 October 1968).

  (Lewis 1971).

1



554.  To Barbara Partee, 12 November 1969

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I don’t think I leave out the semantic aspect of your position; rather, I don’t separate syntactic from semantic differentiation and density. My ‘differentiated’ should correspond to your ‘syntactically and semantically differentiated throughout’. I should make that explicit in the paper. I’ve received Hellman’s extremely interesting paper on ACI with restricted complementation, hence without the universe provably existing.2 Sincerely, David Lewis

554.  To Barbara Partee, 12 November 1969 UCLA Los Angeles, CA Dear Barbara, An accumulation of questions and news. 1 ) Someone thought, I believe, that imperatives, permissions, &c. should be regarded as derived from declarative performatives. More precisely: ‘Go to Hell’, for instance, should have the deep structure S

I command you S

You go to Hell

2   ‘Finitude, Infinitude, and Isomorphism of Interpretations in Some Nominalistic Calculi’ (Hellman 1969).

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Did anyone think this? Or something like it? Does he still? References? I’d like it to be true for semantic reasons – I could do away with the inelegant dodge of having a meaning be a pair of a mood-marker and a truth-condition; as in Convention. 2) Where will I find a precise definition of a transformational grammar? Peters and Ritchie 1969, presumably, but I don’t know what or where that is.1 Montague’s been reading Aspects and Jacobs & Rosenbaum,2 and claims he still hasn’t the foggiest idea what a transformation is; I’d like to try to shut him up, though it’s probably not a worthwhile thing for me to try to do. 3) Speaking of which: he’s on the program for the APA-ASL meeting in New York, to do yet another, allegedly mostly new version of the ‘English as a Formal Language’ stuff. Having read a little transformational grammar, he says he plans to lambaste it more than ever. I’d like to sic Postal or someone like that on him, but I don’t know Postal; but maybe you’d like to publicize the event among the more contentious types at MIT. (27 December, 2:15 PM, Waldorf-Astoria New York, Empire Room) 4) One of our graduate students, Sherroll Ellis, is taking Bedell’s 205A, and has him thoroughly intimidated, or so she says. 5) Regards to Frank, and how’s he coming? Any chance of a final oral over Christmas vacation? I’ll be in the NY area (which could include Cambridge) from 26 December to 6 January. But if there were to be an exam, I’d have to see a good deal of draft pretty soon. What with Angela Davis, teaching, department and university responsibilities, and worrying whether to accept an offer to move elsewhere, I’m accomplishing nothing. When I came back from SF in September, my paper based on the La Jolla talk needed only a few days more to be done. The same is still true. When done, it’ll be much too big, but I’ll mercilessly send you it anyway. Yours, David

  ‘On the Generative Power of Transformational Grammars’ (Peters and Ritchie 1973).   Aspects of the Theory of Syntax (Chomsky 1965); English Transformational Grammar (Jacobs and Rosenbaum 1968). 1 2



555.  To J.J.C. Smart, 17 April 1970

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555.  To J.J.C. Smart, 17 April 1970 UCLA Los Angeles, CA Dear Jack, I just read the Honolulu paper1 at Houston, and they duplicated extra advance copies. Here* they are; I kept the masters, so I can run more whenever I like. Here’s* also a copy of the final version of my big paper on the same stuff, to appear in J. Phil.2 I wonder whether the Honolulu book will ever appear.3 From a selfish point of view I’d prefer it not to for a while, because my Honolulu paper is just right for reading at places like Houston, Berkeley, and Claremont, and I have no other paper that would do as well. The subjunctive conditionals will be a good colloquium paper when I finally get it written, except that when I get it written I’ll send it straight to someone who’ll print it fast! We hear there was a lot of rioting last night in Harvard Square; someone saw a news photo that ‘looked like Watts’. But the LA Times this morning didn’t yet have the story. We have a mass meeting going on right now, next door at the law school; lots of crowds, noise, & helicopters but nothing worse. The regents are meeting at this moment to make their final decision about Angela Davis. So, even if there were no other grounds for looking forward to getting away to Oxford . . . Scott’s theory of descriptions isn’t hard; but his exposition of it is.4 Skip all the stuff about virtual classes, for a start. But you’re quite right: the whole business will go through in any reasonable theory of descriptions. What you wrote (*)  $1 x  [ x ] ⊃ t = ℩ x  [ x ]

is a Russellian equivalent of the modified Carnap sentence; I would say that you ought to have something else to say that if T isn’t uniquely realized then the t’s are denotationless, but you can’t say that unless you have provision for denotationless names. A theory based just on (*), understood according to Russell’s theory of descriptions, is a half-way point between Carnap’s meaning postulate and my definitional identities. Probabilities are problematic, but not a special problem for the Ramsey approach. I think we know how to quantify into intensional contexts especially well when our quantifiers are restricted to entities such as properties, as they tend to be in this case: there’s no problem of identifying something from one world to another,   ‘Psychophysical and Theoretical Identifications’ (Lewis 1972a).   sorry, not here; separate envelope.    2  ‘How to Define Theoretical Terms’ (Lewis 1970b). 3  (Cheng 1975).   4  ‘Existence and Description in Formal Logic’ (Scott 1967). 1 *

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since things like properties aren’t particular to any one possible world. But as to your main questions, what sort of probabilities these are, I don’t really know. They’re not frequencies, and they’re not degrees of belief; I’ll gladly call them Popperian propensities, but I don’t understand at all well what those are. I fear that the propensity ­theory avoids saying anything false by not saying anything very informative. The probabilities I like and understand are rational degrees of belief, as in Dick Jeffrey;5 I don’t see how to connect those with the sort of probabilities you get e.g. in indeterministic physical theories. [. . .] See you soon! Steffi & David

556.  To Richard Montague, 27 July 1970 St. Catherine’s College Oxford, England Dear Richard, I find that in the rush before I left LA, I neglected to get definite bibliographical­ information about two of your papers that I want to cite in my ‘General Semantics’ paper in Synthese.1 (I seem to remember that there may not have been any very ­definite ­information to get.) I should soon receive the galleys, so let me now ask you: 1) according to present plans, when and where is ‘Pragmatics and Intensional Logic’ to appear?2 2) is ‘Universal Grammar’, or a descendant thereof, to appear anywhere?3 Is the book-length version imminent – and, if so, what is the present title and who is to be the publisher? We’re settled here, enjoying ourselves, and getting to work. So far I’ve mostly been catching up on reading, but soon I’ll start – at last! – on the subjunctive conditionals project that’s been waiting since 1967. I hope to have it done by the end of August; we go then to Wilfrid Hodges’ logic conference, and then travel for 3 weeks in northern Europe. We visited Wilfrid soon after we arrived; we’ll see the Cresswells

  The Logic of Decision (Jeffrey 1965).

5

 (Lewis 1970a).   2 (Montague 1970b).   3  (Montague 1970c).

1



557.  To Fabrizio Mondadori, 9 October 1970

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next weekend, just before they go home to New Zealand (a month earlier than they originally planned); and we hope to see Hans later in the summer, either here or in Amsterdam. Steffi sends greetings. Yours,

557.  To Fabrizio Mondadori, 9 October 1970 Headington Hill Oxford, England Dear Mr. Mondadori, Thank you for your interesting letter. Yes, I’m still in Oxford – should be all year – and willing to try to reply. (1) I’m not absolutely sure causal-history coordinates are needed at all; but if they are, I agree that they may well be needed not only for names but for common nouns and many other things as well. I didn’t mention this in the paper because I know Putnam’s ideas (that you mention) only by rumor and didn’t want to discuss them in print before their author did! You’ve seen my paper on theoretical terms;1 I consider there that the extension of a T-term might depend on its history, and this would go not only for proper names like ‘electronhood’ but also for mass nouns like ­‘phlogiston’ or whatever. Causal-history coordinates or no, certainly I won’t say that extensions of common nouns involve only the world-coordinate: I can think of persons who are in the extension of ‘Maoist’ in our actual world in 1969 but not in 1966, so the extension of that common noun depends also on the time coordinate. I certainly think you can be said to know the intension of a common noun and yet be unable to tell whether a given thing falls in the extension of that common noun at a given index. To take a striking example, I hope you’ll permit me to consider a compound common noun: ‘Godel number of a true sentence of arithmetic’. Take any index you like: this common noun is L-determinate, so the extension doesn’t vary from one index to another. Yet given a number, you can’t in general tell whether or not it’s in the extension of that common noun at the given index. (2) Maybe we have to resort to up-and-down-and-up-again projection rules, but I hope not; I’d tolerate plenty of disagreeable complication in the grammar to   ‘How to Define Theoretical Terms’ (Lewis 1970b).

1

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avoid that. Let ‘-’ be a negation operator, let ‘M’ be an operator meaning ‘it has been the case throughout the past month’, and let ‘J’ and ‘B’ abbreviate ‘John is here’ and ‘Bill is here’. (As you see, I ignore structural complexity not needed for the problem at hand.) Maybe one could cook up a transformational component that would allow ‘John hasn’t been here for a month, but Bill has’ to have an underlying structure like this

while letting ‘John hasn’t been here for a month, but Bill has been here for a month’ have an underlying structure like this, as one would expect it to.

(3) There are operators that are worse than intensional, in that you can’t even substitute co-intensive terms within them without changing the intension of the whole. You suggest that ‘alleged’ is such, and I doubt that, but ‘so-called’ is. If someone says ‘Nixon is a pig!’ but nobody says ‘Nixon is a swine!’ (or anything sufficiently close to that), then I take it that even though ‘pig’ and ‘swine’ have the same intension, Nixon is in the extension of ‘so-called pig’ but not in the extension of ‘so-called swine’. Or, if you don’t believe that example either, take the compound S/S: ‘John said in so many words that ____’. I would be inclined to regard these worse-than-intensional operators as disguised direct quotation. That is, the intension of ‘pig’ doesn’t appear in what I call the meaning of ‘so-called pig’, but the intension of ‘ “pig” ’ does appear there. Likewise, the intension of ‘ “swine” ’, but not that of ‘swine’, appears in the meaning of ‘so-called swine’. No violation of Fregean functionality, you see, because ‘ “pig” ’ and ‘ “swine” ’, unlike ‘pig’ and ‘swine’, differ in intension. To make this more plausible, suppose I say ‘Nixon is a snord!’. Now ‘snord’ is not an expression of English, hence can’t appear in the underlying structure of ‘so-called snord’. But ‘ “snord” ’ (the name of a certain meaningless mark or sound) is a well-formed expression of English (a compound one, I should think, since we wouldn’t like an infinite lexicon), and so can appear in the underlying structure of ‘so-called snord’. Now, I think (though this could well be questioned) that ‘so-called snord’ is a well-formed and meaningful expression of English, and that after I have said ‘Nixon is a snord!’, Nixon



558.  To Fabrizio Mondadori, 19 November 1970

241

is a member of the extension of ‘so-called snord’. So I suggest: an operator is ­hyper-opaque (that is, it can tell the difference between expressions with the same intension) iff it can attach to ill-formed garbage to make a well-formed and ­meaningful expression iff it corresponds to direct quotation in the underlying structure. Yours, David Lewis

558.  To Fabrizio Mondadori, 19 November 1970 Headington Hill Oxford, England Dear Mr. Mondadori, Pardon my delay in answering your letter – I was pressed, and still am somewhat, by deadlines for papers to be read at various places. I don’t very well understand what you say about ‘alleged murderer’. Of course I agree that the intension and extension of the compound depend on the intension, not only on the extension, of ‘murderer’; but why do you think this is a problem, and what has it to do with vagueness? We certainly can single out from the class of adjectives those special adjectives such that the extension of an Adj-plus-(common)-noun compound depends only on the extension of the noun; and among those we can further single out those in which the extension of the compound is always a subset of the extension of the constituent noun; and among those we can further single out those such that whenever something x is in the extension of two common nouns C1 and C2, then it is in the extension of both or neither of AC1 and AC2 (where A is the adjective in question). It is this final sub-sub-sub-class that comprises the adjectives that can safely be treated as predicates. But I don’t see the point of this: have we any reason to think these adjectives are special in any other way? Is there any reason to think they form a natural kind for purposes of linguistic theory? Next page: I distinguish between saying that the intension plus the index determines the extension (of a C, N, or S) and saying that if we know the intension and an index, then we can somehow determine the extension. I assert the former; you deny the latter; I think there’s no real disagreement. On T-terms: take a name of a disease as a good example of a T-term. ‘Polio’ necessarily denotes whatever state occupies a certain causal role (realizes a certain

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theory whereby the term is introduced). As it turns out, what occupies that role is the state of being infected by a certain species of virus; so that’s what state ‘Polio’ actually denotes. But it might have been the case (it is the case in another world) that what occupies that role is the state of being cursed by a certain witch; if so, that’s what state ‘Polio’ would have denoted (does denote in that other world). ‘Polio’ thus doesn’t have a determinate denotation. When you ask ‘Does it denote what uniquely realizes T in w or what uniquely realizes T in the actual world?’ I say: it denotes the former in w, the latter here. Denoting is a 3-place relation: term denotes thing at world (or, more generally, at index). Of course, the tricky question is: what does a T-term denote when used in our world to discuss the other world? And to this the answer is: it depends. It depends on details of syntax and context, and they may or may not suffice to settle the question in a given case. History-dependence of intension: I think I meant what I said in the T-terms paper, in conjecturing that we might be ignorant of the intension, not only the extension, of T-terms in use among us if we didn’t know the history of their first introduction. Let the meaning0 be the extension of ‘Polio’, to wit a certain state; let the meaning1 be the intension of ‘Polio’, a function from worlds (etc.) to states; and let the meaning2 (which, unlike the meaning0 and the meaning1, can be discovered from the speaker’s mind) be that which determines how the meaning1 of ‘Polio’ (in my language) depends on the causal history of the term from its introduction up to my present use of it. Meaning2 plus causal history determines meaning1; meaning1 plus possible world determines meaning0. If meaning1 were a constant function, we could leave it out, and go straight from meaning2 to reference; that’s what some causal theorists of reference think (at least about personal names) but not I. I don’t think the meaning1 of ‘Fabrizio Mondadori’ is a constant function, of course, because I think its values in different worlds are not identical but only counterparts of one another. If I understand you, you want to say that meaning1 belongs to abstract semantics while meaning2 belongs to the theory of language use. If so, you ought to be objecting not to the T-terms paper or ‘Languages & Language’, but rather to ‘General Semantics’. There I do not separate meaning1 and meaning2 but rather suggest (in the appendix) having a single function into which you plug both a causal history co­ord­ in­ate and a world coordinate (and other stuff) to jump all the way to an extension. But I think it can be done either way: you can extend abstract semantics to include dependence on causal history along with other sorts of indexicality (as in ‘General Semantics’*) or you can say that the determination of intension by causal history of terms belongs to theory of language use, whereas the determination of extension by intension and world belongs to abstract semantics. On the former choice, ‘intension’ corresponds to ‘meaning2’ of ‘Languages and Language’; on the latter choice, to



559.  To Fabrizio Mondadori, 4 December 1970

243

‘meaning1’. When I said in the T-terms paper that intension might depend on causal history, I meant the kind of intension that corresponds to meaning1. Yours, * The appendix only: since the rest isn’t concerned with causal history, it’s equally compatible with either.

559.  To Fabrizio Mondadori, 4 December 1970 Headington Hill Oxford, England Dear Mr. Mondadori, After Oxford, we go for July and August 1971 to Adelaide; for part of September to New Zealand; and thereafter to Princeton. (I’m now on research leave from Princeton, though I haven’t yet taken up residence there.) In Adelaide, I am to give some lectures on time travel. I’m sending by surface mail a draft (almost the final version) of a paper called ‘Could a Time Traveler Change the Past?’ which I read to the Jowett Society here at Oxford. It will do as a preview of the Adelaide lectures. The other thing I’ve been reading here is part of a longish paper (shortish book?) on counterfactuals. I’m afraid that the Adelaide lectures and the material on counterfactuals are both too unfinished and too long for me to be willing to distribute copies; if I do have a batch of mimeographed copies made up later, I’ll put you on the list. On adjectives: I do not think that any inferences of the forms: (1) x is an A C ∴ x is a C; (2) x is an A C, x is a Cʹ ∴ x is an A Cʹ; (where A is schematic for an adjective, C and Cʹ are schematic for common nouns) are logically valid. So of course I don’t think abstract semantics should account for the validity of any such inferences. Some such inferences are valid in the weaker sense that the conclusion holds at any index at which the premise holds; such validity is accounted for not by logical form, but by a property of the C/C-intension that has been assigned to some particular adjective. Similarly, as you say, for other modifiers. On what it is for a speaker to refer: x refers to thing y by term s on occasion o iff (roughly) there are a language L and a grammar G such that (1) on occasion o, x purports to be conforming to a convention of truthfulness in L; (2) G is the best grammar that generates L; (3) the lexicon of G assigns to s the category N and an

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N-intension ϕ; and (4) ϕ(i) = y for any index i whose contextual coordinates are those of the occasion o. That’s very sketchy; to some extent, you know how I would improve it, and to some extent I don’t know how to improve it. Causal considerations appear, if they do, like this: the relevant pieces of causal history are features of the occasion o, and hence contextual coordinates of any suitable index i. Here I’m throwing in causal history with other sorts of indexicality; that is, intensions are here meanings2. This means that I delineate abstract semantics differently from you (more precisely: I tentatively consider doing so). Why have meanings1 for proper names as well as extensions and the de­ter­min­ ation of extensions by causal history? First, because I’d like to treat names uniformly, and certainly not all names are logically determinate, even if some are. Second, because meanings1 for proper names are not constant functions if, as I claim, no concrete thing is in more than one world. On T-terms: if polio-theory were realized in Australia by the state of being cursed by a witch, and elsewhere by the state of being infected by a certain virus, I’m not sure what we’d want to say. (Or rather, I am sure that we’d want to say a variety of incompatible things.) We might say: strictly speaking, it turns out that there’s no such thing as polio. We might say: polio turns out to be two different diseases. We might say: polio = being under a witch’s curse (in Australia), but polio = being infected by a certain virtue (elsewhere). The first response would be treating this straightforwardly as a case of multiple realization – what you expected me to do. I don’t know what to say about the second. The third amounts to replacing the worlds of the T-terms paper by world-place indices, and claiming that at each such index in our world polio-theory is uniquely realized, but differently at different indices. You ask me why I don’t regard multiple realization in two different worlds (one realization in one, a different one in the other) as on a par with multiple realization in our own world. I can’t say anything useful about why I don’t since I can’t understand why you think I might want to. (Just as I couldn’t say anything if  you asked me why I don’t type with a brown ribbon except: why on earth should I want to?) Do I say that ‘The president of the United States’ is an improper description because it denotes two different people: here Nixon, in another world Humphrey? Nor do I understand what problem you see about the fixed interpretation of the O-vocabulary. How does that impose any restriction whatever on the kinds of possible worlds there might be? Perhaps the trouble is that you think I mean that the extensions of O-terms are the same in all worlds; but that’s not what I mean. Interpretation is specification of intensions which (in the T-terms paper) can be identified with functions from worlds to extensions. Winnie gets multiple realizations



560.  To Fabrizio Mondadori, 7 January 1971

245

in a single world by varying part of the extension of certain O-terms in that world from one realization to another. I don’t allow that: the extension of an O-term has to  be the value of the intension of that O-term for the world in question, and ­nothing else. Sincerely,

560.  To Fabrizio Mondadori, 7 January 1971 Headington Hill Oxford, England Dear Mr. Mondadori, Sorry I didn’t get to your letter sooner – Christmas vacation travels and Christmas vacation guests caused me to put it off. We at least understand well how we disagree about T-terms. Let me ask you: If ‘electricity’, ‘electron’, and ‘proton’ are L-determinate, how do you account for the truth of ‘Electricity, it turns out, consists of a stream of electrons; but it might have been (for all we used to know) a stream of protons instead (in the opposite direction, of course)’? I know what to say about this: ‘electricity’ is an indeterminate name which denotes different processes in different worlds; we’ve found out that ours is one of the worlds in which it denotes a stream of electrons, not one of the worlds in which it denotes a string of protons. (I don’t imagine that the question I’m asking you is unanswerable; but I’m curious to know how you answer it.) Warning: I use ‘denote’, ‘refer’, and ‘name’ pretty much interchangeably. I’m aware that Chastain uses ‘denote’/‘refer’ to mark some distinction, but since he was reluctant to show me his work, I don’t know what distinction it was. Similarly, I can only guess what you mean by ‘secondary reference, in Chastain’s terminology’. Your three questions: (1) is there reason to suppose that proper names have meaning? Yes. They have denotation. They have meaning1 which is not just a function of the actual denotation, because it can happen that an identity sentence with proper names on both sides, ‘Twain is Clemens’, say, is contingently true – and not just because the causal histories and conventions might have been different. One can speculate, without at all changing the actual denotation of ‘Twain’ and ‘Clemens’, and without interfering with the conventions involving them or the causal histories of their use, about what would have been the case if Twain had not been Clemens – that is, about what is the case in certain worlds in which ‘Twain’ and ‘Clemens’, with their actual meaning1, differ in denotation. Finally, I think that proper names have

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meaning2 – that is, there is a definite way in which their meaning1, and hence i­ndirectly their denotation, depends on causal history. (2) What are we supposed to discover in the mind of the speaker in the case of meaning2? A representation of the way in which denotation of a name (or maybe even a suitable non-name) depends on all the things it does depend on, including causal history. This means – and I think this is what mostly bothers you about my notion of meaning2 – that the truth of the causal theory of reference (if it is true) can be read off from the intensions – meanings2 – assigned to names in the correct abstract semantics. (3) How do I define the denotation in a grammar G of a nonsentential constituent – say, a name – in G? Suppose G is the sort of grammar imagined in ‘General Semantics’. The name n denotes the thing t at the index i in G iff there is an N-intension ϕ(i) = t and belongs to the lexicon of G. (This is the answer you expected me to give.) You speak of showing that there is agreement between the interpretations of nonsentential constituents given by a language L and by a population P. As I see it, this is topsy-turvy. To find the interpretation given by P, first find the language and grammar of P, then find the interpretation given to the constituents by that language. This is so even given the causal theory of reference since, if the c. t. r. is true, ‘interpretation’ in the above should be meaning2-assignment. I understand that you see it differently: you hope to say what it is for a speaker to refer to a thing by a word more directly – so that, for instance, I could know enough about you to know that you refer to the moon by ‘Luna’ without knowing enough to know the truth-conditions of a single one of your sentences. The trouble is, your account seems to make much use of the notions of intending to, and expecting others to, refer to . . . by . . . . I doubt that an account of intending-to-refer, or of expecting-someone-to-refer could be given that wouldn’t pre-suppose a more holistic theory, like mine. But life would certainly be easier if I were wrong about that! Yours,

561.  To F. Jeffry Pelletier, 11 January 1971 Headington Hill Oxford, England Dear Jeff, Probably you’ve found the Plantinga by now; but if not, here.1 Your Fresno State outrage is juicy, but what do you expect from Fresno State? That the ‘research’ library of UCLA can’t afford to take Noûs is, in its quiet way, quite an outrage too.  ‘De Re et De Dicto’ (Plantinga 1969).

1



561.  To F. Jeffry Pelletier, 11 January 1971

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Speaking of outrages: the latest one here is the impending deportation of Rudi Dutschke, student revolutionary turned student, of all things. His picture was on the front page of a recent Times, and it turns out he looks for all the world like Carl Cranor! I don’t see what’s bothering you about de re and de dicto. Quite right: sometimes people think of de re modality as involving a predicate-plus-adpredicate compound, sometimes as involving an (open)-formula-plus-adformula compound. But so what? As you say, yourself, the two seem to involve exactly the same difficulty of understanding. It seems pretty much an accident of notation which way you do it. If you have an adpredicate and wish to use it to modify a (non-atomic) formula, get yourself an abstraction operator which attaches to a formula to make a predicate: a Church lambda, read ‘is an x such that . . .’. (See on this a good paper by Thomason & Stalnaker in Noûs 1968.) If, on the other hand, you have an adformula and wish to modify a predicate, that’s easier still: just make an atomic formula from your predicate and modify that. The point is that you can go back and forth between predicates and formulas quite freely, given the appropriate technical gimmicks; as of course you should be able to, since they both express properties (or relations-inintension). A mass-noun system that makes ‘Blue water is a liquid’ anything but true does seem, on the face of it, unpromising. I don’t think you get anywhere worrying about how such a system leads to a kind of essentialism. It’s got worse troubles: viz., that the aforementioned sentence happens to be obviously meaningful and true. I shall be interested to see what inclines Montague to say otherwise; I’ve asked for a copy, and hope to get it eventually by sea mail (I didn’t ask him to hurry). I can’t say much about your thesis chapter that I didn’t already say about the proposal. In general I like the new section III. I’m not too happy about your discussion of non-sortal count nouns, though. How about ‘triangle’? (Subject to a special stipulation: a triangle doesn’t have to contrast with its surroundings to be a triangle: so this piece of paper has many inconspicuous triangles as parts. Non-sortal, I believe, doesn’t provide a criterion for counting. How many triangles are part of this page? Not divisive; not collective. But not the opposite of divisive and collective either: some parts of triangles are triangles, some sums of triangles are triangles. Grammatically a count noun by the texts you give: ‘a triangle’, ‘every triangle’, ‘few triangles’, ‘7 triangles’ are (a) well forced, (b) capable of appearing in unnegated, nat­ ural, true sentences. So ‘triangle’ is a non-sortal count noun, but (a) it doesn’t have the properties you say it should have, and (b) it doesn’t normally act as a proxy for other sortals, or as a sign of quantification over them. A good example of a proxy that you don’t mention: ‘ones’, as in ‘Joe managed to hide three of them properly, but the police found all the other ones’.

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‘All stuff is fluid in nature’ is just as intelligible as ‘All stuff is fluid, solid, or plasma in nature’, though (unlike the latter) it’s false. I’m still waiting for the new stuff, on denotations and truth-conditions. I guess I think there are two ways to go: Way 1: Mass nouns are names . . . Sub-way 1A: . . . of scattered concrete physical objects Sub-way 1B: . . . of abstract entities. Way 2: Mass nouns are predicates (e.g. ‘wood’ is to be analyzed out in favor of ‘wooden’, and so on). As you say, a mixture of Ways 1 and 2 leaves a lot to be done by meaning postulates or the like. I guess I think that 1A and 2 are both workable; 1B workable but likely to turn out not very different from 2; a mixture workable but clumsy; a 3rd essentially different way unlikely to appear. Thank you for the very good picture! Yours, Enclosed: Plantinga, ‘De Dicto et De Re’ ‘Holes’

562.  To Rolf Sartorius, 21 March 1971 Headington Hill Oxford, England Dear Professor Sartorius, Thank you very much for your new paper on social norms.1 As you’d guess from Convention, I’m inclined to agree with such a view. There’s a difference from my approach that is not a disagreement, but concentration on different aspects of the phenomenon of social norm: I try to minimize force of habit as part of what keeps a convention going. Of course, I don’t deny that we are creatures of habit, and ordinarily conform to our conventions by habit, not by the sort of practical reasoning I talk about. But I think it important that we have reason to conform that is independent of any habit – that would be there even if we were not creatures of habit. (See most

  ‘Individual Conduct and Social Norms: A Utilitarian Account’ (Sartorius 1972).

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of p. 141 where I talk about the relation between actual habit and possible explicit practical reasoning.) I can’t quite say that there would still be conventions even if there were no such thing as habit (and it were common knowledge that there wasn’t). A minute grain of some sort of inclination to follow precedent, or expectation of inclination to, or . . . is needed; but I am more interested in the tricky kind of practical reasoning that would, if necessary, suffice to amplify that minute grain into something big enough to be a strong reason for action. You make much more of the fact of habit: we are, de facto, trained and trainable creatures, the existence of habit gives us act-utilitarian reasons to behave otherwise than we would without them, and the possibility of creating or modifying habits gives us act-utilitarian reasons to behave in certain ways. This is so in two cases (1) when the existence of habits adds to our reason for doing what we would have reason to do even without habits, (2) when the existence of habits gives reason to do what we would otherwise have act-utilitarian reason not to do. What I say in Convention pertains to the other half of the redundant motivation in case (1), not at all to case (2). I think it’s unfortunate that you associate Smart so strongly with the notion that, for the act-utilitarian, rules can be nothing but ‘rules of thumb’. He certainly knows better now; I heard him talk about utilitarianism last fall, and I’m pretty sure he’d agree with most of what you say. But I think there are also traces in his Outline that he knew better then: look at pp. 33 ff.2 He certainly speaks of the utility of cultivating ‘habits’ or ‘tendencies’; recognizes that these may be valuable otherwise than by tending to cause right action without the need for calculation; and (I think) shows appreciation that such habits may create utilities that must be taken account of and that wouldn’t have been present otherwise. Of course, he’s disinclined to call these ‘rules’, but rather ‘habits’ or ‘tendencies’. The associated rule – rule of thumb – is that it’s often optimific to give in to these whatever-you-call-thems; and with that you agree. ‘Rule’ is a slippery word, and part of your quarrel with Smart is that you like to use it where he likes not to. I don’t know how well you explain away the ‘insights which render the move to . . . rule utilitarianism initially plausible’. Insofar as rule-utilitarianism is initially motivated by desert-island or last-man-on-earth examples, the considerations that interest you completely vanish. That’s exactly what makes the rule-utilitarian choose these cases to purify the difference between himself and the act-utilitarian. In my experience, rule-utilitarianism gets its plausibility only from desert-island cases, not  (initially or otherwise) from the facts that can also be explained within actutilitarianism in the manner of your paper.   An Outline of a System of Utilitarian Ethics (Smart 1961).

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I enclose my anti-Hodgson paper.3 It’s along the same lines as your anti-Hodgson section, but with more of an attempt at finding the logical mistake in Hodgson’s argument to an absurd conclusion. … Sincerely, David Lewis PS The present address holds until approximately 15 June; back at Princeton after approximately 20 September, travelling in between.

563.  To Pavel Tichý, 30 March 1971 Headington Hill Oxford, England Dear Dr. Tichý, I’m glad we now agree on the matter of denotationless T-terms and truth of the postulate. I was very interested in your remarks about postulates that imply their own unique-realization sentences. It had occurred to me that this might happen; in another paper,1 I imagine a detective setting forth his solution to the crime (in the last chapter) and heightening the suspense by telling the story with ‘X’, ‘Y’, ‘Z’ in place of the criminals’ names – these are the T-terms introduced by his theory of the crime, and ‘theoretical identification’ occurs when we find out who are the three scoundrels who realize the story. I wrote in a footnote: ‘The story itself might imply [that the story is not true of any other triple than Plum, Peacock, and Mustard (the three criminals)]. If, for instance, the story said “X saw Y give Z the candlestick while the three of them were alone in the billiard room at 9:17”, then the story could not possibly be true of more than one triple’. But I had no idea how nice things would be if the postulate did imply its own unique-realization sentence. As you say, my the­ or­ist is committing himself to unique realization if he tacitly claims to have im­pli­ cit­ly defined his T-terms; so why should he mind committing himself to unique realization explicitly by the logical form of his postulate? I don’t believe that the­or­ists

  ‘Utilitarianism and Truthfulness’ (Lewis 1972b).

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  ‘Psychophysical and Theoretical Identifications’ (Lewis 1972a).

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564.  To Jonathan Bennett, 31 December 1971

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really do, in general, put their postulates in such a form that the postulate by itself (without the definitions sentences) logically implies its unique-realization sentence; but I do think they ought to be willing to, so that it would be a legitimate idealization to suppose that they do. My wife and I definitely will come to Dunedin for a little while, very early in September. On our present schedule, we reach Christchurch at 1600 on Wednesday, 1 September; most likely, we take a train to Dunedin first thing, and then work north from Dunedin. Thank you for your invitation; we’ll look forward to ­meeting you. Yours, David Lewis

564.  To Jonathan Bennett, 31 December 1971 [Princeton, NJ] Dear Jonathan, I don’t remember why I was so dubious about belief-acquisition in conformity to a (generalized) convention. (Perhaps I had in mind the case where one voluntarily sets out to acquire a belief, thought you had to have that in mind, and knew that this wasn’t the usual thing.) Anyhow, it now seems to me OK, and an improvement on what I had. As you know, I’d prefer to keep Gricean meaningnn out of the analysis, and obtain it as a corollary; so I’d state your idea as follows. A regularity R in the doings of members of a population P when they are involved as agents or otherwise in a recurrent situation S is a (generalized) convention iff  it is true that, and common knowledge in P that, in any instance of S among ­members of P, ( 1) everyone conforms to R; (2) everyone expects everyone else to conform to R; (3) everyone has approximately the same preferences regarding all possible com­bin­ ations of doings; (4a) everyone has reason to conform to R, on condition that everyone else conform to R; (4b) everyone prefers that everyone else conform to R, on condition that at least all but one conform to R;

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(5a) everyone would have reason to conform to Rʹ, on condition that everyone else conform to Rʹ; (5b) everyone would prefer that everyone else conform to Rʹ, on condition that at least all but one conform to Rʹ, where Rʹ is some possible regularity in the doings of members of P in S such that no one in any instance of S among members of P could conform to both Rʹ and to R. In the cases of communication, R will be a regularity of truthfulness and trust in a possible language ℒ; its alternatives will be regularities of truthfulness and trust in other possible languages. That is, a speaker conforms to R by uttering only such sentences of ℒ as he believes to be true in ℒ; a hearer conforms to R by believing that the truth conditions in ℒ of sentences he hears uttered (addressed to him?) are satisfied. Conditions (4) and (5) are split up because one may have reasons to conform that don’t involve one’s preference for conformity.* If you and I participate in a convention of truthfulness and trust in English and you say to me ‘The sky is blue’ I have reason to believe that the sky is blue (and thereby to conform) on condition that you may have been truthful (and thereby conformed); but this reason is simply evidence for a conclusion, and has nothing to do with preferences. I would still have this reason even if – for some eccentric reason – I would prefer to be an untrusting sceptic who never believed anything on anyone else’s say-so! I wonder whether this change from conventions of truthfulness to (generalized) conventions of truthfulness and trust helps us deal with a difficulty raised by Schiffer against me as follows. Let ℒ be the language we actually use; let ℒ* be a possible language consisting of ℒ plus added garbage; say, ℒ plus the sentence ‘Bobcobdobfobgobhobjobkoblobmobnobpobquobrobsobtobvobwobxobyobzob’ with the truth condition that the sky is blue. Call this sentence * for short. Now: (1) we are truthful in ℒ*, by being truthful in ℒ and never uttering * at all – a fortiori never uttering it falsely – (2) we expect one another to be truthful in ℒ* (in the way specified), (3) we want to be truthful in ℒ* (in this way) if the rest are, (4) truthfulness in ℒ* has alternatives, viz. the same alternatives that there are to truthfulness in ℒ, and (5) all this is common knowledge. So we have a convention of truthfulness in ℒ* just as much as we do in ℒ; and ℒ* is our language just as much as ℒ is – which is absurd! Yes, going to generalized conventions of truthfulness and trust does seem to help. To be truthful with respect to *, it suffices never to utter it, and thereby never to utter it falsely. To be trusting with respect to * it does not suffice never to hear it

*   Thus the (a) clauses; but the (b) clauses are as before, since I can have preferences, but not reasons, regarding others’ doings.



565.  To Jonathan Bennett, 10 January 1972

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uttered; rather, one must have the disposition to respond to it if it ever were uttered by acquiring the belief that the sky is blue. (?) If so, then we’re not trusting with respect to *: we don’t have a (generalized) convention of truthfulness and trust in ℒ*; and, correctly, we do not use the language ℒ*. By the way, what is the manuscript from which these excerpts have come? Article? Book? At some stage, which I leave to your judgement, I’d like to see the rest of it.1 Yours, David Lewis

565.  To Jonathan Bennett, 10 January 1972 [Princeton, NJ] Dear Jonathan, Clauses (3), (4), (5) were all descended from this condition: everyone prefers to conform to R on condition that the others do, since S is a coordination problem and uniform conformity to R is a coordination equilibrium in S. That was scrapped, in II.3, because sometimes we don’t have a sequence of discrete coordination problems, but rather lots of them blurred together. But I wanted to keep the definitive characteristics of coordination problems as far as possible. Condition (3) gives us the predominant coincidence of interest; Condition (4) gives us that uniform conformity to R is a coordination equilibrium; Condition (5) gives us that it is not the only one. Now note that Condition (4) – and analogously (5) for Rʹ – does double duty. In stipulating that everyone prefers that he himself conform to R, on condition that everyone else does, (4) specifies that uniform conformity to R is some sort of equilibrium. In stipulating further that everyone x prefers that anyone else y conform, on condition that everyone but y does, (4) specifies that uniform conformity to R is a coordination ­equilibrium. See pp. 45–6 and 116–8 on why that’s wanted. In the case of generalized convention, clause (4a) specifies that uniform conformity to R is, in a generalized sense, an equilibrium of some sort: as does (5a) for uniform conformity to Rʹ. But what’s to ensure that these are coordination equilibria, rather than conflict equilibria or something else? (4b) and (5b) do this in the same way that (4) and (5) – applied to x’s preference about y, rather than x’s preferences about himself – did originally. But maybe they’re not necessary; either because clause

  ‘The Meaning-Nominalist Strategy’ (Bennett 1973).

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(3) is enough, or because it’s not all that important to rule out non-coordination cases. Your (4) and (5) seem to me to do only the work of (4a) and (5a); they don’t re-unite the halves. They would hold also in a case of conflict equilibrium. I’m much looking forward to seeing the papers. If copies are in short supply, may I make xeroxes and return the originals? Yours,

566.  To Harry A. Lewis, 12 February 1972 Princeton University Princeton, NJ Dear Lewis, Thank you for your paper ‘Combinators and Deep Structure’,1 which I’ve just received. I’m glad to learn of others who are interested in work along these lines. Incidentally, do you know Richard Montague’s writings on natural language? They’re extremely interesting, but they’re written in the densest of set theory and some of them are in peculiar places, such as the proceedings of a conference held by the Olivetti typewriter company (Linguaggi nella societa e nella technica, Edizioni di Communita, Milan 1970). But there’s one in an ordinary journal: the Prior memorial issue of Theoria. The semantics (in some versions) can be all functions-and-arguments; the syntax can have arbitrarily complicated operations for combining expressions. Barbara Partee is writing a long paper to compare Montague’s grammar with trans­ form­ation­al grammar; Montague himself detested the latter, and thus had no interest in revealing parallels. Principally, I’m writing to comment on your comments on ‘General Semantics’. (1) It is extremely odd to claim that our ordinary talk is about such functions as the ones I take to be intensions. Very odd! But why should I so claim? I have no theory of aboutness – any sentence can be used to talk about almost anything, if the context is right (and without departing from the standard meaning of the sentence) – but I should think that the last thing for a sentence to be about would be its own intension, or the intensions of its constituents. The extensions of some (not all) of its constituents, perhaps. (2) I want to allow for a possible language with a modifier that attaches to some verbs to mean ‘in London’ and to other verbs to mean ‘in Paris’. More precisely, I want to allow this situation: ‘sleeps’ has the same intension in Schmenglish as   ‘Combinators and Deep Structure: Syntactic and Semantic Functions’ (H. Lewis 1973).

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in English; so does ‘plays hockey’; ‘sleeps in Londris’ has the same intension in Schmenglish as ‘sleeps in London’ has in English; ‘plays hockey in Londris’ has the same intension in Schmenglish as ‘plays hockey in Paris’ has in English. There are such possible languages – indeed, I’ve just made a start on teaching you one of them. So it would be wrong for general semantics to rule them out. Now I agree that an adequate account of English should explain why ‘in London’ doesn’t have the peculiar sort of intension that ‘in Londris’ has in Schmenglish; but the place for this ex­plan­ ation seems to me to be a specification of the intension in English of the preposition ‘in’. (One might also seek an explanation in terms of convenience of learning and suitability to our communicative purposes for the fact that we use languages like English in preference to ones like Schmenglish.) The goals of my paper are clearly set out at the beginning; it’s no objection that I don’t accomplish different goals, so long as I don’t set up a framework in which those different goals can’t possibly be accomplished – and I think I don’t do that. (3) I agree with you that it would be desirable to have ‘is tall and bald’ as a verb phrase. Geach’s recursive rule (which I hadn’t thought of) is one way to get such compounds: but there are other ways. I would get conjunction of verb phrases from conjunction of sentences by means of variable binding, like this.

I think such a structure might not appeal to you, because I gather that one of the things you like about the use of plenty of functors is that they enable you to do without variables. Here our motivations differ; I like functors for other reasons, but think the devices for doing without variables are intolerably clumsy. Of course, the structure I just drew doesn’t give a general means for getting the effect of Geach’s recursive rule; for every case that is wanted, it will be necessary to have suitable categories of variables and abstraction operators. For instance, Geach’s first example in

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the paper would be done with the aid of variables for verb-phrase intensions and a corresponding abstraction operator (this would require a change in the indices). Indeed, I think it is such structures that make explicit the semantic rule corresponding to Geach’s recursive rule; but whether there’s enough use for such things in syntax to make it worthwhile to introduce the recursive rule instead of clumsy structures with variable-binding remains an open question.

Sincerely, David Lewis

567.  To Kit Fine, 19 February 1972 [Princeton, NJ] Dear Kit, Thank you for the paper on the K4IN systems.1 It’s good to have this in addition to my rather sketchy notes on the lectures. Feel free to discuss the material on counterfactuals and comparative possibility in your course. What sort of semantics are to show E complete for? Routley-Meyer? It seems to me that these are terribly artificial – if there is a completeness proof for E for RoutleyMeyer style semantics, is that to the discredit of E? (The usual completeness results for, say, T or S4 or S4.3 or S5 show that these are good systems; but it seems to me that the completeness results for S2 and S3 show that these were misguided!) I’ve been enjoying myself here, but getting little work done. Two things I have been thinking of:   ‘Logics Containing K4, Part I’ (Fine 1974).

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567.  To Kit Fine, 19 February 1972

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(1) An omniquantifier is a quantifier that binds all the variables free in its scope, thus acting like an arbitrarily long string of ordinary quantifiers. I claim that things that look like tense operators or quantifiers over ‘cases’ in English are sometimes omniquantifiers, as in: (A) Always, x< y or x= y or x> y . (B) Sometimes there is only one r such that xr 2 +yr +z=0 . (In (B), r is of course already bound, so the o’quantifier binds only x, y, z.) Many complications. Frequently quantifiers: (C) Usually, there are two r’s such that xr 2 +yr +z=0 . Restricted o’quantifiers, marked in English by ‘if . . . then’ even if the quantifier is ex­ ist­en­tial: (D) Sometimes if x beats y, then y bites x. (Maybe ‘if . . . then’ is fundamentally a sign of restriction of an operator, not a sentential connective at all. Why is it that beginners find it so natural to make the mistake of restricting $ with ⊃? They don’t restrict " with &!) Restricted variables, marked by indefinite noun phrases: (E) Sometimes a man x borrows a book y from a friend z and never returns y to z. Occurrence of one variable in the restriction of another: (F) Once a boy x who really loved y kissed a girl y who was only fooling x. Erasure of the variables in favor of indefinite noun phrases and pronouns: (G) Once a boy who really loved her kissed a girl who was only fooling him. Binding of an invisible time-variable along with others: sentences (D)–(G). So o’quantifiers are quantifiers over times; but they’re more besides. (2) Suppose you want "A to be true iff A is true not only at every world, but at every world under every reinterpretation of the non-logical vocabulary. In sentential logic, let V be the set of all valuations of sentence letters; let ⊨vp  iff v(p) = 1 (p  a  sentence  letter); ⊭v⊥; ⊨vA ⊃ B  iff ⊭vA or ⊨v B; and ⊨v"A iff  ∀w ∈ V ⊨wA.

Consider the set of sentences true at all valuations under these truth conditions. In a way it’s the modal logic that’s faithful to the intentions of the creators of the subject: "A means that (is true at any v iff) A is a logical truth! In another way, it isn’t a modal logic at all: it isn’t closed under substitution. Cf. Scott, Journal of Phil. 1971, pp. 806–7.2 This modal logic (if such it be) is maximal in the sense that it has no consistent extension closed under necessitation; it is axiomatizable by adding to S5 – or less, but I’m not sure how much less – all axioms of the form ◇D where D is a conjunction of 0   ‘On Engendering an Illusion of Understanding’ (Scott 1971).

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or more sentence letters and 0 or more negations of other sentence letters; and closing under necessitation and modus ponens; it eliminates modality, in the sense that for every modal sentence A there is a non-modal sentence B such that A º B is a the­ orem. So it’s a ridiculous system; but it seems to me the inevitable culmination of one line of thought about what modal logic is supposed to be. Yours, David

568.  To Edward L. Keenan, 14 April 1972 Princeton University Princeton, NJ Dear Mr. Keenan, At a conference at the University of Western Ontario last week, I told Barbara Partee about some ideas of mine, and she was reminded of something in a forthcoming paper of yours. If I tell you what I’ve been doing, will you please send me the paper Barbara was reminded of?1 What are such adverbs as: always, sometimes, never, usually, seldom (and various near-synonyms such as: invariably, mostly, . . .)? Obviously, they’re quantifiers. But over what? Not moments of time; not events. Usually, a quadratic equation has two different solutions; but quadratic equations are not arrayed in time, and are not associated with events. It’s safe to call these adverbs quantifiers over cases. In fact, we can paraphrase them: in all, some, no, most, many, few cases. What’s a case? Try the ‘tuple of its participants, including perhaps various individuals and perhaps also a time, event, or place. These participants, or some of them, may be regarded as values of variables, and the variables may be overt or invisible. So the adverbs quantify over combinations of values of variables. Example: Always, either x is taller than y, or y is taller than x, or x and y are equally tall, or one or both of x and y are not the sort of entities that have heights. ‘Always’ is a ’tuple quantifier: for every pair … or better: for every triple (where t is a time) either x is taller than y at t or . . . The ’tuple-quantifying adverbs can be restricted by if-clauses. Example: Always, if x is the son of y and z, x resembles both y and z. That is: for all triples such that x is the son of y and z, x resembles y and z. (Put in the time-value for yourself.) This is abbreviated also as: Whenever x is the son of y and z, x resembles both y and z. In the case of   ‘On Semantically Based Grammar’ (Keenan 1972).

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568.  To Edward L. Keenan, 14 April 1972

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‘always’, we might as well just be tacking an unrestricted ‘always’ onto a material conditional; but not so in the other cases. Usually, if x is the son of y and z, x resembles both y and z; this means that most triples that satisfy the if-clause satisfy the main clause. It does not mean that most triples satisfy the material conditional; of course that’s true, just because there are very few triples that satisfy the if-clause. You can even say: Sometimes, if x is the son of y and z, x resembles both y and z, and mean this as  a  restricted existential ’tuple-quantification. Two morals might be drawn. (1) Sometimes, ‘if’ is not a sentential connective at all, but a mark of restriction (I prefer this); thus ‘always if . . . then . . .’ and the rest are 2-place operators. Or (2) ‘if’ is a sentential connective of a queer sort, the Rhinelander-Belnap conditional; see Nuel Belnap, ‘Conditional Assertion and Restricted Quantification’, Noûs 4 (1970): 1–12. The R-B conditional ‘if A, B’ expresses no proposition when A is false, expresses the same proposition as B when A is true. If you go this way, you think of the quantifying adverbs as being automatically restricted to ‘tuples such that the formula being quantified is made to express a proposition. (Whichever way you go, note as evidence that freshmen demand to write restricted existential quantifications as $x (. . . ⊃. . .). Why? They don’t want to restrict universal quantification with conjunction! It seems they must have in mind some restriction-marking ‘if’ from ordinary language. (Belnap points this out.)) There’s another kind of restriction, more important. Variables can be restricted to take only values of suitable sorts. This can be permanent: there’s a standing custom in set theory that l is a variable over limit ordinals. Or it can be established temporarily; you can have a footnote at the beginning of the paper that says that in this paper i, j, k, l, m, n shall be variables over integers; w, x, y, z, over persons; F, Y over sentences; and so on. Or a restriction can be established very temporarily by a parenthetical stipulation within a sentence: Usually if x hits y (x and y being men), y is entitled to sue x. Or the restriction can be taken out of parentheses and attached to occurrences – mostly first occurrences – of the restricted variables: Sometimes if man m beats dog d, d turns around and bites m. Or the restrictions can be expressed by in­def­ in­ite noun phrases in apposition with the restricted variables: Sometimes if a man m beats a dog d, d turns around and bites m. Or the variables can be erased (where the in­def­ in­ite noun phrase is present) and turned into pronouns (elsewhere): Sometimes if a man beats a dog, it turns around and bites him. Thus we have a theory of indefinite noun phrases. They have a dual function: (1) to restrict the values of a variable, and thus the sorts of cases under consideration, and (2) to stand in for occurrences of the variables they restrict. A perspicuous symbolic representation of our sentence would be: æ m: man ö ç ÷ Sometimes ç d: dog ÷ ( if: m beats d at t ) d bites m shortly after t. ç t: time ÷ è ø

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Truth conditions: the sentence is true iff some ’tuple of values of the variables in the main clause that satisfies the restrictions also satisfies the main clause. The restrictions comprise both the condition given by the if-clause, if there is one, and the conditions given by the common noun phrases associated with the variables. Likewise in general: true iff all, some, no, most, many, or few of the ‘tuples of values of variables that satisfy the restrictions also satisfy the main clause. Remarks. (1) The ’tuple-quantifying adverb may be deleted. (2) This is not, alas, a fully general account of the indefinite article. Consider: A Sikh usually wears a turban. The account above works for ‘a Sikh’ – it restricts a variable bound by ‘usually’ and in addition stands in for that variable – but not for ‘a turban’. The latter is an independent existential quantifier. (3) Sometimes noun phrases with ‘some’ or ‘any’ could be treated as I have treated noun phrases with the indefinite article: Usually, if any idiot makes any such proposal, his friends ignore it. Often, if someone says something, only those near to him hear it correctly. (4) If the quantifying adverb is not deleted, it may stand in various places in the sentence it governs. Finally, it isn’t necessary that the common noun phrases that restrict the variables should be simple. They might be compounded from common nouns together with modifying adjectives, prepositional phrases, or relative clauses. (Contra Geach, I take relative clauses as adjectives that attach to common noun phrases to make common noun phrases.) So we have: Sometimes if an angry man beats a dog that has fleas when the sun is shining, it bites him. æ m: angry man ö ç ÷ Sometimes ç d: dog that has fleas ÷ ( if: m beats d at t ) d bites m shortly after t. ç t: time when the sun is shining ÷ è ø And there is nothing to prevent the complex restricting common noun phrases from themselves containing occurrences of the variables. Then one variable gets restricted only relative to a particular value of another variable. (Or it might be several other variables.) We could put this in a less cumbersome way by saying that rather than restricting the variables one at a time, such restricting common noun phrases (like if-clauses) restrict the admissible ’tuples of values of variables. So we can have: Sometimes if a man beats a dog that he owns, it bites him. æ m: man ö ç ÷ Sometimes ç d: dog that m owns at t ÷ ( if: m beats d at t ) d bites m shortly after t. ç t: time ÷ è ø And there is nothing to prevent variables from being involved in one another’s restrictions: A man who borrows a book that he wrote about her from a girl who stole it from him in the first place always returns it to her.



569.  To Edward L. Keenan, 14 May 1972

261

æ m: man who borrows b from g at t ö ç ÷ b: book that m wrote about g before t ÷ m returns b to g after t. Always ç ç g: girl who stole b from m in the first place before t ÷ çç ÷÷ è t: time ø Or: A boy who was only fooling a girl who really loved him kissed her (alternatively, if the restrictions are put in for variables in a different order: A boy who was only fooling her kissed a girl who really loved him). æ b: boy who was only fooling g at t ö ç ÷ Sometimes ç g: girl who really loved b at t ÷ b kissed g at t. ç t: time ÷ è ø (‘Sometimes’ is deleted.) So here is an account of at least some Bach-Peters sentences; and it is not contrived ad hoc, but comes naturally out of an independently motivated treatment of the ’tuple-quantifying adverbs. Sincerely, David Lewis Historical postscript: in ‘On Denoting’, Principia, and Introduction to Mathematical Philosophy, Russell explains the now-commonplace quantifiers by means of the adverbs ‘always’ and ‘sometimes’. He suggests that we read ( x ).Fx and ( $x ).F respectively as ‘Fx is always true’ and ‘Fx is sometimes true’ or, for short, ‘Fx always’ and ‘Fx sometimes’. Likewise when there are many variables: ( $x, y,z, …) . F(x, y, z, …) comes out as ‘F( x , y, z , ¼) is sometimes true’.

569.  To Edward L. Keenan, 14 May 1972 Princeton University Princeton, NJ Dear Ed, Thank you for the two papers.1 I’m sure that what Barbara must have been reminded of was your discussion of ‘double descriptions’ in SBG.2 This nicely complements my stuff, since I rather stay clear of the definite article. 1   ‘Two Kinds of Presupposition in Natural Language’ (Keenan 1971); ‘On Semantically Based Grammar’ (Keenan 1972). 2   (Keenan 1972).

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I should have written sooner to tell you what you’ll have discovered already when you receive this: that there are various uncertainties and pressures that will have prevented me from coming to look for you at your Daedalus meeting. Sorry! I have one change in mind for the adverbs of quantification: now it seems to me pointless to distinguish two kinds of restriction. Let’s do them all as if-clauses in underlying form, so that I’ll write instead of what appears at the top of p. 3 of the ­letter rather this: æ if: m is an angry man ö ç ÷ if: d is a dog that has fleas ÷ d bites m shortly after t. Sometimes ç ç if: t is a time when the sun is shining ÷ çç ÷÷ è if: m beats d at t ø But while treating all restrictions alike in underlying logical form, I can still say that we have possible surface expressions for the first two if-clauses that are not available for the fourth: viz. surface structures in which the indefinite noun phrase from the if-clause replaces the restricted variable, or stands in apposition to it. This move re-opens the option of saying that indefinite noun phrases are restricted existential quantifiers – but in the if-clause of underlying form, not in the place where the noun phrase ends up! Thus I can do ‘A man who owns a donkey usually beats it’ as æ if: ($man who owns d, x) x = m ö Usually ç ÷ m beats d. è if: ($donkey, y) y = d ø (I leave the time implicit.) Then the surface ‘a donkey’ comes from ‘ $donkey’ in the second if-clause, and the surface ‘a man who owns a donkey’ comes from that together with ‘∃man who owns’ in the first if-clause. So indefinite noun phrases have come from restricted existential quantifiers – for which I trust my notion is selfexplanatory – in a roundabout way; but the restricted existential quantifier you might look for first, namely ‘( $man who owns a donkey, x)’, is nowhere to be found. Nor could it be there – the trouble with it is that it doesn’t bind a variable outside for the donkey! Gil Harman points out that the sentence could have been ‘Usually if there is a man who owns a donkey, he beats it’ or ‘Usually if there is a donkey that a man owns, he beats it’; in these variants the unmistakable manifestations of an ex­ist­ en­tial quantifier on the surface make it even more urgent to work one into the underlying form somehow. Yet that can be done in no straightforward way, since you can’t



570.  To G.H. Merrill, 17 September 1972

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expect to have ‘There is a man who owns a donkey’ or ‘There is a donkey that a man owns’ as underlying constituents of the sentence.3 Yours, David Lewis

570.  To G.H. Merrill, 17 September 1972 Princeton University Princeton, NJ Dear Mr. Merrill, Thank you for letting me see your paper on de re modal logic.1 It was not forwarded to me while I was away this summer, but now I’ve read it. Kripke will be here next Tuesday, and I’ll give it to him then. (He is based at Rockefeller, but teaches occasionally at Princeton and at many other places.) I liked the paper, but I do have some minor criticisms. [. . .] (4) Your claim at the beginning that ‘this semantics serves as a formalization of the metaphysical views regarding necessity and reference which are embraced by Kripke’ misled me, and may be expected to mislead others. You do agree with the sort of thing said in the Kripke passages quoted on your pages 30–33.2 Fine; but here Kripke is not expounding doctrines that are distinctively his; you and he are in­de­ pend­ent­ly agreeing with something that is common to many other people, and that your reader should not associate especially with the name of Kripke. What is dis­tinct­ ive­ly Kripke’s – and what your first paragraph misled me into thinking that you also were advancing – is the idea that many seeming cases of de re modality are really cases of de dicto modality involving rigid designators; or, if you prefer, cases in which the distinction between de re and de dicto collapses. Example: 100°C might not have been the boiling point of water. My view: 100°C is a non-rigid designator, denoting at every world w the boiling point of water at w (100°C is defined as the boiling point of water!)

3

  See also ‘Adverbs of Quantification’ (Lewis 1975a).

  Possibly some early version of ‘A Free Logic with Intensions as Possible Values of Terms’ (Merrill 1975). 2   Quotations from ‘Naming and Necessity’ (Kripke 1972). 1

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and the sentence, construed so as to be true, is de re. Kripke’s view: 100°C has been introduced in such a way as to be a rigid designator for whatever temperature is the boiling point of water at our actual world, and the sentence is true de dicto. Now: do you want to be taking Kripke’s side of this argument? I doubt it; but that is the impression your first paragraph gave me, since I don’t think of Kripke as any more of a takerseriously of de re modality than many other people, and do think of him as characteristically taking things to be de dicto that I would take to be de re. (5) I think your arguments against Kripke’s thesis that names are rigid are very unpersuasive. (A) The semantics doesn’t allow you to prove that any term is rigid. Of course not! You built it expressly to provide for non-rigid terms. Nobody doubts that you can have a language with non-rigid terms; the question is whether ordinary proper names (and the like) are non-rigid. (B) If terms are rigid designators, the de re/de dicto distinction collapses and we lose the power of a de re modal logic. But nobody wants to say that terms in general are rigid! Kripke would say as gladly as you or I that there are plenty of non-rigid designators. My hat, the lady I saw you with last night, the boiling point of water are uncontroversially non-rigid, and call for a modal logic that makes sense of their de re occurrences. The question is not of terms in general, but of ordinary proper names – roughly, the ones you capitalize. (C) The languages of the populations of other worlds are totally irrelevant. The question about rigidity is: does the denotation of such-and-so name, under the meaning we have given it, change from one world to another? When Kripke talks about the denotation of a name at another world, he means its denotation there in our language, not in the language of the natives of that world. How else would you make sense of Possibly, Miss Universe might have been called ‘Miss Cosmos’ instead? I don’t mean (though this is also true) that there is a world w such that the woman denoted at our world, in our language, by Miss Universe is in w called ‘Miss Cosmos’ (instead of ‘Miss Universe’). And I don’t mean that there is a world w such that the woman denoted at w, in the native language of w, by Miss Universe is in w called ‘Miss Cosmos’ (instead of ‘Miss Universe’). What I do mean is that there is a world w such that the woman denoted at w, in our language, by Miss Universe is in w called ‘Miss Cosmos’ (instead of ‘Miss Universe’). So there’s no question of linguistic enslavement of the inhabitants of other worlds; it’s a question of the reference we give to our designators in talking modally or counterfactually about those other worlds, as opposed to the reference we give to our designators in talking about our own world. Sorry to go on at such length about objections; in many ways I liked the paper quite well. Yours, David Lewis



571.  To G.H. Merrill, 4 October 1972

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571.  To G.H. Merrill, 4 October 1972 Princeton University Princeton, NJ Dear Mr. Merrill, I see that we agree much more than I thought last time I wrote! [. . .] (4) I’m glad that you weren’t talking about the native languages of other worlds. Then I misunderstood what you said about linguistic enslavement. Not having the paper, it’s too late to reread the passage and figure out what else you meant. The claim ‘Any language capable of expressing certain modal statements must be interpreted within a semantics where names are rigid designators’ is not Kripke’s. Of that I’m very sure indeed! Kripke’s claim is not that we need rigid designators to gain expressive power – to the contrary! – or that we couldn’t have anything but rigid designators. His claim is that we do in fact use ordinary proper names – such names as Plato, Rochester, Saul Kripke, Argentina, Stalin, heat – as rigid designators. It is a claim about natural language; or, if you prefer, about the sorts of formal interpretations that would best imitate natural language. He doesn’t need to claim that, without exception, proper names of ordinary language are rigid; though he certainly claims that for the most part they are. I’ve asked him what he thinks about various titles, patronymics, and what-not, and he had no very firm opinion. (So he might or might not agree with me that ‘Miss Universe’, though it superficially resembles other proper names, is non-rigid; or ‘Master’, when used without the article to denote the present master of an Oxford college; or ‘Rex’ used to denote the present king.) And nobody claims that all proper names are rigid while all compound terms are non-rigid. I think Kripke thinks that, although Saul Kripke’s hat is non-rigid, Saul Kripke’s father or Saul Kripke’s left ear is just as rigid as the proper name Saul Kripke itself. Yours, David Lewis

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572.  To G.H. Merrill, 16 October 1972 Princeton University Princeton, NJ Dear Gary, [. . .] I would never expect Kripke to mean by (1), τ might not be η, either your alternative (i) or your alternative (iv).1 It’s either (ii) or (iii) – more often (iii) for Kripke than for you or me. Where you or I might see a non-rigid use of τ and the de re in­ter­pret­ ation (ii), Kripke would tend to see a rigid use of τ and the de dicto interpretation (iii). Example: Heat might not be mean molecular kinetic energy. I think Kripke thinks that this is most naturally understood de dicto, as (iii), and is false since heat and mean molecular kinetic energy rigidly designate the same thing. I, on the other hand, think that heat (and perhaps also mean molecular energy) is non-rigid, and that the sentence is ambiguous between the de re interpretation (ii) on which it is false and the de dicto interpretation (iii) on which it is true. Kripke is unwilling to provide any straightforward sense in which that sentence is true – not that he claims that no such sense is available in our actual language. Second example: he certainly thinks that Hesperus is rigid, thinks that Hesperus might not be Hesperus is de dicto, (iii), and thinks that it is unambiguously false. (Of course, if Hesperus is rigid, the sentence is false on (ii) and (iii) alike; but he thinks he can tell that he ordinarily intends it as the falsehood (iii) rather than the falsehood (ii).) Be is, I think, meant in Kripke always as identity (except when he’s talking about wrong-thinking views like mine); so (iv) is pretty much beside the point. (Sorry – I should say that I’m thinking of cases where η is a term, not of course cases where it’s a predicate.) Why do you or I think Hesperus might not be Hesperus is, in one legitimate sense, true? Kripke thinks that’s because we confuse it with Hesperus might not have been called ‘Hesperus’. That is, he thinks we confuse the denotation of Hesperus in our language at another world with the denotation of Hesperus in another language at another world where that language is used. That is, he thinks we made the same mistake that I wrongly thought you made in the ‘linguistic enslavement’ passage of the paper. Yours, David 1   ‘(i) In some possible world, the denotation of τ at @ differs from the denotation of η at @. (ii) In some possible world w, the denotation of τ at @ differs from the denotation of η at w. (iii) In some possible world w, the denotation of τ at w differs from the denotation of η at w. (iv) In some possible world w, the thing denoted by τ at @ does not have the properties of the thing denoted by η at @’ (Letter from G.H. Merrill to David Lewis, 12 October 1972, p. 2).



573.  To Terence Parsons, 14 March 1973

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573.  To Terence Parsons, 14 March 1973 Princeton University Princeton, NJ Dear Terry, ‘Meinongian Semantics’ was lots of fun.1 I can’t say anything about it and the historical Meinong, but anyway a Meinong who held those views would have been a clever and worthwhile philosopher! I want to suggest a problem and its solution. It’s adapted from an objection I’d make against a free logic treatment of truth in fiction; but I think you – in your cap­ acity as Meinong – can get around it. Too bad for me: I wanted to use the objection to show that you need a modal operator ‘it is the case in such-and-such fiction that . . .’ to make sense of truth in fiction. I still think that’s a good way to do it, but maybe not an inevitable way. Background reading: ‘The Tale of Scrulch’, as follows. Once upon a time, far away, Scrulch terrorized the peace-loving folk of the valley. Scrulch was a fire-breathing dragon with alternate green and purple scales. Scrulch lived in a cave on the side of the highest mountain, and there he kept his treasure. Most of all did he treasure his ten gold rings. But one day a knight climbed the mountain, slew Scrulch, and restored the ten gold rings to the heirs of their rightful owners. And they all lived happily ever after. The End. Quiz: Scrulch had ten gold rings. True__X__; False ___. So there really were those ten gold rings that Scrulch kept? Then what has become of them today? – No, it’s only a story. They didn’t really exist! Ø( $10 x)(Ee x & x is-a-gold-ringn & Scrulch n kept n x). Then we might think that what’s true is: ( $10 x)(x is-a-gold-ringn & Scrulch n kept n x). But I don’t think that can be it. OK if there were just one of Scrulch’s gold rings; it’s a perfectly good object. (It doesn’t exist; it is existent; it’s possible; it’s incomplete.) But how do the ten rings differ, if they’re ten different objects? It’s not as if the story said that one had a sapphire, one a ruby, . . . . And if they’re not different (if they have exactly the same nuclear properties) then what makes there be ten of them? So we can’t quantify over the rings as objects that exist or as objects that don’t exist.   ‘A Prolegomenon to Meinongian Semantics’ (Parsons 1974).

1

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Of course, you could have a single predicate, and use an atomic sentence for what’s true: Scrulch nkept-ten-gold-rings. But I don’t expect you want to be stuck with infinitely many primitive predicates, any more than anyone else does. So I think you’d better have an abstraction operator that makes n-predicates from formulas, where the predicate so created expresses the property you’d want it to. Then what’s true is: Scrulch n ly ($10 x)(Ee x & x is-a-gold-ringn & y n kept n x). Of course, you have a restriction on nl-conversion: not allowed when the object denoted by the subject term isn’t the correlate of an individual that exists. And this restriction is justified by the non-standard semantics for subject-predicate sentences. The true sentence we’ve arrived at means that the property expressed by the formula after the ‘nly’ is a nuclear property of the object Scrulch; it doesn’t mean that Scrulch satisfies that formula. Yours, David n df n n PS  P = lx ¬P x.

574.  To Tyler Burge, 21 October 1973 Princeton University Princeton, NJ Dear Prof. Burge, I’d like to understand better what your misguided anti-conventionalist theorists – who nevertheless do participate in conventions of language – are like.1 Are they aware that the populations of different places do speak different languages, and that people are always able (after effort) and sometimes willing to change languages? If they live in our world without knowing that much, or if their theories are incompatible with it, they’re mad! As madmen they can be exceptional members of a population in which a convention prevails – no problem there. What if there were a whole

  Cf. ‘On Knowledge and Convention’ (Burge 1975).

1



574.  To Tyler Burge, 21 October 1973

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population of these madmen? I think it wouldn’t be a clear counterexample to anything I say, simply because it wouldn’t be at all clear what we intuitively say about whether they use language in the way that ordinary populations do. If they’re not mad, then I think their anti-conventionalism must be something that doesn’t conflict with the view that language is conventional in my sense. Then they’re welcome to hold their anti-conventionalist theories and still have the proper system of beliefs to make them part of a population with conventions of language. Here it’s important, I think, that their theories consist of generalities, whereas the beliefs they have as participants in a convention are a multitude of particular beliefs. (Convention 64–68; ‘Languages & Language’ 37–38 (1972 revision).) They maybe are anti-conventionalist in that they think that language didn’t originate by agreement. Fine. (I think it myself.) They maybe are anti-conventionalist because they think there are very few humanly possible languages, and many features don’t vary from one to another (like Chomsky, or Stan Peters even more). Fine; only one alternative is needed. They maybe are anti-conventionalist because they think there’s one special language – say, Latin – that’s (1) more satisfactory than any other humanly possible language, (2) God’s language, (3) the language we all think in, (4) innately wired in, (5) the language we’d spontaneously start speaking if we weren’t trained out of it by exposure to other languages used around us. Fine; I can grant this and still claim it’s a convention to use Latin instead of one of the inferior languages. Still more is it a convention if we use one of the others. Some minor points. (1) What about people who stick with God’s language and forgo communication? Or rather, what if they would, or what if it isn’t common knowledge that they wouldn’t? Maybe they think (falsely) that they’re participating in a convention with their neighbors and God; and it’s common knowledge that if all the Others switched they’d switch, but not common knowledge that if some of the others (the less im­ port­ant ones) switched, they’d switch. Then you have a less extreme case along the lines of the one in L&L 42, in which all but one member of a supposed languageusing population don’t really exist. What if it’s not God’s language they stick to, but only the language of their forefathers? I think that might go the same way – there’s a desire both on the part of the forefathers and on the part of the descendants for coordination over time. Not entirely for the sake of communication, granted; though partly for the sake of ­communication, since both sides want the old books to go on being read. (Cf. the diary case, L&L 40.) Then again, a descendant who refuses to switch when the other  descendants do doesn’t go against common knowledge of a preference for

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coordination with all the others. (See what happens if you trick him into thinking he’s made a mistake about the forefathers’ language.) What if they’re just stubborn, not trying to coordinate either with God or with the forefathers (or even with their past selves)? Then you really do have a coun­ter­ exam­ple, at least if it’s a clear-cut case. But I don’t think it is. Once you ask what ­reasons they have for speaking (or responding when others speak), I think you realize that they’re more different from us – alien, even – than they first seemed. Maybe their language-use is a sort of meaningless ritual (like chanting Hare Krishna all day), or maybe they’re a sort of animated instrument. (2) Common knowledge needn’t be knowledge. That’s a slip, first pointed out to me by Bill Hart in 1970. It’s set right in L&L, 6. (3) How many conventions of language in a population? Presumably many, since suitable consequences of conventions are themselves conventions. See C, 80–82 and 143; also the discussion of sub-languages in L&L 48–50. There will also be many convention-dependent regularities which are not themselves conventions. The inter­ est­ing question seems to be this one, however: is there any convention relating to language that can’t be subsumed under the most inclusive prevailing convention of truthfulness and trust? I’ve never written anything about this, but I think probably there are: for instance, conventions about pejoratives, or about socially acceptable forms of address. (It occurs to me that I’ve been giving you references in the revised ‘Languages & Language’, but you may have only the 1968 draft. I’ll send along the new one.) Thanks for your letter, and for showing me your draft. Yours, David Lewis

575.  To Tyler Burge, 5 November 1973 Princeton University Princeton, NJ Dear Prof. Burge, In a certain primitive community, they all drive on the left. None has ever heard of anyone driving any differently from the way they drive. They believe their way of driving to be uniquely part of the natural order. (Ask them to try driving on the right, and they’ll say that obviously it’s humanly impossible. Press them, and they



575.  To Tyler Burge, 5 November 1973

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say that if they tried they wouldn’t succeed in driving at all, there’d be a crash for sure. In fact, it would be far more dangerous than keeping left when confronted with a – demon-driven – car coming at you on your left.) For a less simple case, imagine that they’ve heard of an island where everyone drives on the right; so they recognize that their way is conventional and has a humanly possible alternative. But none has ever heard of alternating as follows: driving on the left except on holidays, and on the right on holidays. They believe uniformity to be uniquely part of the natural order. They would think – if they thought about it, which they never do – that nonuniformity is humanly impossible due to the strength of habits, that an attempt at non-uniformity would result in crashes for sure, that an attempt at non-uniformity wouldn’t be a good idea even if per impossibile others were non-uniform. The two stories are certainly possible; and I think they’ll bring out our dis­ agree­ment more easily than the case of language. For I think you ought to disagree with me about these cases too, in consistency with what you (and your informants) are inclined to say about conventions of language. What I say, and expect you to deny, is of course as follows. (1) In the first case, driving on the left is not a convention. In fact, it’s a kind of case which I went to some trouble to exclude. (2) In the second case, driving on the left is a convention, for it has at least one suitable alternative. But driving uniformly on the right or left is neither a convention nor a convention-dependent consequence of a convention, since it is common to all the eligible alternatives. So it is in no sense conventional in the population. To someone who feels that driving on the left in (1), or driving uniformly in (2), is conventional, I’m prepared to concede some points, but not much. First: their nonconventionality is unstable: let the population think a bit, and come to know ex­pli­ cit­ly what they have the wherewithal to know already, and these things would become conventional. Second: maybe they’re already conventional under the ideal­ iza­tions that would have to be made to represent the agents as rational with minimal – but significant – distortion of what they’re actually like. Third: they have many of the features of genuinely conventional regularities, so it’s not stretching things too badly to liken them to good cases of conventional regularities. Fourth: in fact, it may be within the limits of vagueness to call them conventional. I’m sure my official way of resolving vagueness is one correct way, but other ways may be as correct. I’d say that mine is strategically advantageous, though: the thing to do is to get an analysis that fits the central cases, and then say that things are ‘sort of conventional’ if they are im­port­antly like the central cases. But if you think that driving on the left (or uniformly) in the cases I’ve described is a perfectly clear, central case of conventionality, then I flatly disagree. I don’t know what to say next, except to invite you to take some sort of interest in

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conventionality-in-the-sense-of-Lewis although it’s something you don’t have a word for in your dialect of ordinary language. After all, analysis isn’t everything: one can also ask what phenomena are characteristic of language use (or driving) as these would be if they were stable practices among highly rational and knowledgeable agents. Yours, David Lewis PS Who’s presently chairman at UCLA? I want to write and ask to be considered for summer school teaching next summer.

576.  To William M. Schuyler, Jr., 24 April 1974 [Princeton, NJ] Dear Prof. Schuyler, Grandy gave me your paper ‘Existence as a Predicate’. I rather liked it, and I’d be glad to advise a dissertation on such matters. I’ve so informed Gil Harman, and I believe he’s already seen to whatever formalities there are. Your request comes at a good time, because two other dissertations I’m supervising are just now getting finished and will soon be out of my hands. I should warn you that I’m on leave in Spring 1975, and may be away then and in the following summer. That should be no serious problem, since I won’t be completely out of touch for long at a time, and I’ll be glad to work with you by mail as fast as in a normal term. I’ll also be away this July (and a little bit of August) at a workshop connected with the Linguistics Institute;1 but that shouldn’t be long enough to make a problem. My reactions to your paper are 1) that there’s no reason at all not to quantify over a domain including fictional characters and other unactualized possibles, using a predicate of existence; but 2) that doing so is by no means enough to straighten out problems about talking about fictional characters. This leaves me in full agreement with the motivating points at the beginning of the paper – e.g. about the legitimacy of comparing fictional and historical characters, or of being undecided about whether someone is one or the other. Also I am in agreement with your defensive moves later on. But I expect that in the end you will need something like modal operators to make sense of some truths about fictional characters.

  LSA Linguistics Institute, UMass-Amherst.

1



576.  To William M. Schuyler, Jr., 24 April 1974

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Some small matters. What you say about ‘really’ on page 5 is insufficiently general, I think. It can change the application of the verb in all sorts of directions – more extended, less extended, neither more nor less but differently extended. In a certain town there lives a wise old lady, illiterate and uneducated but skilled through long experience in healing the sick. There also lives there a silly young fellow, straight out of medical school and properly licensed, who never does anything right. I can properly say of either one that she/he is really a doctor, and the other isn’t. (I can’t say both things in the same breath, though.) My ‘really’ marks some sort of shift in standards – in relative importance of competence and credentials – but it fits the two directions of shift equally well. And neither direction is an expansion or a contraction. On page 20, I’m not sure how much your point about use of ‘exists’ not entailing ontological commitment amounts to. Is it just that if ‘exists’ is used non-committedly (‘Who cares what exists?’) then it doesn’t commit you to much of anything? That’s what your argument supports, but I would have thought you wanted something more – what I don’t know. I would suppose that positive assertions that soand-so’s exist do carry ontological commitment to so-and-so’s, that being nothing more nor less than commitment to the truth of what you’ve asserted, viz. that soand-so’s exist. You may not like my own reasons for agreeing with you that quantification over fictional characters, with a predicate of existence that they don’t satisfy, is OK. I think of fictional characters as things of the same sort as ourselves, differing only in location. We inhabit one possible world; they inhabit another. They and their worlds don’t differ in kind from we and our world. So in quantifying over them I’m not quantifying over some new and exotic sort of thing – just over distant things of an already-familiar sort. It’s no worse to have fictional characters that don’t (actually) exist in your domain than it is to have historical characters that don’t (now) exist. I suspect that this motivation may be alien to you; if so, you might want to say why your position differs. I suspect it’s harder to say than it might seem. By the way, we’ve met; though you may not remember me by name. When you were here in the early ’60’s, I often was in Princeton visiting such people as Bob Moore, Larry Shepley, Dick Burger, and Charles Chastain. I was then a graduate student at Harvard, working also for Hudson Institute; sometimes I stayed in Princeton and commuted to Hudson. Sincerely, David Lewis

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577.  To William M. Schuyler, Jr., 3 June 1974 [Princeton, NJ] Dear Bill, I’d assumed you planned to incorporate the paper in the thesis. No problem.1 On other uses of ‘really’: what I said was meant more as an elaboration of your point than as an objection to what you said. On ontological commitment: I agree that saying that various fictional characters exist doesn’t commit us with respect to our world. (Except that calling them ­fictional, rather than merely possible, commits us to the existence in our world of certain works of fiction.) But as you can tell from Counterfactuals, I’m not so happy with saying that our world is somehow basic or primary or main. Incidentally, Adam Morton’s views on the primacy of the actual world might be to your liking; I’ll ask him to send you some of his stuff. On trans-world travel: I don’t think it’s possible. I suppose the SF with branching and travel is OK, but I don’t agree that the different branches are different possible worlds. Here’s the argument: travel requires that the person who arrives is the same as the one who departs. Personal identity requires a more-or-less informationpreserving counterfactual (and in my view, causal) dependence among the properties of nearby stages. So trans-world travel requires non-trivial trans-world counterfactuals: if my earlier stage in world w had been different, my subsequent stage in world wʹ would have been correspondingly different. Put that into the machinery in my book and you get out hash. For similar reasons, no trans-world perception – not even through a very special telescope. On having to use modal operators in the end: note that some of the truths about Sherlock Holmes are quantified. He’s smarter than any crook, with the sole exception of Moriarty. What’s the domain of quantification? Roughly, the class of crooks that inhabit the same world as Holmes. What else? Actual crooks? No – one feature of the fiction is that the crooks in the fiction are smarter than actual crooks, so that would be too weak. If on the other hand some actual crook, maybe F.M. Cinque, turns out to be smarter than Holmes that’s irrelevant. How about fictional crooks? No; I suppose Fu Manchu is smarter, but he’s in the wrong fiction so he’s irrelevant too. (He is as I intended the statement to be taken; I’m aware that it could be taken otherwise.) How about fictional crooks in the Sherlock Holmes

1   Schuyler received an MA in Philosophy at Princeton University in 1963. He started his career as Instructor at the University of Louisville and became Assistant Professor in 1969. Apparently, he did not go ahead and begin a PhD at Princeton University. He was promoted to Professor at Louisville in 1975.



578.  To Michael Devitt, 20 January 1975

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s­ tories? That’s closer, but still not right. Suppose you have in the stories a certain gang of crooks, said to be very smart, even smarter than Holmes. They are relevant, and falsify what I said. But now suppose the gang is only introduced collectively – its members aren’t mentioned individually. Maybe the stories don’t even say how many there are. Then I don’t think the individual gang members are fictional characters, though the gang as a whole is. But it’s the gang members who falsify the claim by being in the domain and outsmarting Holmes. I don’t see how to handle this without in effect going to intensional operators or their translations into extensional possibleworlds-theory. Yours, David Lewis

578.  To Michael Devitt, 20 January 1975 Princeton University Princeton, NJ Dear Michael, Thank you for your paper on the ambiguity of names.1 I did read through it this time, with mixed feelings. What inflamed me before is still there and still inflames: line 6 on page 2. I hope it’s not what you meant to mean, but I hold you responsible for the clear meaning of your words, whatever you may have had in mind: you claim that the philosophizing of others, myself for one, gives you legitimate cause to take offense. You’re welcome to find the positing of possible worlds misguided, useless, mistaken, bad, or many other things – but not offensive. As for your program, I like it well enough. Even the friend of possible worlds needs to know how much can be done without them, and how. I think you’re right that they contribute little to the study of names and disambiguation thereof. You recognise that you’re not done until you handle modalities; I agree, and wish you success. I’d also remark that if causation itself is a modal affair (more precisely, if it involves counterfactual dependence) your treatment of names will end up depending indirectly on your apparatus for handling modality. Pages 13–14 are unfortunate; I hope you’re willing to change them to avoid spreading misunderstanding, and I hope it’s not too late. I don’t hold the contextual theory of disambiguation you discuss, or anything like it, I never did, and I don’t   ‘Semantics and the Ambiguity of Proper Names’ (Devitt 1976).

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know of anyone else who does either. I don’t believe I’ve ever discussed dis­am­bigu­ ation in print; what I believe is that it largely depends on what the speaker had in mind, and that context may or may not serve as a clue to that. In short, I believe very much what you do about disambiguation, and I like the positive parts of your paper quite a lot. Here’s the situation, as I see it. An intension is a function from indices to extensions. A constant function is a function; some names are completely rigid and their intensions are constant functions. When this is so, but only when this is so, the possibility that extension depends on index is of no practical importance. Some rigid names are ambiguous: ‘One billion’ may rigidly name the number 109 or it may name the number 1012; the name has both intensions (two different constant functions) in my language and no doubt in yours, though perhaps not in the languages of our stayat-home compatriots. I don’t think it’s right to say that this name has a single nonconstant intension, one that looks at features of context to determine whether the extension on a given occasion is 109 or 1012. Ambiguity is not the same thing as indexicality. On any occasion (in the appropriate population) the name has both intensions and both extensions. It is also true, however, that on different occasions the name is differently disambiguated; sometimes speakers mean one thing by it, sometimes the other, sometime they may even mean by it something that isn’t one of its meanings in their language at all. It’s not that all but one of the meanings go away on an occasion when disambiguation succeeds; it’s that the speaker makes conversational use of one only of the several meanings. I haven’t much to say about how this happens, but I believe I could consistently adopt your view (perhaps with changes in terminology) and I think, offhand, that I’d be glad to do so. It’s almost the same with ordinary proper names of people, with a couple of extra complications. First, I don’t think these are strictly rigid but only quasi-rigid via the counterpart relation: the extension at another world must be a counterpart of the extension here at ours. That’s another issue, independent of what we’re now interested in. Second, I think the extension does depend on the causal history of the speaker, and that our conventions associate with the name a non-constant function that captures that dependence. (Plugging in a particular causal history we get another quasi-constant function out; it’s a matter of indifference to me which of the two – meaning2 or meaning1, in the jargon of ‘Languages & Language’ – is called the meaning.) But this dependence isn’t supposed to be doing the job you have in mind. It’s supposed to handle the difference in extension of ‘Liebknecht’ between Joe, who has heard of (is causally connected in the right way to) the father but not the son, and Moe, who has heard of the son but not the father, and me, who has heard of both but confused them, and you, who have heard of both and distinguished. It isn’t meant to handle the difference between you yesterday, having the father in mind and talking



578.  To Michael Devitt, 20 January 1975

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about him, and you today, having the son in mind and talking about him. Once you’ve heard of both, I say that ‘Liebknecht’ is ambiguous and has two extensions and two meaning1s for you (though only one meaning2) from then on, whoever you may have in mind and be talking about on any given occasion. Even if on a certain occasion you were being funny and actually meant David Armstrong, still then as always you would have the meaning1s that pick out the father and the son quasi-rigidly, and you wouldn’t have any meaning1 (or better: the word in your language wouldn’t have any meaning1) that picks out David Armstrong. What you meant – your meaning on this occasion – may be either, both (failure of disambiguation), or neither of the meanings of the name in your present language. Why have all these functions, if a lot of them are going to turn out constant or quasi-constant, or at least independent of many of the coordinates of the index? I detected the thought in your paper: the index-dependence must be there for some reason, is the reason maybe to handle disambiguation? No; it’s for the sake of uniformity. I want the intensions of all denoting terms to be entities of the same sort. Since ‘you’, ‘I’, ‘this place’, ‘this time’, ‘the oldest spy’ are indexical and need to be assigned functions that capture variation of extension with features of context and matters of contingent fact, ‘Liebknecht’ is assigned a function of the same sort (or rather several such functions as meaning1s, though only one as meaning2) even though the index-dependence is quasi-constant and hence more or less idle. Reading ‘Languages and Language’ through your eyes, so far as I can, I see that the brief discussion of dependence on causal origins lends itself to misunderstanding. It’s too late for me to do anything about that; the paper will soon be out. But if you can do anything about not spreading misunderstanding, I’d be grateful. Let me end with a puzzle. I can’t handle it; offhand I don’t think you can; I don’t know any theory (as opposed to a non-explanatory position that takes acts of referring as primitive) that does it justice. Someone of my political persuasions might very well have said in disgust, contemplating the trial of the Chicago 7: ‘Hoffman is just as bad as Hoffman!’ Let’s pretend I said it, though unfortunately I didn’t. On my view, the sentence has many meaning1s in my language: n2-n to be precise, where n is the number of different Hoffmans I’ve heard of. There’s nevertheless a perfectly good question what I meant by it on this occasion (or, in terminology you might prefer but I dislike, what it meant on this occasion). Did I mean that Julius was just as bad as Abbie, or that Abbie is just as bad as Julius? Surely these are two different hypotheses; there’s a matter of fact about the matter; and as it happens (let’s pretend) it’s the first that’s true and not the second. (It might be less clear-cut if I’d said ‘The Hoffmans are equally bad’.) What does this fact consist in? Just that I would have said (if asked) that I mean that Julius was just as bad as Abbie? No; I might have said so insincerely. Just that

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I would have said so in a spontaneous way, feeling as if I was being truthful? No; I might have done that and been mistaken, thanks to demonic interference. In saying which I meant, I was reporting, rightly or wrongly, something else about the state of mind that led me to say what I did. What? Nothing about the belief I meant to express, or the belief I meant to make you (pretend I was talking to you) share, or the belief I at least wanted to make you think I held, or . . ., will do at all. For it’s common knowledge that, necessarily, Julius is just as bad as Abbie if and only if Abbie is just as bad as Julius. In my jargon, the prop­os­itions expressed by the two disambiguations are identical. In others’ jargon there may be two different propositions, but they’re indistinguishable so far as Gricean intentions and all other relevant propositional attitudes in the present case are concerned. Which Hoffman did I have in mind? Of course I had both in mind, and that’s why I compared them as I did. It’s not as if I first had Julius in mind, said ‘Hoffman is . . .’, rummaged around for a predicate, suddenly thought of Abbie, and so finished off with ‘. . . just as bad as Hoffman’. The whole sentence exercises my capacity to refer to both Hoffmans, and the causal connection of my present mental state to both. It’s just make-believe to think of part of my sentence as stemming from one such capacity and the rest from the other. Nor did images of first Julius and second Abbie flash before my mind’s eye, nor would it have made any difference if they had. Maybe something could be done with the fact that if I meant that Julius is just as bad as Abbie I should already have been presupposing that Abbie is pretty bad, whereas if I meant that Abbie was just as bad as Julius I should instead have been presupposing that Julius was pretty bad. But I don’t think that’s it. Somehow the difference in presupposition requirement should be explained by the difference in what I meant, not vice versa. Further, we can suppose that the difference in presupposition requirement made no difference in the case at hand and so didn’t enter into explaining what I said; for (let’s pretend) it was common knowledge between us that we both supposed that both were pretty bad. I’ve sent the papers you asked for. I regret that my principal response to your paper was to nine words which could easily not have been there, and to a misunderstanding of my work which was more my fault than yours. I can’t disregard either of those things; but I can think of what would remain with those parts blacked out, and say once more that I found it interesting and good, and that I’m strongly inclined to think that this or something similar is right. Yours, David Lewis PS I hope you won’t mind my giving a copy of this to Hartry, since he and I also have talked a lot about this sort of thing.



579.  To Michael Devitt, 2 May 1975

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579.  To Michael Devitt, 2 May 1975 Walton Street Oxford, England Dear Michael, I’m sorry that I’ve taken so long to reply to your letter of 6 February; I’ve been traveling, and finishing up a very overdue book review.1 As you say it’s too late to do anything about the misinterpretation, so I hope the delay won’t matter. What about GS, page 23?2 (This must be the same as page 174 of the book, which is the only version I have available here.) What could I have been talking about if not the contextual disambiguation of such names as ‘Liebknecht’? For one thing, about the indexicality of such names as ‘the present king of France’, ‘my hat’, ‘I’, or ‘next Tuesday’. There is a usage, more common when I wrote the article in 1967–8 than it is today, in which all of these would be called simply ‘names’, and such special names as you have in mind would be called ‘ordinary proper names’ or something like that. (But Church even uses ‘proper name’ broadly, though he remarks that it’s somewhat artificial to do so.) There is another usage, popular now among those interested in the peculiarities which distinguish ordinary proper names from other denoting terms, to call only the former ‘names’ and to have no one convenient word for the latter. If writing today, I would probably do well to include a note that I was not following the latter usage. But that really ought to be obvious from other evidence: (1) name-forming functors of categories N/x (for any category x) are permitted, although these do not form ordinary proper names of people or places; and (2) ­variables are explicitly treated as names. Indeed, I think there may be at least a few non-composite, capitalized, other­ wise-ordinary proper names in English that are neither rigid nor quasi-rigid. ‘Rex’; ‘Miss Universe’; ‘Warden’ (as used at Oxford without a definite article to denote the present warden); ‘Mrs. Peter Geach’; ‘Ground zero’; ‘Stalin’; ‘Mark Twain’; ‘Stoke-onTrent’; ‘Ho Chi Minh City’; ‘Sherlock Holmes’; ‘Henry VII’ – each of these cases seems to me to provide some reason to doubt that Kripke’s picture (with quasi-rigidity in place of rigidity) applies universally, even after I am persuaded that it applies usually. I would wonder also about other actual human languages – all evidence I’ve ever seen against rivals to Kripke’s picture has been concerned with English and it shouldn’t be taken for granted that a description theory, say, is wrong also for Fijian. I imagine it

  ‘Review of Olson and Paul (ed.), Contemporary Philosophy in Scandinavia’ (Lewis and Lewis 1975).   ‘General Semantics’ (Lewis 1970a).

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won’t be soon that anthropologists will understand the issue well enough to give us reliable answers. Finally, recall my aim (at the outset) to propose a formula ‘general enough to work for a great variety of logically possible languages’ and not to make any strong empirical claims about language. If I provide functions from indices to extensions to be the intensions of names, and if in practice it turns out that these functions can always be quasi-constant, that’s OK. I’ve merely failed to capture one rather surprising general fact about actual human languages. But if I lay down a stipulation that the intensions of names are constant, then even if I get away with it by reclassifying or explaining away all apparent exceptions, that’s still not OK given the aim to provide a neutral framework for semantics. Other points. (1) If you called Armstrong ‘Liebknecht’ and it stuck, OK, I’d call it a change in language and creation within some small subcommunity of Englishspeakers of a new meaning1 for ‘Liebknecht’. The constant meaning2 would encode a dependence on causal history, and all who picked up the name from you would have a new causal history. But suppose you only said it once, perhaps even failing to make yourself understood. I suppose that could be regarded as a private and temporary change in language; then we need a theory of language-change that explains why it’s so very easy. I’d rather go a different way and say that not all communication (still less all attempted communication) involves the use of one’s language in conformity to the conventions of truthfulness and trust that govern it. (2) Not all names, not even all the ordinary proper names you have in mind, will have the same meaning2; what’s true is that they’ll all have meaning2s that are parallel in the way they work. ‘Tweedledum’ will have a meaning2 which yields a meaning1 (or maybe none or several) for a speaker at a time by looking at the base of the causal chain(s) by which he picked up ‘Tweedledum’; ‘Tweedledee’ will have a different meaning2, though of the same sort, that is sensitive rather to the bases of the chains by which the speaker picked up ‘Tweedledee’. Does this mean that it is not conventional which names have meanings2? No; for it is conventional that the meaning1s of names depend on causal histories at all and not, say, on who satisfies some associated cluster of descriptions. Or ‘Tweedledum’ could have had a constant meaning2 such that it rigidly designated the number 137. What’s true is that the meaning2s of ordinary proper names depend on convention only to the extent that the role of causal histories in naming itself depends on convention. I suppose another consequence is that the meaning1s are in a way more conventional than the meaning2s; that is, there are alternatives to our actual meaning1s that leave our actual meaning2s unchanged. On the puzzle: little more to say. Certainly it’s true that the causal networks based on Abbie and on Julius were involved in different ways in the productions of the sentence ‘Hoffman is just as bad as Hoffman’. That’s not make-believe; it’s not



580.  To J.J.C. Smart, 13 May 1975

281

even unduly speculative. What’s make-believe is to specify the difference as follows: since I meant that Julius was just as bad as Abbie, the first utterance of ‘Hoffman’ came entirely from the Julius-network and the second entirely from the Abbienetwork. I do want to insist that both networks entered into causing the sentence as a whole (and that I compared the two because I had both in mind) and that the causes of the parts of the utterance are the causes of the utterance as a whole. Had the Juliusnetwork been absent, or substantially different, the second utterance of Hoffman as well as the first would have been absent. You can say that there’s a certain way in which the Julius-network entered into causing the first utterance and not the second, and in which the Abbie-network entered into causing the second but not the first; and in which the Julius-network would have entered into causing the second but not the first, and the Abbie-network would have entered into causing the first but not the second, if I had meant that Abbie was just as bad as Julius. True; but also it’s true that there’s a certain way (a different way) in which the Abbie-network entered into causing the second and not the first, the Julius-network entered into causing the first but not the second, etc. How do these ways differ? As a philosopher, you don’t owe me a neurological account of the difference; but I do think you owe me more than simply: the first sort of causal involvement is the sort that yields reference. Yours,

580.  To J.J.C. Smart, 13 May 1975 Walton St. Oxford, England Dear Jack, I’ve taken another look at Bohnert’s review of ‘How to Define Theoretical Terms’,1 and I’m still puzzled – and a bit annoyed – by it. For one thing, I think your marginal note is right: Beth’s theorem would apply when every interpretation of the O-vocabulary determines a unique realization, whereas I had in mind the case where one given interpretation of the O-vocabulary (plus the facts) determined a unique realization. Second, I don’t know that there is any Beth’s theorem for languages richer than quantification theory, whereas I would think that real-life scientific the­ or­ies, like it or not, are formulated with the aid of intensional or higher-order notions.

  ‘Reviewed Work: How to Define Theoretical Terms by David Lewis’ (Bohnert 1971).

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(On the other hand, I don’t know that there aren’t extensions of Beth’s theorem that would serve.) But most important, Beth’s theorem is an existence theorem: it doesn’t say what the explicit definition looks like, nor that it fits a standard form from one theory to the next. I don’t know whether it has a constructive proof; the proof I’ve just looked up isn’t constructive. But even if it does, it’s by no means the same thing as a definite and uniform proposal about the form the definitions of T-terms should take. Yours,

581.  To Kendall Walton, 10 September 1975 [Princeton, NJ] Dear Professor Walton, You’re most welcome to use my paper ‘Fiction’ in your seminar.1 I’m just back from half a year away and my files aren’t accessible, so I’m afraid I can’t immediately make you a xerox. I could later if necessary; but why don’t you make a copy of John Bennett’s copy instead? I regret to say that I don’t have a better and later version to send you. I wrote the paper to be a section of Counterfactuals, but left it out because the book was too long. I’ve done nothing since except for making it self-contained by removing cross-references to other parts of the book. It would have been a quick job to finish it and send it off to a journal, except that Saul Kripke came along with his arguments that Sherlock Holmes does not exist (and hence the Holmes stories are not true) at any possible world. I know more or less how to answer Kripke, but the need for an answer turns a small rewriting job into a big one and I haven’t done it yet. I’m rushed now, so I can’t explain here what changes I would make in the paper. Perhaps, as you say, we can find a chance to talk about it. I hope so. Sincerely, David Lewis

  ‘Truth in Fiction’ (Lewis 1978).

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582.  To Nuel Belnap, 29 October 1975

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582.  To Nuel Belnap, 29 October 1975 [Princeton, NJ] Dear Nuel, Many thanks for your offprint on Åqvist on questions.1 I regret to say that I should have read it and hadn’t. So I was ignorant that you’d already said many of the same things about Åqvist that Steffi and I say in a forthcoming review: Part 2 of the enclosed.2 Sorry! You’ll find few surprises in what we say, but might still find it of some interest. I’m not at all sure what’s true about telling falsely whether. I wouldn’t much mind coming around to your view that telling falsely whether is a perfectly good case of telling whether. But your argument isn’t decisive: surely false answering to a whether-question is answering, and true answering is telling-whether, and false answering is at least purporting to tell whether, but I needn’t grant that false answering therefore is telling whether. I think your evidence could be explained away – though I’m not sure it ought to be! – by this observation: Very often, we say of someone that he Φ’s when he doesn’t really Φ (at least not in the literal and central sense) but does purport to Φ. ‘Nixon was very sincere’. ‘Johnny is a cowboy, and he’s shooting Indians’. ‘Mad Fred is running away from the Martian spies’. ‘She told me whether Santa Claus exists’. (Not really, that is not truly, but she purported to tell me, that is she purported to tell me truly.) I’m also disinclined to fight back about linguistic versus propositional objects of ‘tell’. But again the evidence seems inconclusive. If I ask to be told whether A or B, and you know that A, and you reply with sentence Aʹ, and Aʹ is a remote logical equivalent of A, then it’s a datum that this was not a perfectly satisfactory and standard case of telling whether. But it’s not a linguistic datum, but rather an explanatory hypothesis, that this was not a case of telling whether A or B; the rival hypothesis is that it was a case of telling whether A or B in a pragmatically objectionable way. I haven’t any notion how to choose between the two hypotheses. I’m not by any means happy with ‘ “Whether” Report’;3 I may abandon it, and I’ve been trying to stop the spread of underground-press copies. It seems too gimmicky, and I don’t think the gimmick of double indexing buys enough to pay its way. Why not a straightforward treatment of the ‘whether’-clause as a term denoting the

  ‘Åqvist’s Corrections-Accumulating Question-Sequences’ (Belnap 1969).   ‘Review of Olson and Paul (ed.), Contemporary Philosophy in Scandinavia’ (Lewis and Lewis 1975). 3   (Lewis 1982b). 1 2

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true one of the alternatives? I said it was better to treat it as a sentence because it went into places suitable for sentences. But (1) those places are also suitable for what look uncontroversially like terms: ‘He told me what John had told him’, ‘He knows that theorem’, etc. (2) Some of those places aren’t suitable for ordinary sentences: ‘*He wonders that the sky is blue’, ‘*He asks that the phone is ringing’. (3) Most places ­suitable for sentences aren’t suitable for ‘whether’-clauses: ‘*If whether Fred is dead then Holmes will solve the case’, ‘*John believes whether Fred is dead’, ‘*?John says whether Fred is dead’, ‘*Please tell me whether whether Fred is dead or not or not’. So I need lots of selection restrictions, just as I would if I treated ‘whether’clauses as terms. The only thing worth having that my gimmick buys, I think, is an explanation of why the lists in ‘whether’-clauses are strung together with ‘or’. But what’s the use of making these ‘or’s truth-functional when we already know, I take it, that many uses of ‘or’ aren’t truth-functional? When and if we have a satisfactory general ­theory  of all other uses of ‘or’, that will be the time to see if it fits the ‘or’s in a ­‘whether’-clause. A further shortcoming of ‘ “Whether” Report’: as you very well know, it’s an easy but very special case when you have a set of alternatives of which it’s presupposed that exactly one is true. I don’t see how to generalize my treatment beyond that special case in any natural way. Yours, David Lewis

583.  To Saul Kripke, 7 November 1975 [Princeton, NJ] Dear Saul, I’ve been thinking about how to streamline and tighten up the argument I gave last Wednesday night at our seminar. Since I’ll be out of town for a while (and since I’d like to write it down for my own benefit) let me give it to you in writing instead of waiting until I see you next. Now it’s directly against the doctrine of a hierarchy of sense, indirect sense, . . .  whereas in the seminar it was rather against your defense (viz. that it might suffice to learn one grand sense instead of infinitely many petty ones) against Davidson’s



583.  To Saul Kripke, 7 November 1975

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­ nlearnability argument against the hierarchy; but arguing against1 rather than u against3 the hierarchy at least leaves me more or less on the same side! 1) Let’s say that the grand sense of the word ‘amphictyony’, for instance, is something that suffices to determine its reference in all contexts, however oblique. That’s meant to be a (partial) definition; I don’t say whether the grand sense is something fancy, such as the whole of a hierarchy of senses, or whether it’s something more ordinary, such as the ordinary sense. 2 ) It appears that we can and do learn grand senses of words. Moreover, one way we can learn them is by being told – for instance, you told us (at least roughly) what was the grand sense of ‘amphictyony’; the informant in your example told someone the grand sense of ‘alienist’, and so on. 3) How does the telling work? Like this, presumably: you assert a sentence (*) -----------------amphictyony---------------i n which the question occurs; the only way for (*) to be true is for ‘amphictyony’ to have a certain grand sense S; trusting in your truthfulness, we take it that ‘amphictyony’ does have grand sense S. 4) What is the reference in (*) of the word ‘amphictyony’? 5 ) It is something sufficiently informative to determine the grand sense of ‘amphictyony’. Else the assertion of (*) couldn’t accomplish its purpose; for there would be two possible grand senses S and Sʹ which would determine the same reference in the context (*) and hence (since only the reference is involved in truth conditions) would equally well make (*) true. Then the information that (*) was true wouldn’t settle whether the grand sense of ‘amphictyony’ was S or Sʹ. 6) According to the hierarchy doctrine, however, the reference of ‘amphictyony’ in (*) is determined by, but doesn’t determine, the sense of ‘amphictyony’ in (*); and that sense, in turn, is the reference of ‘amphictyony’ in other contexts, for instance ‘Saul says that (*)’. Then the reference of ‘amphictyony’ in (*) doesn’t suffice to determine the grand sense of ‘amphictyony’. 7) So the hierarchy doctrine is false. 8) And what’s true is that the reference of ‘amphictyony’ in some contexts suffices somehow to determine the reference of ‘amphictyony’ in all contexts. 9 ) I assumed that the telling of the grand sense was accomplished by a single sentence with a single occurrence of ‘amphictyony’. I suppose there’s no loss of generality in

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supposing it’s a single sentence; conjoin as many as you need. I’m not sure whether there’s loss of generality in supposing only a single occurrence. But if that’s objectionable it doesn’t matter. The revised conclusion of (5) is that the finitely many references of ‘amphictyony’ in its contexts in (*) suffice to determine the grand sense, and so the reference in all contexts; and that also contradicts the hierarchy doctrine. 10) Note that I say nothing about the form of (*). In the seminar we imagined it to have the form The grand sense of ‘amphictyony’ is . . .……… Then we both went wrong: I said to look at the reference of the left-hand side, you said to look at the reference of the right-hand side. But really the thing to do is look at the reference of the word ‘amphictyony’ itself. Yours, David

584.  To G.H. Merrill, 2 December 1975 Princeton University Princeton, NJ Dear Gary, Many thanks for your letter about necessary truths in fiction. Let me comment quickly on a couple of points, and hope for a chance some time to talk at leisure. I was puzzled by what you said about your analysis (2B)1 of (2) ‘Sherlock Holmes must be a British detective’. I think (2) could defensibly be taken either as (2B-1) or (2B-2): (2B-1) In every f-world, Holmes is a British detective. (2B-2) In every closest f-world, □Holmes is a British detective.

What puzzles me is that your object-language formulation of (2B) looks like (2B-2), but you then give your (2B) the truth conditions of (2B-1) instead. (Let’s disregard failures of the Limit Assumption, and let’s equivocate about whether the ‘closest’ f-worlds are to be the ones closest to actuality or the ones ­closest to the collective belief worlds of the community of origin.) 1   ‘(2B) In f, □Sherlock Holmes is a British detective’ (Letter from G.H.  Merrill to David Lewis, 19 November 1975, p. 1).



584.  To G.H. Merrill, 2 December 1975

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(2B-1) has the consequence, as you say, that whatever is explicit about Holmes in the stories is counted necessary. Given that this is a somewhat esoteric concept we’re investigating – or perhaps inventing – I don’t see why you need to mind this. Loosely speaking, Holmes’s essence under (2B-1) is the role specified by the stories: the characteristic without which one cannot occupy the role. (2B-2) is an equally legitimate concept, however, and it seems to me to be more what you want. Let’s take the embedded necessity sentence as de re with respect to Holmes, and interpret it by means of counterparts. Then we have this: Whenever w is one of the closest f-worlds, v is a world accessible from w, x plays the role of Holmes in w, and y is a counterpart in v of x, then y is a British detective. That is obviously different from (2B-1): v needn’t be an f-world, let alone a closest one, and y needn’t play the role of Holmes. By his similarity to x who does play the  role, y probably plays the role to some extent, but perhaps very imperfectly. It is questionable whether (2B-2) is true; if we replace being a British detective by ­having a certain height (stated in the stories but unimportant) then what we get is doubtless false. Maybe your (2C)2 is still a different concept, and if so I don’t have much to say about it. But perhaps it comes to the same thing as (2B-2). That would be so, I think, under certain moderately plausible assumptions. Let f and fʹ be fictions, c be a 1-1 correspondence between the roles specified by f and fʹ, let w be an f-world and let v be an fʹ-world. Iff the fʹ-roles are played in v by counterparts of those who play the corresponding f-roles in w, call v a variant of w. Suppose first that fʹ is a permissible alternative to f iff every closest fʹ-world is a variant of some closest f-world. Suppose second that every variant of a closest f-world is a closest fʹ-world for some fʹ which is a permissible alternative to f. Are these suppositions at all plausible? If so, they merge your (2C) with (2B-2). I would like that. I don’t think (2B-2) is the only legitimate sense that can be given to the notion of the essence of a fictional character like Holmes; but it has the virtue of being what we get if we simply combine the pre-existing treatment of de re modality by means of counterparts with my general treatment of the ‘In f’ operator as a quantifier over the closest f-worlds. Yours, David 2   ‘ “In f, □Φ” is true iff Φ is true in every permissible alternative of f’ (Letter from G.H. Merrill to David Lewis, 19 November 1975, p. 2, his italics).

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585.  To Philip Kitcher and Patricia Kitcher, 13 April 1976 Prospect Ave Princeton, NJ Dear Philip & Pat, The significance of the dime: according to superstition, a knife is a dangerous gift. It might cut the friendship! Somehow, the dime prevents that. Maybe it helps that the gift isn’t just a knife. The tradition has two versions: one in which the coin comes with the knife; another in which you’d pay us a dime for the knife, making it a sale instead of a gift. The latter sounds like a rationalization of the custom – fishy – so we stick to the less reasonable version. Steam beer is now readily available in Princeton. I hope it lasts! I agree that it’s not always correct to straighten out the contradictions. They might be crucial to the plot. But if so, do you still want to hold on to a non-trivial notion of truth in fiction? Not if truth in fiction is supposed to be closed under ­implication, and it’s implausible to drop that! I suppose there are four strategies ­altogether. (1) Straighten out contradictions – we agree that’s sometimes inappropriate. (2) Give up – I might be content with that for the cases you mention. (3) Use impossible worlds, or suitable surrogates for them – this gives us the problem of distinguishing subtly impossible from absurd worlds (or world-surrogates), else anything goes and we’re back to (2). (4) Look at what’s true in maximal consistent fragments of the fiction – this isn’t very different from (1), but it allows us to get an inconsistent set of things all true in an impossible fiction: φ1, . . ., φn, ψ true in fragment F1, φn+1, . . ., φm, ~ψ true in fragment F2, hence we could perhaps count all of φ1, . . ., φm, ψ, ~ψ as true (in a special sense) in the whole fiction. This makes contradictory sets of sentences true in the fiction, but not yet contradictory single sentences. [. . .] Yours, David & Steffi [. . .]



586.  To Peter Lamarque, 28 February 1977

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586.  To Peter Lamarque, 28 February 1977 Princeton University Princeton, NJ Dear Mr. Lamarque, Many thanks for your interest in my paper ‘Truth in Fiction’. The paper is to be published in American Philosophical Quarterly, probably later in 1977. There will be very little change from the January 1976 version, which I believe must be what Stalnaker showed you. I agree that we can distinguish truth within a fiction – the topic of the paper – from something else: the verisimilitude of the fiction, we might call it. This is a matter of agreement between some of what is true in the fiction and some of what is true; and hence of similarity between (the closest of) the worlds of the fiction and our actual world. What makes something a fantasy, for instance, is that so much of what is true in the story isn’t true, and hence there are great differences between even the closest of worlds where the story is told as known fact and our world. But I think there’s a third thing that some people have in mind speaking of ‘artistic truth’; and perhaps you have something of the sort in mind when you say parenthetically that artistic truth is different from realism. Suppose some important general proposition is obviously true in a fiction and also true, but not obviously true, in actuality. Then reading the fiction might call one’s attention to an important truth that had been ignored hitherto. Maybe also once one thought about the matter one would have reason to recognize that the proposition was true; then the fiction would impart knowledge. Or maybe the reader might believe the proposition not for any good reason, but only because it was true in the fiction; then the fiction would persuade by exploiting the readers’ suspension of disbelief, but might nevertheless succeed in causing one to believe some important general truth. (Of course, a fiction could just as easily impart error.) Again, the analysis starts from some such notion of truth in fiction as mine, and involves a comparison between truth in fiction and truth. But that’s not the whole story, since the importance and generality and nonobviousness of the shared proposition also must be considered. I don’t know The Black Prince, but I am aware of other cases in which a narrator is not to be trusted. In the final version of my paper there is a footnote reading in part ‘There are exceptions. Sometimes the storyteller purports to be uttering a mixture of truth and lies about matters whereof he has knowledge, or ravings giving a distorted reflection of the events, or the like. . . . In these exceptional cases also, the thing to do is to consider those worlds where the act of storytelling really is whatever it purports

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to be . . . here at our world’. (I think this note was illegible in the copy you saw.) I think therefore that we’re in agreement about Bradley Pearson and the like. Finally, I agree with you that we usually patch up an impossible fiction. We talk of what’s true in the consistent minimal corrections; or (equivalently) what’s true in maximal consistent fragments of the story. Some of the things in your letter resemble a discussion of ‘fictional epistemology’ in a paper by Patricia and Philip Kitcher (Department of Philosophy, University of Vermont, Burlington, Vermont).1 You might ask them for a copy of their work on the matter. They consider the reader, or the audience of a play, gradually forming hypotheses, assessing their plausibility, changing their minds, and finally ending up with opinions about what’s true in the fiction in more or less the sense of my paper. I think of the matter this way (thanks partly to Kendall Walton): just as the author pretends to be telling the truth, so the audience pretends to be reading the truth (or otherwise finding out about it) and reasoning as he goes on the basis of more and more complete information.2 Sincerely, David Lewis

587.  To Peter van Inwagen, 9 May 1977 [Uppsala, Sweden] Dear Prof. van Inwagen, I’ve sent a copy of my paper on fiction.1 It is just the sort of anti-Meinongian treatment you mentioned as one option. I think it fits neatly with your treatment2 – I see no opposition and incline to accept both. Mine might afford an analysis of your Primitive  A.  Yours fills a gap which I note in the paragraph beginning on page 4. While we give different analyses of ‘Holmes lived on Baker Street’ the two should be equivalent. Many thanks for the copy. Your Spain sentence, while it seems plausible enough to me as an instance of a genuine disjunctive antecedent, might not convince the opposition because ‘on one

  Patricia and Philip Kitcher. 1976. ‘What Is Experimental Theater?’ (unpublished).   See ‘Fearing Fictions’ (Walton 1978).

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  ‘Truth in Fiction’ (Lewis 1978).   ‘Creatures of Fiction’ (van Inwagen 1977).

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588.  To Philip Kitcher, 23 February 1978

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side or the other’ seems redundant and parenthetical. But I’d like to hear what Ellis says about it! Yours David Lewis

588.  To Philip Kitcher, 23 February 1978 Princeton University Princeton, NJ Dear Philip, [. . .] I’ve therefore found time to look at your paper on theoretical change at last.1 I found it interesting, and mostly I liked it. My principal reservation was not about the solution but about the choice of the problem. The issue is whether the content of the old and the new theories can be expressed in neutral language, so that there will be a language in which to explain how the two differ and what are their relative merits. I should have thought that of course there was: everyday language minus the theoretical terms of either theory. As follows: We agree that if we burn something in air, the composition of the air changes in a way that inhibits further burning; and that if we heat red calx of mercury in air, the composition of the air changes in an opposite way that facilitates burning. You think this is because burning adds some substance to the air, heating red calx of mercury removes that same substance, and that the capacity of air for that substance is limited; and you have certain technical terms that reflect that supposition. I rather think it’s because burning removes a substance that’s part of normal air; heated red calx of mercury emits that same substance; and there’s a limited amount of it available in ordinary air. My terms reflect that supposition. Also, even if the terms ‘dephlogisticated air’ or ‘mercuric oxide’ are theory-laden in such a way that they might suffer a failure of reference if the introducing theory is false, still there are terms ‘so-called dephlogisticated air’ and ‘what you call “mercuric oxide” ’ that are not theory-laden, have their reference whether the theory is right or wrong, and can be considered part of the common language. There are no witches, but we can still say truly of people that they are the sort who truly would have been called witches in the old days.   ‘Theories, Theorists and Theoretical Change’ (Kitcher 1978).

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Two things to point out. (1) Neutral language doesn’t have to be neutral between all possible theories, just between the two theories under comparison. (2) It doesn’t have to be a pure observation language, whatever that might be. So it’s OK to include ‘emits a substance’, ‘removes a substance that’s part of the normal air’, etc., since these terms are neutral, if not between all possible theories, at least between phlogiston chemistry and oxygen chemistry. The problem about the reference of ‘dephlogisticated air’ is an interesting one, and I like your solution. But I think it has more to do with semantics than with phil­ oso­phy or history of science. In the case of phlogiston chemistry, at least, there’s plenty of neutral language available no matter what happens to the reference of ‘dephlogisticated air’. In effect, what I’ve done is to imitate in ordinary language Ramsey’s way of eliminating theoretical terms. Ramsify out the theory-laden terms from the old and new theories, and you express the rival contents in a common neutral language. If almost everything were theory-laden that might leave you without any nontrivial content; but it’s not so in this example, and I believe not in the other ones either. Two small points. (1) On page 16, first item listed under ‘modern theory’; wouldn’t it be better to say ‘air which is poor in oxygen’? The oxygen-poorness, not the nitrogen-richness, is the modern counterpart of the phlogistication as that which inhibits further combustion. (2) I don’t understand what’s going on in the Cavendish quote on p. 19. If the ‘burnt air’ is the air mixed with the inflammable air and exploded, then the condensate is not at all acid if the burnt air is almost entirely dephlogisticated. Chastain gave a lecture here two or three years ago which seems a bit relevant. His idea was that if the speakers continue to be acquainted with the referent (‘gold’ but not ‘Moses’) then to some extent, and depending on the mixture of referential intentions (which may vary from context to context), the chain is constantly starting over. When all goes smoothly that makes no difference; but when there are mistakes it does matter. The ‘Madagascar’ case is one example. Another is the man who works in Fools’ Fort Knox, spending every working day shifting bars of fools’ gold, which he calls ‘gold’. I think the case of the working chemist, uninterested in theoretical issues but wanting to talk about his bell jar full of dephlogisticated air, would be a parallel case. Still better would be the merchant who sells cylinders of compressed dephlogisticated air for a living, having no notion why it’s called that! [. . .] Our best to Pat; I hope to write soon about her partial analysis paper.2 Yours, David 2   ‘Two Versions of the Identity Theory’ (Kitcher 1982). See Letter 442. To Patricia Kitcher, 24 February 1978, Volume 2: Part 4: Mind.



589.  To Allen P. Hazen, 15 November 1978

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589.  To Allen P. Hazen, 15 November 1978 Princeton University Princeton, NJ Dear Allen, I think you’ve indeed missed the force of Gareth Evans’ paper.1 As I interpret it, it is a correct proof of the thesis it is meant to prove. It suffers only from over-condensed exposition, which hides both the point of the paper and the argument meant to establish that point. Let me tell you how I read the paper. I don’t think I’m going too far in reading things into the paper so that it will make good sense; I think I have textual evidence that what I’m filling in is what Evans had in mind. (I must say, though, that I’d feel surer of what I say if I had the paper in front of me – the mail is slow.) Let’s ask – I’ll send a copy of this to Evans in the hope that he’ll tell me whether I’ve understood him properly. (I’ll blank your name off. Your comments were not for publication, so I assume also they’re not for publicizing.) First, concerning the operators D and Ñ. I think Evans didn’t intend them to play the role of possibility and necessity operators in modal logic, but rather contingency and noncontingency operators. Compare Montgomery and Routley on formulations of modal logic with contingency or noncontingency as primitive (Logique et Analyse, 1966, ’68, and ’69). Even the notation is the same! If so, then, as you know, Evans is right that D and Ñ are duals, and that they generate a modal logic as strong as S5. But why does Evans speak of ‘strengthening with a “definitely” prefix’? DP is not a strengthening of P, since it might be true because P is definitely false. However, I think Evans could perfectly well have meant strengthening P by conjoining DP to it; though if he did mean that, he could have said it more plainly. In short, I think that what you suggest as an improvement on Evans is just what Evans intended all along. Evans might or might not endorse our view that D and Ñ mean ‘on some but not all of the resolutions of vagueness’ and ‘on all or none of the resolutions of vagueness’, just as a modal logician might or might not be com­fort­ able with the idea that modal operators are quantifiers over worlds. But I’d expect him to agree that such a way of understanding D and Ñ will do at least as a guide to their logic. Now to the main point. I note that you discuss just about every line of the paper – except the first paragraph! But the first paragraph does state the goal. And the stated goal is not to show that identity statements are never vague. True, that’s the stated conclusion of the proof that follows – a proof that you and I believe to be fallacious.   ‘Can There Be Vague Objects?’ (Evans 1978).

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But the stated goal of the paper is to attack the notion that vagueness comes from vague objects in the world, rather than from indeterminacy in our language. (I really wish I had his exact words here, but I hope I have the gist of them.) So what does that have to do with the fallacious proof that follows? We think there are vague identities. I think Evans thinks so too. We think there’s a fallacy in the stated proof that identities are never vague. I think Evans thinks so too. But what does the vague-objects man think? We can diagnose the fallacy, but the vague-objects man cannot accept our diagnosis. So (unless he can tell an alternative story of where the fallacy lies) he’s stuck with the argument that we consider fallacious, and he’s stuck with the unwelcome conclusion that identities are never vague. Because he thinks that vagueness is in the world, rather than thinking of vagueness as semantic indeterminacy, an escape route from this unwelcome conclusion is barred to him. You may think this is steep. If Evans wrote down the argument not as something that he endorsed, but rather as something his opponent was stuck with, he should have said so! To be sure. But Evans did say that he was arguing against the vagueobjects man, and didn’t say that he was arguing against vague identities. If you don’t buy my interpretation, what do you make of the first paragraph (and the title)? How does the issue between vague objects and semantic indeterminacy get into the act at all? An argument against vague identities wouldn’t be a reason to prefer one ex­plan­ ation of vagueness to another; if anything, it would be an argument against vagueness generally (for the reason you give), and hence against all explanations of vagueness.

(1) (2) (3) (4) (5)

Ñ( a = b ) ˆxÑ( a = x )(b ) a = b (hyp. for reductio ) ˆxÑ( a = x )( a ) Ñ( a = a )

Here, I take it, is the fallacious part of the argument. We could regard it as one big jump by fallacious use of Leibniz’s Law from (1) and (3) to (5). But I think it’s clearer, and also it’s what Evans does, to subdivide as here. The Leibniz’s Law step from (2) and (3) to (4) is legitimate, and the suspect steps are from (1) to (2) and from (4) to (5). (1) to (2) is suspect because b is perhaps nonrigid; (4) to (5) is suspect because a is perhaps nonrigid. And indeed one or other of b and a must be nonrigid, if (1) is to be true. Obviously I’m using ‘nonrigid’ analogically: a designator is nonrigid or rigid according as its denotation does or doesn’t vary from one resolution of vagueness to another. But the reason why (1) requires nonrigidity of at least one of a and b, the reason why the step to (2) requires rigidity of b, and the reason why the step to (5)



589.  To Allen P. Hazen, 15 November 1978

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requires rigidity of a are all exactly parallel to the modal case. (Understand the modal case kept simple, without counterpart theory – maybe the terms are designating numbers.) But the vague-objects man doesn’t think either a or b is nonrigid. He doesn’t think of vagueness as semantic indeterminacy. He thinks that a rigidly designates a vague object in nature, b likewise rigidly designates a vague object in nature, and these two designata are vaguely identical – whatever that may mean. So he can’t say what we say about the fallacy in one or both of the steps from (1) to (2) and (4) to (5). (Or, if you prefer, about the fallacy in the big step from (1) and (3) to (5).) The argument should look good to him. So he’s stuck with its conclusion. So he’s wrong. That’s what I believe to be the point of the paper. When the argument is given, that’s the vague-objects man talking; and he’s getting himself into big trouble. He’s committing what is a fallacy according to the treatment of vagueness he rejects – the semantic indeterminacy theory – but not according to the theory he accepts. So what should the vague-objects man do? Give over his wrong-thinking notions? Of course, but what short of that? I don’t think he’d be well advised to disbelieve in vague identities. Rather, I think the right way out for him is to deny that you get a vague identity by prefixing ∇ to a plain identity. That’s a good move for us, but not for him. He ought to be saying that there’s plain identity (the least reflexive relation among objects, vague or otherwise) and there’s vague identity, a relation broader than identity. Finding something true of a and not of b shows that a and b aren’t just plain identical, but doesn’t show that they aren’t vaguely identical. Definitely not plainly identical doesn’t imply not vaguely identical, because vague identity isn’t plain identity modified by a sentential operator. The target against which Evans’s attack succeeds is, I think, a sort of bastard theory: a belief that vagueness is in nature, allied with a way of thinking about vagueness that implicitly puts the vagueness in language. The vagueness of terms is in nature, but the vagueness of sentences is in language. If you think that, of course you’ll get in trouble with identities! You’d better be uniform one way or the other. I wish I had the text – doesn’t Evans say that he’s attacking the combination of belief in vague objects with some other doctrine? Yours, David PS (to be blanked off in the copy for Evans). [. . .]2

  See also ‘Vague Identity: Evans Misunderstood’ (Lewis 1988c).

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590.  To Angelika Kratzer, 9 July 1979 [Melbourne, Australia] Dear Angelika, No objections to your mentioning my results about your semantics and partial orderings. I’d rather you call it a ‘personal communication’, rather than mentioning the notes by title, since I’m still far from pleased with them in their present form. I hope to write a short paper,1 but I don’t know when I’ll find the time. As for v. Kutschera, send me the address and I’ll send him a copy of the notes. Also, I’ve sent you a copy of the ‘. . . De Se’ paper separately. Thank you for the draft from Bielefeld,2 which I liked. Two comments. One is that you’ve made a change, in effect imposing a requirement of centering: the intersection of f(w) is {w}. Also you now speak of ‘assigning to every world what is the case in it’. Would I be right to suppose that this is not a change of view between your Konstanz paper and your Bielefeld paper; rather, your Bielefeld paper is restricted to a special case, whereas your Konstanz paper was also meant to cover such cases as the deontic conditionals for which centering and the description of background as ‘assigning to every world what is the case in it’ would have been inappropriate? In discussing Veltman, you suggest that what he means by saying that prop­os­ ition p belongs to f(w) is that p is a belief that I hold in world w. That’s a clear proposal, but I rather doubt that it is what Veltman meant. At the same time, I have no clear idea of what Veltman did mean! He explains it by saying something like this: p is a belief I hold about world w. Here I am at my own world, having beliefs about other worlds as I might be at Monash having beliefs about other universities. But that’s no good: I can have beliefs de re about other universities but not about other worlds, since I can stand in relations of acquaintance to other universities but not to other worlds. In fact in reading Veltman I’ve tended to concentrate on the formalism and disregard the intuitive explanation. If he did mean that f assigns to each world the beliefs I hold in that world, he’d be in trouble of the sort you explain; and of another sort also. Consider one of my favorite examples: if I looked in my wallet I’d find a penny. I take it that this is true (given my actual circumstances, though not in some bizarre possible circumstances) iff there is a penny in my wallet. To get this right, f ought to assign to any world similar to this one whichever is the true one at that world of the pair , where p is the proposition that there is a penny in my wallet. (I mean, ought to assign that as   ‘Ordering Semantics and Premise Semantics for Counterfactuals’ (Lewis 1981c).   ‘Partition and Revision: The Semantics of Counterfactuals’ (Kratzer 1981).

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591.  To J. Michael Dunn, 9 September 1979

297

one member among others of f(w).) But it isn’t so that in every world similar to this one, I believe the true one of the pair; rather, in any such world I believe neither. Some further developments connected with my notes. (1) I now have a clearer notion about the divergence in treatments of the vacuous case. Note first that whenever f(w) includes the set W of all worlds, your original truth condition and my version (1) are equivalent; and note second that according to your original truth condition it makes no difference whether W is included in the sets f(w) or not. So your truth condition is equivalent to my truth condition plus the stipulation that W belongs to each f(w). When we switch to the equivalent ordering semantics, we have truth condition (2) plus the stipulation that the field of the ordering consists of all worlds. That is, we have the condition of universality, as I called it in Counterfactuals. That will affect the logic. If you define ‘outer modalities’ as in Counterfactuals 1.5, universality validates (and condition (1) without universality doesn’t validate) S5 as the logic of the outer modalities; hence S5 must be available as the derived outer modal logic from any complete axiom system for conditionals. The question whether P is complete for partial orderings (without centering or universality) is still in a bit of a turmoil, but it appears that it is. There are proofs of roughly this by Stalnaker, Burgess, and Veltman. But Stalnaker’s and Burgess’s proofs are so far only sketched, and Veltman’s has a mistake which probably isn’t serious but might be. (He in effect assumes universality, as above, but his allegedly complete logic doesn’t yield S5 for the outer modalities.) Yours, cc: Hans, Max

591.  To J. Michael Dunn, 9 September 1979 Victoria University of Wellington Wellington, New Zealand Dear Mike Dunn, I just heard a paper by Graham Priest announcing that classical logic is a degenerate research program in the sense of Lakatos, paraconsistency is the coming thing, and we might as well get on the bandwagon today rather than be run over by it tomorrow!1 (All trimmed up with the rhetoric of red revolution!) I paid a bit more   Cf. ‘The Logic of Paradox’ (Priest 1979).

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attention to it than I might have since I’ll be spending July–August 1980 at ANU and expect to be cast as the classical stooge. I thought: no hope of persuading them it’s absurd, but wouldn’t it spoil the fun if I could persuade them it’s not radical? And indeed it seems to me that what Graham said makes perfectly good sense classically. He said the trouble with disjunctive syllogism was this: when p is both true and false, and q is false only, p ∨ q is true (as well as false) by the standard truth (and ­falsity) conditions, and likewise ~p is true (as well as false); so two premises both (inter alia) true lead by d.s. to a conclusion which is false (only). So d.s. is invalid in the commonplace sense that isn’t truth-preserving. Now as I understand it, when you or Nuel use this true-as-well-as-false semantics, what you have in mind is true-according-to-P as well as false-according-to-P, where P is a belief system, data bank, or whatnot . . . which may have been con­tam­in­ ated with misinformation and thereby made inconsistent. Fair enough; but this gets you a 4-valued set-up (2 designated values) since P may be incomplete as well as (or, rather than) inconsistent. Priest wanted only three values – both, true only, false only – since he claimed to be talking about truth or falsity according to the world, and so has no special stake in truth-value gaps. My thought was that the 3-valued version makes classical sense as follows. Stop me if you’ve heard this; any comments or relevant references gratefully received. It’s a logic for ambiguity. Any decent textbook tells us that the atomic sentences are supposed to be disambiguated, and we’ll get into nasty trouble if we fail to disambiguate and switch meanings halfway through an inference. Suppose we turned down the good advice to disambiguate, and instead tried to keep out of ­trouble by weakening the logic. The concepts of unambiguous truth and falsity are no use to us. Rather, we have truth-on-some-disambiguation and falsity-on-somedisambiguation. (Abbreviation: osd.) A sentence can be true-osd and false-osd; trueosd and not false-osd; or false-osd and not true-osd. No fourth, unless we believe in truth-value-gaps-osd on independent grounds. The most we can ask of valid reasoning if we won’t disambiguate is that it be truth-osd-preserving. The connectives are as expected: ~p is true-osd iff p is false-osd, false-osd iff p is true-osd; p & q is true-osd if both p and q are true-osd, false osd iff either p or q is false-osd and so on. Notice: this is ok only if we allow that a constituent may be differently disambiguated at different occurrences in a compound. But why not? Scrooge fancied a walk by the river so he walked along the bank on his way to the bank to deposit his money. If p has a true disambiguation P1, and a false disambiguation P2, p & ~p is true-osd because it has the true (mixed) disambiguation P1 & ~P2. Formally, it’s just the scheme Priest described – a scheme which I gather traces back to something of yours. But the thought that maybe we live in an impossible world doesn’t enter into it.



592.  To Allen P. Hazen, 22 July 1980

299

Even so, it fits some of the motivation. The things that were supposed to be both true and false were such things as the liar sentence. A more conservative view would indeed have it that the liar sentence has been left semantically indeterminate. A general view of indeterminacy is that it’s like ambiguity: the indeterminate sentence is ambiguous between the alternative legitimate ways of resolving the indeterminacy. Then the liar sentence is true-osd and false-osd, and dauntingly hard to disambiguate! If ever we needed a logic for ambiguity . . . Yours, David

592.  To Allen P. Hazen, 22 July 1980 [Canberra, Australia] Dear Allen, Thanks for your letter. I got the feeling I’d heard much the same tune twice within a few days, so took the liberty of sharing your letter with Chris Mortensen here. He’s also been thinking the best way to make sense of true-as-well-as-false is if it means true/false according to some sort of informal mathematics, not necessarily constructive, with no hope that the mathematics is consistent because it’s the truth about the Platonic realm. He knows more than I do about the history of such efforts, so is better able than I to see what’s going on in your comparisons with Johansson and Nelson. It does seem to me that it’s a truth-according-to interpretation, not one involving plain truth. And it seems to me therefore that the medicine of fragmentation might be suitable – can the maker of mathematics always be seen as making consistent overlapping fragments of theory that disagree? Conjecture: it can always be done somehow. Bolder conjecture: what’s more, it can always be done in a non ad hoc way, so that the boundaries of the fragments have some independent ‘psychological reality’. Cf. issues about grammars. I’m not sure how badly I need the bolder conjecture. Am I on safe ground if I just say that the right fragmentation is the one that makes the right things come out true-according-to whatever it is? ‘Routley’s radical ravings’? I don’t know about that. Radical, sure. Necessarily and a priori wrong, sure. But there’s a certain fiendish ?????? about it all. Consistency? Of course that’s not it; that praise would be neither welcome nor accurate! Wellworked-outness.

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I don’t know about Belnap being pragmatic and open-minded. The paper about the question-answering machine is after all the doctrine as preached to the infidel. Cf. Belnap and Dunn ‘Entailment and Disjunctive Syllogism’,1 about a character called the True Relevantist who wouldn’t even be tempted to use the disjunctive syllogism. The authors don’t claim that this fictional character speaks for them, but it sure comes out seeming that way! They certainly express admiration for the T.R. Besides, I think the business about the question-answering machine is rigged. The design limitations are made to order so that it will turn out best to close under relevant implication. But a mere existence proof isn’t good for anything. If A., B., & Sons build question-answering machines cheaper than anybody else’s, I might sens­ ibly buy one even if it’s too stupid to do all the reasoning it should, and even if it’s too stupid not to do some of the reasoning it shouldn’t. In fact, Belnap seems to be straining at the gnat and swallowing the camel. The computer doesn’t do quodlibet, because if it gets fed a contradiction then it will have maybe 50% probability of giving a wrong answer. Why might it be fed a contra­dic­ tion? Because, informants and keypunchers being what they are, it gets fed a lot of misinformation, and it might get fed misinformation and truth about the same topic. Say it’s fed 90% truth and 10% error. Then it’s risky to let it do quodlibet, sure enough. But it’s far more risky to let it do adjunction. Given appropriate independence assumptions, 50% of what it gets by adjunction is wrong; but about 88% of what it  gets by adjunction of 20 different things it’s been told is wrong! So why does Belnap deny it quodlibet and give it unlimited adjunction? Could it be that he has something in mind besides designing the best possible question-answering machine for your money? I wondered idly if fragmentation – same thing as non-agglomerative modality – had anything to do with the fragmentation of partial Boolean algebras in Kochen; but I don’t know enough to explore that. I’m glad you had a look. Yours,

  (Belnap and Dunn 1981).

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593.  To Robert B. Brandom and Nicholas Rescher, 19 December 1980

301

593.  To Robert B. Brandom and Nicholas Rescher, 19 December 1980 Princeton University Princeton, NJ Dear Bob and Nick, I’m writing to thank you very much for the copy you kindly sent me of The Logic of Inconsistency.1 I’ve just read it, and I’ve found it extremely interesting – some of the most interesting philosophy I’ve read in a long time. So far as the world and possible worlds are concerned, I remain a dogmatic standardist. It’s not that I have any reason to feel sure that inquiry must converge to a standard world; but if it doesn’t, then it hasn’t (can’t possibly) converged to the world. So far as belief-worlds are concerned, however, or fictional worlds, or worlds portrayed by a theory, or worlds as they are required to be by some deontic system, I certainly recognize a need for toleration of inconsistency as well as incompleteness; and I agree with you in looking at an inconsistent state of affairs as built up out of consistent ones that disagree with one another. I’ve sent you a draft titled ‘Logic for Equivocators’2 which discusses this under the name of ‘fragmentation’, and illustrates it with an example from my own recent inconsistent belief; the revised version will of course mention your treatment. I would be interested to see what happens when your treatment is extended by addition of fully truth-functional connectives. In addition to your conjunction and disjunction, we might have a second pair of connectives K and A that obey the standard rules for standard and nonstandard worlds alike: /KPQ/w is T iff /P/w and /Q/w both are T, and is F iff /P/w or /Q/w is F. /APQ/w is T iff /P/w or /Q/w is T, and is F iff /P/w and /Q/w both are F. Then you get the relevantist approach to inconsistency as the logic of ~, K, and A, joined with your approach as the logic of ~, &, and Ú; but your account of what a nonstandard world is serves for the semantics of both. I’m also interested in the question why you didn’t make the structure of ‘possible’ worlds distributive, so that aÇ × (b È× c) = (a Ç× b) È× (a Ç× c), and a È× (b Ç× c) = (a È× b) Ç× (a È× c).   (Rescher and Brandom 1980).   

1

  (Lewis 1982a).

2

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By not imposing distributivity – not factoring out by the appropriate equivalence relation – you get a much more complicated structure, and much more opportunity for differences among worlds that aren’t reflected in differences in what’s true of them. I’m a bit curious about why you want this structure. Yours, David cc: Chris Mortensen

594.  To Lloyd Humberstone, 22 May 1981 Princeton University Princeton, NJ Dear Lloyd, Many thanks for your paper on intersections of accessibilities.1 It’s interesting that new departments of modal logic keep turning up. On the legal-and-moral ­example, I think you’re needlessly diffident. Whatever it may or may not prove about our ontology, ordinary language does cheerfully quantify over ways for things to happen, and anybody could understand you if you said: there’s a legally permissible way for me to get married, and there’s a morally permissible way, but no way is both morally and legally permissible. I wonder if there’s any connection with my interest in fragmented belief, fragmented truth in fiction, fragmented theories, etc. As you recall, I think that relevantism is the wrong approach to studying the partial closure under implication of the inconsistent corpora we’re sometimes forced to settle for, and the right approach is to treat the partially closed corpus as a union of fully closed, consistent fragments – typically with a lot of overlap between the fragments. (The main problem being to explain away the evidence that there isn’t even closure under one-premise implication.) For each fragment, belonging to (= being implied by) that fragment is a K-modality, given by an accessibility relation. Take belief; for fragment Bi of my belief system, the accessible worlds – my beliefi worlds – are those that fit the beliefs in fragment Bi, and my beliefs in fragment Bi are just those propositions true throughout my beliefi-worlds. (I neglect non-propositional belief de se.) Belief, in one sense, is given by the union of the fragments. I believe it iff it’s so according to some fragment. Wholehearted belief, as we might call it, is given by the 1   Lloyd Humberstone. ‘Intersections of Accessibility Relations’ (unpublished). Humberstone used the legal-and-moral example in ‘The Formalities of Collective Omniscience’ (Humberstone 1985, 413).



595.  To Robert Solomon, 19 June 1981

303

intersection of the fragments: I believe it wholeheartedly iff it holds at every world that is somehow or other accessible. Then what’s BI? Nothing of interest, of course, in the case I’m mainly interested in where the fragments disagree, my total belief system is inconsistent, and the accessibilities don’t overlap. But in less extreme cases it may have some intuitive content. Again it’s easier to go through possibilities. What happens is that I’m of two minds (or more) about whether some possibilities are doxastically open to me, about whether I really have beliefs that rule them out. Then there’s a distinction between (1) my beliefs definitely don’t rule it out that A happens somehow, and (2) there’s some way for A to happen that my beliefs definitely don’t rule out. The latter is ¬BI¬A.  So BIA is: there’s no way for A not to happen that my beliefs definitely don’t rule out. ‘It’s not clear to me just how A could fail to happen’ might do as a reading, if we read that so it’s compatible with ‘It’s clear to me that A might somehow fail to happen’. Of course, these readings suggest that A is a prediction of a future event. I suppose generalization is possible. Sorry, I don’t know Edgington. Nor do I know about the Fitch derivation, which certainly seems as if it must be fishy somehow! Sorry we’ll miss you in Melbourne. If you were coming back through the USA, when would it be? Any chance we could see you then? Yours, David

595.  To Robert Solomon, 19 June 1981 La Trobe University Melbourne, Australia Dear Bob, This is a letter about two points connected with your talks; had time permitted, I’d have talked to you about them. Concerning angry turkeys without self-conceptions. The turkey is angry. Anger involves some sort of judgement: ‘I am being attacked’, maybe. (Maybe for a human it would be ‘. . . attacked unjustly, gratuitously, without provocation’; but those add­ itions, which give it an element of indignation, seem a bit beyond a turkey. So let’s keep it simple.) If we parse it like this

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Philosophical Letters of David K. Lewis The turkey judges that: I am being attacked

the content of the judgement seems to require a self-conception that the turkey ­arguably lacks. I suggest parsing it rather like this: The turkey judges-that-I-am: being attacked or The turkey self-ascribes: being attacked That is, the content doesn’t involve a self-conception; the content is just the property of being attacked, not the state of affairs: I am being attacked. Switch the part about the self from the content of judgement into the judging relation. Then try analyzing the judging relation of self-ascription whole. Instead of asking: what relation do I have to a state of affairs when I judge it to obtain? you ask: what relation do I have to a property when I judge myself to possess it? There seems to me to be no reason why you have to reintroduce a concept of self in answering that second question, any more than you have to introduce a concept of obtaining in answering the first question. In other words, resist the step from self-ascribing being attacked to judging that a state of affairs involving myself obtains. Concerning right and wrong brands of paraconsistency. Suppose an idealist or pragmatist thinks that truth is not to be distinguished from truth according to the most coherent possible theory, or the theory we would reach at the end of inquiry, or . . . . And suppose he is persuaded that there are two equally coherent most coherent theories, which disagree; or that inquiry might end with either of two equally adequate theories; or that endless inquiry under ideal conditions will give us nothing better than a succession of disagreeing partial theories from incompatible standpoints; or something like that. In short: truth means truth according to the best theory; but there are irremediably more than one best theory, and the best theories disagree. One response is to say that where the best theories disagree, there is no truth of the matter. The alternative response is that all the best theories are true, and where they differ there are true contradictions. Someone who holds this view needs paraconsistent logic, according to which not everything that follows classically from a true contradiction is true. I say that he needs discursive paraconsistent logic, not rele­ vant paraconsistent logic. The idea of discursive paraconsistent logic is that it’s never quite safe to reason from more than one premise at a time, since if you use two different premises they



595.  To Robert Solomon, 19 June 1981

305

might come from two different fragments of the truth, and a consequence of them might be a bastard, true neither according to one fragment nor according to the other. It’s often safe in practice to combine premises, since often they will be drawn from a single fragment; but logic, which is supposed to tell us what kinds of reasoning are unconditionally safe, won’t allow any many-premise reasoning. Even the inference A B _____ ∴ (A & B) is verboten; A might come from relativistic physics, B from quantum physics, (A & B) might belong to neither, and despite the disagreements between relativistic physics and quantum physics, there might be no better physics possible than the inconsistent combination of the two. Notice that the true contradictions tolerated on the discursive line always are pairs of theses: A, not-A. They never are single contradictory theses, (A & not-A). The thing that saves contradictions from trivializing the theory is that you can’t deduce much of anything from the pair without first conjoining them into a single thesis, and the step from conjuncts to conjunction is not in general OK, it’s OK only when the conjuncts come from the same fragment. Relevant paraconsistent logic is a bit harder to explain. Technically, the idea is to stop contradictions from implying everything by requiring conclusions of inferences to have something in common in subject matter with the premises, and observing that contradictions may be limited to certain subject matters. You can go freely from conjuncts to conjunction, however, hence going from disagreements between the parts of your system to single contradictory theses. Semantically, the key idea is rejection of ordinary notions of how negation works. I think that accords ill with the motivation I’ve imagined; which was that the closest we can get to truth, if we’re unlucky, is truth according to a union of disagreeing theories – theories in our ordinary language, theories framed with ordinary negation. Indeed, I doubt that relevant paraconsistent logic has any important philosophical applications, though I’ve invented an unimportant application for it. Relevant paraconsistency is the specialty of the house in Canberra; discursive paraconsistent logic gets little notice there. Discursive paraconsistent logic was invented by Jaskowski, and there are some people in Brazil interested in it. Rescher and Brandom in the US, and Peter Schotch and Ray Jennings in Canada, belong to the discursive branch, though I’m afraid that Schotch and Jennings, at least, wouldn’t like my idea of what it’s good for philosophically. (Jennings is at Simon Fraser; with luck

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he might be around when you are.) In general, whichever brand you study, you’ll see a hell of a lot of algebra, model theory, and proof theory, precious little discussion of the philosophical point of it all, and still less of that which withstands examination. It’s all too clear that the mathematical tale is wagging the philosophical dog – the tale being indeed a rich and non-trivial one, for those who like such stories! I’m sending you a preprint1 which talks briefly about some of these things, and commends the method of fragmentation – i.e. discursive paraconsistent logic – as a logic for inconsistent theories or belief systems. I didn’t specifically mention the inconsistent theories that might if we’re unlucky lie at the end of inquiry, but what I say applies to them. I think, of course, that if the theory at the end of inquiry or the most coherent possible theory turns out to be a fragmented inconsistent theory, that just goes to show that truth according to it isn’t truth; but truth according to it may yet be a legitimate object of study and its logic may be worth investigating. Yours, David

596.  To William G. Lycan, 2 September 1981 [Princeton, NJ] Dear Bill, If God tells you that the inscrutable sentence on the placard has some syntactic structure, but doesn’t tell you what the structure is or what the intensions of the atomic constituents are, of course you don’t understand it. You don’t know its meaning in the sense of ‘General Semantics’, Section V. The same is true if God doesn’t tell you whether the sentence is structured or not. But if God assures you that the sentence has no (semantically relevant) structure, then I say you do so understand it. Let me try to talk you into that. Anything can be given a proper name, or at least anything you can be acquainted with can. OK? If, ex hypothesi and per impossible, God showed you all the worlds where the inscrutable sentence is true and all where it is false and you kept track of which were which, you would then be in a position to name the truth set: Fred. Indeed, you’d have a hell of a lot fuller understanding of ‘Fred’ than of most proper names with respect to which you’re competent. Then also you understand the sentence ‘This world belongs to Fred’.   ‘Logic for Equivocators’ (Lewis 1982a).

1



597.  To Kendall Walton, 21 December 1981

307

Now, if you understand a sentence, and you also know, concerning a second sentence, (1) that it is necessarily equivalent to the first, and (2) that it has no semantically relevant structure, then you understand the second. For what’s left to know? Let ‘Ginx’ be introduced, without structure, simply by the stipulation that, necessarily, it’s true iff Vegemite is made out of crushed worms. I say that you now understand ‘Ginx’. OK? So you understand the inscrutable sentence on the placard. We’re just back from Australia, and I wish we weren’t. Hope your visit to T&M in ’82–3 works out. Yours,

597.  To Kendall Walton, 21 December 1981 [Princeton, NJ] Dear Ken, Thank you for your letter. Two brief replies. ‘It is only rarely fictional, of the actual author, that he is doing so [viz. writing or speaking the words of the text]’. Maybe I can agree, given my original theory (and a fortiori for a modification in which the audience’s make-believe plays more of a role). For I think it’s part of my original view that – In the stories: (the text comes to us from a doctor named Watson) Not: in the stories: the text comes to us from Conan Doyle. And maybe even – In the stories: not: the text comes to us from Conan Doyle. I put this by saying that Conan Doyle pretends to be a doctor named Watson. And I didn’t make clear whether that meant (1) pretending to be Watson rather than himself, or (2) pretending to somehow be Watson and still be Conan Doyle as well. I think (1) would be better. This puts us into tough, and irrelevant, issues about counteridenticals; let me just say that it should be possible to make the machinery flexible enough not to rule out (1) as nonsense. Let’s imagine that ugly Dave’s boasting has enough of a plot to it so there is a fiction within the fiction – though in fact that it isn’t completely clear. ‘I don’t see why this iteration is in danger of collapse’. Well, because of the ‘different question’ that you go on to consider – if the singer could be taken to pretend to be ugly Dave telling the truth, that would collapse the iteration (on my theory). And to the question why

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that’s wrong, I suppose the answer you give may well be right, though I’d prefer something less inner. I suppose the corresponding problem for your theory is: why should the audience make believe they’re hearing lies instead of truth? To which I suppose you would not answer by appeal to the singer’s thoughts, given that you think of him as a prop-maker rather than party to the game. See you here later this year, Yours, David Lewis

598.  To F. Jeffry Pelletier, 13 September 1982 [Princeton, NJ] Dear Jeff, I thought that Uglyism might be formulated in standard first-order logic, ­without either the machinery of many-valued logic or the pseudo-modal machinery of supervaluations, ‘definitely’ operators, etc. The domain would just consist of the vague objects, whatever those are; with maybe some precise ones also. The extensions of the predicates would be sets of these objects. The intended interpretation will assign the predicates the sorts of extension suitable for saying about vague objects the things you want to say about them if you’re an Uglyist. For instance, ‘is exactly 25 square miles’ will be false of all the vague mountains in the domain, true at most of the precise mountains (if such there be). But ‘is def­in­ ite­ly more than 5 square miles’, ‘is roughly 25 square miles’, ‘is big’ will be true of some of the vague mountains. The identity predicate applies, exactly always, just to the pairs of an object and itself; a vague object, like any other, is identical to itself and nothing else. But there might be another predicate, ‘is roughly identical to’, that relates non-identical vague objects, or that relates vague objects to their precisifications (if such there be). It would be axiomatic (definitional?) that precise objects, as opposed to vague ones, are roughly identical only if identical. There’s no property that a vague object – or any other – neither has nor lacks. When a vague mountain fails to have any exact size, it lacks all the exact size-properties, though it has various inexact size-properties. The principle is general: whatever entities you believe in, you can talk about them in standard logic. Of course, you can devise other languages as well – e.g. an Uglyist’s



599.  To Saul Kripke, 11 November 1982

309

many-valued logic. What I don’t buy is that there’s any ontological view, Uglyism or anything else, that enforces non-standard logic, multi-valued or anything else. I don’t say that it’s best to formulate Uglyism in standard logic – only that it’s possible. Yours,

599.  To Saul Kripke, 11 November 1982 [Princeton, NJ] Saul, In the heat of battle, I made a mistake in conceding your point about Conditional Excluded Middle. I now think Calvin’s in the clear. The following are equivalent, given the shared presuppositions of all concerned. I follow Bas’s terminology on ‘classical’ and ‘super-’ valuations. CEM 1. Any admissible supervaluation makes true A ⁄ B ∨ A ⁄ ~B CEM 2. Any admissible classical valuation makes true A ⁄ B ∨ A ⁄ ~B CEM 3. Any admissible classical valuation makes true one of the pair of A ⁄ B, A ⁄ ~B It seems to me perfectly proper, outside certain technical contexts, to use ‘Conditional Excluded Middle’ indiscriminately as a name for CEM 1–3. The odd man out, far more dubious, and maybe without serious defenders, is 4. Any admissible supervaluation makes true one of the pair of A ⁄ B, A ⁄ ~B We can agree that it would be bad to give the name ‘C.E.M.’ to 4, or to suggest that it is a ‘lively issue today’. It’s not clear to me that any of De Molina, Plantinga or Stapp and Eberhard need 4. I defend Calvin thus: it’s reasonable to suppose that he meant CEM 3 rather than 4. You could say that it would have been useful to distinguish CEM 3 from 4; I reply that not only was that not obligatory, it would even have been a bad thing to do – an excessive digression from the historical topic. There’s a philosophical issue* in the background. Do you think of some supervaluation as the intended interpretation of our language, and the classical valuations as auxiliary machinery? Or do you think of some of the classical valuations as several equally intended interpretations – our intentions or whatnot being rather indecisive   (Issue? Maybe just a point of terminology.)

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– and the supervaluations as a way of talking about our indecision? If you see it the first way (like Bas) you’ll say ‘true’ and mean ‘true on the supervaluation’. If you see it the latter way (like me) you’ll often be happy to ignore our decision and pretend we’ve fixed on one classical valuation and speak of truth w.r.t. that; and when you do want to pay attention to indeterminacy you’ll say ‘super-true’, ‘definitely/de­ter­min­ ate­ly true’, or something like that. cc: JB

600.  To Saul Kripke, 12 November 1982 [Princeton, NJ] Saul I see that I need to defend not only Calvin but also myself on this point!1 I remain happy with the defence I gave you yesterday. In my case there’s a further point: the X ⁄ Y’s are propositions. So semantic indeterminacy affects not the truth value of any one of them, but rather the exact Props × Props → Props function expressed by ⁄. (I’m not sure this isn’t so in Calvin’s case too.) cc: RJ, JB

601.  To Thomas Kuhn and Philip Kitcher, 14 January 1983 Princeton University Princeton, NJ Dear Tom and Philip, Thank you both for your commensurability (draft) papers from the PSA.1 I’ve just finished reading them, with great interest. There’s a lot on which all three of us agree, in opposition to inter alia the Kuhn of popular imagination. In particular – 1   This (handwritten) letter is accompanied by p. 24 of ‘Causal Decision Theory’ (Lewis 1981b). Lewis circled the sentence: ‘Conditional Excluded Middle, which says that either X ⁄ Y or X ⁄ –Y holds at any world (where –Y is the negation of Y)’ (Lewis 1981b, 24). 1   ‘Commensurability, Comparability, Incommensurability’ (Kitcher 1982).

Communicability’

(Kuhn

1982);

‘Implications

of



601.  To Thomas Kuhn and Philip Kitcher, 14 January 1983

311

( 1) There’s middle ground between incomprehension and translatability; (2) There’s apt to be plenty of neutral language available to the parties in a dispute over theoretical questions (and to fence-sitters, agnostic bystanders, . . .); it won’t be neutral between all theories whatever, it won’t be a pure observation language, but it will be neutral enough to this dispute. (3) Even if translatability is lacking, that needn’t prevent reasoned assessment of the merits and difficulties of competing theories; for we can consider the neutrallanguage consequences of theories stated in partly untranslatable language. But I take a position to the right even of Philip. Although I agree with Tom against Philip that preservation of reference does not suffice for adequate translation, nevertheless I think I want to stick up for translatability itself. I would suppose that in a theoretical dispute, the whole content of the competing theories could be expressed in language neutral with respect to that dispute. (It would be convenient to extend the neutral language definitionally; but definitional extension is dispensable, and isn’t what you mean when you speak of ‘extension’ of language as part of ‘interpretation’.) Note that I’m not saying that the whole of each of the ‘loaded’ languages is translatable; but that enough is. Each of Priestley and Lavoisier could present his doctrine in full within the translatable part of his language; equivalently, within the neutral language. If Priestley can state his doctrine in full without using the word ‘Phlogiston’ (or without using it exactly as it is used among the phlogistic chemists) then we don’t need a translation of ‘Phlogiston’ to have translatability enough. It may be that ‘Phlogiston’ is translatable, and yet, contra Tom p. 4, there is a language into which ‘both theories, conceived as sets of statements, can be translated without residue or loss’. Here is what I have in mind. Priestley believed – and he might have been prepared to put it this way explicitly, at least after suitable questioning – that there were a pair of substances that, singly or jointly, satisfied a long list of conditions stated in  neutral language. (Or, in my jargon, realized a theory otherwise stated in O-vocabulary.) Presupposing that there was such a pair, he used ‘phlogiston’ and ‘dephlogisticated air’ to name, respectively, the first and the second elements of the pair. Being a sensible chap and not a philosopher, he didn’t trouble to make up his mind what the names were supposed to denote in case he was wrong but not rad­ic­ al­ly wrong, so that there were things that (singly or pairwise) satisfied various substantial parts of his list of conditions. (Remarks before we go on. (1) A pair is too small – it ought to be ‘phlogiston’, ‘dephlogisticated air’, ‘principle’, ‘element’, . . . . But I wanted to get at least some of the interdefinition of terms that Tom sees as a barrier to translatability. (2) Some of these conditions may be egocentric, or indexical: for instance, that these two substances

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are abundant, i.e. abundant in our surroundings. (3) They may be metalinguistic: they are supposed to be the same two substances that I, Priestley, have heard referred to as ‘phlogiston’ and ‘dephlogisticated air’ by others.) Because Priestley sensibly hasn’t bothered to make semantic decisions about hypothetical cases, his meaning is ambiguous or indeterminate. Let ‘Phlogiston1’ mean ‘that which, together with another substance, satisfies all twenty conditions’; let ‘Phlogiston8’ mean ‘that which, together with another, satisfies all of the first five, at least four of the next five, and at least three of the remaining ten’ and so on, not ad infinitum, but throughout a vast list of ‘Phlogistonn’s. Priestley believes that any ‘Phlogistonn’ denotes the same substance as any other, that’s why it would be a waste of time to decide just what he means. Call these the precisifications of his word ‘Phlogiston’. We could say that the original word is ambiguous among the precisifications except that ‘ambiguous’ suggests a small number of unrelated senses, and suggests that normally one only is intended; whereas here we have a vast number of very closely related senses, and Priestley’s intentions are not definite enough to resolve the ambiguity. (Why should they be?) Sad to say, Priestley is mistaken; all the most stringent of the precisifications are denotationless – though not senseless, in view of what they would have denoted under other conditions – and although some of the less stringent ones have denotations, they don’t all have the same denotation. Thus ‘Phlogiston247’ denotes hydrogen, ‘Phlogiston46’ and ‘Phlogiston653’ denote affinity for oxygen, ‘Phlogiston79’ denotes deoxygenated air, i.e. nitrogen, . . . . They don’t do these jobs of denoting in unrelated ways, mind you; it always works by satisfaction of some of the same list of conditions. (Or better: by teaming up with a partner to jointly satisfy . . . .) Now, Lavoisier, or the agnostic bystander, or the historians in our time, know all that I’ve just said about Priestley’s word, its ambiguity, and its many precisifications. (Maybe we’d need a bit of prompting to state what we know in such a way as I did!) That knowledge is what you both call our ‘interpretation’ of Priestley; and when we have it, we have something intermediate between translation and incomprehension. With that I presume you’ll both agree. Can we translate Priestley? We have all the precisifications; they are definable in, they belong to (a merely definitional extension of) neutral language. They capture, among them, the senses as well as the actual and counterfactual denotations of Priestley’s word ‘Phlogiston’. They seem more suitable as translations than a word like ‘hydrogen’ or ‘deoxygenated air’ or ‘that which differs from itself’ (a stock ex­ample of the guaranteed-denotationless term) or the like, which capture the de­nota­tions of various of the precisifications – or so we think, anyway – without capturing the sense of any of them. And, as I said, I’m with Tom against Philip about



601.  To Thomas Kuhn and Philip Kitcher, 14 January 1983

313

the need to capture sense if we’re to have adequate translation. And I’m obviously not the sort of ‘new theorist of reference’ who doesn’t believe in senses. The trouble is that the precisifications aren’t ambiguous enough. None of them captures more than one of the senses between which Priestley’s word was ambiguous. It wouldn’t even be right to switch from one to another with context, guided by a principle of translating Priestley so that he comes out always meaning the most sensible thing in the range available to him. The right translation would have to be ambiguous between the precisifications. And I don’t see how we can introduce an ambiguous term into our neutral language by merely definitional extension. Try it: dat =df dog/cat (ambiguously) You get the idea; but it ain’t a definition! (Maybe one could exploit preexisting ambiguity to do the trick though.) But what does it matter if ‘Phlogiston’, like ‘dat’, is untranslatable? Priestley’s theory is not therefore untranslatable. For Priestley didn’t need the conveniently and harmlessly (he thinks!) ambiguous word ‘Phlogiston’ in order to state the whole content of his theory ‘without residue or loss’. For he thinks that there are a pair of substances that satisfy (jointly) all the conditions on the list; let him just say so. Or, if he wishes to distinguish what he takes to be the firmer from the more tentative parts of his theory, let him say that he is quite sure there are a pair of substances that satisfy the first five, and at least four of the next five, and at least half of the last ten; and let him say that he is inclined to think that these same substances satisfy the remaining conditions as well. Yours, David PS I’ve skipped the whole issue of whether to take definitions by theoretical role plain, or rigidified. I’m not convinced that linguistic evidence really supports rigidification; or even that there’s a genuine question. But even if theoretical terms are rigidified, I don’t think getting the reference right is adequate for translation.2

  Cf. Lewis’s remark on Kuhn in Letter 422. To J.J.C. Smart, 18 February 1965, Volume 2: Part 4: Mind.

2

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602.  To Thomas Kuhn, 16 April 1983 [Princeton, NJ] Dear Tom, Thank you for the revised version of the PSA paper,1 and for your letter. Yes, it would be a good idea for us to talk about theoretical terms, translatability/ commensurability/comprehensibility etc. I’m sure an opportunity can be found – I haven’t any present plan to be in Boston, but I’m there often enough. I don’t grant you that ‘a term that is ambiguous must be recognized as such by a native speaker’ – not when the ambiguity is between closely related senses that we seldom need to distinguish. Thus I think our word ‘restaurant’ is ambiguous in a way we seldom notice. Sometimes it is a word for certain buildings; in this sense, a ­res­taur­ant can change owners, change name, change the sort of food it serves. Sometimes it is a word for certain businesses: in this sense, a restaurant can move to a new building. I think I could talk some, but not all, native speakers into recognizing this ambiguity; few would notice it without a good deal of persuasion. So it is with Priestley and ‘phlogiston’. I hope that if he were patient and our conversation weren’t sidetracked, I could get him to consider how his words apply to the situation we take to be actual; I think he should say, and I hope he would say if properly asked, that in a sense nitrogen would be phlogiston and in a sense it wouldn’t. I distinguish this from the ‘esprit’ case; here, I take it you think we (the French) have a unitary concept applying to a range of things, actual and possible, for which we don’t have any unitary concept. That’s no reason to call ‘esprit’ ambiguous, even if we don’t always translate it the same way, I agree. I called ‘phlogiston’ ambiguous not because we might translate it differently on different occasions, but because I thought that the phlogistic chemists hadn’t decided how it should apply in (what they took to be) merely hypothetical cases; the alternatives between which they were undecided, then, would be the disambiguations. Yes; we may suppose that ‘Priestley had made all the semantic decisions ­relevant to the application for the term “phlogiston” just in case phlogiston did exist’. That is, just in case something that was definitely phlogiston, that fulfilled the phlogiston-role perfectly, did exist. The indecision covers only cases in which his theory would have been at least partly wrong. But that’s still ambiguity, I think, though if Priestly had had the luck to be right, it would be an especially harmless kind of ambiguity.

  ‘Commensurability, Comparability, Communicability’ (Kuhn 1982).

1



603.  To Margaret Gilbert, 24 May 1983

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I don’t really see how the interdefinition of several terms changes the fact that  the several conditions making up the role are unified by the theory that there’s something that realizes them all; and that the several precisifications of the language are unified by the way they all apply to the same thing if indeed the role is perfectly realized. Yours, cc: Philip Kitcher

603.  To Margaret Gilbert, 24 May 1983 [Princeton, NJ] Dear Margaret, Thank you for ‘Some Limitations . . .’.1 I liked it. You’re right that I don’t think that rationality as such implies a tendency to follow salience; or, in particular, to follow precedent. What I do think is that a tendency to follow is consistent with rationality; and a tendency to expect others to follow salience is consistent with mutual expectations of rationality. It occurred to me that a single example could have done to illustrate both your points at once. Say that we have a coordination problem that has arisen once before, so there’s a precedent but not a well-established convention; but unfortunately it’s clear this time that the solution suggested by precedent isn’t the absolute best point; but there is an absolute best point, somewhat but not overwhelmingly better. Then it’s enough to say that rational agents might well go either way: that settles that they’re not certain to go for the best point, and also that they’re not certain to follow precedent. An amusing possibility – I forget where I saw it, maybe Schelling – is that there are a lot of solutions tied for best, but one solution that’s salient by being worst – worse, that is, than anything except the failures to coordinate. That is, you might have pure coordination with zero payoffs off the diagonal, 1’s at most places on the diagonal, and a .98 at one place on the diagonal, and no other source of salience. I think rational agents might very well coordinate on the .98. Yours,

  See ‘Rationality, Coordination, and Convention’ (Gilbert 1990).

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604.  To Arnim von Stechow, 24 May 1983 Princeton University Princeton, NJ Dear Arnim, I’ve looked at your ‘Comparing . . . Comparison’,1 though I haven’t the background in syntax to pay close attention to all parts of it. I like the idea of using double indexing for yacht sentences and the like. I mention the possibility very briefly in ‘Counterfactuals and Comparative Possibility’, Journal of Philosophical Logic 2 (1973) 436–7; but without looking inside the clause with double-indexed truth conditions to see how it is built up from constituents. I’m not sure that use of an ‘actually’ is the best way to introduce the double indexing; it seems to force you to introduce one or the other of two things that might be slightly unwelcome because alien to what we see on the surface. (I do not think that’s a very serious objection.) We could of course introduce quantification over degrees or the like, and put in the ‘actually’ thus: Some d: (x is ³ d long & Actually Not: x is ³ d long) Or we could introduce a comparative operator between sentences (x is long) is more the case than (Actually: x is long) (which would fit the true-at-more-delineations approach). Both seem a bit artificial; and I think the artificiality is produced by requiring ‘Actually’ to be a sentential operator. It could be instead a predicate modifier; and one that, as it were, modifies a twoplace predicate at one place or the other. Let ‘Actually-2’ be a predicate modifier that attaches to two-place predicates and modifies the second place. Then ‘x is longer than it is’ (in the reasonable sense) could be simply (Actually-2(longer))(x, x). I enclose a letter to Kit Fine2 which ends with the suggestion that if he wants to ­analyze a certain sentence without resorting to one or another of various questionable entities (which, to me, is not something very necessary to accomplish!) he needs not the double-indexing sentential operators but rather double-indexing predicate modifiers.

  ‘Comparing Semantic Theories of Comparison’ (von Stechow 1984).   Letter 162. To Kit Fine, 8 March 1983, Volume 1: Part 2: Modality.

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605.  To Julia Driver, 27 May 1983

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Initially, Allen Hazen (Melbourne) and I discussed double-indexing predicate modifiers several years ago; I don’t remember clearly, but I think the idea was more his than mine. Yours, David

605.  To Julia Driver, 27 May 1983 Princeton University Princeton, NJ Dear Julia Driver, Thank you for your letter. I’ve enclosed copies of the page proofs of a set of postscripts to ‘Truth in Fiction’, in my Philosophical Papers, Volume I (Oxford University Press, 1983).1 I don’t know when the book will actually be available. They’ve announced several dates, all of them now past. These postscripts are the only thing I’ve written further. The postscripts include some discussion of inconsistent fiction. If not more detailed than what’s in the paper, it’s at least different. It relies on what I’ve called the method of fragmentation, which is discussed in another connection in my ‘Logic for Equivocators’. Noûs garbled that in printing, so I’m sending you a proper copy. Bob Brandom and Nick Rescher have done some closely related work, though I’m afraid they want it to be part of a kind of idealism. Another of the postscripts suggests a solution to some cases of overlapping ­fictions, using Kendall Walton’s idea that the audience makes believe that they’re learning true history, and might well make believe that they were learning it from several sources. But I don’t see that this helps with your case, given the difference in communities of origin. I agree with you that the right treatment of your Hamlet-Heathcliff sentence would not be to go to a world where both stories are told as fact, and which is ­somehow close to the belief worlds of both communities of origin. I have some ­suggestions about the right way to proceed, but not what I’d call a full solution. We know what the truth conditions should be. First find the belief worlds of the community of origin of Hamlet; then find the closest worlds to these where Hamlet is told (enacted?) as fact; then find all the possible people who play the Hamlet-role in these worlds; these are the Hamlets. Then likewise find the belief worlds of the   ‘Postscripts to “Truth in Fiction” ’ (Lewis 1983c, 276–80).

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community of origin of Wuthering Heights; then find the closest worlds to these where Wuthering Heights is told as fact; then find all the possible people who play the Heathcliff-role in these worlds; these are the Heathcliffs. Now your sentence is true roughly iff the Hamlets are more depressed than the Heathcliffs. Perhaps it should be: iff each of the Hamlets is more depressed than any of the Heathcliffs. So far, so good. But we don’t just want an ad hoc solution to the analysis of a particular class of sentences; we want a general treatment of talk about fictional ­characters, from which this solution drops out automatically, and that’s what I haven’t got. My guess is that it’s wrong to think of this as a problem especially about truth in fiction. We’ve got a general problem about what I’ll call modal comparatives. It’s a common problem to your sentence (1) and to ( 2) Fred is less depressed than he might be. (3) Fred would be more depressed if the Mets won than he would be if the Jets won. (4) Fred could be more depressed than Ned could be. Each time, we’re comparing depressions; but we’re comparing them across possible worlds, rather than within a single world. Your sentence falls into place if we think of the tacit truth-in-fiction operators as modalities, as I think we should. If you’re prepared to hypostasize some entities that can be regarded as abstract ­degrees of depression, you’re home. (1)  For some d:  in Hamlet, Hamlet was more than d depressed & in Wuthering Heights, Heathcliff was less than d depressed. (2)  For some d:  Fred is less than d depressed & it might be that: Fred is more than d depressed. and so on. I think there’s no real problem concocting entities to serve as degrees of depressions, points on an ordinal scale, given that you’re prepared to compare depression in the first place. Note that you don’t need a quantitative measure. But it seems a bit hoky to use this in analysis of ordinary language; for even if you’re willing to believe in the degrees, your average clod in the street doesn’t; so is it fair to say that he means an existential quantification over them when he says (1) or (2) or . . .? Maybe we shouldn’t worry, I’m not sure. I know a couple other treatments of modal comparatives, but they also seem a little hoky. Maybe you should apply to Rich Thomason: he could probably think up all the solutions I know, and another six, before breakfast. Sincerely, David Lewis



606.  To Julia Driver, 27 June 1983

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606.  To Julia Driver, 27 June 1983 [Princeton, NJ] Dear Julia Driver, Thank you for your 20 June letter; and for the Ralph Clark paper,1 which I hadn’t seen. On fragmentation: no part of the story is supposed to be forgotten altogether. You don’t delete the inconsistent portions, you divide them: the shoulder wound goes in one fragment, the leg wound in another. Of course, there can be a lot that doesn’t need dividing, that goes in all the fragments: for instance that Watson’s wound was a war wound (not, say, a hunting accident). The motivation for fragmenting, instead of having truth value gaps, ought to be to your liking: the point is to preserve the intuition that ‘the author has the final say over what is true in his fiction’. If Conan Doyle plainly says that Watson was wounded in the leg, then there’s no getting around it: it’s true in the stories that Watson was wounded in the leg. The author hath spoken. And if elsewhere he says it was in the shoulder, no getting around that either. The big worry about fragmentation, in connection with fiction and in other applications too, is that every contradiction has to be divisible – it has to turn into a disagreement between two (or more) statements that are themselves consistent. Else we get collapse: no one fragment can contain the undivided contradiction without everything coming out true in that fragment, hence true in the whole corpus. So what’s true in naïve set theory, where the contradiction can be traced to a single axiom schema? I hope there’s some sensible way to regard even that as a divisible contra­dic­tion, but it rules out any simple general account of where to cut the fragments. Sincerely,

607.  To Arnim von Stechow, 29 June 1983 Princeton University Princeton, NJ Dear Arnim, On not liking to quantify over degrees: I don’t really mind. For I believe in a rich enough ontology that I won’t have any trouble constructing entities to play the role   ‘Fictional Entities: Talking About Them and Having Feelings About Them’ (Clark 1980).

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of degrees, so that whenever A is more X than B, A gets associated with something in the constructed system of degrees that exceeds what’s associated with B in the system’s built-in ordering. But not everybody believes in such a rich ontology. Or, at least, not everyone claims to. If you discovered that the only way to do semantics for comparatives required quantification over degrees, that would be good news for me: the nominalist-actualist betrays his principles whenever he says that Goodman is a wiser philosopher than Plato! But I think it’s too good to be true; so I’d like to see semantics done more neutrally. Or rather, I’d like to see the best possible effort toward neutrality; I wouldn’t mind seeing it fail. I think you stack the deck with examples about height or length. In these cases,  there are indeed degrees that almost everyone believes in, and everyone talks  about. So let me stack the deck the other way. I say that Aristotle is more ­boring than Plato; or that Aristotle is more boring than Plato is sarcastic. A general treatment of comparatives has to handle ‘more boring’; and if a general treatment quantifies over degrees, then in this case it quantifies over degrees pretty remote from ordinary thought or language. If we get a degree-free treatment of comparative boringness, then the next question would be whether to stick with it in the special case that we definitely have degrees, or whether to have different treatments for the different cases. Suppose we had a degree-free general treatment of comparatives, and we wished to return to cross-scale comparatives like your ‘Ophidia is longer than broad’; we could bring in the degrees then, in the special case where we definitely have them and the cross-scale comparison definitely makes sense. For we turn the ‘longer than broad’ comparison into a comparative that applies directly to the common scale of degrees, and that does not cross scales: ‘The degree to which Ophidia is long is greater than the degree to which Ophidia is broad’. Then the general degree-free theory applies to ‘greater’ – without, which is a merit, introducing meta-degrees to be the degrees to which an ordinary degree (a length or breadth) is great. Why shouldn’t ‘Ophidia thinks she is longer than herself’ mean something sensible, viz. what you get by applying the predicate modifier I called ‘Actually-2’ to the second place of ‘longer’? I agree that it shouldn’t mean that. I would hope for a syntactic way to bar the reading; but on the question whether that’s feasible given other desiderata for syntax, you know much more than I do. How about ‘Ophidia is longer than we thought’? You say the complement is certainly a sentential. Not obviously so, though you may well know of decisive syntactic reasons that aren’t obvious. I offer – in a tentative way, with little idea whether they’d square with the rest of reasonable syntax – two ways that might be tried. The first treats ‘We thought’ as a sentence modifier; the second, as a predicate modifier that does the same trick of attaching itself to one place of a comparative as my



608.  To Arnim von Stechow, 21 July 1983

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‘actually-2’ does. ‘Actually-1’ is like ‘actually-2’ except that it modifies the first place rather than the second. First suggestion: We thought: Actually-1(longer) (Ophidia, Ophidia) Second: We-thought-2 (longer) (Ophidia, Ophidia) (I don’t mean to suggest that ‘We-thought-2’ lacks internal structure, but I haven’t suggested what its structure might be.) My colleague Mark Johnston is working on a related matter, so I’m taking the liberty of sharing this correspondence with him. Yours, David

608.  To Arnim von Stechow, 21 July 1983 Princeton University Princeton, NJ Dear Arnim, No, I’m afraid I don’t think the ‘how’-questions and their answers suffice to ­settle whether a general treatment of comparatives should use degrees of whatever is being compared. First, because it seems to me that there is one kind of case that doesn’t work as nicely with degrees as the cases you considered do. Conversation: – How boring is Aristotle? – He is more boring than most authors. In fact, he is more boring even than most philosophers. In fact, even if you take only those philosophers who are more boring than most philosophers, Aristotle is more boring than most of those! – Oh. Thank you for the warning! If Aristotle is that boring, I shall study ­paraconsistent hermeneutics instead. Now in your example, the answer was different. ‘He is that boring’ [said after listening to Henze’s boring symphony]. In that case, it’s quite plausible to suggest as you did that the demonstrative ‘that’ refers to a degree of boredom, namely the degree just exemplified by the symphony. But in my example, no particular degree of ­boredom – if there are such things – has been exemplified, referred to before, or otherwise made salient enough to permit demonstrative reference. What went

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before, if understood in terms of degrees, was not an equation but an inequality. Or rather, three inequalities. If anything at all has been said about Aristotle’s degree of boringness, all that has been said is that it is some degree that exceeds the degrees of most authors, etc. So if ‘that’ is supposed to achieve demonstrative reference, what specific degree is available to be demonstrated? I don’t think this is decisive against the degree treatment. You could complicate the story: there are exact degrees, and there are degree-intervals. In your example, ‘that’ referred to an exact degree; in mine, it referred to a degree-interval. A half-open interval, with a lower bound but no upper bound; and a somewhat vaguely specified interval, given the vagueness of ‘most’ (and ‘philosopher’) but that’s no worry, we just apply our general recipes for dealing with vague denotation. I’ve tried to bypass a complication that appears in your example. I take it that we compare boringness of authors (including composers) by comparing the boringness of their works; and we compare the boringness of their works by comparing the boringness of experiences of acquaintance with their works. Second, because I think there is another way to account for your examples, without degrees. Take it that ‘How boring is Aristotle?’ is not a request to be told a degree, but rather is a request for information of a comparative sort about his boringness. That is why the question can be answered – as it can be – by saying something comparative, even if no exact degree is given. Also, it can be answered using adadjectives: ‘very boring’. But I think that’s implicitly comparative: ‘very boring’ means roughly the same as ‘more boring than most of the ones that are boring’, ‘very, very boring’ means roughly ‘more boring than most of the ones that are very boring’, and so on. (I don’t know whose idea this analysis of ‘very’ is – not my own.) If there are degrees, then information about them will do as one way of giving (by implication) information of a comparative sort, so the fact that ‘how boring?’ could get the answer ‘3.6 drears’, if only we had degrees measured in drears, is consistent with my suggestion. Then I turn to the ‘that’ which you suggest might refer to a degree. Might it rather function anaphorically, as something we might call a pro-ad-adjective? Thus I say ‘Aristotle is more boring than Plato’ and you say ‘that boring’ just to abbreviate the phrase I’d used; ‘that’ stands for the ad-adjective phrase ‘more . . . than Plato’. There are at least some other cases in which ‘that’ acts as a pro-form. ‘Aristotle is boring’ – ‘If he’s that, you may be sure that Lewis never reads him’. It would be nice if there were a wide range of such uses, but I don’t think my proposal depends on it. Can you come up with more? I have no trouble with the idea that ‘Aristotle is more boring than we thought’ compares Aristotle with his less boring counterparts in what used to be our belief worlds. ‘If Aristotle is as boring as that [viz. if reading his works is as boring as



609.  To Julia Driver, 27 September 1983

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listening to Henze’s symphony] then he is more boring than I thought he was; for Aristotle as I used to think that he was [i.e. Aristotle as he is in what used to be my belief worlds, i.e. Aristotle’s counterparts in my former belief worlds] is not that ­boring [i.e. reading his works is not as boring as listening to Henze’s symphony]’. Your (8) and (9)1 are understandable, but not grammatical, in English. Grammatical English comes close to (8): we can say ‘How boring did we think Aristotle was?’, and the only difference is in the location of ‘was’. We can’t say ­anything very close to (9). What would I think decisive? I suppose two things in combination. (1) The treatment involving degrees can be implemented without severe artificialities in syntax (where the standard of severity is set by the artificialities we have to put up with in the rest of syntax); and (2) a degree-free treatment cannot be. You are arguing for (1), and I’m quite prepared to believe it; (2) is the harder part, since it means establishing a negative. In any case, I don’t know enough about syntax to have views on such a question, or even to understand the arguments. I find that syntax is not something one can learn a little about, then a little more, . . . . The arguments for any way of doing one thing seem to turn on what has already been decided about how to do the rest. I’m off to Australia tomorrow; back in late September. I’m afraid I can’t give you a satisfactory mailing address there, but anything to Princeton will get to me eventually. Greetings to Max. Perhaps he would like to see these letters? Again, I’m sharing them with Mark Johnston here. Yours, David

609.  To Julia Driver, 27 September 1983 [Princeton, NJ] Dear Julia Driver, Sorry to be so long answering your 27 July letter – I’ve been away almost two months. Whether you could fragment the story about Fred the round square would depend, I suppose, on how the story goes. There might be parts that have a lot to do 1   ‘(8) How boring did we think was Aristotle? (9) How boring we thought Aristotle was, he was more boring than that’ (Letter from Arnim von Stechow to David Lewis, 22 July 1983, p. 2).

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with the roundness of Fred and nothing to do with the squareness (as when he rolls down a hill), and others that have to do with the squareness but not the roundness. Then you could divide the story, without artificiality, into a fragment according to which he’s round, not square, and one in which he’s square, not round. It might be part of both fragments that he’s called ‘Fred the round square’ – but what’s in a name? But the contradiction might be more indivisibly built into the plot: what happened when they traced around him with a compass, what doubters said when they first saw him, . . . . Then indeed the contradiction might be indivisible, or divisible only in excessively artificial ways. If so, I think we shouldn’t want to have a non-trivial account of what’s implicitly true according to the story; the best we can do is fall back on what’s explicit, what the story says in so many words. Sincerely,

610.  To Marvin Belzer, 30 September 1983 Princeton University Princeton, NJ Dear Marvin Belzer, Thank you for your ‘Normative Kinematics. . .’.1 I have now read it; haven’t worked through the details of your examples and proofs, but I assume they’re OK. I’m sorry I didn’t write to you sooner. The reason is that I was away for two months from July. I like the paper. It does seem to be the sort of thing I was looking for as a solution to my problem about permission.2 The reason why I myself didn’t extend my ‘answer 3’ in the way you suggest is quite simply that I didn’t think of it. It’s not that I know of some problem that you have overlooked. I’ve agreed all along that it’s an oversimplification to take permissibility as all-or-nothing. But I’d thought, wrongly as it now seems, that it would be a good idea to separate the complications about levels of permissibility from the complications about the kinematics. I do have a question. Not an objection, a question. To help me state it, I’m going to restate your proposal in a different way. Capital letters will stand for propositions, i.e. sets of worlds. Since we have a permissibility-ranking of worlds with only finitely many levels, we can introduce a   ‘Normative Kinematics (I): A Solution to a Problem About Permission’ (Belzer 1985).   Cf. ‘A Problem About Permission’ (Lewis 1979c).

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610.  To Marvin Belzer, 30 September 1983

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selection function: I’ll write fA for the set of best A-worlds, i.e. the ones that are most permissible or closest to permissibility. Instead of the imperative !-¡ notation, I’ll use the deontic O and P that are on the keyboard. Consider the case in which B is a contrary of A. Now I can restate your rules like this. ( 1) Suppose the master decrees that P(A/A ∨ B); and suppose that’s initially false; so that accommodation is required, i.e. the ranking must change to make true what the master has said. Then initially fB is ranked better than fA, but after the change fA must be either better than or equal to fB. Then (a) the new fA is to consist of the same worlds as the old fA; (b) the ranking of all worlds outside fA is to be unchanged; and (c) fA is to move relative to the other worlds so that it is ranked equal to fA. ( 2) Suppose the master decrees that O(A/A ∨ B); and suppose that’s initially false, because initially fA and fB are ranked equal. After the change, fA must be ranked better than fB. Then again (a) the new fA is to consist of the same worlds as the old fA; and (b) the ranking of all worlds outside fA is to be unchanged. This time (c) a new level is to be interpolated between the original level of fA and fB and the next better original level, and fA is to move to this new level. ( 3) Suppose the master decrees that O(A/A ∨ B); and suppose that’s initially false, because initially fA is ranked worse than fB. Then we make the change specified in (1) followed by the change specified in (2), so that it’s as if the master had said first P(A/A ∨ B) and then O(A/A ∨ B). These rules are largely dictated by conservatism, or ‘minimality’ as you say. We don’t move fA farther than we have to; we don’t change the membership of fA; we don’t do anything to the ranking outside fA. Fine. But there’s one thing that is not dictated by minimality. Why did we push fA around, to produce an outcome that could just as well have been produced by moving fB? Subject to the same kinds of conservatism: don’t move fB farther than we have to, don’t change the membership of fB, don’t do anything to the ranking outside fB. Why pick on fA? Why not equalize fA and fB, to accommodate P(A/A ∨ B), by moving fB relative to the rest, putting it on the worse level of fA? (Or they could both move and meet halfway; that’s less conservative in that more worlds get moved, but more conservative in that no one world gets moved as far.) Or in case (2), why move fA to an interpolated level just better than its original level? Why not instead move fB to an interpolated level just worse than its original level? Subject to the same kinds of conservatism, of course. Those are not rhetorical questions. I can think of two answers. I wonder if you can see any reason to prefer one of the answers to the other, or if you can offer a third answer, or if you can find a way of making my two answers look less different than they do at first.

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The first answer is that our sentences P(A/A ∨ B) and O(A/A ∨ B) somehow focus on the A-worlds, and don’t focus on the B-worlds. Therefore it’s appropriate that in accommodating them A-worlds should move and B-worlds should stay put. A is foreground, B is background. The second answer, at least seemingly different, is that P(A/A ∨ B) is a permission sentence; it’s appropriate that it should be accommodated by making some worlds more permissible relative to background, not by making some worlds less permissible. A permission should make life easier, not harder. Whereas O(A/A ∨ B) is an imperative; it should make things more stringent; the appropriate way to accommodate it is to avoid making anything more permissible than you have to. So if you have fA, fB, and C initially all on a level, and you split that level to make fA better than fB, then C should end up on the worse level with fB, not on the better level with fA. Both these answers rely on the syntactic form of the dyadic deontic sentences. In one presentation of the problem (‘Scorekeeping . . .’ enclosed) I tried to bypass the semantics of deontic sentences by imagining that the master explicitly says things about the ranking of worlds. I meant that for a simplification; but now it seems to make the problem harder, by taking away syntactic guidance as to which worlds ought to get moved. At the end of the paper – page 37, lines 3–4 – you very briefly express a worry that things may be more complicated in real life. I wonder if I could put it thus; and if so, I somewhat share the worry. Suppose we accommodate P(A/A ∨ B) by moving fA to equality with fB; to do this, we make fA better by five levels. We leave the rest of the A-worlds where they were, motivated by conservatism. But thereby we widen the gap between fA and the second-best A-worlds; that is between fA and f(A-fA). Was that really what we wanted? In one way, it would have been more conservative to move the A-worlds as a rigid block, leaving comparison between them unchanged not only in order but in degree. (I realise we haven’t really introduced proper degrees – but I’m thinking of level-counting as a rough and ready approximation to degrees.) Should we maybe have made every A-world five levels better, so as not to introduce exaggerated gaps between the best and the rest of them? The master could have done this by means of a whole lot of P-sentences; should he be deemed to have done so even if he really didn’t? I’m not at all sure one way or the other. I think Bob Stalnaker would share my interest in your paper and I’m sending him a copy of this letter. Sincerely, David Lewis



611.  To Graham Priest, 3 October 1983

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611.  To Graham Priest, 3 October 1983 [Princeton, NJ] Dear Graham, I took home a copy of ‘On Paraconsistency’1 which I’ve now read with interest, and even with occasional agreement. I noted the passage saying that usability in certain contexts of disjunctive syllogism is a point that ‘needs to be handled with some care’ (123). The need for care may connect with some perplexity that I, and my colleague John Burgess, have felt about a remark of Richard’s. He says (EMJB, 894) that ‘classical logic can be recovered in those situations (consistent and complete ones) where it is valid. Likewise, other logics can be enthymematically recovered . . .’.2 If I understand this, and I’m not at all sure I do, what’s meant is that we get valid inferences if we add some extra premise X to arguments that fail to preserve truth in the presence of paradox. That is, X, ¬A, A Ú B / B, or even X, ¬A, A / B, is valid simpliciter, because somehow X says that the situation is unparadoxical. A first question is what X looks like – it can’t be ¬ ( A& ¬A ), not if that goes paradoxical along with A itself, and is paradoxically true in just the situations meant to be excluded. A second question is why there can’t be a true contradiction of the form X, A, ¬A. I can think of answers – X just means that there’s no such contradiction – but they parallel arguments against simpler contradictions that I’m sure you’d reject as question-begging. A third question concerns use of the endorsed logic as a closure condition for implicit belief (or theoretical commitment, or truth in a story, or . . .). If X expresses the consistency of the situation, I’m sure you wouldn’t believe X. But I would; and yet I might fall into contradiction unwittingly despite believing X; and yet I wouldn’t believe everything.

1   ‘On Paraconsistency’ (with R.  Routley). Research Report #I3, Research School of Social Sciences, Australian National University 1983. Reprinted as the introductory chapters of Paraconsistent Logic: Essays on the Inconsistent (Priest, Routley, and Norman 1989). 2   Exploring Meinong’s Jungle and Beyond: An Investigation of Noneism and the Theory of Items (Routley 1980, 894).

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This leads up to a request. Would it be possible to see the paper of yours which was cited as showing the need for care, ‘Reductio ad absurdum et Modus Tollendo Ponens’?3 I hope it discusses ‘enthymematic recovery’, but I’d like to see it whether it does or not. Many thanks, Yours, David Lewis cc: Burgess

612.  To S.R. Miller, 2 December 1983 Princeton University Princeton, NJ Dear Seumas Miller, Thank you for your paper.1 It was good to hear from you. It’s possible that I may see you next (southern) winter; I’ve accepted an invitation to visit Witwatersrand briefly, and expect to travel to some of the other English-language universities. L.J. Suzman, Wits, is in charge of arranging the travels, since I don’t know enough; and time is short; thus I don’t know which places he’ll pick. I suggest this reply to your first example about the language of Ronald and Yuri. It somewhat resembles the reply you consider on page 4, but it doesn’t claim ambiguity. First a parallel case. It seems that the generalisation (G1) is true; whereas its instance (I1) is false, supposing Fred to be ignorant. (G1) For any number n, Fred knows that n is the number of planets iff n is the number of planets and Fred knows how many planets there are. (I1) Fred knows that the number of planets is the number of planets iff the number of planets is the number of planets and Fred knows how many planets there are. How can this be? I reply that (I1) is not really an instance of (G1), at least not in a sense of ‘instance’ that makes valid the inference from generalisation to instances. It’s fallacious to instantiate on non-rigid terms in an intensional context, and the inference  ‘Reductio ad Absurdum et Modus Tollendo Ponens’ (Priest 1989).

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1   A paper on Lewis’s theory of convention that seems to have never been published. It and Lewis’s response in this letter relate to several of Miller’s publications on convention. See for instance ‘Conventions, Interdependence of Action, and Collective Ends’ (Miller 1986).



612.  To S.R. Miller, 2 December 1983

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from (G1) to (I1) would be an example of that fallacy. For ‘the number of planets’ is a non-rigid designator of the number 9, and ‘knows’ creates an intensional context. A legitimate instantiation of (G1) would have to give you an instance like Fred knows that 7 is the number of planets iff 7 is the number of planets and Fred knows how many planets there are Or Fred knows that 11-2 is the number of planets iff 11-2 is the number of planets and Fred knows how many planets there are. (Fred is ignorant of astronomy, not arithmetic; so I won’t worry about further ­problems of hyperintensionality that cast doubt, perhaps wrongly, even on what we get by instantiating to the rigid term ‘11-2’.) Likewise I maintain that something like (G2) is true – I simplify – whereas you correctly note that its seeming instance (I2) is false. (G2) For any language L, the tribe use L iff they expect and endeavour that no ­sentence of L is uttered unless it is true in L. (I2) The tribe use the language of Ronald and Yuri iff they expect and endeavour that no sentence of the language of Ronald and Yuri is uttered unless it is true in the ­language of Ronald and Yuri. I say that (I2) does not follow from (G2), so its falsity casts no doubt on (G2). (And likewise for a less simplified formulation, in which a more complex system of attitudes, constitutive of a convention, replaces ‘expect and endeavour’.) For (I2) comes from (G2) by fallacious instantiation to the non-rigid term ‘the language of Ronald and Yuri’ in the intensional context created by ‘expect and endeavour’. *** On page 194 of Convention, ‘sustained by an interest in communication’ is glossed as ‘. . . in being able to control one another’s beliefs and actions to an extent by producing sounds and marks’. Almost the same phrase reappears at the end of Section II of ‘Languages and Language’; but in view of my addition of trust to truthfulness, it might have been a good idea to add ‘. . . and in putting one’s own beliefs and actions to some extent under the control of others [in the population]’. That looks like what you call the ‘weak sense’. So I think the case on pp. 6–7 is met. As for the case on p. 12, I can’t comment; because I don’t really understand what’s supposed to be going on in the tribe this time. *** You come to believe, when you trust the speaker, by inference from premises. The logic isn’t conventional, and the coming to believe isn’t a conventional act. Yet

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you come to believe in conformity to a convention; because it’s (part of) the other’s conformity to the convention that gives you one of your premises, thereby giving you your reason to believe. Sincerely, David

613.  To Frank Jackson, 10 July 1985 [Princeton, NJ] Dear Frank, [. . .] I think I won’t apply for Robert’s A$1000. I’ve already asked Barry if he can arrange an Ormond flat and a mailbox at Melbourne Uni, and I think it might save embarrassment to be connected with only one place at a time, minimal though the connection with Melbourne Uni will be. But at any rate I can let the matter wait until I arrive. This is backward. I should begin by announcing that we will indeed be coming. I enclose the itinerary. The four weeks shown as being in Melbourne are meant to include some time elsewhere: maybe a visit to Jack, maybe driving in western NSW, but not planned yet. Partly it depends on whether Steffi will be with me for the full time; partly on how Barry does for us with Ormond; partly on whether it’s feasible to hire something with four-wheel drive in Broken Hill. *** This has been a right bastard of a year. Most importantly, because Steffi’s job search went on and on. At last she has one definite offer – not quite ideal, but certainly good enough to be content with – and another prospect that might (or might not) be better if it comes through. The uncertainty in her travel plans is because if she takes the offer in hand, she must start immediately but can take three weeks off later; whereas if she gets and takes the other, maybe they’ll let her not start until September. Besides, cat Bruce died. His virus caught up with him at last. First it hit the bone marrow, but it was possible to keep him going at about 75% of normal with blood transfusions. Then it hit something else, we don’t really understand what, and finished him off very suddenly. We miss him very much. Besides, both my books – Papers II1 and Plurality of Worlds2 – dragged on much longer than they were supposed to. But they’re both done now; they’re through copy editing, and I’m expecting proofs soon.   Philosophical Papers II (Lewis 1986c).   

1

2

  On the Plurality of Worlds (Lewis 1986b).



613.  To Frank Jackson, 10 July 1985

331

Besides, there was the periodontist. *** Working on the books (and then catching up with a backlog of other work) has meant an embargo on philosophical correspondence, but I have wanted to make one comment on your rest and motion paper with Robert.3 I liked it very much, and – despite what I’m about to say – I agree with it almost completely. But I think more needs saying at one point. Near the end you remark, without comment, that on your approach (0) X has an indeterminate velocity at t = 0 ‘comes out false, as it neither has an indeterminate left-hand velocity nor an indeterminate right-hand velocity’. Isn’t that an embarrassment? Is this ‘exactly the result that [has] intuitive appeal’? Don’t you want to say that the velocity is indeterminate whenever the left- and right-hand velocities differ? I feel the need of a patch, and I’d patch something like this. We know what it means to say that Φ is true on a given resolution of a semantic indeterminacy (e.g. the indeterminacy of left- versus right-hand velocity); and Φ is super-true iff Φ is true on all resolutions of the indeterminacy. (In van Fraassen’s terminology: true on the supervaluation iff true on all the classical valuations.) Likewise Φ is super-false iff Φ is false on all resolutions of the indeterminacy. We can introduce a determinacy operator into the object language: ‘determinately Φ’ is super-true iff Φ is super-true, super-false otherwise. So (1) Not: for some v: determinately: X has velocity v at t = 0 is true; whereas (2) Not: determinately: for some v: X has velocity v at t = 0 (3) Determinately: not: for some v: X has velocity v at t = 0 are false. Maybe (0) means (1). Or maybe it’s ambiguous between (1) and (2) or (3), but (1) is the preferred disambiguation because of the near-triviality of (2) and (3). Either way, that’s why (0) seems true. Now if there’s a determinacy operator, it creates exceptions to your general principle that ‘statements about velocity . . . are true (false) if both interpreting them as statements about left-hand velocity and interpreting them as statements about right-hand velocity make them true (false). They are indeterminate otherwise’. For by that principle, (1) would be false; whereas by my stipulative introduction of the determinacy operator, (1) is true. But isn’t it good enough for your purposes to say

  ‘A Question About Rest and Motion’ (Jackson and Pargetter 1988).

3

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that the general principle works for some large part of the language, the part without any determinacy operators or the like? It would be hard for you to insist that the principle holds in full generality. Because what stops me, if I choose, from introducing a determinacy operator, hence an exception to the principle, by stipulation? And if so, then it’s an open linguistic question whether the language has a determinacy operator already. (Maybe a tacit one, in some sentences; maybe one that doesn’t take the form of a sentential adverb.) Once it’s an open question, the evidence – namely, that (0) seems true – suggests that indeed the principle does have exceptions. Kripke called this sort of problem to my attention several years ago. He thinks it’s a very serious objection to the whole idea of supervaluations that you can deviously make things come true that suggest the opposite of what you really believe. Thus a supervaluationist, although really he thinks that it’s extremely indeterminate how many beans make a heap, has his way to say that there is a determinate line between not enough and enough. And Putnam (as I interpret him), though of course he really thinks that reference is horribly indeterminate, has a way to say that it’s determinate ‘internally’. I think Kripke over-reacts; the proper response is not to condemn the whole idea of supervaluations as a license for skulduggery, but rather to be prepared to distinguish readings that give the ‘determinately’ different scopes, the way I just did. See you soon, Yours, David

614.  To Gregory Currie, 20 August 1985 Melbourne, Australia Dear Greg, Thank you very much for the ‘Fictional Truth’ draft.1 I found it very interesting. Here are some newish postscripts to ‘Truth in Fiction’;2 you’ll see that the first two diminish the difference between our positions quite a lot, though not by any means eliminating all difference. [. . .]   ‘Fictional Truth’ (Currie 1986).   ‘Postscripts to “Truth in Fiction” ’ (Lewis 1983c, 276–80).

1 2



614.  To Gregory Currie, 20 August 1985

333

Your section 2 conveys an impression, which I think you did not intend, that you think a theory that begins with the notion of truth in a possible world will be in trouble with all of (A)–(E). Not so, of course, if the theory that begins with truth in a world proceeds to truth throughout a class of worlds. (Compare theories that treat belief as truth throughout a class of ‘doxastically’ accessible worlds!) For a truththroughout-a-class theory, (C) and (D) are dead easy. My ‘method of union’ in the postscripts also covers (B) and part of (A) – namely, the part about closure under deduction from two or more premises – without being any the less based on truth in possible worlds. As for (E), I’ve got the distinction between truth in fiction that doesn’t or that does depend on background and the comparative similarity relation – that’s Analysis 0 versus Analysis 1 or 2 – and that distinction is part, at least, of what you’re asking for. We’re left with part of (A) and part of (E), and the two can be combined. What a theory based on belief might offer (if belief itself works the right way) that a theory based on truth probably can’t is a progression by deduction alone – without appeal to background, and without mixing premises out of conflicting fragments – that goes from explicit truth in fiction to implicit, and then on to further consequences so remote and unobvious that they’re not true in the fiction at all. If that’s indeed a desideratum, you’ve got it and I haven’t. Questions. First a preliminary one, to which I hope I know the answer. In the first-person case, when you make believe the author is asserting, is that the same as making believe that the narrator is asserting? Do you make believe the Holmes stories are told by Watson? I should think yes – if not, I don’t understand your position as well as I think I do. Next. There’s a well-known problem about lying narrators. Some book by Nabokov is the usual example; I’ve used the Flash Stockman (postscript D) instead. I have to handle lying narrators by allowing exceptions – authorized in my footnote 7 – to what I otherwise say. Not nice. Whereas you have no problem with lying narrators: when you make-believedly listen to Ugly Dave asserting, you make-believedly figure out that he’s lying, not as good as he says he is, and that he himself believes this. So it comes out true in the song that he’s lying – as it should. But now take instead a deluded narrator – a tale of successful deception, told from the standpoint of the dupe. (Can you think of a clear example? The best I can do is the song ‘Six Nights Drunk’, but that’s not quite right – the dupe gets at least a bit suspicious.) As you make-believedly listen to his assertions and figure out what’s happening, you makebelievedly conclude that he’s sincere enough but obviously he’s been tricked and things aren’t as he thinks. What’s true in this fiction is not what it would be reasonable to infer that the author (= narrator) believed if you thought the fiction was the product of nondeceptive assertion.

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For me, no new problem – it falls in with the lying narrator, and it’s covered by the exception in my footnote 7. But I think it’s worse for you. Can you handle it other­ wise than by making an exception to what you otherwise say? [. . .] Final question: Aren’t there other reasonable but illegitimate ways of (makebelievedly) inferring the author’s beliefs besides the one you mentioned, viz. know­ ledge who he was? Suppose he militantly says ‘firefighter’, ‘chairperson’, ‘letter carrier’ . . . instead of ‘fireman’, ‘chairman’, ‘postman’. You’ll make-believedly infer, and reasonably so, that he believes women are oppressed. But is that enough to make it true in the fiction that women are oppressed? Or suppose there turns out to be a correlation between two seemingly unrelated beliefs. Some believe and some don’t that (1) Reasonable people can work out their differences if they talk long enough. Some believe and some don’t that (2) The minor choices we make in everyday life never make any perceptible difference to what happens centuries later. It might turn out that believing (1) is extremely well correlated with believing (2). (I don’t suppose the question has ever been investigated.) The correlation might be explained by a common cause – say, some sort of toilet training. All this might become known to you, and throughout the author’s community. It might be true in the fiction according to your proposal that (1). But is that, by itself, enough to make it true in the fiction that (2)? Yours, David

615.  To Terence Horgan, 23 December 1985 [Princeton, NJ] Dear Terry, Thank you for your letter about Analysis 2 in ‘Truth in Fiction’ and the ­speckled band. The point is well taken, and new to me. My motivation was to stop Gans’s argument that the snake did not climb the rope, and Holmes therefore bungled. That I did accomplish. But you’re right to say that that’s not good enough. Not only do we want it not to be true in the story that



615.  To Terence Horgan, 23 December 1985

335

the snake did not climb the rope; we also want it to be true in the story that the snake did climb the rope. And that I did not accomplish. I think it’s otherwise with the other example: psychoanalytic criticism. There I think it’s right that nothing much one way or the other should come out true in the fiction concerning the childhood traumas or the subsequent psychoanalytic condition of the characters. So we need to beware of doing too much – of upsetting the good outcome of the psychoanalytic example while fixing the bad outcome of the snake example. A local fix is called for, not a big change. I wrote ‘Holmes’s infallibility . . . is not a countervailing resemblance to actuality; our world contains no infallible Holmes’. That’s right, but might be misleading. Holmes’s infallibility could still have some weight in another way: by what I called ‘carry-over from other truth in fiction’ (page 274). Even if we have to depart gra­tuit­ ous­ly from some of the collective belief worlds (or from actuality) to get an f-world where Holmes doesn’t bungle, it’s worth it on balance to do so because Holmes is far from a bungler in the other stories. That’s the solution I think I favor. Of course, it means that the snake example no longer works as an argument against Analysis 1; the advocate of Analysis 1 could join the advocate of Analysis 2 in using carry-over to explain why what’s true in the fiction is that the snake climbed the rope and Holmes was right. But we could still use the psychoanalytic example to motivate Analysis 2. (Motivate it as an option: I don’t say that Analysis 1 and the psychoanalytic critics are determinately, unequivocally wrong. Or that Gans is.) Here’s another modification I thought of. It wouldn’t replace the carry-over explanation; but it would mean that the infallibility of Holmes needn’t be a very weighty advantage to swing the balance. Suppose that instead of taking similarity of f-worlds to collective belief worlds one at a time, you take similarity of f-worlds to some sort of center of gravity or average of the collective belief worlds. Then the snake climbing the rope would have no weight one way or the other in making an f-world more or less close to the background of collective belief. That wouldn’t favor f-worlds where the snake climbs the rope over those where Holmes bungles; but it would be neutral, so only a small weight in favor of the former would suffice. Then carry-over can provide that small weight. (Suppose it were very well known that Russell’s viper can’t climb a rope. Then would it be true in the fiction that Holmes bungled? Or that the snake climbed? Not sure, but I rather think the former. If so, that suggests that the weight of carry-over is limited.) Another idea. Again, it couldn’t do the whole job, but it could team up with carry-over. Before they read the story, doubtless the community had no opinion about whether Russell’s viper could climb a rope. But after? I dare say the readers trusted the author to get such things right, and came away thinking the snake could

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have climbed the rope, and expecting one another to come away thinking so, and so on. So, ex post facto and if we ignore the difference between the readers and the entire community, Analysis 2 gives the right answer. But that’s not a solution all by itself. For I suppose it’s because it was true in the fiction that the snake climbed the rope that the readers concluded that the author knew that Russell’s viper could climb a rope. If instead it had been true in the fiction that Holmes bungled, the readers would have drawn no such conclusion. Imagine that the readers reason thus. (Of course, it’s imaginary to suppose such explicitness – really the thing would happen more automatically.) Are we supposed to believe that Russell’s viper can climb a rope? If so, then (by Analysis 2) it will turn out true in the story that Holmes was right; if not, it will turn out that he bungled, or it won’t turn out either way. That would never do: we know Holmes from the other stories, and he’s supposed to be more or less infallible. (Carry-over.) So we are supposed to believe that Russell’s viper can climb a rope. We trust the author not to give us a story in which we’re supposed to believe that unless it’s true. (Here their trust is misplaced.) So Russell’s viper can climb a rope. Other readers will reason as I do; so now it’s overt among us that Russell’s viper can climb a rope. Now it’s true in the fiction (by Analysis 2) that the snake climbed and Holmes didn’t bungle. Feel free to share this letter with your seminar (on the understanding that it’s not to be cited without permission – sorry to say what should go without saying, but I’ve had some bother on this point lately). Yours,

616.  To Terence Horgan, 18 February 1986 [Princeton, NJ] Dear Terry, [. . .] Even though my backlog of unread reading matter is 21ʺ high, I still look ­forward to reading the papers described in your prospectus.1 1   One paper that came out of Horgan’s prospectus was ‘Metaphysical Realism and Psychologistic Semantics’ (Horgan 1991).



616.  To Terence Horgan, 18 February 1986

337

Here’s a view about Mt. McKinley that I’m comfortable with. It’s just an a­ pplication of my general supervaluationist approach to all kinds of semantic ­indeterminacy. Metaphysics. Mt. McKinley (for short: McK) exists. It’s a material object. Material objects are what Quine says they are. There’s no such thing as a vague or ill-defined object. Semantics. We are often indecisive in settling exactly the denotation of our names, or the extensions of our predicates. (And maybe it’s impossible for us to be fully decisive; certainly it would be a lot of work and would serve no purpose to try.) ‘McK’ has indeterminate denotation; it ‘partly denotes’ or it ‘denotes on some de­lin­ ea­tion of vagueness’ or it’s ambiguous between denoting each of many material objects – more or less inclusive versions of the mountain, or inclusive in different ways. Call these objects the McK-candidates. (But note that ‘McK-candidate’ itself has indeterminate extension.) It’s settled, true on every delineation of the vagueness, true on all disambiguations, super-true, . . . that ‘McK’ denotes one and only one of the McK-candidates. But it denotes different ones on different resolutions of the vagueness. ‘Mountain’ also suffers from indeterminacy, and in more than one way; but every resolution of its vagueness puts one, and only one, of the McK-candidates into its extension. Further, ‘McK’ and ‘mountain’ are correlative: not every combination of the resolution of the vagueness of one and the vagueness of the other yields a resolution of the joint vagueness of both together. Every resolution of the joint vagueness makes it the same McK-candidate that both is the denotation of ‘McK’ and is in the extension of ‘mountain’. For the most part, truth-on-all-resolutions (or -almost-all-reasonable-resolutions) is what takes the place of truth simpliciter in determining what’s correct to assert. But there can be exceptions and loopholes to this – it can’t be pushed to extremes. The usual principle applies: construe what’s said so that it makes sense as a thing to say, even if that breaks a general rule. Consequences. All of the following are correctly assertible according to the general rule. Those marked * are to some degree, or in some contexts, disfavored by the make-it-make-sense rule. McK exists. McK is a mountain. McK is in Alaska. I’ve never climbed McK. There is no other mountain in roughly the same position as McK. *McK is only one mountain. McK is a material object.

338

Philosophical Letters of David K. Lewis *McK is a Quinean object. *McK has exact boundaries. It is not the case that McK has boundaries exactly at --------. *McK is not a vague object. *‘McK’ denotes McK. Yours, David

617.  To R.M. Sainsbury, 4 October 1988 [Princeton, NJ] Dear Mark Sainsbury, Thank you for the draft material from Vagueness.1 I have several comments. --[. . .] It’s not quite right that Lewis ‘argued that belief in vague objects cannot account for the existence of vague identity sentences’. My point, which I take to be Evans’ point as well, is that you can’t combine such an account with the idea that vague identity sentences result from ordinary identity sentences having indeterminate truth value. More precisely, you can’t have all four of the following. (I use subscript ‘r’ to mean ‘relative to regimentation r’ and I write ‘V’ for the inverted triangle.) (0) Some sentences of the form ‘V(a = b)’ are true. (1) In such cases, the names ‘a’ and ‘b’ are rigid designators; that is, each of them denotesr the same thing for all r; and at least one of them denotes a vague object. (2) We interpret ‘=’ as identity; that is, a sentence of the form ‘a = b’ is truer iff what ‘a’ denotesr and what ‘b’ denotesr are identical. (3) ‘V’ means ‘it is true on some but not all regimentations that’; that is, a s­ entence of the form ‘VΦ’ is truer iff Φ is truer for some r, and is falser for some other r. What’s refuted is the combination of the vague-objects view, (1); the observation that there are vague identities, (0); and the treatment of vague identities as resulting from indeterminacy of truth value on the part of genuine identity sentences, (2) plus (3). This is how I read the statement in Evans’ introductory paragraph that he’s arguing 1   Sainsbury was writing a book on vagueness but abandoned the plan; ‘the draft material’ that Lewis refers to is some part of the manuscript. For one related article by Sainsbury, see ‘What Is a Vague Object?’ (Sainsbury 1989).



618.  To David E. Over, 25 January 1989

339

against the coherence of a combination of views. Here too I have some support from the ‘Yes, Yes, Yes!’ letter;2 but less conclusive than my support for Evans thinking the argument fallacious and its conclusion false, because my letter to Anonymous3 wasn’t as explicit as I’ve just been about what I took the second half of the combination to be. You can’t have all four of (0)–(3); but you can consistently have any three, and  in particular you can consistently ascribe vague identities to the existence of vague objects – that is, retain (0) and (1) – if you reject either (2) or (3). Suppose you construct ersatz vague objects (for short: evos) as nonconstant functions from precisifications to precise objects, as people often suggest; then one thing you can do to restore consistency is to replace (2) by (*2) We interpret ‘=’ not as identity but as a sort of local coincidence: identity of the values picked out by the denotata of the terms that flank it, instead of between those denotata themselves. Thus: a sentence of the form ‘a = b’ is truer iff, where ‘a’ and ‘b’ respectively denoter evos A and B, A and B yield the same value for the argument r. Alternatively, you can keep (2) unaltered and replace (3) by (*3) We interpret ‘V’ as a predicate modifier that operates on the identity ­relation to give a relation which holdsr between evos X and Y iff they yield the same value for some but not all arguments. One of these moves is what you’re suggesting in the draft, but which one it is depends on the relation between ‘V( = )’ and ‘=’. [. . .] Sincerely, David Lewis

618.  To David E. Over, 25 January 1989 [Princeton, NJ] Dear David, Thank you for showing me your manuscript.1 I do have some comments. There is indeed a slip in Evans’s paper, easily rectified. There are not ‘serious technical   Letter from Gareth Evans to David Lewis, 24 November 1978.   Letter 589. To Allen P. Hazen, 15 November 1978.

2 3

  ‘Vague Objects and Identity’ (Over 1989).

1

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flaws’ showing that ‘he did not have a coherent logic in mind for his attempted proof’. (And may I say that your language would be over-harsh even if you were altogether in the right?) A helpful thing to know is that the triangles are borrowed from modal logic, where they mean ‘it is contingent whether’ and ‘it is not contingent whether’. In a modal logic at least as strong as T, the triangles are interdefinable with the box and diamond: noncontingent A iff necessary A or necessary not-A contingent A iff possible A and possible not-A necessary A iff noncontingent A and A possible A iff contingent A or A In view of the interdefinability, standard systems can of course be axiomatized with the triangles as primitive. But the interesting thing is that if you look at what’s easy and hard to write using triangles, you come up with some interesting new approaches to axiomatization, even of standard systems. Read all about it in four papers by Montgomery and Routley in Logique et Analyse, 1966, 1968, and 1969. Concerning your claim that ‘the logic for the operators . . . would not be anything like S5’, see especially the first two papers: ‘Contingency and noncontingency bases for normal modal logics’ and ‘Non-contingency axioms for S4 and S5’. Of course, it’s to be expected that S5 formulated with triangles as primitive will look different from S5 with box as primitive, just as S5 with diamond as primitive looks different from S5 with box as primitive. You wouldn’t expect to get a theorem (i) 

if possible (if A then B) then (if possible A then possible B)

if you took diamond as primitive; and no more should you expect to get (ii) 

if noncontingent (if A then B) then (if noncontingent A then noncontingent B)

if you take triangles as primitive. What you do get, however, is (iii)  if A, then [if noncontingent (if A then B) then (if noncontingent A then noncontingent B)]. Likewise, mutatis mutandis, if triangle is interpreted as an operator of definiteness – nonvagueness as opposed to noncontingency. The ‘indefinitely’ operator must be read as ‘it is indefinite whether’ – ‘in­def­in­ ite­ly true that’ makes no sense. Then since Evans explicitly stipulates that the ‘in­def­



618.  To David E. Over, 25 January 1989

341

in­ite­ly’ and the ‘definitely’ are duals, that forces you to read the latter also with a ‘whether’. No need to scratch your head and wonder, no need for guesswork, no need to turn to my paper for retroactive support. And once you read ‘definitely’ as ‘it is definite whether’, you have no problem about applying duality to (3) – as you eventually say, but only after first suggesting that there is some problem. Your remaining problem concerns how Evans got (5). He says that lines (1)–(4), and Leibniz’s Law, ‘may each be strengthened with a “definitely” prefix, enabling us to derive (5)’. Here’s where Evans really does make a slip, but it’s easy to fix. Everything works if you take the result of adding the prefix to be conjoined in each case to the original sentence, rather than replacing the original sentence. Though ‘definite A’ is not a strengthening of A, ‘A & definite A’ is. Though you don’t have (iv)  if definite (if A then B) then (if definite A then definite B) (when ‘definite’ means ‘definite whether’), you do have (v) 

if [(if A then B) & definite (if A then B)] then [if (A & definite A) then (B & definite B)]

and that’s what gets you from (1)–(4) and L’s Law, plus what you get by prefixing ‘definite’ to them, to (5). As to the second half of your paper, it seems to me to be a special case of a more general point. Yes; the believer in vague objects can fend off refutation by denying that ‘classical’ logic applies to his special subject matter. Quite so; and any philosopher can fend off any refutation by denying that whatever logic is used therein applies to his special subject matter. Stumped by the problem of evil? No worries, God is not bound by human logic! Are you Meinong and is Russell getting the better of you? – Noncontradiction applies only to the realm of Sein! The photon is a funny beast: it can go through slit A or through slit B, and then hit the plate, without going through slit A and then hitting the plate and without going through slit B and then hitting the plate. And so ad infinitum. You ‘doubt that either of these non-classical positions can be refuted by a simple, knock down technical argument on its own’. Well, doubt no more: of course they can’t be. There’s no knocking down anyone who’s ready in a pinch to change the rules. If it’s a fair move in philosophical debate to call logic itself into question, nobody need ever be refuted unless he wants to be. Any player has a sure-fire strategy for forcing stalemate and avoiding defeat. What hath Quine wrought? Sincerely, David Lewis

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619.  To R.M. Sainsbury, 26 January 1989 [Princeton, NJ] Dear Mark Sainsbury, Thank you for your December letter. I don’t know why it took about a month to get here – that’s too long for air, too short for surface. I’m puzzled by your puzzlement. In talking about a range of alternative positions, some of which do and some of which don’t countenance vague objects, of course I don’t go once and for all for a metalanguage that avoids quantification over vague objects. If they exist, we might as well quantify over them in the metalanguage. If they don’t, we’d better not. My point in the October letter (apart from the exe­get­ ic­al matter) was that the target of the Evans argument is not vague objects per se, but rather a mix: a certain way of combining ideas out of the vague-objects theory and the semantic indeterminacy theory. 0-1-2-3 in my letter is the statement of this mix; so of course it is stated in a way that mixes quantification over regimentations and quantification over vague objects. Not just any mix gets refuted. 0-1-*2-3 and 0-1-2-*3 are unrefuted mixes; or rather, ersatz mixes, since they put evos in place of genuine vague objects.1 And are those the only alternatives? No; what I said is that you can’t have all of 0-1-2-3, but I don’t say that *2 is the only possible substitute for 2, or that *3 is the only possible ­substitute for 3. If someone believes in genuine vague objects, and also in sharp precisifications of them, he can have 0-1-#2-3. (#2) We interpret ‘=’ as a relation of coincidence between genuine vague objects, defined in terms of precisifications associated with those vague objects. (A regimentation selects, for each vague object, one of its associated precisifications.) A sentence of the form ‘a = b’ is truer iff, where ‘a’ and ‘b’ respectively denoter genuine vague objects A and B, the precisification of A selected by r and the precisification of B selected by r are identical. Or he can have 0-1-2-#3. (#3) We interpret ‘V’ as a predicate modifier that operates on the identity relation to give a relation which holdsr between genuine vague objects X and Y iff X and Y have some common precisification, but not all and only the precisifications of X are precisifications of Y.

  The word ‘evos’ is short for ‘ersatz vague objects’.

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619.  To R.M. Sainsbury, 26 January 1989

343

(Note that some of the subscript r’s are idle: the one on ‘denoter’ in (#2) and the one on ‘holdsr’ in (#3). I include them for the sake of uniformity with the other options I’ve listed.) Obviously, one could formulate (#2) or (#3) equivalently in terms of evos associated with genuine vague objects, but it may be clearer to go straight to the associated precisifications in a single step. It looks to me as if you’re going for (#2) – maybe not as the option you’d accept, but as the one that’s supposed to show that the original mix 0-1-2-3 stands unrefuted. Well, you can avoid evos, and you can speak instead of genuine vague objects and their associated precisifications – that’s what it means to go for (#2) instead of (*2). But you’re not saving (2), so you’re not saving 0-1-2-3. Are you casting doubt on the claim that ‘=’ means identity? Yes and no. You’re casting doubt on the claim that a sentence of the form ‘a = b’ is truer iff what ‘a’ denotesr and what ‘b’ denotes are identical. For under (#2) what ‘a’ denotesr and what ‘b’ denotesr are two different vague objects with some shared precisifications. The identity is between precisifications associated with those two vague objects, not between those vague objects themselves. Identity is involved in the meaning of ‘=’ according to (#2), sure enough. But what’s happening is not just that the predicate expresses a relation, the relation is identity, and the sentence is true iff that relation holds between the denotations of the subject terms. There’s funny business of some sort. You get a choice about how to describe the funny business. You could say that ‘=’ doesn’t mean identity, but rather the relation of having the same precisification selected by r. (That’s the choice I took in writing #2.) Or you could say that ‘=’ means identity, but there’s a special funny rule for evaluating subject-predicate sentences – it’s not the denotation of the subject term itself, but rather an associated precisification, that must satisfy the predicate to make the sentence true. Or you could say that the sentence doesn’t really have the form ‘a = b’ – that’s mere surface form, and deep down it’s really ‘the selected precisification of a = the selected precisification of b’. You pays your money and you takes your choice. But I say there’s got to be funny business somewhere. I’m perfectly content to accept as true that for some n, Snowdon has exactly n acres. And even: definitely, for some n, Snowdon has exactly n acres. The false one is: for some n, definitely, Snowdon has exactly n acres. No doubt there’s some conversational reason why saying the true one (in some contexts) may misleadingly suggest the false one. Does the ‘exactly’ modifying ‘n acres’ get mistaken for a ‘definitely’ modifying the whole clause, because the careless hearer just picks up a general air of exactitude? Sincerely, David Lewis

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620.  To David E. Over, 27 February 1989 [Princeton, NJ] Dear David, On the analogy of vagueness-as-semantic-indecision to modality, you’re of course right that one disanalogy is that we don’t have a single ‘actual’ precisification. So a truth-teller can’t aim to say only what’s true on the actual precisification; he could aim to say what’s true on all (supervaluationism), or what’s true on almost all, or what’s true on not too few, or just what’s true on some. The valid sentences are given by S5, as you say. But it’s true that you have various notions of inference depending on which property is supposed to get preserved – truth on a given ­precisification, truth on all precisifications, or truth on some precisifications. Some of these notions do lead you into non-classical logic, in a sense. It’s not that they ­challenge classical logic, but they do supplement it, simply by saying new things in answer to new questions. For instance, versions of relevant logic turn out to be what preserve the property of truth on some precisification when you allow mixed precisifications that may precisify different occurrences of the same atom differently. I enclose something about this.1 I don’t see why you think that Section 4.3 of Plurality called for ‘a restricted notion of vague identity’. I thought of it just as a matter of semantic indecision. ‘Vague existence, speaking restrictedly, is unproblematic’. It’s vague whether, restricting ourselves to suitably cohesive objects, there exists an object consisting of these five boards; for I mixed the glue badly, and the boards are very weakly stuck together. There is (speaking unrestrictedly) an object consisting of the five boards; it’s a bit cohesive, but not very; I haven’t settled quite what it takes to fall within what I called a restriction to ‘suitably cohesive objects’. I’m undecided between two ways of taking the restriction, one of which does and the other of which doesn’t admit the object consisting of the five boards as something within the restriction. No vague objects; no vague identity; no vague existence; no vague domains. It’s just that I’m undecided about what domain I’m restricting to. Likewise if it’s indefinite whether there are one or two objects ‘in a vague domain’, that’s not a domain such that it’s vague how many objects are in it; rather it’s indecision between a domain with one object in it and a different domain with two. Sincerely, David Lewis

  ‘Relevant Implication’ (Lewis 1988b).

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621.  To Graham Priest, 31 August 1989

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621.  To Graham Priest, 31 August 1989 Melbourne, Australia Dear Philonous, Your argument went more or less as follows.1 Notation: ‘U’ is the predicate ‘unconceived’; ‘T’ is the propositional operator ‘it is conceived that’; and ‘ε’ abbreviates the epsilon-term ‘εxUx’. I say that it is conceived, and truly, that some things are unconceived; you claim to refute this. Thus: 1.T$xUx ü 2. $xUx ýþ 3. $xUx ® Ue 4. T$xUx ® TUe 5. TUe ® ØUe 6. Ue 7. ØUe CONTRADICTION

for reductio Hilbert’s principle 3, Affixing principle Conception principle 2, 3, Modus Ponens 1, 4, Modus Ponens; 5, Modus Ponens

So which of the three principles do I accept, and which do I reject? – All three, and all three. I claim there is an ambiguity about the implication in line 3, and about the proposition expressed by ‘Ue ’. Different resolutions yield different versions of the principles. Each principle has acceptable and unacceptable versions. But no way does your refutation succeed. First the implication. ‘F ® Y ’ holds as a propositional implication iff the prop­os­ ition actually expressed by ‘F ’ strictly implies the proposition actually expressed by ‘ Y ’. It holds as a sentential implication iff, at every world where ‘F ’ expresses a prop­ os­ition true at that world, ‘ Y ’ also expresses a proposition true at that world. In symbols, where ‘F  w ’ denotes the proposition expressed at w by ‘F ’ , where we identify a proposition with the set of worlds where it is true, and where ‘@’ denotes our actual world, it’s the difference between "w[ w Î F @

w Î  Y @ ] ( propositional ), and

"w[ w Î F  w

w Î  Y  w ] ( sentential ).

1   This letter and the two after it relate to Beyond the Limits of Thought (Priest 1995), and in particular to ch. 4: The Limits of Conception.

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And next the proposition expressed by ‘Ue ’. It might be (1) a singular prop­os­ ition, concerning the things actually denoted by ‘e ’, to the effect that this thing ­satisfies ‘U’. If so, I take it to be true. In this case, however, there is no reason to think that the singular proposition actually expressed by ‘Ue ’ will be the same as the singular proposition expressed at another world by the same sentence. We would get this  singular proposition if we took ‘U’ to be an extensional predicate and ‘e ’ to be rigidified. Or it might be (2) a general proposition, to the effect that whichever thing is denoted by ‘e ’ satisfies ‘U’. If so, again I take it to be true. In this case we should take ‘Ue ’ to express the same proposition at all worlds. We would get this general prop­os­ ition if we took ‘U’ to be an extensional predicate and ‘e ’ to be unrigidified; or if we took ‘e ’ to be not a denoting term at all but rather a quantifier phrase, and took the extensional predicate ‘U’ to be the argument of ‘e ’ rather than vice versa. Or it might be (3) a conceptual proposition, to the effect that the property associated with the term ‘e ’ – namely, the property of being an unconceived thing – satisfies ‘U’ in a different way from the way in which trees etc. might satisfy ‘U’, namely by being a property of which we have no conception. If so, I take ‘Ue ’ to be false; and to express the same proposition in all worlds. We could get this conceptual proposition by taking ‘U’ intensionally: it operates on the sense of ‘e ’, not the denotation. Or it might be (4) a Meinongian proposition, to the effect that the generic object associated with ‘e ’ has the property expressed by ‘U’. A generic object is associated – whether or not identified with – a property bundle. So our proposition is true iff unconceivedness is in the bundle consisting solely of unconceivedness, which of course it is. On, now, to your three principles. Affixing first. It takes us from ‘F ® Y ’ to ‘ TF ® TY ’ . I accept it when ‘F ® Y ’ holds as a propositional implication. I suppose conceiving that P means conceiving of a way for P to come true; and that is a fortiori a way for Q to come true if P strictly implies Q. But I reject Affixing when ‘F ® Y ’ holds merely as a sentential implication. Let P and Q be two propositions such that, at our actual world @, both are true, P is conceived, Q is not conceived. Let Qif w =@ F  w = P for all w,  Y  w = ìí îP otherwise



Now ‘F ® Y ’ holds merely as a sentential implication, but at our actual world ‘ TF ’ is true and ‘ TY ’ is false. Conception next. In general, TFa ® ØUa where F is a predicate and a is a singular term; in the case at hand, TUe ® ØUe . I accept it when ‘Fa ’ , in this case ‘Ue ’, expresses a singular proposition: to conceive the proposition, one must conceive the



622.  To Graham Priest, 19 November 1989

347

thing it is about. I also accept the case at hand when ‘Ue ’ expresses the conceptual proposition. But I reject it when ‘Ue ’ expresses the general proposition; or, of course, the Meinongian proposition. Finally, Hilbert. In general, $xFx ® F(e xFx ). In the case at hand, $xUx ® Ue . I accept it as a propositional implication when ‘Ue ’ expresses the general prop­os­ ition. I accept it as a sentential but not as a propositional implication when ‘Ue ’ expresses the singular proposition. I accept it (under an interpretation that is surely unintended) when ‘Ue ’ expresses the Meinongian proposition. I reject it when ‘Ue ’ expresses the conceptual proposition. So if it’s the singular proposition, I insist on reading line 3 as sentential implication and I reject your use of Affixing to reach line 4. If it’s the general proposition, I reject your use of Conception to reach line 5. If it’s the conceptual proposition, I reject your use of Hilbert to reach line 3. And if it’s the Meinongian proposition, again I reject your use of Conception to reach line 5. No step is wrong on all ways of taking your argument – hence its appeal. But on every way of taking it, some step is false. Sincerely, Hylas

622.  To Graham Priest, 19 November 1989 [Princeton, NJ] Dear Philonous, Thank you for your 7 September letter. I’m sorry I’ve been so slow to answer. I’m glad we can agree that the issue concerns the Conception Scheme, interpreted with U as extensional, e (short for epsilon) flaccid, and implication propositional. Thus interpreted, we agree that TUe is true. We disagree over ¬Ue. You think it true because ‘to conceive of something is simply to bring a phrase denoting that thing before the mind’. So, at least, you understand the notion. But only you, I think. Who else would claim to conceive of the nearest star never yet observed – conceive of that particular thing, since we agreed to take the predicate extensionally – just by bringing that phrase before the mind? But also, I hope you meant ‘to bring a phrase unambiguously denoting that thing before the mind’. If you did not, then absolutely everything was conceived – and not by the Deity – on the day when Alvin Plantinga named everything ‘Charley’ (Noûs 3

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(1969), page 253).1 Indeed you and I are conceiving of everything right now, because I have brought the ambiguous name ‘Charley’ before our minds. No! (Someone could say that an ambiguous name is brought before the mind under one disambiguation or another, and if you do not conceive of x, then ‘Charley’-quaname-of-x is not before your mind. But this shouldn’t suit you, because it makes your notion of conceiving of a thing depend on some prior notion.) If you do insert ‘unambiguously’, however, then I do not think an epsilon-term qualifies. I deny that you really have brought before the mind a term that unambiguously denotes anything. For I think the best way to understand the epsilon operator is as forming an ambiguous term, indeterminate in denotation over the range of all suitable things. We can’t say just which suitable thing it denotes (even in a case where we definitely do conceive each of the candidates) and that’s not because there’s some secret we can’t find out. Rather, it’s because nothing has been done, secretly or openly, to settle the matter. This does nothing to detract from the utility of epsilonterms, and nothing to give them a funny logic, because it’s open to us to cope with (and conceal) their indeterminacy of denotation by the method of supervaluations. If e is ambiguous, the sentence Ue is ambiguous. But the ambiguity of it won’t make any difference to the proposition expressed, at least not if propositions are individuated modally rather than in some finer way. So I think we can continue to accept TUe without worrying about the ambiguity. Yours,

623.  To Graham Priest, 13 February 1990 [Princeton, NJ] Dear Philonous, Let U be an extensional predicate; let e be a flaccid designator of some U, if some U exists (both as you stipulated). Then Ue expresses the proposition true at world w iff there is some U at w. That proposition, I say, is true; and it is conceived that it holds. Therefore the conditional ‘If TUe, then ¬Ue’ is false. What if e is ambiguous (as I say it is) as well as flaccid? Nothing changes. Ambiguity may not matter. A sentence with an ambiguous term may still come out unambiguous. Example. Suppose we somehow define two well-orderings of everything, O1 and O2. Let e1 designate the U that comes first in O1, let e2 designate the U  ‘De Re et De Dicto’ (Plantinga 1969).

1



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349

that comes first in O2, and let e be ambiguous between e1 and e2. Ue1 expresses the proposition true at w iff there is some U at w, Ue2 expresses the very same prop­os­ ition, so Ue expresses, unambiguously, the proposition that it expresses on both dis­ am­bigu­ations of e. Example. Suppose e has as many different disambiguations as there are different well-orderings of everything: for each well-ordering O, eO designates the U that comes first in O. Still, for each O, UeO expresses the proposition true at w iff there is some U at w; and Ue expresses this proposition too, unambiguously. You ask me to compare this with ‘Philonous thinks that Aristotle is a great philosopher’ where Aristotle is ambiguous between naming the magnate and naming someone else. (You think the magnate is a great philosopher, but you have no such opinion about his namesake.) You say the sentence is true on one dis­am­bigu­ ation, false on another. I agree, but the case isn’t parallel. Here the ambiguity does matter. Ga1 expresses the singular proposition that a certain person, the magnate, is a great philosopher; and this proposition you do believe. Whereas Ga2 expresses the different singular proposition that a different person, the magnate’s namesake, is a great philosopher; and that proposition you do not believe. We might take a different line about e. (I’m easy; I followed your stipulation.) Let e now be an ambiguous rigid designator of some U, if there is any. For each wellordering O, let eO be a rigid designator of the U that comes first in O. Ue expresses different propositions under different disambiguations of e; all of these propositions are true. Likewise TUe expresses different propositions under different dis­am­bigu­ ations of e; all of these are false. So on this line, the conditional ‘If TUe then ¬Ue’ is true on all disambiguations – super-true, as you say. And on this line, the parallel with your Aristotle example goes through. But on this line, though I accept Conception, I accept Hilbert only as a sentential implication and so reject Affixing when applied to Hilbert. See my 31 August 1989 letter. I don’t mind taking ‘I am thinking of an impossible object’ as unambiguously true. But if I do, then I cannot at the same time follow your stipulation to take ‘an impossible object’ as an epsilon-term that flaccidly designates some impossible object; nor can I take it as an epsilon-term which rigidly designates some impossible object. Instead I must adopt some other interpretation of epsilon-terms, and of ­predicates like U or ‘I am thinking of’. I mentioned these alternatives in the 31 August letter: the ‘conceptual’ or ‘Meinongian’ interpretations. The conceptual in­ter­pret­ ation, I claimed, makes Hilbert fail; the Meinongian interpretation makes Conception fail. I agree about indefinite descriptions being a bit of a red herring. I like to think that epsilon-terms really are definite descriptions of the form: ‘the first --- in the wellordering O of everything’. Specify some O by coordinatisation of the universe, and  we have an ordinary definite description; leave it unspecified and we have an

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ambiguous definite description. What changes if we specify O is that then we do have, if not exactly ‘before the mind’, at least in the language, an unambiguous name for each tree, each star, . . . . (Maybe each electron, despite indeterminacy of position – if so, it’s thanks to the Pauli exclusion principle!) That’s why I think there’s more to being conceived than just being named. Yours,

624.  To Marga Reimer, 24 September 1990 [Princeton, NJ] Dear Professor Reimer, Thank you for your paper about definite descriptions and salience,1 which I’ve just read. I found it very interesting. I agree with you that ‘the F’ won’t denote the most salient F if the most salient F is something that might better be denoted another way, say by a pronoun or a name. Your examples are convincing. The point is new, so far as I know. I’m not sure, though, that salience qua F is the way to deal with your point. To the extent I understand what salience qua F means, I fear that George might be salient qua man as well as qua George, etc. I wonder why not just say that ‘the F’ denotes the most salient of the F’s not most appropriately denoted some other way? I think maybe that in the ‘George is talking to the man’ example, the reason why ‘the man’ doesn’t denote George isn’t that George might better have been called ‘George’, but rather that George might better have been called ‘himself’. I find it peculiar – very peculiar, but not outright incorrect – to say ‘George is talking to George’ and mean that George is talking to himself. I would guess the speaker meant that George was talking to someone else named George. Similarly for any other referring expression except ‘himself’. Even if it’s very well known that George is Alice’s father, I would be reluctant to take ‘George is talking to Alice’s father’ to mean that George is talking to himself – I might guess the speaker means to suggest that George isn’t Alice’s real father, or I might guess the speaker means that George is talking to someone who is Alice’s father in some metaphorical sense – Alice’s priest, maybe.

1   ‘The Maximal Salience Theory of Definite Descriptions’, which became chapter 2 of her dissertation: The Semantic Significance of Referential Intentions (Reimer 1992, 49–98). See also ‘Do Demonstrations Have Semantic Significance?’ (Reimer 1991).



624.  To Marga Reimer, 24 September 1990

351

My talk about guises wasn’t meant to be the same thing as your salience qua F. I had in mind secret-identity cases. Unbeknownst to Lois Lane, Superman is a reporter; and he is now very salient, more so than anyone she knows to be a reporter; so he is the most salient reporter; yet he’s not the one denoted when Lois says ‘the reporter’. Not, that is, unless in his guise as Clark Kent he is the most salient reporter. It’s not necessarily out of the question to bring the audience’s state into referential semantics. We sometimes have to. For instance, if the speaker says ‘The song you know best is Irish’, then what’s referred to, hence the truth of the sentence, depends on your state. But should definite descriptions governed by salience go the same way? I suppose the normal, presupposed case is that a certain F is most salient both to speaker and to audience, and this is common knowledge between them. (This includes common knowledge of the effects of shifts under the rule of accommodation.) Suppose the description means ‘the F most salient to us (setting aside things best referred to some other way)’. Does that mean that the description is denotationless if the case is abnormal, the presupposition fails, and the audience’s salience ranking is not what the speaker takes it to be? Not necessarily. A description may denote what doesn’t quite satisfy its condition, provided it comes close enough and closer than any alternative. I suppose ‘the king of Iraq’ denotes Hussein even though he isn’t strictly speaking a king. This is apt to be a messy business, with indeterminacy about what does and doesn’t come close enough. So if the presupposition of common knowledge of shared salience breaks down, I suppose ‘the F’ might (in a not fully indeterminate way) denote the F most salient to the speaker, or the F the speaker wrongly thinks is most salient to the audience, or even – maybe, I’m not sure – the F most salient to the audience but not to the speaker. The reason I don’t like bringing in intentions to refer is just the threat of circularity. Suppose you snabulize iff you stand on your head while intending to snabulize – this analysis leaves us not much the wiser about what snabulizing might be! I would be happier with intentions characterized some other way: intentions to bring a certain thing to the hearer’s attention, intentions to get the hearer to have a belief de re about a certain thing, or something of that sort. A small point: on page 29, you say I stipulate that a sentence is true or false at ‘some individual consciousness’. Not quite. I know that some things are conscious, but I don’t know if there are any such entities as ‘consciousnesses’. I actually spoke of things with points of view, such as people and animals. (Nowadays Tom Nagel has made ‘point of view’ into a code word for something like ‘soul’, but that happened long after I wrote Counterfactuals, so don’t read it back into what I said.) A thing with a point of view needn’t be conscious in any very strong sense. Think of an air defence system with a central computer. It views the air around it from a certain point,

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namely the location of its radar dish, so it has a point of view. It pays more attention to some things than to others. In some stretched sense it’s conscious of attacking objects coming at it, and of the missiles it’s firing; but it doesn’t have experiences that it’s conscious of. Sincerely, David Lewis

625.  To Graeme Forbes, 3 December 1990 [Princeton, NJ] Dear Professor Forbes, I’m still in fairly full agreement with my former self who wrote scorekeeping about definite descriptions. The two changes that come to mind don’t seem to matter for your purposes. 1) I think it may happen that even when salience has done its work, there are still two F’s with equal claim to be most salient, hence equal claim to be denoted by ‘the F’. (Or more than two, of course.) In that case I would be inclined to treat ‘the F’ not as denotationless, in the Russellian way, but as ambiguous or vague in denotation. (I would probably have agreed to this at the time of scorekeeping, but would put much more emphasis on it today.) 2) Marga Reimer (Tufts) pointed out to me (in a draft paper which may become part of her MIT dissertation) that ‘the F’ often won’t denote the maximally salient F if the maximally salient F is something that we’d expect would have been referred to in some different way. In a context in which you are the most salient metaphysician, if you say ‘the metaphysician’ you probably shouldn’t be taken as referring to yourself – for if you’d meant to refer to yourself, why not just say ‘I’? Similarly (Reimer’s ex­ample) if you say ‘George is talking to the man’ when George himself is the most salient man (especially now that you’ve named him) you probably don’t mean that George is talking to himself, but rather that George is talking to the most salient man other than himself. I’m not fully pleased with all the morals Reimer draws, but as to the phenomenon itself, I think she’s surely right. Thank you for the two papers.1 Sincerely, David Lewis   ‘The Indispensability of Sinn’ (Forbes 1990); ‘Solving the Iteration Problem’ (Forbes 1993).

1



626.  To Max Cresswell, 13 March 1991

353

626.  To Max Cresswell, 13 March 1991 [Princeton, NJ] Dear Max, ‘Meaning Without Use’1 needed a little more work due to comments from Schiffer and Hawthorne, and due to your letter. I put it aside. But now I’ve finished it and sent it off to the AJF , and here’s a copy for you. You’re welcome to share it with colleagues and students at UMass and Wellington, and you may make copies for that purpose; but until I can confirm that it’s been accepted, I’d like you to pass on my usual request: no further recopying and no citation. The problem given in your 31 January letter isn’t solved by conventions of truthfulness alone, as you say. In L1 ‘runs’ means runs, in L2 it means moves, and that’s the only difference. The population is truthful in L1; they try not to say ‘David runs’ when David doesn’t run; a fortiori they try not to say ‘David runs’ when David doesn’t move; so they’re truthful also in L2; and this is appropriately conventional; so conventions of truthfulness don’t tell us why they use L1 rather than L2. Agreed. But then you say ‘similarly with the trust clause’, and there I dis­ agree. Applying the likelihood-ratio definition, the measure of trust for the sentence ‘David runs’ is T1

= Probability (‘David runs’ is said / David runs) Probability (‘David runs’ is said / David doesn’t run)

for L1, and T2

= Probability (‘David runs’ is said / David moves) Probability (‘David runs’ is said / David doesn’t move)

for L2. I grant you, both ratios exceed one-to-one; but unless the people give neg­li­ gible probability to David hopping or crawling or rolling or walking, if L1 is the right language for the population, T1 should substantially exceed T2. So the population will be trusting in L1 to a substantially greater extent than in L2. The remaining problem concerns the special case that the people do give neg­ li­gible probability to hopping, etc. Then T1 and T2 will be near enough equal, and both high enough, and trust will no more distinguish L1 and L2 than truthfulness will. That’s the sort of case I take up under the ‘Refinement’ heading in footnote 4 of the paper.   ‘Meaning Without Use: Reply to Hawthorne’ (Lewis 1992).

1

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No news about Monty.2 Do you have any news about the Perth chair? – Not inside information, I mean, but public news that hasn’t yet reached us? Our big news is that Steffi and her colleague LuAnne Edwards have left Government Finance Associates (not amicably) and set up in business on their own. Their new firm is called Municipal Capital Management, Inc. (for short, McMinc – rhymes with ‘ink’). It’s the same line of work as before: advice to local governments, school boards, etc. on the issuing of tax-exempt bonds. Two clients so far, and a third is expected to become official any day now. That’s already enough to pay the rent, and more, though not yet enough to pay themselves salaries. I’m off to England over spring break, leaving in an hour. I’ll fly to Shannon on Aer Lingus, then train from Limerick and ferry from Dunleary, on the theory that Saddam has no grievance against Ireland. Yours,

627.  To Roy Sorensen, 21 May 1991 [Princeton, NJ] Dear Roy Sorensen, I see no problem of principle about mixed precisifications, though you’re right that they complicate the story I told in ‘Scorekeeping’.1 Instead of a uniform standard, I suppose the ‘component of score’ would have to be a pair of different uniform standards; and there’d have to be some way for a speaker and hearer to keep track of which standard applies to which occurrence of the vague word. I suppose the likely way of keeping track is just the usual pragmatic principle: what’s right is what makes the message make sense. I came close to an example in ‘Counterfactual Dependence and Time’s Arrow’; see the last-but-one paragraph of the ‘Two Analyses’ section of the paper, pp. 42–3 of the reprint in my Φ Papers II. To make sense of some things we undeniably want to say, I say we must grant that two different comparative similarity relations enter into the interpretation of a single sentence: one that governs the counterfactual, another that governs explicit judgements of what is ‘very different’. In the context of this

  David Lewis. ‘The Monty Hall Problem’ (Janssen-Lauret and MacBride forthcoming).

2

  ‘Scorekeeping in a Language Game’ (Lewis 1979d).

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628.  To Thomas McKay, 20 February 1992

355

explanation I perfectly well might have said, though as it happens I didn’t: ‘With two similarity relations in play together, it can happen that the most similar antecedentworlds to our world are less similar to our world than some other antecedent-worlds are’. If I’d said that, I think it would have been easily understood in context, and it would have been true thanks to a mixed precisification. I think another kind of example involves words for kinds of craftsmen. I think I could say ‘Few painters are painters’ and mean, and with luck be understood to mean, that few of those who paint are very skilled at painting. (Disregard the housepainter vs. picture-painter ambiguity; let it be understood it’s house-painters we’re talking about.) Being a painter is partly a matter of doing it, partly a matter of being skilled at it; and how much which dimension counts is a vague matter. Yours, David Lewis

628.  To Thomas McKay, 20 February 1992 [Princeton, NJ] Dear Tom, Thank you for your paper.*1 I was sorry to miss it at the APA – there were few enough things I wanted to go to, but most of them were all at the same time. Some comments – Page 13. I don’t fully believe your linguistic data. Sentence (14) ‘Every boy will get what they select’, if taken in the sense that makes it synonymous with (13), sounds rather bad to me. Actually, it sounds like the ungrammatical singular ‘they’ that people use instead of sex-neutral ‘he’ for fear of being called sexist – though with ‘boy’ I guess you’re still safe in saying ‘he’. Sentence (15) seems to me to be almost OK with ‘his’, only faintly peculiar, certainly not worse than (14) in the sense of (13). And there’s a difference of meaning between the two variants of (15): the variant with ‘their’, but ­ othing against not the variant with ‘his’, could be true because although Alice had n any one song of any one baritone, she was troubled by something about all their songs taken together – maybe the fact that these songs were all very much alike. Page 14. I’m quite sympathetic to the idea that sometimes, even if a sentence is firstorderizable, it should still be seen as quantifying a plural variable in the manner of   ‘Plural Reference & Unbound Pronouns’   

*

1

  (McKay 1994).

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Some boys X are such that: each x of X got what x selected. I note that even if (17) gets that reading, it can still be followed by (17+) . . . and then, for fun, carried a piano upstairs. Why do you say that the second reading of (17) is not a bound variable treatment? Why isn’t it Some boys X are such that: each x of X got what X selected with a bound plural variable? Afterward, those boys may have become contextually salient because they are the truth-making instance of the quantification just uttered; but they may not have been in any way salient beforehand. Consider: There were so very many boys there, getting together into so very many little groups to make their different joint selections; so even though what each boy got was determined at random, still it’s very highly probable that some boys got what they selected. Page 17. I don’t think the truth of (27) requires that Bill has met each of the surgeryperforming doctors that John knows. It can be followed by (27+) Other doctors that John knows, whom Bill hasn’t met, perform ­surgery too. But (27) can instead be followed by (27++) They sometimes carry pianos upstairs, too so I still want to take it as a plural. Page 21. Similar comments. It seems to me (39) can be followed by (39+) Such a person usually also meets some other critics whom he can distinguish very easily. So I think the critics in question, for a given person, needn’t be all the critics that the person has met; and I also think the critics in question needn’t be contextually salient, relative to that person, beforehand (though they may be so afterward, just by being the truth-making instance of a quantification – if indeed there is a quantification). I think (39), with ‘many people’ given wide scope, means something like Many people x are such that, for some critics Y, x meets Y and x cannot distinguish among Y. When I say that plural quantification is irreducibly plural, I’m taking the whole ­apparatus of quantifiers and bound variables as a package deal. I don’t care whether you say that the irreducible pluralness attaches to the quantifiers, to the variables, or to both together. Yours, David Lewis c: Boolos (on the chance that you sent him your paper)



629.  To Frank Jackson, 6 April 1992

357

629.  To Frank Jackson, 6 April 1992 [Princeton, NJ] Dear Frank, [. . .] I agree with the general line that moral terms are implicitly defined by a folk theory. That doesn’t look like what I say in ‘Dispositional Theories of Value’,1 but I think it’s compatible. The modified Ramsey-sentence method of definition is always available, but depending on what the folk theory says it may be equivalent to a def­in­ ition in some simpler form – as it might be, a definition in dispositional form. Does the ‘maturing’ of folk morality consist just of its improvement as a result of moral reflection? Or does it include also what must be done to square folk morality with relevant commitments in logic and metaphysics? I’m thinking that there are two different ways to answer the threat that Mackie is right. And I think he is right, at least to this extent: naive folk morality does contain the untenable idea that values necessarily attract. We could say (1) that this idea would, because untenable, have to vanish in the course of maturing; and that it is the future, improved theory that defines the terms. Or (2) that the idea remains present in the ‘matured’ theory; and  hence there can’t be perfect satisfiers of the definitions and deservers of the names; but imperfect satisfiers can come near enough to realizing the theory and can thereby deserve the names well enough. I doubt there’s any real issue between these alternatives. [. . .] Yours,

630.  To Thomas McKay, 27 May 1992 [Princeton, NJ] Dear Tom, A quick but partial reply. (15ʹ) and (15) with ‘his’ both strike me as a little peculiar, not perfectly OK, but not definitely starred. I don’t get much difference between the two.

  ‘Dispositional Theories of Value’ (Lewis 1989a).

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In the story of the many boys getting together into little groups to make joint selections, I thought that the last clause could mean that probably: for some X, X are some of the boys, and each one of X got what X jointly selected. I can see that it doesn’t have to mean that. It could also mean that probably: there are more than one of the boys x such that x got what x, together with some others, jointly selected. Whenever x is a baritone, Y are critics, Y are many (or, more than one), and x meets Y, x can’t distinguish among Y. Yours, c: Boolos

631.  To John Hawthorne, 15 June 1992 [Princeton, NJ] Dear John, Thank you for your paper1 and letter! Your case of sentence-by-sentence French Mary (Marie?) is almost the same as the example from Schiffer which led to the reply in my footnote 8. (One sort of bent grammar that might be represented in the brain just is the sentence-by-sentence list. The way it’s bent is that the language doesn’t have any further sentences at all, and the sentences it does have aren’t given any grammatical relations.) So you’ve already read my answer to your example: I stand by extrapolation, even when that forces me to say that what’s in Mary’s brain does not at all fit the real grammar of her language. If you and Schiffer convinced me to retreat, though, I’d fall back to ‘deep psychology’ in preference to the other two options you offer. I hoped to send you copies of my correspondence with Schiffer, but I can’t find it. Schiffer has since written a reply to me – whether forthcoming I don’t know. You and he might do well to compare notes. ‘Bent’ is not especially Lewis’s lingo: it started life in discussion of Reichenbachstyle rules of induction, and reappeared in Oxford discussions of rule-following – I’m pretty sure it’s in Blackburn, for instance. I see the advantage of taking trust to be expectation of sincerity; the cor­res­ pond­ing drawback is that we complicate the story of the central, straightforward case of communication. Since whichever way we go we have to extrapolate out from the centre, I still want to keep the centre simple.   ‘A Note on “Languages and Language” ’ (Hawthorne 1990).

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632.  To Terence Horgan, 2 February 1994

359

I’m happy enough to speak analogically of language-use in cases far from the central case. People who only use language to think aloud would be one such analogical extension. Hardwired L-trust and L-truthfulness would be another. Indeed I’m quite easy-going about this, and have no particular objection to talking about the ‘language’ in which the eye tells the brain what it sees. I suspect there’s something fishy about the idea of a community of sceptics who never believe anything, but have another attitude, ‘acceptance’ or whatnot, which is their workaday substitute for belief. I suspect their attitude is belief, and all that’s left of their scepticism is an allergy to the word ‘believe’. This issue was going to be a big part of Michaelis’s dissertation. I’m not sure what he’d now say about it. I’m not sure whether what I said about straight extrapolation solves the ‘tensions’ problem. What I more suspect is that we’ve got a correct and incorrect description of one and the same grammar; not two rival grammars, one of which should be thrown out for bentness. I’m definitely planning to come to your Φ Mind conference. Michaelis gave me no details at all about it, but I expect I may be able to find out more when I get to Melbourne Uni (which will be about the same time you get this letter) or, failing that, at the AAP. Yours, David Lewis

632.  To Terence Horgan, 2 February 1994 [Princeton, NJ] Dear Terry, I read with much interest your paper on the ‘forced march’ sorites.1 My hope is that the supervaluationist line – vagueness is semantic indecision – can yield robust vagueness (which, I agree, is what’s wanted) if we say that not only have we left it undecided within a certain range R0 of alternatives just how tall is tall; but also we have left it undecided within a certain range R1 of alternatives just how far R0 extends; and also we have left it undecided within a certain range R2 of alternatives . . . . I hope that works, else we’re in big trouble, namely the trouble you find yourself forced to settle for.

  ‘Robust Vagueness and the Forced-March Sorites Paradox’ (Horgan 1994).

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But I had a smaller comment, which I hope is consistent with the general line above. (I think it’s based on something I got from someone else, but if so I forget the source.) The forced march demands that we say, for each n, whether or not Bn+1 differs in any way at all from Bn in semantic status. We know what happens if we say that they sometimes differ (wimpiness); we know what happens if we say that they never differ (incoherence); but what if we say that they always differ? The differences would be subtle: not just plain false versus true, not just plain definitely-false versus false-but-not-quite-definitely-false, . . . . But there are plenty more where those came from. You yourself rightly note on page 19, (A1), what a variety of differences in semantic status there might be. How would it be to say that at every point in the sequence of B’s there’s some subtle difference of status or other, different subtle differences at different points? That seems suitably egalitarian to be more robust than wimpy – or at any rate, it dodges the more obviously objectionable forms of arbitrary lines. There may yet be some sort of objectionable arbitrariness; I’m not sure. But it’s not as bad as having to believe in a sharp but arbitrary line between tall and not-tall, or between tall and tallish-but-not-definitely-tall, or . . . Yours, David Lewis

633.  To Scott Soames, 11 December 1994 [Princeton, NJ] Scott Our notion of a rigid designator was around, not under that name, well before we learned it from Naming and Necessity.1 For instance, I quote from something I wrote myself in 1967 or early 1968. (My second draft is dated April 1968; it appears in JΦ 67 (1970) pp. 435–6.) A logically determinate name is one which names the same thing in every pos­ sible world. Its sense is a constant function. Numerals, for instance, seem to be logically determinate names of numbers. But ‘the number of solar planets’ is a logically indeterminate name of a number. Here in our actual world it happens to name the number 9. Elsewhere it may name other numbers, or nothing at all.

  (Kripke 1980).

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633.  To Scott Soames, 11 December 1994

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Anything can have a logically indeterminate name – even a property. (This should have been obvious, but wasn’t.) Take the name ‘the physical property detected by means of the instrument with catalog number 12345 in so-and-so catalog’ (filling in the name of a catalog). This happens, perhaps, to name the property of fluorescing in the ultraviolet. But if the catalog numbers had been different, it would have named some other property, or none. I quote this not to make any claim on my own behalf, but just to illustrate what was state-of-the-art at UCLA back then. I rather think we were teaching it even in our undergraduate courses. You plainly see from my examples that when we said ‘name’, ordinary proper names were not especially what we had in mind. I recall no discussion one way or the other of whether ordinary proper names were ‘logically determinate’. Where did I, and my colleagues, get this idea of logical determinacy? If asked at the time, I’d probably have said that it was Carnap’s; it came from Meaning and Necessity (1947),2 along with the idea (M&N, section 40) of construing intensions for names as functions from (representations of) possible states of the universe to (representations of) individuals. That would have been badly misleading. Carnap in 1947 perfectly well could have distinguished the case that the intension was a constant function from the case that it wasn’t; but I don’t see that he ever does. Instead, he defines L-determinacy in section 17 of M&N, long before he gets around to identifying intensions with functions. What he says doesn’t look like our modal concept of rigidity. Rather, it looks like our concept of ‘mere tags’, ‘direct reference’, or ‘rigidity de jure’. (17-4) A designator is L-determinate in S if and only if the semantical rules of S alone, without addition of factual knowledge, give its extension. (This isn’t meant to be a definition: he thinks it isn’t precise enough. Instead, it’s a guide to constructing particular definitions of L-determinacy in particular languages. For instance in a coordinate language, ‘individual expressions of standard form’ are defined to be numerals (understood as coordinates of positions); other individual expressions are L-determinate iff they’re L-equivalent to these numerals. See sections 18–19.) Why do it that way around, instead of using constancy of the intension? – Because in 1947 Carnap’s intensions are functions from linguistic representations of states

  (Carnap 1947).

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to linguistic representations of individuals. The representations of states are state-descriptions (conjunctions of atomic sentences); the representations of individuals are L-determinate individual constants. So he has to explain L-determinate individual constants before he can get around to introducing intensions. Later he changed his mind: he thought it would be better to take the representations of states as models, and the extensions simply as the individuals themselves. (See Schilpp, Φ of Rudolf Carnap, pp. 890–2.)3 He’d made this change already in some duplicated class notes from 1955; and there he does define a logically determinate designator as one that has the same designation in any two admissible models. (Admissible means: satisfying the meaning postulates.) --There’s also Hintikka’s idea of ‘modality as referential multiplicity’. This goes back at least to a 1957 paper of that title (Ajatus 20, pp. 49–64) but is more easily found in Knowledge and Belief (1962), pp. 138ff.4 Referential opacity and difficulty in quantifying into opaque contexts are due to what we’d now call non-rigidity. K&B, pp. 138–9: In so far as the person . . . does not know everything there is to be known about the world he has to keep an eye on more than one ‘possible world,’ that is, he has to take into account more than one way things might actually [!] be, as far as he knows . . . Among other things, the person . . . will have to keep an eye on the different ways in which names (and other individual terms) might refer to different individuals . . . He then hooks this up with his analysis of ‘a knows who b is’ as ExKa(b = x); and this is meant to apply to the case where ‘b’ is a proper name (‘Dr. Salazar’) as well as the case where ‘b’ is a description (‘the dictator of Portugal’). K&B, pp. 152–3: Existential generalization with respect to a term – say b – is admissible in such contexts if b refers to the same man in all the ‘possible worlds’ we have to consider. [E.g. those that are epistemically possible for subject a.] Now b clearly refers to one and the same man in all these states of affairs if there is someone who is known by [a] to be referred to by b; for then there is no state of affairs compatible with what [a] knows in which b should fail to refer to him. In short, b refers to the same man in all the ‘possible worlds’ we have to consider in this special case if it is true to say ‘[a] knows who b is’. Since Hintikka does not assume that everyone must know who Dr. Salazar is (or Dr. Jekyll, or Mr. Hyde), evidently he does not hold that ordinary proper names are modally rigid!   ‘Replies and Systematic Expositions’ (Carnap 1963).   

3

  (Hintikka 1962).

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634.  To Scott Soames, 12 December 1994

363

Was Hintikka one source for us at UCLA? Maybe – Stanford wasn’t far. --If I had more time, I’d look also at Montague’s earliest modal logic paper (1955 colloquium, published 1960)5 and at Kanger, Provability in Logic (1957).6

634.  To Scott Soames, 12 December 1994 [Princeton, NJ] Scott I’ve now had a look at Montague, ‘Logical Necessity, Physical Necessity, Ethics, and Quantifiers’ (conference talk, May 1955; published 1960; reprinted in Montague, Formal Φ).1 There’s no discussion there of rigidity of individual constants, but he clearly has the concept. Models serve inter alia as representations of possible worlds. There are various relations – what we’d now call accessibility relations – between these models. A model is a triple [D, R, f].* D is the domain; R assigns classes of n-tuples of members of D to n-place predicates and assigns members of D to individual constants; and f assigns members of D to variables. (Thus the ‘model’ is what we’d often call a model plus a value-assignment; this allows quantification and modality both to be treated in terms of relations between models.) Montague’s original semantic rule for necessity (FΦ, p. 76) is [D, R, f]L[Dʹ, Rʹ, fʹ] if and only if D = Dʹ and f = fʹ. By requiring that f = fʹ, he in effect stipulates that variables are rigid; he does not have any corresponding stipulation for individual constants. He also gives a modified version, claimed to validate exactly the sentences L-true in the system of Carnap’s ‘Modalities and Quantification’ (1946). Let D be a set; let Des be a one-one correspondence between D and the individual constants of the language; call R determinate iff its assignments to individual constants agree with those of Des. Let D° = D and let R° be determinate. The Carnap-style semantic rule for necessity is [D°, R°, f°] satisfies ‘Necessarily Φ’ iff, for every [Dʹ, Rʹ, fʹ] such that D° = Dʹ and f° = fʹ and R° is determinate, [Dʹ, Rʹ, fʹ] satisfies Φ. So this time he in effect stipulates that the individual constants as well as the variables are rigid.   ‘Logical Necessity, Physical Necessity, Ethics, and Quantifiers’. Reprinted in (Montague 1974).   (Kanger 1957).

5 6

 (Montague 1974).   *  I’ve changed notation.

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635.  To David Sosa, 18 October 1995 [Princeton, NJ] Dear David, Thank you very much for your paper.1 I’d wondered whether you and I had been thinking along similar lines, and indeed we had been. There are some things I’d say differently, but I don’t think these differences represent real disagreements. I would have said that the hypothesis that names take wide scope and the hypothesis that names are rigidified are two rival explanations of the same phenomena; whereas you say that wide scope is compatible with, and explains, rigidification. OK; I think this just means that you mean a little less than I do by ‘rigidification’. You explain it (on page 2) in terms of the truth conditions of sentences (under dis­am­bigu­ ations) with respect to counterfactual situations; whereas I would have explained it in terms of the semantic values of names themselves, as constancy of denotation. (And thus I would also have said that if names turn out to be incomplete symbols without semantic values, then a fortiori they can’t be rigid. But what you call rigidification could still take place.) You give the impression of wanting to defend the sort of descriptivism that takes ‘Aristotle’ to abbreviate ‘the last great philosopher of antiquity’. But it seems to me fairly clear – though maybe not quite as clear as it ought to be – that really you are not defending this theory overall, but only defending it against one objection. Myself, I think famous-deeds-and-distinctive-peculiarities descriptivism is an utterly hopeless theory on other grounds: because we’re often ignorant or mistaken about the famous deeds or distinctive peculiarities of those we can name, because many people we can name aren’t famous for much of anything (especially when they’re children), etc., etc. And, for all you say here, you might agree completely with me about this. The descriptivism I’m interested in defending would be one that associates ‘Aristotle’ with a description like ‘the one I’ve heard of under the name “Aristotle” ’, or maybe ‘the causal source of this token: Aristotle’ – and if you want to know what that sort of description means, I refer you to Kripke’s causal ‘picture’ (about which he seems to me to be unduly modest), and to the writings of Chastain and Devitt. You begin by considering the scope of the description in the complex sentence ‘With respect to counterfactual situation S, the greatest philosopher of antiquity was fond of dogs’. At first, this seems to ignore Kripke’s very emphatic insistence in the preface that he’s talking about something that happens in simple sentences. So the reader may begin to think you’ve missed Kripke’s point. But you haven’t: the crucial   ‘Rigidity in the Scope of Russell’s Theory’ (Sosa 2001).

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636.  To Peter Vanderschraaf, 13 December 1996

365

move, which I suggest might better have come sooner and with much more fanfare, is that if a description (abbreviated or otherwise) is eager enough for wide scope, its scope may cross sentence boundaries, and also boundaries of quotation and disquotation. You think – and I agree – that it’s fair to treat the following alike; and in each case, to say that ‘Aristotle’ may take wide enough scope to cover all the rest. (a) With respect to S, Aristotle was fond of dogs. (b) This is the case with respect to S: Aristotle was fond of dogs. (c) Consider the simple sentence ‘Aristotle was fond of dogs’. That sentence is true with respect to S. (And likewise if we put in what is uncontroversially an abbreviated description: ‘t.g.p.o.a.’ instead of ‘Aristotle’. And likewise if we put in the unabbreviated description.) Kripke in effect accuses us wide-scopers of solving the problem of (a) while ignoring (c). Our reply is that (c) functions as a mere stylistic variant of (a). Again, thank you! Yours, David Lewis c: Scott Soames

636.  To Peter Vanderschraaf, 13 December 1996 [Princeton, NJ] Dear Peter Vanderschraaf, I’ve recently had occasion to read your paper ‘Convention as Correlated Equilibrium’, Erkenntnis 42 (1995): 65–87. I note your claim that you have generalized my treatment by pointing out that there are ‘conventions which do not correspond to Nash equilibria, a fact which Lewis does not discuss in his work’ (page 74). It turns out that what you have in mind are conventions which correspond to correlated equilibria; and it turns out that these are just Nash equilibria in a game in which the rows and columns are not single actions, but rather are contingency plans whereby actions may depend on extraneous events. A familiar example would be the game of Intersection: row-chooser and column-chooser drive up to the same intersection at more or less the same time, and what do they do? There’s a traffic light there which, as usual, shows different colours to row-chooser and column-chooser. The contingency plans each one might follow include:

Philosophical Letters of David K. Lewis

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1: 2: 3: 4:

stop on the red, go on the green stop on the green, go on the red stop unconditionally go unconditionally

Coordination equilibria – Nash coordination equilibria of contingency plans, or if you prefer Aumann coordination equilibria of actions – include the actual convention: everybody follows contingency plan 1. Everybody following 2 would be equally good. Coordination of 3 for row-chooser and 4 for column-chooser, or vice versa, would do – at least if there was some way for each to tell which one he was. Miscoordination results in a smash. Now please look at Convention, pages 122–130 where you will find discussion and several examples of coordination of contingency plans, including the game of Intersection. I note that Brian Skyrms also thinks it would be a good idea to ‘extend Lewis’s treatment [sic] to encompass correlated equilibria’, and credits the alleged extension to you (Evolution of the Social Contract, page 69); so I’m sending him a copy of this letter. Sincerely, David Lewis

637.  To Brian Skyrms, 24 January 1997 [Princeton, NJ] Dear Brian, Thank you for your letter. A note such as you suggest would, I think, be useful; and I appreciate it. As to whether it might best come from you, from Peter Vanderschraaf, or both together, I have no opinion – except that certainly there needn’t be two separate notes! History: when in Convention I set up games where the rows and columns of the payoff matrix contingency plans, not single actions, was I making an advance without being aware of it? Not at all! I thought I was doing something standard and familiar, and I was right. See, for instance, von Neumann & Morgenstern, Section 11.1.1–2.1 I don’t see why Aumann’s notion of correlated equilibrium wasn’t a reinvention of the wheel – or rather, the invention of a more cumbersome substitute for the wheel we had before, which was the notion of a Nash equilibrium combination of   The Theory of Games and Economic Behavior (von Neumann and Morgenstern 1944).

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638.  To Frank Jackson and Philip Pettit, 30 March 1998

367

strategies – where strategies are contingency plans for a sequence of moves responding to whatever there may be to respond to, whether moves by another player, or ‘moves’ by something extraneous to the game, or ‘chance moves’ by some sort of randomizer; and where the payoffs from combinations of strategies are expected values. In particular, I don’t see the point of dragging in a treatment in terms of cor­rel­ ations between the randomizers observed by the separate players, so long as we’re talking about coordination games where there’s no randomizing going on in the first place (and there’s nothing to be gained by introducing any). The generality of the framework contributes nothing to thinking about the special case at hand. You ask me whether I had in mind that a player gets to know (2a) the random vector, or (2b) only the projection of this vector on a subspace assigned to that player. This question looks like an artifact of the formalism: you tell me what random vector you have in mind, I’ll tell you whether the players get full information about it. Does a player get to know everything such that (a) it doesn’t depend just on what strategies he and the other players follow, and (b) his actual payoffs depend partly on it? Probably not. (E.g. he doesn’t know whether he’s going to catch a cold while playing the game.) Does he know everything such that (a) [as before] and (b) his subjectively expected payoffs depend partly on it? That’s easy: if he’s a suitably idealized sort of a character, he has a subjectively expected payoff for any combination of strategies, depending on nothing further. Yours, c: Dick

638.  To Frank Jackson and Philip Pettit, 30 March 1998 [Princeton, NJ] Dear Frank and Philip, It looks as if I can come to the Thursday show at Columbia, but not the Tuesday show at NYU. When I mentioned that to one of our graduate students, Cian Dorr, he managed to find the Tuesday expressivism paper on the web. Ain’t science wonderful! I think I agree fully with your paper,1 nevertheless here’s a letter of comment. ---

  ‘A Problem for Expressivism’ (Jackson and Pettit 1998).

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In footnote 3, referring to a paper I don’t think I’ve seen, you suggest that Geach’s argument purports to prove too much. I agree; but instead of thinking further about indicative conditionals, I’ve been thinking about a different example. When people in philosophy books go to the footy, they express their emotions by shouting ‘boo’ and ‘hurrah’. When real people go to the footy they express plenty of emotions, but seldom if ever do they say ‘boo’ or ‘hurrah’. Many of the things they say by way of expressing their emotions are declarative sentences. In many cases – in all the cases that make barracking a fine art? – they are make-believedly asserting things. It’s no wonder if make-believe assertions simulate the logical behaviour of real assertions. But sometimes I think something simpler is going on. Suppose someone expresses a con-attitude by shouting ‘Collingwood sucks!’ If it’s a grown-up shouting, I suppose it’s very likely a make-believe assertion – the same assertion that might be made as friendly advice to someone who wonders where to go in search of suit­ able sexual partners. But it seems to me that very often those who say such things are young, innocent children. They can’t be make-believedly asserting, because they haven’t a clue what they’d be make-believedly asserting. Or are they really so­ innocent? – Maybe sometimes not. But if it’s even possible that even one of them is unaware of the meaning, and just thinks that these words are conventionally used to express a con-attitude, I have my example. I don’t suppose they very often shout ‘ “Collingwood sucks” is true!’ or ‘It’s true that Collingwood sucks!’ But it would be no surprise if, after someone shouts ‘Collingwood sucks!’ someone a few seats away shouts ‘Ain’t it the truth!’. Something like disquotation is going on: the second endorses the sentiments expressed by the first. And I can imagine a conditional parallel to Geach’s: ‘If Collingwood sucks, so does Geelong!’ The point, to adapt an adaptation by Kevin Zaragoza and Blackburn, would be to express a dim view of the sort of sensibility that takes a dim view of Collingwood without taking an equally dim view of Geelong. If Geach were right, not only would expressivism be wrong for moral judgements – which is easy enough to believe – it would be wrong for any syn­tac­tic­ al­ly declarative sentence whatever. If Geach has proved that, he’s proved too much to be right. --When I was partway through teaching an intro ethics course for the first time ever, a few weeks ago, I realised I had to explain the difference between subjectivist fact­ ual­ism, and expressivist non-factualism. ‘I support Essendon’ and ‘C’arn the Bombers!’ are both of them utterances conventionally reserved to be uttered by those who support Essendon; either one will produce in hearers the belief that the speaker supports Essendon; either one is intended to produce that effect, and to produce it by producing



638.  To Frank Jackson and Philip Pettit, 30 March 1998

369

recognition of the intention to produce it. So what’s the difference? And likewise for ‘I disapprove of stealing’ and ‘stealing is wrong’ (as understood by an expressivist). What I came up with was this. Either way, it’s a linguistic misdeed, and it’s a way of misleading people, to say such a thing when one does not in fact support Essendon. But it’s more of a misdeed if you’ve falsely said ‘I support Essendon’ than if you’ve insincerely said ‘C’arn the Bombers!’ Either way, hearers will be entitled to draw a conclusion, and the conclusion will be false; but in the one case they’re en­titled to a greater degree of belief, hence they’ll be more seriously deceived, hence they’re entitled to be more angry if they find out about it. That’s to say, it’s like the difference between saying ‘I support Essendon’ and saying ‘I solemnly swear on this stack of bibles that I support Essendon’. --In hindsight, I thought that this line was not a million miles from what I said in chapter 4, section 4, of Convention about the difference between indicative and imperative signals. (I was talking in part about signal lanterns, flags, and whatnot; so at that point there was no question of marking the distinction as a syntactic one.) The basic idea is that communicator can tell, but audience can’t, which one of situations s1, s2, . . . obtains; audience can tell which one of actions a1, a2, . . . communicator performs; it’s common knowledge between communicator and audience that they both prefer to have audience give response r1 if s1 obtains, r2 if s2 obtains, and so on. So they can solve their coordination problem by a contingency plan whereby communicator’s signalling actions depend on the situation and audience’s responses depend on communicator’s actions. In this basic case, there’s no saying whether a1 should be called an indicative signal that s1 obtains or whether it should be called an imperative signal to do r1. But suppose there are exceptional cases. First, suppose audience is in a position to tell whether exceptional circumstances obtain, and communicator isn’t; and if exceptional circumstances do obtain, then what best serves the preferences of both is a different pattern of dependence of response upon situation. Then the best signalling convention is one in which communicator’s actions depend as before upon the observed situation, but audience gets to exercise some discretion in how to respond to the signals he sees. If discretion lies with the audience (only) in this way, I say that the signals are indicative. Or suppose instead that communicator is in a position to tell whether exceptional circumstances obtain, and audience isn’t. Then the best convention is one in which communicator gets to exercise discretion, but audience sticks to a contingency plan in responding to communicator’s signals. If discretion lies with the communicator (only), I say that the signals are imperative. ---

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My old line about indicative and imperative signals hooks up, but imperfectly, with my new line about more or less serious misdeeds. If a signal is indicative, so that audience’s contingency plan allows discretion and communicator’s doesn’t, then if the communicator departs from his plan he has just plain violated the convention; whereas if the audience departs, he has only misused the discretion which the ­convention granted to him. Whereas if the signal is imperative, it’s the other way  round. So the misdeed seems greater if it’s an indicative signal than if it’s an imperative signal. But to get the rest of the way to hooking up the two ideas, I need to get from imperatives to expressions of attitudes (from prescriptivist expressivism to emotivist expressivism) and I don’t see how to do that. Yours, David Lewis PS Back to the fine art of barracking. Much of it, I said, is make-believe asserting: about the umpy’s eyesight, about the purses carried by the players, and so on. I wonder how plausible it might be to say something similar about moral judgements. By an objectively prescriptive judgement I’ll mean a factual judgement that is ne­ces­sar­ily motivating. Comments. (1) By ‘factual’ I don’t just mean that it can be endorsed by saying ‘that’s true’; I mean that its truth supervenes on being (or something of that sort). (2) I’ll allow that the necessary motivation is conditional: the judgement necessarily motivates any being that has what it takes to be a believerdesirer, or something like that. But I don’t want to begin the slippery slope to trivi­al­ isa­tion: it necessarily motivates any rational being, a rational being is one who responds to reasons, some reasons are ‘external’, so in short it necessarily motivates anyone who responds to moral truths. That said, I take it Mackie was right. In the first place, there can be no ob­ject­ ive­ly prescriptive judgements; in the second place, we very often do seem to think and talk as if moral judgements are objectively prescriptive. Objective prescriptivity is a fiction. Well, there are more things than two we can do with a fiction. We can reject it. We can embrace it. Or we can make-believedly embrace it. We can say things because they are true in the fiction, plus factual background. (Exactly as we say things that are true in the fiction that the umpy is blind, together with factual background about what just happened in the field.) If we make-believedly accepted the fiction of ob­ject­ ive prescriptivity, that would be a way of expressing pro-or-con-attitudes (and, in the bargain, a way of expressing open-minded indecision) without straightforwardly reporting that we have these attitudes. Moral fictionalism is an expressivist theory, but one which attempts to explain the appearances Mackie called to our attention.



639.  To David Kaplan, 4 February 1999

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Does it matter that the fiction is not just false but impossible? – I don’t think so. I think Graham Priest is right to insist that we can and sometimes do make believe that impossibilities are true. I don’t understand how we do it, my life would be easier if we didn’t, nevertheless I think we do. I don’t really want to say that ‘we’ are moral fictionalists. But maybe some of us are. Or maybe at least some of us are not-definitely-not. Or maybe at least some of us ought to be, since it would be as good an equilibrium as any among our conflicting inclinations. Yours, David Lewis2 c: Gideon Rosen, Mark Johnston

639.  To David Kaplan, 4 February 1999 Princeton University Princeton, NJ Dear David, I have two comments on the talk I heard you give at the APA. The first concerns negation. I note that negations can be used to take exception not only to the truth value of what’s been said but to quite a lot of other features that prima facie have nothing to do with truth value. Understatement – Stalin did not ‘fall short of the highest moral standards’ – he was evil! Pronunciation – It’s not a tomahto, it’s a tomayto (or vice versa). Political correctness or incorrectness – She’s not the chairperson, she’s the chairman (or vice versa). Pomposity – It’s not happening at this point of time, it’s happening now. Bad grammar – Their mission is not to boldly go where no man has gone before. Incorrect idiom – He didn’t kick the pail, he kicked the bucket.   Lewis signs off twice.

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And so on, and so forth. Maybe these aren’t literal uses of ‘not’ – that’s a kind of question I never know how to decide. Maybe they’re short for ‘It’s not appropriate to say that . . .’, so that the real negated sentence is false after all. Anyway, whatever further story you do or don’t tell, it’s clear that these at-least-superficially non-truthfunctional negations are commonplace. So it’s only to be expected that negations will sometimes be used by way of taking exception to expressive content, and it proves nothing one way or the other about whether false expressive content makes the ­sentence false. My second comment concerns whether there can be syntactically declarative sentences with purely expressive content. Moral judgements have been alleged to be that, but their status is too controversial to allow them to be a test case. (Myself, I think expressivist meta-ethics is a serious contender, but I’m far from convinced of it.) It would be nice to have a less contentious example, and I think I do. When people in philosophy books go to football matches, they express their feelings by shouting ‘Boo!’ or ‘Hurray!’. When real people go to the footy, they express their feelings by shouting, sure enough, but very seldom do they shout ‘Boo!’ or ‘Hurray!’. They shout quite a lot of things, of quite a lot of different syntactic forms. Some are just noises, some are imperatives, some are questions, some are makebelieve factual assertions (say, about the umpy’s defective eyesight). But some, I think, are declarative sentences with purely expressive content. ‘Collingwood sucks!’ is syntactically a declarative sentence. Its expressive content is that the speaker hates the Collingwood Football Club. If it were said by someone who is in fact a Collingwood supporter – say, to avoid a beating – it would be insincere, but it wouldn’t be a lie. (Whereas if he’d said ‘I hate Collingwood’, that would have been a lie.) The sentence has an original meaning, pertaining to the sexual habits of Collingwood players. Doubtless this has a lot to do with the origin of the expressive content. But this other meaning is irrelevant. It need not even cross the minds of those who shout ‘Collingwood sucks!’ by way of expressing their hatred. It’s even possible that some of them never learned the original meaning, and only know the sentence as something you say to express hatred. After someone shouts ‘Collingwood sucks!’ someone sitting nearby might endorse the sentiment by saying ‘Ain’t it the truth!’. So it appears, at least superficially, that this purely expressive sentence has been said to have a truth value. I leave it open whether this appearance is deceptive. The sentence can be negated: someone else nearby responds ‘Not so!’. It can be  made the antecedent of a conditional: ‘If Collingwood sucks, so too does Carlton’. Whatever exactly may be going on here, we have parallels to the ­phenomena



640.  To Richard Joyce, 20 July 2000

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that are said to refute the hypothesis that moral judgements are purely expressive declarative sentences. Yours, David c: Simon Blackburn, Michael Smith

640.  To Richard Joyce, 20 July 2000 Princeton University Princeton, NJ Dear Richard, I’ve now read the first three chapters of The Myth of Morality.1 It may be several weeks before I’m able to read more, so I wanted to write about what I’ve read so far while my impressions are fresh in my mind, even though I take it this won’t reach you until September. The first thing to say is that I much enjoyed reading it, thanks to the complete clarity of presentation. Thanks to that same clarity, I can say quickly how I think I disagree. I grant that a lot of moral theorizing is infected with error, but I don’t grant that the error is ‘nonnegotiable’. A theory that avoids the errors – such as, I hope, the unpretentious subjectivism of ‘A Dispositional Theory of Value’2 – is still a theory of the moral concepts. Whereas (I agree with you) a corrected theory of phlogiston or tapu that avoids the errors would not be a theory of phlogiston or tapu at all. It might perhaps retain the words, but it would not retain the original concepts. I stand by what I said in ‘How to Define Theoretical Terms’.3 But I also say that not every term is a theoretical term; and that a theoretical term may be defined by something less than the entire body of theorizing in which it figures. Phlogiston and tapu are good examples of non-negotiable error, but let me give you what I take to be an example of negotiable error. The ancients and the moderns both say that the sun rises. The ancients had an erroneous theory about sunrise. They thought that the rising sun moved in the absolutely vertical direction – this being a single, uniform direction that always and everywhere points from fallen

 (Joyce 2001).   2  ‘Dispositional Theories of Value’ (Lewis 1989a).   (Lewis 1970b).

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things to the things that will fall unless somehow supported. (Which ancients? Educated medievals, and even educated ancient Greeks knew better. I mean people more ancient than that, but I’m not sure quite who.) Moderns disagree, and think there’s no such thing as the absolute vertical. Yet it seems to me that ancient and modern talk of the rising sun is not committed to the ancient error, the ancients meant what we do when they said that the sun rises, and what they said was true. I’m inclined to think that the case of morality is like the case of the rising sun, and unlike the cases of phlogiston and tapu. For this reason we can put morality on a less pretentious, more satisfactory foundation without changing the subject. We will indeed be disagreeing with some prevalent (if not universal) metaethical in­tu­ itions, but we will not be discarding the original moral concepts. For this reason I’d call myself not a moral fictionalist but a meta-moral fictionalist.4 Now I turn to Chapter 3. Here I’m a little more at sea. You have a classification of kinds of reasons, and I have my classification, and I can often but not always tell how yours maps onto mine. Further, I can’t always tell – this should be clearer when I read on – when you’re speaking in propria persona and when you’re presenting the kind of thinking you’ll end up denouncing as erroneous. So possibly in the end we’ll have no disagreement here, but I can’t tell yet. So let me start by presenting my own account of reasons, initially in simplified form. A reason is a premise of a good (but perhaps less than conclusive) argument to the conclusion that the agent has a reason to do something. The agent has a reason to do something iff doing that thing serves

ìA. his desires ü ì1. his beliefs. ü í ý according to í ý îB. the dictates of morality þ î2. the truth. þ

Two beginnings times two endings gives four different senses of ‘has a reason’ ­altogether; and correspondingly there are four senses of ‘reason’. I said that this was simplified. Let’s complicate it. In the first place I admit there’s a third beginning (for a total of six senses): C. the aims and rules of such-and-such circumscribed practice such as the practice of etiquette or of gladiatorial combat. I mention this for the sake of completeness and to make contact with your discussion, but – that done – let me set it aside. More important, A and B and 1 and 2 all subdivide. So we could say that we have a proliferation of A1-ish senses, and likewise of A2-ish senses, B1-ish senses, and B2-ish senses. Better, perhaps, to say that we have four vague senses, but a proliferation   Cf. ‘Quasi-Realism Is Fictionalism’ (Lewis 2005).

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of alternative precisifications of both the beginning and the end. Anyway, A could be replaced or expanded alternatively by all his present actual desires his degrees of desire his wholehearted desires his permanent or deep-seated desires those of his desires that he desires to have those of his desires that he would retain under suitable reflection those desires that he is disposed to have under suitable reflection … As for B, it could be expanded alternatively by the fulfilment of his obligations the avoidance of wrongdoing the practice of virtue and avoidance of vice the maximising of value of consequences … As for 1, it could be replaced or expanded by all his actual beliefs his degrees of belief his whole-hearted beliefs those of his beliefs that he would retain under suitable reflection the beliefs that are warranted by his total evidence … And as for 2, it could be the whole truth the part of the truth that is presently fixed the part of the truth that is presently known by somebody or other the part of the truth that is presently knowable … Now I think we are in the vicinity of an error about reasons: one that is rife in moral philosophy, and maybe occurs also in the moralizing of ordinary folk. It is not the error of thinking there are B-ish senses of ‘reason’. I would like there not to be, because B-ish senses of reason are mentioned in dishonest moral suasion that relies for its effect on the addressee’s tendency to confuse B-ish reasons with A-ish ones.

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But the decision whether there are to be B-ish senses is not mine to make and the linguistic community has outvoted me. Rather, the error is to think that A-ish reasons and B-ish reasons are rival candidates for the status of reasons simpliciter. I think that A-ish reasons are reasons in one sense, and they are reasons the agent has regardless of the dictates of morality (except that he may have a desire to serve the dictates of morality). And there are B-ish reasons, and these are reasons the agent has regardless of his desires (except insofar as the dictates of morality require him to indulge his desires). And that’s that. I don’t understand how there can be a third, indiscriminate sense of reason. Anyway, not unless it’s a mere disjunction, in which case a disagreement about whether A-ish or B-ish reasons have a better claim to be considered reasons simpliciter would make no more sense than a disagreement about whether cats or dogs have the better claim to be considered cats-or-dogs. I think there’s no status for which A-ish reasons and B-ish reasons are in competition. More precisely: no status for which A1-ish and B1-ish reasons are in competition, and likewise no status for which A2-ish and B2-ish reasons are in competition. If that’s the error, where do you stand on it? – I don’t know yet. You do talk of reasons simpliciter, ‘practical’ reasons, ‘real’ reasons; but as I said, whether you were speaking in propria persona or whether you were expounding what you take to be erroneous will not be clear to me until I read on. If that’s the error, I don’t believe it’s a non-negotiable commitment of the practice of moralizing, as opposed to being a non-negotiable commitment of some moralists. Likewise, I agree with you that motivation internalism is an error, but I also agree with you in doubting that it’s non-negotiable. Request: I have a graduate student, Josh Green, who is writing his dissertation on error theories. May he read your manuscript? Three people at Macquarie Uni (Sydney, NSW 2109) have been writing a joint paper on moral fictionalism, and I think you should get in touch with them. They are Daniel Nolan, Greg Restall, and Caroline West.5 Yours, David c: gh, gr, mj

  See ‘Moral Fictionalism Versus the Rest’ (Nolan, Restall, and West 2005).

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641.  To Richard Joyce, 23 July 2000

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641.  To Richard Joyce, 23 July 2000 [Princeton, NJ] Dear Richard, I’ve now read on part-way through chapter 7, but it may be weeks before I can get to the rest. So here’s another interim response. Though you’ll get this and my 20 July letter at the same time, it would be best to read that one first, since the main part of this one picks up where my 20 July letter left off. But first, some trivia. [. . .] Now, back to the varieties of reasons, picking up where my 20 July letter left off. I think we have a real disagreement, but it’s fairly superficial. What I called ‘A-ish reasons’ are the reasons that hook up, perhaps directly or perhaps modulo some ideal­iza­tions, with the agent’s belief-desire motivation. (Even the A2-ish reasons do, if we include the idealization of being fully informed.) Thus they explain the agent’s actions – perhaps his actual actions, perhaps the actions that he would be disposed to perform under some idealizations. B-ish ‘reasons’ – the dictates of morality – do not hook up with motivation in the same way and do not explain action. (Not by themselves, anyway. A desire to obey the dictates of morality plus a belief about what the dictates of morality are could of course explain action – but that would be an A-ish reason.) B-ish ‘reasons’ are not to be confused with, and are not even in competition with, A-ish reasons. To conflate them is an error, and is a widespread error. So far, I think we agree. But I say that, for better or worse, the dictates of morality are called reasons; and while I would have found it less confusing and more honest if the term ‘reason’ had been reserved for A-ish reasons, I reckon that linguistic usage has gone against me. So I say that A-ish and B-ish reasons are ‘reasons’ in two completely different senses, and the error is to lump them together. Whereas you insist that reasons, rightly speaking, do hook up with motivation and explain action; wherefore B-ish ‘reasons’ are not genuine reasons at all, and the error is to say that they are. Have I got this right? [. . .] It was section 2.6 that gave me a bum steer, and made me think you might be one of those who wanted a catch-all concept of ‘practical reason’ that conflated A-ish reasons with B-ish reasons (if there were any). The reason you wrote it that way was that you were proceeding in an orderly fashion, not yet presupposing answers to questions you had not yet discussed. Fair enough – but a bit of emphatic foreshadowing right away would have made all the difference.

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Our main disagreement remains. Sure, a morality that avoids the errors, a subjectivist and relativist morality (potentially relativist, depending on whether our underlying moral dispositions really do turn out to differ), is very different from one that is not subjectivist and relativist. But not, I think, to the point where its concepts are not recognisably moral concepts at all. The errors are like the ancients’ errors about motion or about the rising sun, not like the errors about phlogiston or tapu or witches. Thus I feel free to carry on saying that Stalin, or God as portrayed by most Christians, is horrendously evil, even if I don’t want to say that their evil-doing consists in violating inescapable categorical imperatives, or in doing things they have overriding reasons not to do. Even when we hang war criminals, we need not tell ourselves that they have violated categorical imperatives! Yours, David Lewis c: gh, mj

642.  To Simon Blackburn, 17 November 2000 Princeton University Princeton, NJ Dear Simon, Thank you for your comments. Here are some replies. Deflationism comes to the quietist’s aid. I’m not so sure of that. I think of deflationism (or the redundancy theory of truth, or . . . – call it what you will) as applying in the first instance to the truth of propositions. I’m free to say ‘Toora loora loora loo’, but since what I’ve said does not express any proposition, I’m not free to prefix ‘It’s true that . . .’ or ‘Really . . .’ or ‘It’s a fact that . . .’ (or any iteration of these) to it. Likewise if I say ‘This very sentence is true’, which fails to express a proposition not by reason of unsuitable syntactic form but by reason of ungroundedness. Likewise if I say ‘There is no such place as Mundabungra’, which fails to express a proposition by having nonsense syllables where a name should have been. And likewise if I say ‘Collingwood sucks’, which, in my view, fails to express a proposition because it amounts to ‘Boo to Collingwood!’ in the syntactic guise of a declarative sentence. (Imagine I’m an innocent child who has no idea that this same sentence can be used so that it does express a proposition.) And likewise if I say ‘Bullfighting is wrong’ and – contrary to what I believe – some unqualified form of non-cognitivism is true. Someone might



642.  To Simon Blackburn, 17 November 2000

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indeed prefix ‘It’s true that . . .’, etc., to some of these sentences, but that could be understood as a piece of make-believe. ‘REALLY REAL’ versus ‘really real’. Unless more is said, I don’t think there’s any intelligible distinction here. What is there for a disowning prefix to attach to? Well, given what I just said, there’s no sense in attaching it to ‘It’s REALLY REAL that bullfighting is wrong’ without also attaching it to ‘It’s really real that bullfighting is wrong’, and indeed to ‘Bullfighting is wrong’. But if a noncognitivist doubts that ‘Bullfighting is wrong’ expresses a prop­ os­ition, he should attach the disowning prefix to ‘Bullfighting is wrong’, ‘It’s really real that bullfighting is wrong’, and so on and so forth. Further, I take it that one thing the moral realist you have in mind says is a meta-ethical view – call it, following Mark Johnston, detectivism – that contradicts projectivism. If you want to earn and exercise the right to quasi-assert everything this moral realist asserts, you’ll quasi-assert detectivism. We surely agree that assertions of projectivism are intelligible, and I should think that denials of projectivism, and assertions of detectivism, are equally intelligible. So there’s something else ­intelligible that the moral realist asserts that you could quasi-assert by attaching a disowning prefix. But here I’ve been assuming that the aim of the project is to earn and exercise the right to echo everything the moral realist says – not only his moralizing, but also his meta-ethical remarks. (Assuming, as I’m not sure is true, that these can be clearly disentangled.) If your aim is more limited than that, and you don’t wish to echo realist meta-ethics, then there’s a far easier way than the one I proposed to say why you’re a quasi rather than a queasy realist. Does realist semantics fit the quasi-realist? Fitting his linguistic dispositions doesn’t mean making what he says come out true. (It isn’t a matter of Davidsonian charity.) Realist semantics is right for the the(ological real)ist because it makes sense of why he says what he does, despite the fact that it also makes him out to be saying things that are untrue (maybe false, maybe without truth value) in virtue of reference ­failure. One possible reply to the argument I considered in my second paragraph is that what makes realist semantics right for someone is that it makes what he says come out true by his lights; in that case, what fits the realist doesn’t fit the quasirealist, even if their linguistic dispositions match perfectly, because truth by the realist’s lights differs from truth by the quasi-realist’s lights. This only works if we limit deflationism in the way I suggested above; otherwise there’s no difference in what’s true by one’s lights and the other’s. A different reply is that the linguistic dispositions aren’t meant to match ­perfectly but only over a limited range (as was considered above).

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Is moral realism the default position? Maybe there’s something modest we could mean by ‘moral realism’ that makes it the default position. But if ‘moral realism’ is construed to require an (undisowned) assertion of detectivism and denial of projectivism, then I think not. Good luck to you both for your move to Cambridge! We’ll likely see you there – we’re in Cambridge more often than we’re in Chapel Hill. Yours, David

643.  To Denis McManus, 20 November 2000 Princeton University Princeton, NJ Dear Denis McManus, Thank you for sending me your paper about dispositional theories of mean1 ing. I think I fully agree with what you’ve added to the ongoing discussion. But you and all the rest seem to agree on something I see no reason to believe. It’s said that there are ‘primitive’ tribes who think that when there are more than three of something, there are infinitely many. I’d guess that this is not a piece of scientific anthropology, but either an ethnic slur or a mistranslation. Anyway, whether or not any such thing is true of primitive tribes, it does seem to be true of philosophers. Why should anyone think that we know of infinitely many exceptional possible cases in which a meandering river would fail to erode its outer bank? Here’s what I think must happen. Someone starts thinking up cases. Fodor lists four. I’d imagine that he took about ten minutes to think of those four. Then he stops, having a long enough list to make his point – but with a sense that it was so easy so far that he could surely have gone on. And then he (maybe not Fodor, but some of the others you mention) makes the breathtakingly hasty generalization that there are infinitely many exceptions! But suppose he had gone on. And suppose he has a big enough grant to pay many other smart people to help him. How long do you think he and his helpers could go on before they ran out? (Let ‘running out’ mean that the time since finding the last new idea is more than half of the total time spent so far on the project. Assume he doesn’t cheat by subdividing cases that were already on the list, or easily   ‘Boghossian, Miller and Lewis on Dispositional Theories of Meaning’ (McManus 2000).

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could have been: somebody builds a wall along the outside bank out of concrete that costs $1/ton, . . . costs $2/ton, . . . costs $3/ton, . . .) How long do you think? My fairly confident guess is: less than a day. My more confident guess is: less than a year. My still more confident guess . . . . Anyway, by the time he runs out of new ideas, he has no good reason to think there are any more still to be found. The characteristic method of philosophy, applied this time to the finite list of exceptional cases, seems to be: if you can’t think of it in ten minutes, it doesn’t exist. Another way to make my point. Only finitely many ‘except if . . .’ clauses are shorter than the longest book I own. If there are infinitely many ‘except if . . .’ clauses we’d want to add to the generalization about meandering rivers, all but an infinitesimal minority of them are longer than the longest book I own. Do you think even one clause you’d want to add is that long? The mind is remarkably complex, but it isn’t infinitely complex. It’s made of finitely many neurons; indeed, it’s made of finitely many particles. It’s no surprise that it can handle concepts more complex than anyone can figure out in ten minutes, or in a day, or even in a year. But I can’t really imagine how a finite system could master an infinitely complex concept! I think this ‘one, two, three, infinity’ phenomenon is to blame for maybe 50% of the widespread pessimism about conceptual analyses and folk theories. The other 50% can be blamed on indeterminacy in what is and isn’t to be included. (Is the Pope a bachelor? Some people seem to find salient a resolution of semantic indeterminacy on which the answer is ‘no’.) Yours, David Lewis

PART 6 Epistemology

644.  To Michael A. Slote, 16 February 1966 [Cambridge, MA] Dear Michael, Thank you very much for the copy of your paper on important criteria,1 which arrived this morning. (Do please let me know how much the copying cost, if it did!) I may want to use it in passing in my thesis:2 the prima facie plausibility of the theory is an argument against the claim that intension resides entirely in the rules of use pertaining to a sentence or term. (I probably won’t really argue against that view in the thesis, but I will want to justify not arguing for it; i.e. I need to argue that the question is at least open.) And thank you also for your letter on the Sleigh-Kripke and Goodman paradoxes. I don’t know much inductive logic – I learned a certain approach from Shimony and tend to accept that uncritically. For what it’s worth, here are my ­reactions. Let’s say that C is __caws, R is __is a raven, L is __lacks a broken claw nail. Let’s say h1 is the hypothesis that (x)(Rx ⊃ Cx), h2 is the hypothesis that (x)(Cx ⊃ Lx), h3 is the hypothesis that (x)(-Lx ⊃ -Cx) – i.e., h3 is the contrapositive of h2 – and e is the evidence, namely a lot of cases of R & C & L. Then the Sleigh-Kripke problem is that e seems to bear the same relation to h1 and h2; and h2 is equivalent to h3; and yet after we observe e, we find that we believe h1 much more than we believe h3. In the first place, I want to reject any suggestion that we discriminate between equivalent hypotheses – h2 and h3 – in confirmation theory. In particular, therefore, I want to reject the Nicod criterion you suggest, viz. that e confirms h3 less than e confirms h2. Consider that confirmation theory, if it’s good for anything, is supposed to be good for telling me what degree of belief I ought to have in various hypotheses in various situations. If confirmation theory discriminates between equivalents, presumably it sometimes tells me that I ought to have different degrees of belief in two equivalent hypotheses. But I certainly do not think I ever ought to have different degrees of belief in two different equivalent hypotheses. Consider, for instance, that if I did I would be willing to make combinations of bets such that I would necessarily lose on balance, no matter what turns out to be true (i.e. I would be willing to let somebody make a book against me). So let’s leave the difference between h2 and h3 out of the story, and ask how come I end up believing h1 much more than h2 (= h3).   ‘The Theory of Important Criteria’ (Slote 1966).   

1

  Conventions of Language (Lewis 1967).

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To this my answer is: h1 was antecedently far more plausible to me than h2; the evidence was neutral as between h1 and h2, though it disconfirmed various other hypotheses; so I end up still believing h1. What goes on when a hypothesis h is confirmed is a change of my degrees of belief in which my degree of belief in h is increased. But the increment in my degree of belief in h doesn’t come from nowhere; it comes from some or all of the rival hypotheses. Confirmation is a redistribution of belief in the light of evidence, in which some hypotheses gain at the expense of others. But there may be several gainers; and the gainers may divide up their joint gains in proportion to their initial allocations, so they don’t gain or lose relative to each other, but only relative to the losers. Or still more complicated things may happen. In this case, h1 and h2 both gain belief, i.e. are confirmed, but not at each other’s expense, but rather at the expense of further hypotheses h4, h5, etc. which predicted that something other than e would be found, and consequently got wholly or partly disconfirmed by e. Assume for convenience that we know there are cases of R & -L, as for instance your Oscar. Then we regard h1 and h2 as incompatible hypotheses. Suppose that there are three more hypotheses h4, h5, h6 which are incompatible with one another and with h1 and h2, and such that h1, h2, h4, h5, and h6 jointly exhaust all possibilities (for instance one of them, say h6, might merely be the hypothesis that the other four are all false). We know that both h1 and h2 predict e. Suppose h4 predicts -e (for instance h4 might be the hypothesis (x)-(Rx & Cx & Lx)). Suppose h5 and h6 do not predict -e outright, but they do predict that e is rather unlikely. We might initially have the following distribution of belief over the five mutually exclusive and jointly exhaustive hypotheses: h1, .20; h2, .02; h4, .28; h5, .15; h6, .35 (reflecting the antecedent implausibility of h2 and the antecedent high plausibility of the sceptical catch-all hypothesis h6). Then we observe e. Hypotheses h1 and h2, having predicted e, take e in their stride; h4, having predicted -e, is decisively refuted; h5 and h6, having predicted e was possible but unlikely, suffer serious loss but not de­cisive refutation. The final distribution of belief might be, therefore: h1, .80; h2, .08; h4, .00; h5, .02; h6, .10. Thus h1 and h2 have gained – have been confirmed – at the expense of the rest, but not at the expense of each other; they are in the same proportion as before. In fact there is a proof (a corollary of Bayes’ theorem) that if one’s distribution of degree of belief is to be such that one would be unwilling to let somebody make a book against one, and if two hypotheses both predict the same evidence, then one’s degrees of belief in the two hypotheses must have the same ratio after that evidence is observed as they did before. Your next move should be to ask why – either how come or with what justification – I find h1 antecedently far more plausible than h2. Or in the Goodman case – which,



644.  To Michael A. Slote, 16 February 1966

387

as you see, would be handled in the same way – why I find it more plausible that all emeralds should be green than that they should be grue. Here I have nothing to say in answer – the justification of antecedent probabilities is a thoroughly murky and unpromising part of inductive logic, in contrast to the theory of how given prob­abil­ ities evolve as evidence comes in. In the latter, you can get more or less all your results out of the maxim: don’t have a distribution of belief such that somebody can make a book against you, which seems very convincing. In the former there’s nothing of the sort. What can be said is that in the long run it doesn’t matter what antecedent prob­ abil­ities are unjustifiable, because (within a wide range) it doesn’t matter what your antecedent probabilities are, because your probabilities will tend to converge to the same limit as enough, and sufficiently varied, evidence comes in, no matter where (within limits) they started. Presumably the allocation of antecedent probabilities to hypotheses – or at least a sort of screening to see whether a hypothesis is a candidate for getting ­seriously proposed, i.e. for being given some antecedent probability – is a matter of simplicity, elegance, and all that stuff. Carnap’s inductive methods; various people’s simplicity measure; Goodman’s theory of entrenchment; your theory of differential characteristics; Shimony’s suggestion that we should entertain a hypothesis seriously if any working scientist has proposed it seriously; versions of the ‘principle of indifference’ – all these are attempts to answer the question what antecedent probability hypotheses deserve to be given. I don’t find any of them very convincing, but I like the modest and sociological ones – Goodman’s and Shimony’s – better than the rest. As for your theory of differential characteristics,3 I think it’s likely to be right, but not very informative at all. I think it’s probably true that the properties which are differential characteristics in your sense are the same as the ones whose generalizations we are willing to project (i.e. to whose generalizations we allocate a significant antecedent probability, i.e. whose generalizations we deem plausible). Moreover, they’re the same properties that easily get entrenched in Goodman’s sense; and for that matter they’re the same ones we’re all inclined to call natural rather than artificial. I think all these criteria pick out more or less the same class; they’re all criteria we’re able to apply with good intersubjective agreement, somehow, without understanding very well what we’re doing; but they’re all criteria which leave me puzzled about what’s so special about these properties. I want to know the real essence of the species of natural properties, if it has one; I think you’ve found one more proprium, if not accident. 3   ‘Some Thoughts on Goodman’s Riddle’ (Slote 1967); ‘A General Solution to Goodman’s Riddle?’ (Slote 1968); Reason and Scepticism (Slote 1970, ch. 5, sec. 2).

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If you want to know more about Bayes’ theorem and all that – and you do want to either know more about it or get out of the confirmation-theory business – try Jeffrey’s The Logic of Decision.4 What you want is early in the last chapter; but I’m afraid you have to read most of the rest of the book first. Don’t be put off by the math; it’s slow and easy. If you want to go further, look at Studies in Subjective Probability, ed. by Kyburg and Smokler, and its bibliography.5 I’m afraid Scheffler does not give one a very good understanding of what’s going on, though it will do fine as a guide to stock views and arguments from the literature. I hope you’ll be up some weekend. Yours, David

645.  To Michael A. Slote, 2 March 1966 [Cambridge, MA] Dear Michael, As you say, the same probabilities that go into one inductive argument as prior probabilities are likely to have come out of some other inductive argument – perhaps tacit – as posterior probabilities. Induction does not give probabilities on the basis of evidence alone; it takes pre-existing probabilities and modifies them in the light of evidence. So there must be initial probabilities to get the process started. But you need not demand that ‘there must be some other way to differentiate initial prob­abil­ ities’ because within a wide range it makes little difference what the initial prob­abil­ ities are, so it’s no harm if there was no reason for them to be just what they were. Maybe they are haphazard, innate or capricious, unjustified or even inexplicable, but so what? After enough sufficiently varied evidence piles up, very different initial probabilities will give almost the same final probabilities. The initial probabilities are just to get you started; they come out in the wash later. I do agree with Morgenbesser that white ashtrays and black ravens somewhat support the generalization that all crows are black, but that black crows do so more strongly. This has nothing to do with positive and negative instances in the sense of Nicod’s rule; I can’t attach any weight to that difference without discriminating between equivalent hypotheses. Rather, the difference is that we already knew that

 (Jeffrey 1965).   5  (Kyburg and Smokler 1964).

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646.  To Jane Shelby Richardson, 2 February 1967

389

ashtrays and ravens would not turn out to be nonblack crows, so the fact that they didn’t turn out to be black crows does not change our beliefs; but we didn’t know in advance whether any crows would turn out to be non-black crows, so the fact that none of them did does change our beliefs. Evidence that has too much antecedent probability has little power to confirm anything. (Take the extreme case of tautological evidence: everything you looked at turned out to be either a crow or a noncrow. Clearly this ‘evidence’ has no power to confirm anything, because it had antecedent probability of one.) By Bayes’ Theorem, the posterior probability of a hypothesis h after you have a piece of evidence e is the product of three factors: the prior probability of h, the prior improbability of e (that is, the reciprocal of the probability of e), and the probability of e according to h. In this case, we have one hypothesis and two kinds of evidence both predicted by the hypothesis with probability one; the first and third factors are fixed and the second factor makes the difference. In the case of Sleigh’s or Goodman’s paradoxes, we have two hypotheses and one piece of evidence which is predicted by either hypothesis with probability one; the second and third factors are fixed and the first factor makes the difference. In other cases, of course, the third factor makes the difference. Sorry; I see that I did mistakenly identify differential characteristics with inductively virtuous ones. However, my comments stand. It’s no clearer what is a real difference than it is what sort of generalizations ought to be taken as plausible enough to allow of confirmation. In both cases alike we rely on a distinction we can make but cannot codify, explain, or justify. In both cases, (for all we know) the ­distinction we make is merely a result of past practice and might as well have been different.

646.  To Jane Shelby Richardson, 2 February 1967 UCLA Los Angeles, CA Dear Jane, When we were working on Scriven’s ‘Essential Unpredictability . . .’1 it often reminded us of the question whether God can create a stone He cannot lift. After

  ‘An Essential Unpredictability in Human Behavior’ (Scriven 1964).

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reading the enclosed paper,2 I see that the parallel is closer than we thought. Here’s the argument about the stone: 1 ) God either can or cannot create a stone He cannot lift. 2) If He can, He is not omnipotent; He cannot lift a certain possible stone. 3) If He cannot, He is not omnipotent; He cannot create a certain possible stone. 4) So He is not omnipotent. Here’s Scriven’s argument in parallel form. Cast a predictive technique T (the best one possible) in the role of God. Used by a predictor, T produces predictions as to what an avoider will do. Used by an avoider, T defeats such predictions by replicating them so that the avoider can violate them. Now: 1ʹ) T either can or cannot produce a prediction it cannot defeat. 2ʹ) If it can, it is fallible; it cannot defeat a certain possible prediction. 3ʹ) If it cannot, it is fallible; it cannot produce a certain possible prediction, viz. one of an avoider who will use T to defeat any prediction that is made. 4ʹ) So T is fallible. Savage says the fallacy is in arguing from A to B at step 3: ) God cannot create a stone He cannot lift. A B) So He cannot create a certain possible stone. Likewise we do not allow Scriven to argue from Aʹ to Bʹ at step 3ʹ: Aʹ) T cannot produce a prediction it cannot defeat. Bʹ) So it cannot produce a certain possible prediction. For we say that Aʹ doesn’t entail Bʹ without the Compatibility Premise to guarantee that there can be an avoider who uses T against a predictor who uses T (where by ‘uses’ I mean to imply ‘finishes using’). Yours, David cc: Wade Savage

  ‘The Paradox of the Stone’ (Savage 1967).

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647.  To Michael A. Slote, 16 May 1967

391

647.  To Michael A. Slote, 16 May 1967 UCLA Los Angeles, CA Dear Michael, My objection on differential/projectible properties is no objection to the ana­ lysis you gave; it’s merely disappointment that you didn’t do more still. And that’s an obnoxious sort of criticism I shouldn’t have made. Any analysis is valuable to the degree that the analysans is remote from the analysandum; and differentiality is far enough from projectibility to be interesting. But of course I’d still be delighted to see the chain of analysis extended back further! OK? David Kaplan and I have been talking about the TIC1 and raised an interesting issue. What would you think of this quantitative version? Let the criteria admit of degree (in some cases, maybe only the trivial degrees 0 and 1) and let importances of criteria admit of degrees. An F is anything x such that the sum, over all the criteria ci of F-ness, of the degree to which x has ci times the degree of importance of ci exceeds some threshold value. Kaplan wanted this change; so did I, at first, but now I think it adds no real generality, but gives something equivalent to your TIC as it stands. (If it were not equivalent, I would want the change.) Sorry to hear about various miseries, loathings, and disgusts with Columbia. You’d better be thinking how much it’s worth to you to live in a place with all the important conditions of paradigmatic-city-hood, for I’m not sure you can find any others. Maybe we’ll see you in June; we’ll be east, but with unsettled plans. Yours, David

648.  To Peter Unger, 16 January 1968 UCLA Los Angeles, CA Dear Peter, Thank you for the copies of the two papers on knowledge. ‘Analysis of Factual Knowledge’1 I liked very well just as it was. ‘Our Knowledge of the Material   The Theory of Important Criteria.

1

  (Unger 1968).

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392

World’2 I found a little confusing to read – though fine in every important way – because of the order of topics. I was wondering what you’d say to this example: An idle Cartesian demon is trying to decide who is to be his next victim. He thinks it would be amusing to deceive a philosopher who is an expert on knowledge. He says ‘Shall I work on Unger?’ and then can’t decide whether he’d rather deceive Unger or someone else. So he flips a coin; the coin comes up heads, so he decides to deceive someone else. Now I might argue that, forever after, whenever Unger is right about anything, Unger is right at least partly by accident; for it is by accident that the coin came up heads and the demon decided to deceive someone else. If so, then ever after he has his close escape from being deceived, Unger never knows anything. What do you say about this? I’m tempted to say something like ‘It is entirely accidental that Unger escaped the demon; but given that he did escape, it is not at all accidental that he is right about various things thereafter, just the way other people are’. But I’m making some distinction here which I don’t know how to explain or to defend. And I feel there is uncomfortable similarity between the accident whereby Unger escaped the demon and got to be right about things in the normal way, and the accidents whereby the dreamer with the friend got to be right about the outcomes of races. On the ‘Material World’ paper: when I read the argument starting on page 3, I wondered what ‘information’ was supposed to be: knowledge, beliefs, or something else? It turned out to be something else – but there was this unsettled question almost all the way through the paper. But for the purposes of the paper, why bring in information at all? If you’re trying to present a familiar argument, why not just end premise (i): ‘. . . it will not provide the man with any knowledge concerning the material things which are its causes’, and similarly adjust the other premises? Yours, David

649.  To Jordan Howard Sobel, 3 December 1968 UCLA Los Angeles, CA Dear Howard, I would opt for a ‘finest-analysis’ solution to the problems in your letter of 26 Nov. But to get away with it, I wouldn’t apply the maximization-of-expected-value   (Unger 1970).

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649.  To Jordan Howard Sobel, 3 December 1968

393

decision rule to arbitrary partitions (=df mutually exclusive & jointly exhaustive sets) of actions, but to partitions (or should I say the partition) of combinations of basic actions. Why be suspicious of finest analyses? Because for any action – call it the action of A’ing – there is an infinite sequence of more and more finely specified actions: the action of A’ing under the circumstance that p1, the action of A’ing under the circumstances that p1 & p2, and so on, where p1, p2, . . . are independent propositions. But this is not a sequence of more and more finely specified basic actions. On basic actions, see Danto, AΦQ April ’65; Stoutland, JΦ August ’68.1 The idea is that a basic action is one you don’t perform by performing some other action. Or rather: it’s one you don’t perform intentionally by performing some other action intentionally. I seek teacher’s attention (intentionally) by raising my hand (intentionally); but I don’t raise my hand (intentionally) by doing something else (intentionally). So seeking teacher’s attention isn’t basic, but raising my hand is. Do I raise my hand by contracting some muscles? Yes, but not by contracting some muscles intentionally, so no problem. Do I raise my hand by raising it precisely 17ʺ above my head? Yes, perhaps, but again not intentionally. Think of it this way: the little man it is as if you had in your head has a finite number of output buttons he can push to cause bodily movements, and each of these buttons causes a single basic action. If there are n different basic actions in your ­repertoire – it is plausible that this number is finite – there are 2n combinations of basic actions. The basic actions are not a partition, but the combinations of them are. And this partition is a suitable finest analysis. So: the rational agent performs whichever combination of basic actions has the maximum expected utility (according to his probability and desirability functions), and breaks ties by randomization with each optimum combination of basic actions receiving equal probability. I take it non-basic actions are in general definable as follows: x performs nonbasic action A iff x performs some combination C of basic actions such that C bears a certain specified relation to x’s beliefs and desires, to the circumstances, and to the consequences. For instance, x takes a drink of water (a non-basic action) iff x performs some combination C of basic actions which causes x to swallow water, and x performs C because he believed and desired that C would have that effect (or something of that sort). I hope this is some help, Yours, David

  ‘Basic Actions’ (Danto 1965); ‘Basic Actions and Causality’ (Stoutland 1968).

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650.  To Richard Jeffrey, 17 July 1969 UCLA Los Angeles, CA Dear Dick, I seek advice from an old hand in the textbook trade. Is there a market, do you suppose, for a book I have just written much of (in the form of handouts for a graduate course) as follows: a short introduction to Carnap-Hintikka confirmation theory? The contents are

0 Intensional Semantics 1 Probability Measures (Uninterpreted mathematical theory) 2 Rational Belief: Statics (Notion of degree of belief; coherence and strict coherence theorems) 3 Rational Belief: Kinematics (Conditionalization and your generalized conditionalization; a coherence argument for conditionalization) 4 Scientific Method (A long chapter, not yet written. Sampling examples; enumerative and eliminative induction; de Finetti reduction of objective probabilities; Grue, Ravens, Epistemic utilities and acceptance rules; comparison with wrong-thinking statistical inference – if I ever learn any. All of these rather briefly.) 5 Principles of Indifference (The traditional principle of indifference; ℳ⧞, ℳ*, ℳ§, and ℳ#, the last  two of these being Hintikka’s first two constituent-indifference systems.1) 6 Carnap’s λ-System: One Family 7 Carnap’s λ-System: Many families (Short chapter, not yet written; might not go beyond what’s in Carnap & Stegmüller2) 8 Hintikka’s λ-a System (Presented in a slightly different way than Hintikka does: take ℳλ and  raise the constituents to desired measure by generalized ­conditionalization.)











  ‘A Two-Dimensional Continuum of Inductive Methods’ (Hintikka 1966).   Induktive Logik und Wahrscheinlichkeit (Carnap and Stegmüller 1959).

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650.  To Richard Jeffrey, 17 July 1969

395

Maybe a ninth chapter on relations, if I can find anything to say about them. Maybe split up chapter 4 and move it to the end. A minimum of decision-theoretic foundations, though maybe more than Carnap usually gives. Not a lot of clutter with estimate-functions, qualitative and comparative confirmation predicates, relevance measures, and such. Mathematically self-contained, with proofs for the major theorems; but the mathematics is kept down to hairy high-school algebra by not going to the limit of an infinite universe. Not much comparison with other brands: Hempel, Popper, Reichenbach, etc. Nothing about and-what-is-the-relevance-of-this-to-philosophy-and-modern-man. Merely a single, self-contained source for some technical stuff that’s now scattered around in a dozen papers, some hard to get, some hard to read, all in diverse styles. The now-written part goes to 95 pages; the whole will go to maybe 150.3 It’s pitched at the reader who might otherwise read a University Microfilms copy of Continuum;4 indeed, I assigned Continuum as the text in my course. However, it covers improvements and additions to the subjects since Continuum; I think it’s mathematically less cluttered yet more self-contained; and it’s more Bayesian – pretty much in the spirit of ‘The Aim’.5 A worry: I wouldn’t want to be competing with, or trying to scoop, the ‘Basic System’ book.6 The overlap’s not too bad, but enough to worry about. I take that book to cover much less much more thoroughly – not more rigorously, but in greater detail. A variant: would there be a market for a big book consisting of the little textbook as a long introduction, followed by about a dozen major papers in con­firm­ ation theory – say, half-a-dozen Carnap papers (including maybe part I of Continuum), some Hintikka papers, and some miscellaneous? A copy will not arrive unless requested, since I know how well I like to read unsolicited heaps of ditto-paper, even when not packing for a year. Many thanks for the spare copy of Convention; indeed there are many people whom I want to give copies to. Sandra now drives and owns a car! Yours, David

  For this manuscript on confirmation theory, see (Janssen-Lauret and MacBride forthcoming).   The Continuum of Inductive Methods (Carnap 1952).    5  ‘The Aim of Inductive Logic’ (Carnap 1962). 6   ‘A Basic System of Inductive Logic, Part I’ (Carnap 1971). 3 4

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Philosophical Letters of David K. Lewis

651.  To Paul Teller, 29 February 1972 [Princeton, NJ] Dear Paul, Thank you for your comments on ‘Why Conditionalize?’1 I like especially the distinction between the two sorts of non-conditionalizer who doesn’t know in advance what he’d do instead: the chaotic one and the one with unknown, stable dispositions. I was thinking of the former in my reply to the Kaplan-Harman point. I like your way of stating the conclusion. I did originally state the argument in terms of a conditional bet, but changed it because I thought this way was simpler! What I’ve done, really, is to compress two arguments: (1) the argument that your posterior betting rate on P, after observing E, ought to equal your prior betting rate on P, conditional on E; and (2) the more familiar argument that this prior conditional betting rate ought to equal the quotient M(PE)/M(E) of unconditional betting rates. But since I like to take C(P/E) = M(PE)/M(E) simply as a definition, I thought there was no need to introduce the concept of a conditional bet explicitly. If I had other use for them,2 of course it would pay to re-use them at this point. The argument is not entirely my own. In Putnam’s ‘Probability and Confirmation’, in Morgenbesser, Philosophy of Science Today (a lecture for Voice of America, which I imagine Hilary doesn’t take pride in!), p. 113, he speaks of a rule which violates conditionalization ‘. . . even if one’s bets at any one time are coherent, one’s total betting strategy through time will not be coherent’. I tried to reconstruct the argument hinted at by that sentence. I also can’t think how my argument could be modified to justify generalized conditionalization. In fact, I’m led to this conclusion: the ideally rational agent evolves by non-generalized conditionalization: the requisite sensory acuity is inseparable from rationality. (Or maybe this: being able to have degrees of belief in pure sensedatum propositions is inseparable from rationality.) Of course, this is less re­mark­ able than it seems, since it pertains only to perfect rationality. In many ways, I think, we strike compromises between the ideal of Bayesian rationality and the limitations of our faculties; and generalized conditionalization is one of these ways. (I’m not sure of this!) What is the continuity method of arguing for the axioms of probability?

  Cf. ‘Why Conditionalize?’ (Lewis 1999, 403–17).   In the right margin Lewis indicates ‘them’ refers to conditional bets.

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652.  To Robert C. Stalnaker, 21 April 1972

397

You’ll hear soon from Steffi; she thinks your worry about the meetings is farfetched. Bear in mind that she was, at the time, involved in various ways with staffing work. Also, she is not one of a large number of candidates chasing a fixed number of places; her reappointment depends on various other things more than it does on her ranking within the total field. Yours,   David

652.  To Robert C. Stalnaker, 21 April 1972 Princeton University Princeton, NJ Dear Bob, The afternoon following the last session of the Western Ontario conference, Harper and Thomason and I had some talk about the probability semantics for conditionals; with the result that I’ve been re-reading ‘Probability and Conditionals’1 more carefully and with more interest than before, but also with increasing puzzlement. Let me ask you some questions about the paper, and also ask your opinion of a proposal that seems partly to fit what you were doing, partly not. First problem: it should be, I presume, that for any epf Pr and any fixed C, the function Pr(…/C) is a probability measure in the standard sense;2 that is, meets the conditions: (1) If A and B are logically equivalent, Pr( A/C ) = Pr( B/C ); (2) For any A, Pr(A/C) ³ 0; Pr(t/C) =1, t being a tautology; (3) (4) If A and B are logically incompatible, Pr(A Ú B/C)=Pr( A/C ) +Pr( B/C ) . Except for (2), it’s not obvious how to get these results out of your definition of an epf. Can it be done? Is an epf supposed to determine a standard probability measure for any fixed condition? (Sorry: I neglected to qualify. I should have been saying all along: for any fixed condition C such that Pr( -C/C ) ¹ 1.) Second problem: an epf tells you how to conditionalize once, on a C that may or may not have positive Pr(C/t). But what if you want to conditionalize on a succession of conditions: first on C, then on D, . . . . If Pr(C & D & …/t) is positive, no problem; all the conditionalizations will be normal, quotient conditionalization; so instead of  (Stalnaker 1970).   2  ‘epf’ means ‘extended probability function’.

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a succession you conditionalize once on the conjunction. But suppose two or more of the conditionalizations are not normal. Does the epf carry the information what you ought to do? So far as I can see, it does not do so at stage II; though it does at stage III, thanks to the conditional connective. You can say that the probability of X after conditionalizing first on C and then on D is Pr( D > (C >X )/t ) , but this isn’t available at stage II. Let me suggest a different way to set things up, and ask you to compare it with yours. Instead of an epf, we have two items: an initial probability measure P0 (an item that meets conditions (1)–(4) above), and a rule of revision R. R can be given as input any probability measure P and any proposition C (wff if you prefer) and yields as output a new probability measure Pʹ (unless C is impossible, in which case R yields some sort of absurdity). R must meet certain constraints, thus. (Write P, C ® P¢ to mean that R yields Pʹ given as input P and C.) Constraints on R: (a) If P(C) ¹ 0 and P, C ® P¢ , then for all A, P¢ ( A )=P( AC )/P(C ); ( b) If P, C ® P¢, P¢(C )=1; (c) If P, C ® P¢, Pʹ is absurd iff C is impossible; (d) If P, A ® P¢ and P¢( B)=1, and P, B ® P¢¢ and P¢¢(A)=1, then P¢ = P¢¢ . Relation to your epf’s at stage II: if Pr is the epf corresponding to my pair of P0 and R, then (1) for any A, Pr(A/t)=P0 (A), and (2) for any A and C, taking Pʹ such that P0, C ® P¢, Pr(A/C) = P¢( A ) . The differences I perceive between my set-up and yours are these. First, mine gives the information (already at stage II) about where you end up after several successive abnormal conditionalizations. Second, I separate the statics of probability, which are entirely standard both initially and after any number of uses of R, from the (partly standard and partly non-standard) kinematics of probability; whereas your epf’s have a confusing mixture of static and kinematic information. Third: at the point when the conditional is introduced, instead of the business of levels, we merely lay down this condition, a constraint both on P0 and R: (e) If P is derived from P0 by any number of successive applications of R, and P, C ® P¢, then for all A, P(C >A ) = P¢( A ). (Sorry: ‘A’ and ‘C’ do not here stand for ‘antecedent’ and consequent’.) Remarks: I say ‘standard probability measure’ rather than ‘apf’ only because I don’t quite see how your conditions on apf’s amount to the standard conditions (1)–(4) (together with propositional calculus).3 But I presume that a standard prob­abil­ ity measure should come out being exactly an apf, in which case read ‘apf’ throughout. Second: I conjecture that the point of using epf’s instead of a separate rule of revision   ‘apf’ means ‘absolute probability function’.

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652.  To Robert C. Stalnaker, 21 April 1972

399

is this: if you never want to conditionalize on a condition of probability zero, so you only use normal, quotient conditionalization, then of course the statics determine the kinematics. A single 2-place function gives both. You were trying to preserve this feature in the extended case; but I question whether that was a good idea. So much for my questions about your way of doing things. Let me now go on to something of my own. It’s an answer to the question: how does the probability semantics mesh with the selection-function semantics, beyond being motivated by the same intuition (add the antecedent to what you’ve got and make a minimal adjustment, then see what’s happened to the consequent) and yielding the same axiomatics? I’m not interested in the autonomy of probability semantics; I want to take your truth-conditions for the conditional (for the sake of the argument), insist that the probability of the conditional is the measure of the set of worlds where it’s true, and yet come out with a rule of revision that satisfies constraint (e) above. More precisely: given a selection-function, I want to get a corresponding rule of revision such that (e) is satisfied. Further, constraints (b), (c), (d) also will be satisfied. But in general (a) will not be satisfied. My rule of revision will not agree with quotient conditionalization when a quotient conditionalization is well-defined, in general; therefore it will not be a good rule for learning from experience. (Given the Dutch-book arguments for quotient conditionalization; see the enclosed, which collapses the standard ­relation between conditional betting rates and quotients of unconditional betting rates with an argument that you’re irrational unless your present conditional bets agree with the contingency plan you’ll follow for the future unconditional bets.) What it is a good rule for, I suppose, is precisely the task of entertaining subjunctive suppositions! Let’s keep life simple mathematically by supposing that we have only finitely many worlds to bother with; let’s even identify them with (some or all) valuations of the sentence letters, so that no two will be indiscernible in the language. By the image of world i in proposition (wff?) A (under selection function f ) I mean simply f(A, i). By the image of a set of worlds S in A, I mean the set of images in A of members of S: {f ( A, i ): i Î S} . By the image in A of a probability distribution P, (think now of P as primarily assigning probabilities to worlds, only derivatively to wff’s: but it’s still the same sort of standard probability measure we’ve been considering, thanks to the finitude of everything) I mean, roughly, the probability distribution you get by transferring the probability of each world to its image in A. If several worlds have the same world as their image in A, that world ends up with several shares of probability. If a world is in A already, it’s its own image in A so it keeps its original probability; maybe it’s also the image of other worlds outside A in which case it derives thence further shares of probability.

400

Philosophical Letters of David K. Lewis

Here’s the rule of revision determined by f: call it the rule of image conditionalization under f. P, C ® P¢ iff Pʹ is the image in C of P under f. Constraint (e) holds: P(C >A ) is the total probability of the worlds whose images in C are within A; exactly these are the worlds that contribute their prob­abil­ ity to Pʹ(A) when Pʹ is the image in C of the original probability distribution P. (b) holds: the image in C of the worlds with the non-zero original probability lies entirely within C (as does the image in C of any set), so the image in C of any ­probability distribution P assigns non-zero probability only to worlds in C. Imaging conserves total probability; so where Pʹ is the image in C of P, P¢(C) =1. (c) holds: if C is impossible, the image in C of any P concentrates all the prob­ abil­ity on the absurd world, which presumably yields the absurd probability distribution. Conversely, if C is possible, then no world has for its image in C the absurd world: so none of the probability lands on the absurd world, so we have a non-absurd image Pʹ in C of any probability distribution P. (d) holds: let K be the set of worlds with non-zero probability under P.  By hypothesis the image in A of K is in B, and the image in B of K is in A. So for any k Î K, f(A, k)Î B and f(B, k)Î A , so k has the same image in A as in B. So P has the same image in A as in B. I should have given a letter to another constraint that the rule of revision does yield a probability measure. This holds: probability is conserved in imaging, so the  Pʹ-probabilities of worlds add to 1, so (taking Pʹ(A) of course as the sum of Pʹ-probabilities of worlds in A) Pʹ is a probability measure. Exception for the absurd case, of course. But (a) in general fails! Example: P is concentrated in 4 points, as shown. The image in A of each point is shown by the arrow. P( A > C ) = P¢ (C ) = .3 where P, A ® P¢ P(AC) .2 = = .66 … ≠ Pʹ(C)  although P(A) = .3 ≠ 0 P(A) .3 Could this failure be avoided by a reasonable constraint on P0? Even if the rule of image conditionalization violates (a) for some probability distributions, will (a) nevertheless hold for all descendants of P0 suitably matched to the given selection function? Here I have no definite conclusions; but my hunch is that it is hopeless. Maybe there exist P0’s with the property sometimes; but for every f? And will they be reasonable on other grounds? More generally: if you quotient-conditionalize whenever possible, and stick to your truth semantics for the conditional, I don’t see how you can possibly also impose



652.  To Robert C. Stalnaker, 21 April 1972

401

a constraint that the probability of the conditional is the conditional probability. If this happens when the conditional probability is obtained by quotient-conditionalizing this seems just good luck! On the other hand, when you image-conditionalize, then it’s obvious that the probability of the conditional is the conditional probability. So it seems to me that if you really want probabilities of conditionals to equal the corresponding conditional probabilities, either you scrap the selection-function semantics; or you divorce probabilities of conditionals from the measure of the set where the conditional is true according to selection-function semantics; or you image-conditionalize always, even when you could have quotient-conditionalized. Yours, David PS The other enclosure is a very tentative draft of something I was spouting the first evening of the conference.4 A revision: I’d now like to have all the restrictions initially be if-clauses, but allow a restriction if: x is a --to appear on the surface as either a surface if-clause or the result of supplementing or replacing the variable x by the indefinite noun phrase ‘a ---’. Advantage: one fundamental kind of restriction instead of two; permits (but doesn’t require) going back to holding that in ‘is a ---’ the ‘is’ is the ‘is’ of identity and the indefinite noun phrase ‘a ---’ is a restricted existential quantifier, so that ‘x is a ---’ means ‘x = some ---’. So I’d write instead of what’s in the paper; e.g.: æ if: m is an angry man ö ç ÷ if: d is a dog that has fleas ç ÷ d bites m shortly after t. Sometimes ç if: t is a time when the sun is shining ÷ ç ÷ è if: m beats d at t ø PPS You can also image-conditionalize using a set-selection function, as I’d prefer. In that case the image is blurred. Consequently, you’ll have P(C > A ) £ P¢( A ) , where P, C ® P¢ ; Pʹ(A) does, and P(C > A) doesn’t, get a contribution of probability from worlds whose image in C is blurred so as to be only partly in A.

4   ‘Adverbs of Quantification’ (Lewis 1975a). See also Letter 568. To Edward L. Keenan, 14 April 1972 and Letter 569. To Edward L. Keenan, 14 May 1972, Volume 2: Part 5: Language.

402

Philosophical Letters of David K. Lewis

653.  To William L. Harper, 18 May 1972 Princeton University Princeton, NJ Dear Bill, I spoke to King-Farlow and Binkley at St. Louis, and I gather it’s all set that I will participate in the session on probability semantics at Montreal. Steffi and I plan to be there for the whole time of the meetings. We’ll see you then. Let me warn you what I plan to say; I’ve been developing the idea I thought of at Hooker’s. I think I can show that Stalnaker’s full probability semantics is in bad trouble; but all is well if you drop his requirement that probabilities are revised by ordinary conditionalization whenever possible. I don’t like the ‘epf’ formalism, partly because of the painful business with the sub-functions and partly because it obscures the parallelism with the truth semantics. Let’s state the truth semantics and the probability semantics like this. (T)  I f i is a world, and iA is the minimum revision of i to make A true, then A > C is true at i iff C is true at iA. (P)  I f P is a probability distribution, and PA is the minimal revision of P to make A certain, then P(A > C) = PA(C). Thus we have a revision function for probability distributions, required to meet constraints like those on the selection function for worlds. Now (assuming for simplicity that we have only finitely many worlds) we have also this bridge between truth and probability. (B)  F or any proposition X, P(X) is the sum of the probabilities assigned by P to worlds where X is true. In other words: probabilities are probabilities-of-truth. From (T), (P), (B) it follows that the revision of probabilities must work by imaging: PA must be always the image in A of P – that is, the probability distribution that assigns to each world j the sum of the probabilities assigned by P to worlds i such that j is iA. But obviously imaging isn’t conditionalization; only by the occasional coincidence will they give the same result. Stalnaker is free to opt for imaging when P(A) = 0, but otherwise he’s committed to conditionalization. (T), (P), (B), and the requirement of conditionalization-whenever-possible are inconsistent, except for certain trivial cases. You’re OK if you confine attention to opinionated probability distributions, which concentrate all the probability on a single world! Also you can admit



654.  To William L. Harper, 31 May 1972

403

c­ ertain  probability distributions that divide the probability between two different worlds, if certain very stringent conditions on the selection function are met; but that’s as far as you can go. I’m a bit puzzled about the soundness-completeness results for the probability ­semantics. I think of a four-step proof like this: ( 1) If X is valid in general in the probability semantics, then in particular X is valid if we restrict ourselves to opinionated probability distributions. (2) If X is valid in opinionated probability distributions, then X is valid in the truth semantics. (3) If X is valid in the truth semantics, X is a theorem of C2. (4) If X is a theorem of C2, then X is valid in general in the probability semantics. Of these steps (1) is obvious; (2) works because of the perfect parallelism between the probability semantics restricted to opinionated probability distributions and the truth semantics; (3) is well-known; but what about (4)? Stalnaker shows that the ax­ioms are valid in the probability semantics; and he says that he shows that modus ponens and necessitation preserve validity. But validity is non-zero probability no matter what (Stalnaker, p. 76);1 and what is shown (p. 78) is that modus ponens and necessitation preserve certainty – that is, probability 1. Obviously modus ponens does not preserve non-zero probability: we can have P(A) = P(-A) = P(A ⊃ B) = ½, P(B) = 0. So what am I missing here? Yours, David

654.  To William L. Harper, 31 May 1972 Princeton University Princeton, NJ Dear Bill, Thank you for your Montreal paper; and thank you for arranging my invitation to Montreal, which is now all set.1 Thank you also for setting me straight about how the soundness proof works.   ‘Probability and Conditionals’ (Stalnaker 1970, 76).

1

1   A work-in-progress paper for Counterfactuals and Representations of Rational Belief (Harper 1974). See ‘A Sketch of Some Recent Developments in the Theory of Conditionals’ (Harper 1981, 33, n. 11).

404

Philosophical Letters of David K. Lewis

I’ll talk not so much about the difference between my truth semantics and Stalnaker’s as about the relation between truth semantics and probability semantics. As I warned you, I think I’ve found bad trouble – indeed, fatal trouble – for the prob­ abil­ity semantics as it stands. This has nothing to do with my departure from Stalnaker’s epf formalism, and nothing to do with my disagreement with Stalnaker about the details of the truth semantics. Here’s the problem: suppose we have an ordinary probability distribution P – for convenience, assume there are only finitely many worlds – and a conditional A > C such that P(A) ¹ 0. Then what is P( A > C )? According to the probability semantics, it is P( AC )/ P( A ). According to the truth semantics, plus the assumption that probabilities are probabilities-of-truth, it is the sum of the probabilities of worlds where A > C is true – that is, the sum of the prob­ abil­ities of worlds i such that C is true at f(A, i). These two answers do not in general agree. If you want to believe in the probability semantics and the truth semantics both – let alone if you want to derive one from the other – which are you going to believe? For instance, suppose P assigns probability ½ to world i, probability ½ to world j, and probability 0 to every other world. Suppose also that j is an AC-world; i is a A̅ -world; and f(A, i) is an AC̅- world. P(AC) / P(A) = 1 2 / 1 2 = 1 , since j is the only A-world with non-zero probability and also the only AC-world with non-zero probability. The sum of the probabilities of worlds where A > C is true, on the other hand, is ½ since j is the only ( A > C )-world with non-zero probability. Now you might want to hold on to the probability semantics, giving up either the truth semantics or the assumption that probabilities of conditionals are prob­ abil­ities-of-truth. That won’t help. Suppose you have a probability distribution P and connective > such that (*) P( Y>X/Z) = P(X/YZ) whenever P(YZ) is non-zero. (Here P ( / ) is the ordinary conditional probability function associated with P – we won’t need to enquire into what happens when the condition has probability zero.) Unless P is trivial, there exist A and B such that P(BA) and P(BA̅) are non-zero, such that A implies B, and such that P( B) ¹ 1. That is so, for instance, if there exist three mutually exclusive propositions with positive prob­abil­ ity. Now by special additivity we have (1) P(B >A) = P(B > A/A)P(A) + P(B > A/A)P(A). We can use (*) to simplify (1) as follows: P(B > A) = P(B > A/t) = P(A/Bt) = P(A/B),



655.  To Robert C. Stalnaker, 31 May 1972

405

P(B > A/A) = P(A/BA) =1, P(B>A/A) = P(A/BA) = 0. Substituting in, we have (2) P(A/B) = P(A),\P(AB) = P(A)P(B),\P(AB) < P(A),\P(B/A) < 1. But this contradicts the hypothesis that A implies B! Here we have internal trouble: the probability semantics is committed at least to (*). What you have to do to get out of trouble is to give up the idea – a major idea, unfortunately – that the probability of a conditional is the conditional probability in the ordinary sense, when that is defined. Drop clause (f) in Stalnaker’s definition of an epf, and keep everything else. The corrected prob­ abil­ity semantics will not imply (*), and will not imply that P(A >C) is P(AC)/P(A ) when P(A) ¹ 0. The corrected probability semantics not only will be in agreement with the truth semantics; at least under certain simplifying assumptions, the two are interderivable. Yours, David cc: Stalnaker

655.  To Robert C. Stalnaker, 31 May 1972 Princeton University Princeton, NJ Dear Bob, OK on our non-disagreement about the belief theory and about it being bad to revise belief by imaging. OK on the soundness. I yesterday had a letter from Harper saying the same, and saying that I could dig the details out of the depths of an accompanying mass of illegible purple paper. I was digging away when your letter came and saved me the trouble. In the enclosed,1 I try to explain to Harper in more detail and without the distracting change of formalism what’s wrong. Try too, if you like. As you see, I’ve

  Letter 654. To William L. Harper, 31 May 1972.   

1

406

Philosophical Letters of David K. Lewis

simplified and strengthened the argument that the probability semantics is in in­tern­al trouble. The old proof showed that if you have (*) you can’t have five mutually exclusive propositions with non-zero probability; now it’s down to three. Put it another way: if P supports a probability conditional that satisfies (*), then P is at most 4-valued. Otherwise we have non-extreme probability values c and d such that 0 < c < d < 1–c < 1, and propositions C and D such that P(C) = c and P(D) = d. Let A = C, B = C ∨ D; then A and B satisfy the conditions that lead to contradiction. This is ironic. Brian Ellis developed a ‘probability logic’ that contained (*), and assured himself that it wasn’t trivial by showing that it worked out not only for the 2-valued case but also for a 4-valued!2 Put it still another way: if P supports a probability conditional that satisfies (*), P is either opinionated or semi-opinionated. Just what’s to be expected from the argument in the paper about going from belief conditions to truth conditions to belief conditions, and seeing if you’re back where you started. See you soon. Let’s by all means plan on dinner. Yours, David

656.  To Ernest Adams, 28 April 1973 Princeton University Princeton, NJ Dear Professor Adams, Thank you for your comments on my paper.1 I think you’re right about the large area of agreement between us. I think there’s really only one big disagreement; that’s superficially a verbal disagreement, but lying behind it is a more important disagreement about philosophical strategy. The verbal question is this: can it ever be right to call something a probability function if it doesn’t obey the Kolmogorov axioms – in particular, the requirement that the domain of the function should be closed under Boolean compounding? I think not. Mathematical probability theory isn’t the whole of our concept of

  ‘The Logic of Subjective Probability’ (Ellis 1973).

2

  ‘Probabilities of Conditionals and Conditional Probabilities’ (Lewis 1976).

1



657.  To Richard Jeffrey, 26 March 1974

407

­ robability, to be sure, but it’s a big part and it’s the firmest part. I think that makes it p essential: change the mathematics and, whatever you’re talking about, it isn’t prob­ abil­ity. Clearly you disagree. Obviously, you’re much less conservative in philosophical method than I am. I want to hang on to as much as possible of existing standard probability theory, standard truth-conditional semantics, etc., and make the least change that will explain the facts about assertability of indicative conditionals. You’re much more willing to make a fresh start, and much less optimistic about piecemeal reforms. OK; but then I wish you’d be as innovative in terminology as you are in doctrine, and leave the old words ‘probability’ and ‘proposition’ (with reference to your question why I say that propositions have truth-values) behind for use within the theories where those words have their original home. I’ve looked briefly at your chapter 3, but not worked through it.2 Is the point partly this: it’s appropriate to act on a proposition iff its probability is high, it’s appropriate to act on A → C iff P(C/A) is high, hence P(C/A) is the probability of A → C? If that’s it, I’m bothered by the second premise. I don’t in general know what it is to act on a conditional (as opposed to acting on a total probability distribution) but I do know roughly what it is to act on A → C when A is an action and C is a future consequence thereof. But that’s a special case, and it might be dangerous to concentrate on it. Bob Stalnaker’s present view is that although P(A > C) doesn’t always equal P(C/A), it does when the conditional A > C is regarded as causal; and the conditionals we can in some straightforward sense act on are causal! But the result won’t apply to other conditionals. Sincerely,  David Lewis

657.  To Richard Jeffrey, 26 March 1974 [Princeton, NJ] Dear Dick, Let A be the proposition that it will rain tomorrow; let B be the conjunction of A with the proposition that I assign zero probability to A. Consider the bet

  The Logic of Conditionals: An Application of Probability to Deductive Logic (Adams 1975).

2

408

Philosophical Letters of David K. Lewis é$ 1-e if B B: ê (e > 0) ë$ -e if ~B

It cannot happen that both I am rational and I win this bet. (For if I win it, then I assign zero probability to A, and a fortiori (if I am rational) to B; so (if I am rational) I refuse to take the bet; but I can’t win it if I don’t take it.) But does the unwinnability of this bet mean that (if I am rational) I assign zero probability to B? I think not. Let A be as before; let C be the conjunction of A with the proposition that I take no bet in favor of any proposition that implies A. Consider the bet C: é$ 1-e if C (e > 0) ê -e if ~C ë This bet is unwinnable in the same sense as the other. (For if I win it, then I take no bet in favor of any such proposition as, inter alia, C; then I don’t take this bet; then I don’t win it.) But it obviously doesn’t follow that (if I am rational) I assign zero probability to C. For instance, I might be certain of A, and also certain that I will have no op­por­tun­ ity to do any betting whatever! Yours, David

658.  To Franz Kutschera, 26 November 1975 [Princeton, NJ] Dear Prof. Kutschera, I am very sorry that I have been unable to reply more promptly to your ­interesting letter on conditionals. Let me try now to respond to some of the questions you raise. I would certainly agree that we should distinguish between semantics and pragmatics. I agree further that it is a good strategy, whenever possible, to fix on a pragmatic hypothesis and use it to explore the consequences of a range of alternative semantic hypotheses. Very often, I suppose we can hold fixed the pragmatic hypothesis that our judgements of acceptability are based on subjective probability of truth. When that is so, our judgements of acceptability will serve as evidence and we can indeed work as if semantics were independent of pragmatics. But I think there is no guarantee that this strategy will work always. Our naïve judgements of badness do not come labeled on their foreheads as semantic or pragmatic; that decision must be part of the theory that is put forward to explain the judgements.



658.  To Franz Kutschera, 26 November 1975

409

Certainly the naïve informant knows there is something wrong (in some contexts) with the conditional: if the pot boils, Kutschera is 43. And he knows there is something wrong with the argument: Fred will flunk; therefore if he studies hard he will flunk. But I don’t think the naive informant – or even we, acting as our own informants – can be trusted in judging what sort of badness there is: whether falsity of the sentence and failure of the argument to preserve truth, or whether some other sort of unassertability of the sentence and failure of the argument to preserve assertability. For instance an informant may be unable to distinguish between a sentence that is itself false and a sentence that only hints at something false. His indignation at the deception perpetrated if one asserts the sentence (knowing of its defect) prevents him from making any finer discriminations. The case is the same with syntax and semantics. Any informant knows that the famous sentence * Colorless green ideas sleep furiously. is somehow defective. But when he is asked whether the defect is one of grammar, I do not think his judgement should be respected. His ‘linguistic intuition’ is just a bit of theorizing, and indeed a bit of hasty and ill-informed theorizing. So when you say, for instance, that a conditional requires a connection; or that truth-preserving laws for __ ‘do not hold’ for the indicative conditional, then I agree that an adequate theory must somehow account for the badness of certain conditionals and certain inferences. But I take it to be not part of the evidence, but rather a question of explanatory strategy, whether the badness should be explained semantically (as you prefer) or pragmatically (as I prefer). You have seen, though you find it unconvincing, my pragmatic explanation of the unassertability of certain conditionals that are very probably true under my semantic hypothesis. The pragmatic explanation of the badness of certain inferences that I would regard as truth preserving (strengthening of the antecedent, for instance) is explained in two steps. The first step is to explain, as I have tried to do, why truth-functional conditionals explain Adams’s rule of assertability. The second step is to show, as Adams has done, that if the conditionals obey Adams’s rule then those inferences fail to preserve assertability. I am not speaking of O-assertability, but only of the aspect of the O-assertability that is not too heavily dependent on the details of context. Neither am I speaking of P-assertability, which you simply define as subjective probability of truth. Neither am I speaking of a sort of assertability which is defined only for one special sentence form. The closest I can come to a definition is this: the assertability I have in mind is to be the result of disregarding the more context-dependent ones among the factors that contribute to O-assertability.

410

Philosophical Letters of David K. Lewis

I would certainly wish to reject the principle you mention, that logically equiva­lent sentences have the same degree of assertability, in the sense of assertability of which I was speaking. Your result shows why. Assertability is underdetermined by truth conditions and depends also on surface form. On the example of Oswald and Kennedy: your (2a)1 does not sound to my ear like a clearly acceptable and true sentence, despite the topicalization you mentioned. Again, very many thanks for your comments. Sincerely, David Lewis

659.  To Ernest Adams, 12 November 1976 [Princeton, NJ] Dear Ernie, I’ve read part of your book on conditionals,1 and hope to return to it when time permits. Some time ago you sent me a manuscript on the triviality results and the morals you draw from them; presumably that was part of the book. I haven’t reread it very recently, but as I recall it was a good neutral account of the results and the alternative options for coming to terms with them, and a fair statement of the differences between my response to the results and yours. I can’t remember any ‘unforgivable . . . intemperate outburst’ when I gave my paper at Stanford? What I remember was good, vigorous discussion, on your part and on others’. So there’s no need to speak of my forgiving anything at all, believe me. I’m interested in your suggestion that probabilities of counterfactuals tend to equal the corresponding prior conditional probabilities. (I take it that you, like me, would regard this as no more than a tendency.) My inclination would be to explain it in the way sketched in footnote 10 of my paper on probabilities of conditionals.2 Example: the counterfactual ‘If Oswald hadn’t shot him, Kennedy would have survived his visit to Dallas’ is, in my opinion, very probably true. Now, of course, my conditional probability

1   ‘(2a) If it had not been Oswald, that shot K., then it would have been someone else, who did it’ (Letter from Franz Kutschera to David Lewis, 9 October 1975, p. 5).

  The Logic of Conditionals: An Application of Probability to Deductive Logic (Adams 1975).   ‘Probabilities of Conditionals and Conditional Probabilities’ (Lewis 1976).

1 2



659.  To Ernest Adams, 12 November 1976

411

P(Kennedy survived/Oswald didn’t shoot him) is very low; but prior to the event, this conditional probability was high, in fact just as high as the present probability of the counterfactual. I explain this by supposing that there is some proposition X, roughly ‘apart from Oswald, there was no deadly danger threatening Kennedy that day’ such that (1) the present probability of the counterfactual equals the present probability of X, since in worlds with nonnegligible present probability the counterfactual is true if and only if X is true; and (2) the prior conditional probability also equals the prior probability of X, since in worlds with non-negligible prior probability in which Oswald didn’t shoot Kennedy, Kennedy survived in just those worlds where X was true (and X is independent (under the prior probability function) of whether Oswald shot); and (3) my present probability assigned to X doesn’t differ much from my prior probability assigned to X. Often, but perhaps not always, there will be an X to play this role; and when there is, the present probability of truth of the counterfactual will equal the prior conditional probability. My principal interest in the area of probability nowadays has to do with ob­ject­ ive probabilities, and with subjective probabilities of objective probabilities. I take it that the propensity theorists are right that there are genuine empirical facts about the objective probabilities of such things as radioactive decays; that these objective prob­ abil­ities are independent of our degrees of belief; and that they can’t be analyzed as frequencies, or limits of frequencies, or limits of hypothetical frequencies. If frequentist analyses of objective probabilities aren’t right, what are we left with? Answer: a very clear connection between objective and subjective probabilities, as follows. Let P(A) be the objective probability, at time t, of proposition A; let C be any rational subjective probability function for someone who has made no observations of the facts after time t; but who may have any amount whatever of knowledge about facts before time t; and let x be any real number in the unit interval. Then C(A/P(A) = x ) = x. Example: this coin is about to be tossed. I know anything you please about the past, but have no foreknowledge about the future. Then my degree of belief that it will give heads, on condition that it is a coin with equal objective probabilities of heads and tails, must be 1/2. What is the status of this principle connecting subjective and objective prob­ abil­ities? Two alternatives, and I don’t know which to prefer. (1) It is a condition of rationality on subjective probability functions. Or (2) it shows that objective prob­ abil­ities are, though different from subjective probabilities, yet reducible to them in an indirect way, perhaps along lines sketched by Jeffrey.

Philosophical Letters of David K. Lewis

412

Whatever its status, it is an interesting and powerful principle. Indeed, it almost  seems to encapsulate the whole of our limited understanding of what ­objective probabilities are! I’m afraid I have nothing written up about this; my ideas are changing too fast, or perhaps it’s more that I’m too lazy. I do have something else to send that may interest you, though; a paper about counterfactuals and time.3 I’ll send that separately and you should have it a week or so after this letter. Yours, David

660.  To Ernest Adams, 19 November 1976 [Princeton, NJ] Dear Ernie, Many thanks for your notes on Hacking’s system, which I find extremely interesting. I read Hacking’s book a few years ago, I’m afraid rather unsympathetically, without making the sort of attempt you have to understand what he was doing in terms that I found more congenial. It seems to me that what’s implicit in Hacking’s system is part, but not all, of the principle I’m interested in. Let me try to explain the difference this way; I’ll mix your notation and mine for ease in typewriting, but that should be no problem. Let C be a probability function that corresponds to comparisons of degrees of support; that is, one such that A supports B more than D supports E iff C(B/A) exceeds C(E/D). (I would say that this is so iff C is a rational subjective probability function to have prior to all evidence; Hacking might prefer not to commit himself to  that.) Let ‘d’ and ‘a’ and ‘E’ be used as in your notes. Then Hacking’s implicit ­principle is C(E / a(d)) = d(E) whereas I would endorse not only that, but also C(E / a(d) & X ) = d(E)

  ‘Counterfactual Dependence and Time’s Arrow’ (Lewis 1979b).

3



660.  To Ernest Adams, 19 November 1976

413

for a wide range of X’s: namely, for all the X’s that might be anyone’s total evidence prior to the time when it becomes settled whether E or one of the alternative outcomes is actualized. Another way to put it is this: I endorse C¢ (E / a(d)) = d(E) not only for the case in which Cʹ is the original probability function C, but also for the case in which Cʹ is some other subjective probability function that one might rationally come to hold under the impact of suitable evidence prior to the time when it becomes settled whether E. The motivation is this. If I assign 50-50 subjective probability to heads and tails when I toss this coin an hour hence, that might be because I am certain it is a fair coin. In that case new evidence will make no difference to my beliefs about the outcome; my subjective probability of heads and tails will be stable. (Provided that the new evidence is of the sort that will be available before tossing time, and without precognition or what-not of the actual outcome.) It might be, however, that I assign 50-50 subjective probabilities not because I’m certain that this is a fair coin but rather because I have little idea what sort of coin this is: fair, loaded for heads, loaded for tails, or what. In the latter case, my subjective probability of heads and tails won’t be stable; additional evidence available prior to the toss will change my expectations about the outcome. I’m afraid I don’t read as widely as some; so far as I know, explicit discussion of the principle connecting chance and support (we need a good name for it) occurs mostly in connection with Miller’s paradox.1 Miller and his allies have thought the principle could be used to strike a blow against Carnap on behalf of Popper; to which Jeffrey replies on behalf of Carnap that the use made of the principle is fallacious, though different versions involve different fallacies. See Jeffrey’s discussion of the matter in a JSL review of papers by Miller et al.: volume 35 (1970) pages 124 ff.2 (Also a paper by Jeffrey in Synthese 30 (1975) pages 95ff.)3 But in this defense of Carnap against the Popperian onslaught, the interest and merit of the principle get little attention. I often get to Berkeley, but I’m afraid I have no present plans for a visit. I’ll be at the Eastern meetings – not that they’re a very good setting for serious talk. Yours, David Lewis

  ‘A Paradox of Information’ (Miller 1966).   ‘Reviewed Works: A Paradox of Information by David Miller, et al.’ (Jeffrey 1970). 3   ‘Probability and Falsification: Critique of the Popper Program’ (Jeffrey 1975). 1 2

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661.  To Allan Gibbard, 17 May 1977 Princeton University Princeton, NJ Dear Allan, Many thanks for your letter of 12 May. I think I agree with all that you say. I used sums only for simplicity and to avoid distraction. Of course the right way is to go to integrals. My math is rusty, but the way you do it certainly seems right. Why drag in the dependency hypotheses? Of course you’re right that they’re not needed. We could work directly with conditionals, taking C* (S/A ) = åx × C ( A⁄ P(S)= x ) x



or better the corresponding integral; in the notation of your letter, the subjectively expected value of P(S/A). That’s equivalent: a conditional A⁄ P (S) = x is common to many dependency hypotheses Hd all with d(A, S) = x , and the subjective prob­abil­ ity of the conditional is the sum of the probabilities of the dependency hypotheses in which it figures. The reason for going the long way around is not to simplify the presentation of the kind of expected utility we favor, but rather to explore the connection between expected utility and causal dependence. Every right-thinking person agrees that somehow the reason to take both boxes in Newcomb’s problem has to do with the fact that whether the Being has left the million is causally independent of what you do now. Also Bob Stalnaker made an interesting connection in 1972 between the question of whether conditional probability equals probability of conditional and the presence or absence of causal dependence. Your formulation doesn’t directly deal with causal dependence, and I wanted one that did. As I see it, causal dependence is a pattern of counterfactuals. A single counterfactual A⁄ S (or A⁄ P (S) = x in the probabilistic case) can equally well be part of a pattern of dependence such as

A⁄S



ØA⁄ ØS

A⁄P (S) = .7 or

ØA⁄P(S) = .1

or part of a pattern of independence such as

A⁄S



ØA⁄S

A⁄P(S) = .7 or

ØA⁄ P (S) = .7



662.  To Jordan Howard Sobel, 20 May 1977

415

(See my paper on causation, J. Phil. 1973, which however doesn’t do the probabilistic case.) So if you work with single counterfactuals it’s not clear how dependence is involved in the story, though clear enough that it is. That’s why the complication. Copies of this, and of my draft ‘Gibbard-Harper Decision Theory with Chancy Outcomes’,1 to Stalnaker, Harper, Skyrms, and Jeffrey. Yours, David

662.  To Jordan Howard Sobel, 20 May 1977 [Princeton, NJ] Dear Howard, Dick Jeffrey and I have recently been talking a lot about Newcomb’s problem. So long as it was a fantastic example, he didn’t take it seriously; but he does take ser­ ious­ly an analogous but down-to-earth case. It has been conjectured by Fisher that smoking has no tendency to cause cancer. Rather, cancer and a tendency to smoke are independent effects of a common genetic cause. If you find yourself smoking that should raise your degree of belief that you’ll get cancer but (if you know that Fisher’s conjecture is true) that’s no reason not to smoke. So now Dick, like you and me, wants to revise the standard calculation of expected utility to make it give the rational answer. We’ve been interested in Gibbard and Harper’s development of Stalnaker’s suggestion that you should take probabilities of conditionals in place of conditional probabilities. (Gibbard (Pitt) or Harper (Western Ontario) would gladly send you a preprint of their forthcoming paper.1) But G&H use Stalnaker conditionals, with conditional excluded middle, so that one of You smoke ⁄ You get cancer You smoke ⁄ You don’t get cancer is true, and we don’t like that. We think they’re almost certainly both false: if you smoke you might or might not get cancer. We think you need something probabilistic instead. Look at the subjective probability of conditionals like

  Cf. ‘Causal Decision Theory’ (Lewis 1981b, 24–8).

1

  ‘Counterfactuals and Two Kinds of Expected Utility’ (Gibbard and Harper 1978).

1

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416

You smoke ⁄ you get cancer with probability .3 whatever that means. You might take this as a Stalnaker conditional with a consequent about objective probability instead of about cancer; I explore this in the enclosed very tentative draft. Or you might take it as a Lewis or Pollock ‘would’ counterfactual with consequent about objective probability. Or you might take it as a ‘would probably’ counterfactual with a consequent about cancer (Cf. Section 8 of my ‘Counterfactuals and Comparative Possibility’, JPL 1973). Or you might take it as a ‘would probably’ counterfactual with a consequent about objective probability of cancer. What a mess – probability gets into the act three different ways! But it might be what’s needed. My guess is that what you have is one of these last alternatives, but from the letter I can’t be sure. Incidentally, there’s no quarrel with G&H (or at least G) over this; Gibbard also favors some such complication of his original account. Steffi and I are off to Sweden almost immediately; I enclose a description of our plans. It’s possible, but I’m afraid unlikely, that we’ll be in Scotland. We will leave behind us one complete draft of a UCLA dissertation, in the mail from Steffi to her committee. That will be a very good thing to leave behind! Yours, cc: Jeffrey

663.  To R.N. Giere, 10 October 1977 Princeton University Princeton, NJ Dear Prof. Giere, There’s a certain principle, connecting propensity and degree of belief, that I’m much interested in; and that I’ve nowhere seen discussed at length or even unmistakably mentioned. Passages in a couple of your papers suggest that you may have had it in mind; but maybe I’m reading your words through a distorting lens of my own views and interests. At any rate, if you know of any discussion of it that I’ve missed, whether your own or someone else’s, I’d be very grateful if you could steer me to it. The principle will only be of interest to someone who believes in single-case propensities and also in degrees of belief: for short, propensity P and credence C. I suppose there aren’t many such dualists; most people want the one ‘interpretation of probability’ that will do for all purposes. But for such a dualist, myself for one, the principle will be of the utmost importance. Let me introduce it by examples.



663.  To R.N. Giere, 10 October 1977

417

I am absolutely sure (C = 1) that this randomizer has propensity .7 to produce a certain outcome on the trial that is about to begin: heads, let’s call it. What should be my present credence in the proposition that we’ll have heads? Answer: .7, surely. So far, cf. your footnote 12 in ‘Objective Single-Case Probabilities’.1 Next case. I have a lot of information that would by itself tend to lower my credence that we’ll have heads. Perhaps I know that we’ve had only 10% heads in all the many previous trials that were just like this one in all respects that seem to me perhaps relevant. Nevertheless I’m sure that the randomizer has propensity .7 to prod­uce heads this time. What should be my present credence in the proposition that we’ll have heads this time? Answer: still .7. Credence conditional on a propensity-proposition is stable under other information. But only within limits. Next case: as before, except that by waiting I’ve found out that it did give heads: now my credence that it did should be 1.0. Or by waiting I’ve found out that it triggered a fairly reliable heads-detector; now my credence should be .98, maybe. Next case: my credence is divided between two propensity-propositions. Credence .6 that the propensity for heads this time is .7, credence .4 that the propensity is .8. I have any amount you like of information available in advance, but none of the information I could get by waiting to see. Now what should be my present credence that we’ll have heads? Answer: .6 × .7 + .4 × .8, that is, .74. Enough examples. Now for the principle. Let A be a proposition; let t be a time; let Pt(A) be the propensity at t that A; let x be a number; and let X be the proposition that Pt(A) = x. Let Y be any proposition whatever about the state of affairs prior to time t. Let C be any credence function that might be reasonable prior to t. Then C(A/XY) = y. There it is. You can see what sort of use it could be put to. I wonder where it comes from. Is it part of the analysis of what it is for a C-function to be ‘reasonable’? Is it part of a verificationist (as opposed to truth-conditional) semantics for the notion of propensity? Is it a consequence of some tricky analysis which doesn’t identify propensity and credence outright but does analyze propensity in terms of credence, as in Jeffrey, Logic of Decision section 12.7? I don’t have a view, and I’d like to. But I don’t have to know where the principle comes from to recognise its importance and marvel that it isn’t constantly discussed.2 Sincerely, David Lewis

  ‘Objective Single-Case Probabilities and the Foundations of Statistics’ (Giere 1973).   See ‘A Subjectivist’s Guide to Objective Chance’ (Lewis 1980c).

1 2

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664.  To Brian Skyrms, 15 December 1977 Princeton University Princeton, NJ Dear Brian, Many thanks for your draft on causal factors in rational decisions.1 I have two reactions. (1) The doctrine is fine; there are things I’d add to it, but nothing I’d subtract. (2) The example is not fine; and that’s too bad because in making a case against maximizing ordinary expected utility it would be good to rely on an example more credible than those we have so far: Calvinism, Newcomb, Fisher on smoking, the charismatic king. On the doctrine. I would suggest a simplified exposition which, as you’ll agree, changes nothing. Don’t have H’s as well as K’s. Introduce the partition of K’s from the outset by saying that a K is a hypothesis both about which factors are within our control and about the state of the factors outside our control. Better yet, since con­trol­ labil­ity is a matter of degree (suppose that by applying an intense field I could increase the decay probability of an atom ever so slightly), take it that a K is a hypothesis about the degree of controllability of various factors. One extreme case of such a hypothesis will be e.g. ‘cancer works by predestination and I’m predestined to escape it’ – what you now would call an Hn & Kni. Taking the K’s that way – erasing the line between your K’s and your H’s – then I would only add this: The proper partition of K’s is the one that associates with each Ki a definite bundle of counterfactuals about what the probability (= single-case propensity) of various outcomes would be if I did various alternative actions. An overfine partition does no harm; an over-coarse one is OK so far as what you say goes, but prevents me from taking my next step, which is as follows. The Pr(Cj/KiA)’s are to be read off from the counterfactuals associated with (= implied by) Ki; if Ki implies that A ⁄ Prop(Cj) = x, then take Pr(Cj/KiA) as x. This, together with a probabilistic counterfactual analysis of causal dependence, seems to me to make the connection that you allude to but don’t explain: the connection between your introduction of the K’s and the contention that ‘classical decision theory must be revised to take account of causal factors’. This addition also makes clearer the connection between your solution and the Gibbard-Harper solution. I think it’s wrong to think of them just as two rival approaches. Rather, G-H is an elaboration of a special case of your solution.

  Causal Necessity: A Pragmatic Investigation of the Necessity of Laws (Skyrms 1980, 128–39).

1



664.  To Brian Skyrms, 15 December 1977

419

Unless you disbelieve in counterfactuals altogether, surely you’ll agree that at least sometimes a K will imply a bunch of counterfactuals A ⁄ C (or maybe A ⁄ Prop (C) = 1) that associate with each alternative action A one member of the partition of C’s. When so, the probabilities of the K’s that imply the same A ⁄ C counterfactual sum to Pr(A ⁄ C); and for any such K, A, and C, Pr(C/KA) = 1; and for any K that implies A ⁄ Cʹ, where Cʹ ≠ C, Pr(C/KA) = 0. Apply your formula to the special case in which all the K’s are of the sort that imply A-C counterfactuals, and you get exactly the G-H formula (with C’s for their S’s). So theirs is a special case of yours, which you too should accept at least as one possible sort of case. No quarrel; they also regard the case they treat as special. What Harvard Business School should teach is that (1) the G-H formula applies only in a special case, and (2) if you want to understand the counterfactuals that figure in it, be guided not only by the formal semantics but also by your judgements of what would and wouldn’t be under your control (more generally, what would and wouldn’t depend causally on what) according to various hypotheses about the world. Turning now to the example. The key feature is that someone with the lesion tends to increase cholesterol intake. We don’t know why – but we’d better know more than you tell us if the example is to serve its purpose of showing standard decision theory giving the wrong answer. It’s all too easy to develop the example so that standard theory also supports taking the eggs. Is it that the lesions cause an increased desire for cholesterol-rich foods? If yes, can you detect this increased desire? Then it’s like the case of the tickle in the taste buds, and maximizing utility gives the right answer. If no, you don’t have enough selfknowledge to follow a policy of maximizing expected utility; hence you’re not in a position to be a fool by following that policy. You don’t know what you want (and hence don’t get the bad news) until you see what you choose. It remains true that there’s a utility-maximizing choice (refuse) and a rational choice (accept) even when you don’t know your utilities well enough to follow a policy of maximizing utility. But there’s no opportunity to be a fool! Besides, are we to take it that eggs benedict are pleasant as well as being either harmless or (if you have lesions) beneficial? Then you’ll want them whether you have lesions or not, and watching yourself choose them won’t bring you the bad news that you have lesions that have increased your desire for them. But then taking them will maximize utility after all. I think the example should be this. Disregarding health, eggs benedict arouse mixed feelings – by no means wholly favorable. Lesions increase their favorable aspect. But your feelings remain so mixed and so confused that only by actually choosing can you discover your preferences (and thereby get the bad news, maybe). You can’t trust thought experiments, feigned choices, or introspection to reveal the

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strength of your preferences. You’re not then a customer for the Harvard Business School – not able to use decision theory to satisfy your preferences more efficiently. That’s because you can’t know your preferences well enough until it’s too late. It remains that the canons of decision theory can be used to evaluate your choice as rational or otherwise, by the aid of information about you that you don’t have at the time. And indeed, in this evaluation you will count as more rational if you don’t maxi­mize expected utility. But you can’t use these same canons of rationality to guide your choices without learning something which, if learned, would change your problem into an uninteresting one. Yours, David cc: Cartwright & Jeffrey

665.  To Lawrence H. Davis, 24 January 1979 [Princeton, NJ] Dear Professor Davis, Many thanks for your letter. I find it quite interesting. You take my point that Prisoners’ Dilemma is a Newcomb problem, and straightway you argue against ratting in Prisoners’ Dilemma in a way that precisely parallels the usual case for taking only one box in Newcomb’s problem. Having long been unconvinced by the case for  one-boxism, I am of course equally unconvinced by your exactly parallel case against ratting. There’s a real clash of intuitions here. I don’t think it’s likely that anybody will discover any fancy new argument that will produce conversions one way or the other. Usually when someone is introduced to Newcomb’s problem (and doesn’t get confused) it takes only a few minutes to appreciate the case for one view or the other and develop firm views. Nozick’s report accords with my own experience in introducing people to the problem: ‘To almost everyone it is perfectly clear and obvious what should be done. The difficulty is that these people seem to divide almost evenly on the problem, with large numbers thinking that the opposing half is just being silly’.1 Well, I don’t think you’re just being silly, but I do think you’re clearly and obviously wrong about what should be done, since when you do, this very case seems to me a perfectly convincing counterexample to the principle.   ‘Newcomb’s Problem and Two Principles of Choice’ (Nozick 1969, 117).

1



665.  To Lawrence H. Davis, 24 January 1979

421

So for instance I think the case of Prisoners’ Dilemma (or the original Newcomb story) is all that’s needed to refute the view that it’s the most elementary wisdom always to be guided by indicative conditionals such as your (3*).2 I don’t expect you to agree of course. And when I bring you a causal decision theory which advises ratting, I will expect you to tell me that the case of Prisoners’ Dilemma (or the original Newcomb story) is all we need to refute that decision theory; you should of course not expect me to agree. I think it’s a real standoff. The only surprise will be for those who have gone one way on Prisoners’ Dilemma and the other way on Newcomb’s Problem. Unlike you and me, they are in an unstable state and may change their minds about one or the other. I agree with you about the status of (3*) to this extent. (1) It holds because the agents think alike – whether they are alike rational is beside the point. (2) It is indeed something known for certain in some versions of Prisoners’ Dilemma, and something with a significant probability in other, more down-to-earth versions. (3) It is something compatible with my condition (2) of causal independence. (4) The case that (3*) is known with certainty, the case that it has probability 99%, and the case that it has only just enough probability to make estimate reliability exceed (1+r)/2 should be decided alike. I disagree only on one rather central issue: whether (3*) is a correct guide to rational choice in a case of this sort. I think it’s a correct guide only if it reflects causal dependence of outcome on action, which in many cases it does but in this case it doesn’t. I think causal dependence is the crucial thing; counterfactuals enter the story exactly to the extent that they reflect causal dependence. I think counterfactuals are slippery enough so that they could conform to (3*) rather than reflecting causal dependence without violating any fully determinate semantic rules; e.g. that’s the way they’d go in a context in which (3*) had just been put forward. (I do think, though, that in default of special context there’s a strong tendency for the relevant counterfactuals to go the causal way.) I have a paper coming out in Noûs later this year3 which discusses the difference between counterfactuals of the sort that would conform to (3*) in a suitable context and counterfactuals of the sort that are relevant to causal dependence; the latter, in my view, are the ones relevant to rational choice. Sincerely, David Lewis

2   ‘(3*) I will get my million if and only if I do not take my $1000’ (Letter from Lawrence H. Davis to David Lewis, 15 January 1979, p. 1). 3   ‘Counterfactual Dependence and Time’s Arrow’ (Lewis 1979b).

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666.  To R.N. Giere, 25 May 1979 [Princeton, NJ] Dear Ron, Here’s a non-blank page 40,1 which should do much better than the blank one at making sense of what follows. Propositions don’t have chances all by themselves; they have chances at a world at a time. I do view the whole world as one big chance process. At least I do if there’s a global direction of time; if there isn’t I’m not sure what to think. If the reconstructions of Quantum Theory that you mention are right, the Principal Principle is wrong.2 I think that’s a good, but not decisive, reason to take a dim view of them. I think the sponsors of these reconstructions need to tell us what they put in place of the Principal Principle: how are our credences about what they call ‘chances’ related to our credences about outcomes? After they tell us, that will be time enough to decide whether what they are talking about really deserve the name of ‘chances’. My hope is that we can put off crossing this bridge until we come to it, and then never come to it because some more conservative way of dealing with Quantum Theory works out. But I wish I knew more about all this. Thanks for your letter. Yours, David Lewis

667.  To Brian Skyrms, 29 June 1979 [Melbourne, Australia] Dear Brian, Hitherto I’ve thought that I fully agreed with the treatment in ‘Newcomb without Tears’;1 our only difference was that I would, and you wouldn’t, like to go on and say that an HiKni is analyzable as a big conjunction of conditionals.

  Of ‘A Subjectivist’s Guide to Objective Chance’ (Lewis 1980c).   In Ronald Giere’s letter to Lewis, it is not stated what these specific reconstructions of Quantum Theory are. It is merely stated that if certain reconstructions are right, then ‘ “real” chances need not follow the standard laws (or not in all respects)’ (Letter from R.N. Giere to David Lewis, 22 May 1979, his italics). 1 2

1   See ‘The Role of Causal Factors in Rational Decision’ in Causal Necessity: A Pragmatic Investigation of the Necessity of Laws (Skyrms 1980, 128–39).



668.  To Gregory Kavka, 10 July 1979

423

But now I think I have a slight objection to make. Your H’s seem to treat being outside or inside the agent’s influence in an all-or-nothing way. But really it’s a matter of degree. Example. Coin-tossing is a genuine matter of chance, but by an exercise of my powers of psycho-kinesis I can somewhat change the chances. My powers aren’t much, however. By a supreme effort of will, I can raise the chance of heads from 50% to 53%. Is the fall of the coin within my influence? Yes, but only to a slight degree. Suppose I am certain that all the causal factors are within my influence to a slight degree. Then there’s only one H with significant credence, and it doesn’t split into subordinate K’s because there are no factors (wholly) outside my influence according to it. So your calculation reduces to Jeffrey’s. But it shouldn’t, since the influence I think I have over such things as my genetic makeup, the Martian’s actions yesterday, whether I am predestined to be saved, . . . is very slight, and shouldn’t ­matter for most decision problems. You might reply: I can’t think that all the factors are within my influence; for if X is within my influence, then Y, namely the way X (or the chance of X) depends on what I do, is still outside my influence. OK; but I think you might as well just start (as I do) by characterizing the H’s or K’s as hypotheses about how things depend on what the agent does. I don’t think Y can really be called a ‘causal factor’; and if it holds in virtue of some Z which is a causal factor rightly so called, then what about influence over Z? Yours, David cc: Frank Jackson

668.  To Gregory Kavka, 10 July 1979 Monash University Melbourne, Australia Dear Professor Kavka, Many thanks for your letter of 2 May. I’m sorry to have taken so long to answer. I might plead pressure of other business, but the truth of the matter is that I didn’t see how to answer your main point properly until I talked it over with Frank Jackson at Monash. Your point comes in various forms. What becomes of my solution if I have good reason to believe that the prediction of success is premised on my not playing by whim? If I will be severely penalized for playing by whim? If my partner won’t play if it has been predicted that I will play by whim?

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I reply: if I play at all, what am I to do? Red, White, and Blue are tied. (If they aren’t, that’s another and presumably easier problem.) I can’t play without resorting to some tie-breaking procedure. Using my tie-breaking procedure, whatever that is, is what I call playing by whim. But let’s call it henceforth ‘using my tie-breaking procedure’ since that will make clearer why I can’t avoid it if I’m given a tie. Suppose I’m given a tie between Red, White and Blue; I’m told that it has been predicted that if I play, I’ll win without using my tie-breaking procedure. This is a prediction I can’t believe, and it’s intuitively rational to disregard it and not play. Suppose I’m given the same tie; I’m told that if I use my tie-breaking procedure coordination will be achieved but also I’ll be severely penalized. If I believe this (and also if I don’t) it’s intuitively rational not to play. Suppose – your version – I’m given the same tie; accordingly, I know that any sensible predictor will have predicted that if I play I’ll use my tie-breaking procedure. I’m also told that if that prediction has been made, my partner won’t play. Now in­tui­ tive­ly it doesn’t matter what I do. In a nutshell: of course I won’t play if (1) you present me with a tie, and (2) you see to it that resorting to my tie-breaking procedure isn’t an eligible option! The moral of the Hunter-Richter game seems to me to be this. (It could be shown also in a simpler coordination game.) It is not so, as might have been thought, that when the utility of two options is equal, then also the utility of using my tiebreaking procedure equals the utility of the options between which the tie is broken. Rather the utility of using the tie-breaking procedure may exceed the utility of either of the tied options. Yours, David Lewis cc: Frank Jackson, Hunter & Richter

669.  To Brian Skyrms, 19 September 1979 Princeton University Princeton, NJ Dear Brian, Sorry, it seems to me you are missing the problem. For you and for me and for most people, hypothesis



670.  To John Pollock, 19 June 1980

425

Kn: nothing is outside our influence gets very, very little credence. But I ask what is it rational to do if you’re a peculiar fellow who gives Kn credence of one, or close to it; but who also thinks (so he’s not completely silly!) that the degree of his influence over the past is very, very small. I say that your calculation comes out telling this guy (though not more sensible people like you and me) to maximize Jeffrey utility; and I say that he shouldn’t do that (for much the same reasons you and I shouldn’t). He’s almost like someone who thinks the past is outside our influence, and his calculation should come out almost the same. (The case of the telekinetic powers wasn’t meant to be already a problem for your calculation; it was just meant to illustrate what I mean in calling influence a matter of degree.) When I have copies, I’ll send you a paper1 I wrote in Australia which deals, among other things, with the matter of supervenience. I’ve become more and more pessimistic about supervenience of chances on the history of particular fact; I continue to believe in the supervenience of everything else – causation, law, ­ ­counterfactuals – on history and chances together. Yours, David cc: Jackson, Jeffrey

670.  To John Pollock, 19 June 1980 [Canberra, Australia] Dear John, Frank Jackson and I have been talking about the shipment of vases and his letter to you of 4 June 1980. I also want to defend the view that assertability of indicative conditionals goes by conditional probability, but my first response to your example was different from Frank’s. But after some talk, it seems to us that a full response includes both – there is a range of cases to consider. Background is that 75% of the shipment are ceramic vases, yet 75% of the rejects are plastic. Why so? Surely because not many ceramic ones get dropped. In   ‘A Subjectivist’s Guide to Objective Chance’ (Lewis 1980c).

1

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fact background implies that the drop rate for ceramic vases is 11% only. The statistics are like this.

We’re not told the drop rate for the plastic ones, but we might guess. Frank and I guessed differently. (I’m speaking of what Frank says in the body of the letter – the postscript is a different case.) Frank’s guess was: presumably the ceramic ones are handled with care, dropped much less than the plastic ones. Very likely the plastic vases have a much higher drop rate. Mine was: presumably the drop rates are equal, and hence low (11%) all around. A more cautious man wouldn’t guess, but would have some spread-out subjective probability distribution over alternative drop rates for the plastic vases. Someone who makes Frank’s guess thinks of the B ® D conditional as follows: If the vase in question was dropped, it may very well have been plastic, in which case it didn’t break. So it is wrong to say that if it was dropped it broke. Someone who makes Frank’s guess in an extreme form might even guess that the plastic vases have a high enough drop rate – much higher than 33% – to put them in a large majority among dropped vases. Such a one would think: if it was dropped, it probably was plastic and didn’t break. So not only is it wrong to say that if it was dropped it broke – it’s even right to say that if it was dropped it didn’t break. (This extreme version is the response in Frank’s 4 June letter.) The new information that it’s a reject makes no



670.  To John Pollock, 19 June 1980

427

difference. If you guess that the plastic ones have a high drop rate, you don’t say that if the vase in question was dropped, it broke. And if you think the plastic vases have a very high drop rate, you even say the opposite. Someone who makes my guess thinks of the conditional as follows. Presumably the two kinds of vases have equal drop rates, so if the vase was dropped or if it wasn’t, it was most likely ceramic. So it’s fairly safe to say that if it was dropped it broke. Again the new information makes no difference. Given that the drop rates are equal, 75% of dropped rejects are ceramic, so it’s still fairly safe to say that if the vase was dropped, it broke. The cautious man thinks: who knows how many plastic vases are dropped? He thinks of both the possibilities just considered, and others in between, and others in which the plastic vases have an even lower drop rate than the ceramic ones (maybe they’re lighter and easier to handle). No conditional about whether it broke if it dropped is assertable for him, either before or after the new information arrives. Again the new information makes no difference. So Frank disagreed with you about the assertability of the conditional before the new information arrived, whereas my first thought was to disagree with you about the assertability of the conditional after the new information. But on second thought, it could go either way if we’re dealing with a rash guesser. (The case of the cautious man is like that of the man who guesses Frank’s way.) And either way, the new information doesn’t make a difference. All this fits the calculation of conditional probability – still, I think what I’ve said is honest linguistic intuition, not the theory talking. Let P mean that the vase is plastic, and C that it is ceramic. Then we have: prob(B/D) = prob(C/D) = Prob(CD)/(prob(CD) +prob(D/P )prob(P)) = 1 /(1 + 3prob( D/P )), since prob(CD)=1/12 and prob(P)=1/4.





probR ( B/D) = Prob(C/DR)= prob(CDR)/(prob(CDR)+prob(D/P)prob(p)prob(R/D) = 1 / 1 + 3prob(D/P), since prob(CDR)=1/12 and prob(P)=1/4 and prob(R/DP)=1.



Frank’s guess makes prob (D/P) high and makes prob (B/D) and probR (B/D) low – perhaps as low as 25%. My guess makes prob (D/P) low and makes prob (B/D) and probR (B/D) high: if the drop rates are equal, prob(D/P)=11% and probR ( B/D) =75% . The case of the cautious man is intermediate.

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You should soon get a paper on counterfactuals – the last I’ll write for some while, I hope.1 It’s based partly on something I did last year comparing Angelika Kratzer’s theory with various versions of ordering semantics, and partly on something I started several years ago and never finished concerning our disagreements about partial orderings and the Limit Assumption. My address until mid-August 1980 will be Department of Philosophy, RSSS, The Australian National University, Canberra A.C.T 2600, Australia Thereafter Princeton, though I won’t be home until mid-September. Yours, David cc: Frank Jackson, Lloyd Humberstone

671.  To Allan Gibbard, 14 August 1980 Australian National University Canberra, Australia Dear Allan Gibbard, Thank you for your letter of 30 June. Sorry to be so slow in answering – it isn’t all the forwarding delay. Causal Dependence. I think going to the trouble of imposing a distinctness requirement to avoid Kim problems is not needed to make the theory give right answers, but is needed – too strong; is helpful – to make the theory link up with common-sense psychology. I think that’s not only a selling point, but also important to my view that decision theory is part of the common-sense psych. that implicitly defines the mental states. It’s a nuisance, but no worse. Distinctness stops up from using {I kill Truman, He dies but I don’t kill him, He doesn’t die} as our partition of S’s; but I conjecture it’s at least possible – even not too hard – to find some less natural partition that will do the trick. What’s necessary is that where A is ‘I shoot at Truman’ [or some maximally specific version] we must be able to distinguish AS1’s on which I shoot and kill from AS2’s on which I shoot and don’t kill but he dies anyway.   ‘Ordering Semantics and Premise Semantics for Counterfactuals’ (Lewis 1981c).

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672.  To D.H. Mellor, 20 November 1980

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Tickleism. You and Greg Kavka have both said I’m too soft on the tickle defence. I’m inclined to agree, but for what is at least superficially a different reason from the ones you and Greg give. Less superficially it may come to the same thing – I haven’t thought it through very well. (1) To make the tickle defence watertight, the agent’s self-knowledge must be absolutely certain – not just close to certain. (2) But as we know, absolute certainty means absolute unwillingness to learn – pig-headed disregard of the evidence. The tickleist’s ‘rational’ agent will never, ever learn to distrust his t­ ickles, no matter how much reason he gets to think they’ve misled him about his own credences and values. (You and Greg both seem to give the tickleist the benefit of char­ it­able interpretation here, but it’s charity he dare not accept in view of (1).) (3) I say that’s a funny kind of rationality! In short, certain self-knowledge and willingness to learn from experience both look like requirements of ideal rationality, except that they conflict. The tickleist either compromises (in which case we make Newcomb problems after all) or goes to the daft extreme of sacrificing one aspect of rationality in favor of another. Yours, David cc: Kavka, Skyrms, Jeffrey My address remains Princeton; I leave here in 9 days and get home on 13 September.

672.  To D.H. Mellor, 20 November 1980 Princeton University Princeton, NJ Dear Hugh, Thanks for your paper on conscious belief.1 I liked the original version, and I like the quantitative and indexical version better. It ties in with two recent papers of mine, both of which I’ve sent you separately. In one, ‘Logic for Equivocators’, I discuss inconsistent belief as a sort of superposition of differing belief systems, each one consistent; different ones surface and manifest themselves when different sorts of questions arise. When two of these fragments disagree so that in one system I believe P and in another -P, then there’s a sense in which taking both together I believe P, and I believe -P, but I don’t believe P & -P and its various logical consequences. Offhand

  ‘Consciousness and Degrees of Belief’ (Mellor 1981a).

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this doesn’t seem to help with failure of beliefs to be closed under one-premise ­implication and under equivalence; but Bob Stalnaker has some fascinating ideas – unwritten, so far as I know – about how fragmentation could help with those ­problems also. The other paper, ‘Causal Decision Theory’, is more directly related and leads me to suggest an extension of what you say. The relevant part concerns the ‘Tickle Defence’ – a supposed proof that orthodox, Logic-of-Decision-style decision theory gives the correct answer (take both boxes) on Newcomb’s problem and no fancy alternative theory is needed. Here’s the idea. Supposedly the prior state caused the big evil and also causes you to take the small good; so taking the small good is evidence that the prior state obtains and you’ll get the big evil; so the expected value of taking the small good is lower than that of declining it; so you should decline it, despite the fact that that will not at all prevent the prior state and the big evil! (So far, the usual complaint that LoD goes wrong.) The Tickleist replies: but how does the prior state cause you to take the small good? By way of your beliefs and desires, if you’re rational, and no other way. So the actual choice of the small good tells you no more about your prospects for the big evil than the beliefs and desires that caused that state already told you. Given that you know your own mind, as an ideally rational agent should, the act has no evidential value over and above that of evidence you had already at the time of deliberation. So it turns out, as it should, that the expected value of taking the small good exceeds that of declining. I say: the Tickleist is right about the ideally rational agent, if by definition the ideally rational agent knows his own mind perfectly. (As H. Dumpty said, words mean what you make them mean.) But in real life we know our own minds imperfectly, the choice has evidential value of its own, this value makes the LoD calculation go wrong as the usual complaint said it did, decision theory should if possible say something about people who know their own minds imperfectly, so we do after all need a fancy decision theory to give right answers about Newcomb problems – the original one, and also less bizarre ones in real life. (Of course the one-boxer, who disagrees about what is the right answer, sees this as a rescue of LoD – contra the Tickleist, it might give one-boxist answers after all!) Now here’s a suggested extension of what you say. When I believe p but don’t assent to it, I may be disposed to do the things that would benefit me iff p (to put it roughly), but I’ll differ from the assenter in, for instance, not saying that I believe that p. Further, I suggest, I’ll differ from the assenter in not using the fact that I believe that p as evidence for various things it would, if recognized, be evidence for. My belief that I’m surrounded by enemies may be evidence that I’m losing my marbles. If I’m not too far gone and know something about psychiatry, maybe I’d get the connection, conditionalize on the evidence, and go to the shrink if I assented that I was



673.  To Ellery Eells, 15 December 1980

431

surrounded by enemies; but not so long as I only believe it. And that fits. To learn from evidence e, you have to believe that e. To learn from evidence B*p, you have to believe that B*p. Just believing that p won’t do it. (Parallel story for beliefs about one’s own desires, no doubt, which is more often considered in the Tickle Defence.) I’ve told it non-quantitatively, but of course I intend that to abbreviate a quantitative story of the sort you considered. Your guy with imperfect insight is just the sort to whom the Tickle Defence doesn’t apply. His choices are reasoned, since the de­ter­ min­ants of choice work through his beliefs and desires, but he doesn’t conditionalize on the evidence that his beliefs and desires are such-and-such because he doesn’t believe that (or not to degree 1, anyway) and hence he learns less from insight than he would from seeing what he ends up doing. Believe to degree .5 that I can spend two or three days in Cambridge in late March. Will it be term time? Would anybody like me to read a paper, ‘Logic for Equivocators’, say? Yours, David cc: Jeffrey

673.  To Ellery Eells, 15 December 1980 [Princeton, NJ] Dear Ellery, Thanks for your nice paper ‘On Some Alleged Counterexamples. . .’.1 Owing to the clarity of it, I know exactly where I disagree; I agree with all you say except for assumption (17).2 Three comments. ( 1) You say, on page 34, ‘At least if decision theory is to be prescriptive’ then (17) must hold. Right; but there’s a significant role left for decision theory as approximately descriptive, and as constitutive of the concepts of belief and desire, even if it can’t always be used prescriptively. (2) Assuming for the sake of the argument that (17) is a condition of rationality, that would make it a legitimate idealization; but if we can avoid any idealization, in ­particular that one, we get a theory of wider scope.   Cf. ‘Causality, Utility, and Decision’ (Eells 1981). See also Rational Decision and Causality (Eells 1982, ch. 4).   ‘(17) P(RФ(DM)) = 1. That is, I assume that near the time of decision, DM knows what his degrees of belief in the members of Ф are and what his desirabilities for the maximally specific members of Ф are’ (Eells 1981, 318–19). 1 2

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(3) I question that (17) is a condition of rationality, since it requires the agent to be absolutely certain about a contingent matter on which his methods of gathering information are fallible. Even if you are a perfect introspector, is it rational for you to be certain that you are, hence not at all open-minded toward any evidence that might come along to suggest that you are not? If ‘On Some Alleged Counterexamples . . .’ is forthcoming, I’d like to cite it in ‘Causal Decision Theory’ instead of your dissertation. In the same vein, I’d like you to cite ‘Causal Decision Theory’ as forthcoming in the Australasian Journal of Philosophy, rather than as a manuscript. Thanks. Yours, David Lewis

674.  To D.H. Mellor, 14 October 1981 Princeton University Princeton, NJ Dear Hugh, Thank you very much for the book,1 which I look forward to reading; and for the nice photos. The trip home wasn’t bad. The worst delay wasn’t due to the traffic controllers at all – the customs staff at San Francisco had been cut 50%, with the effects you might expect. Being home also has something to be said for it. Steffi had been waiting for news of the Grand Final and was almost ready to phone the consulate, but yesterday she got a letter from Robert Young saying that Essendon had been eliminated early in the playoffs and Collingwood had won. Concerning the need to predict utilities. (1) Why not take the outcomes to be utility-level propositions: the proposition that such-and-such utility level is reached somehow? (These will be equivalence classes of worlds under the relation of indifference, if indeed worlds have utilities and worlds are the maximally specific pos­si­bil­ ities.) (2) Why not attach utilities to worlds? This is the way I formulate subjective decision theory, and it’s the way Dick tends to in recent papers. (An expected utility is then the integral of a random variable – a point function – w.r.t. a probability

  Real Time (Mellor 1981b).

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674.  To D.H. Mellor, 14 October 1981

433

­ istribution. Or something more complicated of the same sort in the causal version.) d It’s psychologically unrealistic – sure it is. But I think we never were trying to describe processes that go on inside more-or-less competent decision makers. We’re describing (one aspect of) what an ideally rational agent would do, and remarking that somehow we manage to approximate this, and perhaps – I’d play this down – advising people to approximate it a bit better if they can. (3) Given a full description of a world, you could not be wrong about how happy it would make you. You know that you are D.H.M., and right there in the description of the world it tells you exactly how happy D.H.M. is at each moment of his life. Likewise for anything else relevant to utility of worlds. (4) As for how happy it would make you to know that this world was actual, why is that relevant? Maybe you’re so curious that it would delight you to know just which world was actual, regardless of how nice a world it is. (Or maybe you so look forward to the pleasures of future curiosity that it would dismay you.) I think the proper question, though by no means the whole of the utility of a world, is: how happy would you be if that world were actual? Not: . . . if you came to know that it was actual. (5) The maximally specific possibilities aren’t worlds but ­individuals-in-worlds. The prospect of this world being actual, for instance, is unspecific between the prospect of being D.H.M. in this world and the prospect of being D.L. in this world. Of course you couldn’t choose between those two prospects, but you might, if sufficiently confused, be uncertain which of them might be the one you get if you do such-and-such. When I was a student, Philippa Foot visited MIT and gave a seminar on ethics. Mostly it was a very good seminar. But there was one topic which she thought im­port­ant and which seemed to me then, and ever since, to be a complete non-issue. Does erring conscience excuse? We have a chap who scrupulously consults his conscience and strenuously obeys it in the face of great temptation. Unfortunately, it tells him to obey the Führer, kill Jews, und so weiter. Now, what shall we think of him? What moral judgement shall we pass? Praise him for his steadfast sense of duty and adherence to principle? Judge him wicked, in view of the content of his principles? That was supposed to be a difficult and interesting question. I never could see it. The right answer, surely, is that he’s a mixture of virtue and vice, of admirable and abominable characteristics, and when we’ve said that we’ve said enough. We never need to make one single overall moral judgement, all things considered. (We might need to make an overall practical judgement – say, that he’s even more of a menace than less conscientious Nazis are.) I think your man who’s very good at choosing actions to serve his desires according to his beliefs, but very bad at desiring good things and very bad at believing what’s reasonable on the evidence (also, very bad at believing what’s true) is a like case. I have some things to say about his rationality, sure enough. When it comes to rationality, he has some strengths and some weaknesses. Isn’t that

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enough to say? Who needs to answer the question – yes, but does that pattern of strengths and weaknesses make him rational? Yours, David

675.  To Wlodek Rabinowicz, 11 March 1982 Princeton University Princeton, NJ Dear Rabinowicz, Thank you very much for your paper ‘Two Causal Decision Theories’.1 I’ve read it with great interest, and it has increased my understanding of the relation of my treatment and Sobel’s. Let me comment on several of the points you raise. Concerning centering. Certainly I am committed to some form of centering: if A and B hold at world w, then A⁄ B holds at w, and that is because no other A-world is as close to w as w itself is. But if A and B hold at w, I do not want to conclude that, at w, there is a tendency of 100% to w and hence to B, and zero tendency to any other world, given A. At least, this is so if I follow Sobel’s lead and understand that ‘tendency’ is to be related to our ordinary talk about chance. For instance, suppose a coin will shortly be tossed. Suppose that in fact it will fall heads. If it were tossed, it might with 50% chance fall heads; if it were tossed, it might with 50% chance fall tails. (For suppose it is a fair coin and an indeterminate world.) But if it were tossed, it would fall heads – for it will be tossed and will fall heads – and it is not so that if it were tossed, it might fall tails. In Sobel’s terminology, I think I should say that at this world, there is 50% tendency for it to fall heads if tossed, 50% tendency for it to fall tails if tossed. So, if ‘tendency’ connects to ordinary talk of chance, and if I am to hold on to centering for the similarity relation that governs would and might counterfactuals, then I cannot also hold on to the connection between that similarity relation and tendency that you state as (ii) on page 7. So let that connection be cut. Then I have a disagreement with Sobel 1979 about would-counterfactuals; but not a disagreement that affects our decision theories. I try to assimilate Sobel’s tendency function to my imaging function given by WA ( W¢ ) = C(W¢ /AK W ),   ‘Two Causal Decision Theories: Lewis vs Sobel’ (Rabinowicz 1982). Cf. (Rabinowicz 2009).

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675.  To Wlodek Rabinowicz, 11 March 1982

435

and that function will, on my view, not be (more than weakly) centered (in the sense of your page 7) in all cases. That is, it may happen that C(W/AK W ) ¹ 1. In the sense of centering relevant to use of imaging or tendency functions in calculating utility, I think I join Sobel in centering only weakly. I think this may answer the difficulties posed by Theorems 1 and 2 of page 15, since I think these use the centering of the imaging function that I would not accept. Concerning dependency hypotheses. Let a practical dependency hypothesis be ‘a maximally specific proposition about how the things [the agent] cares about do and do not depend causally on his present actions’ – that is, let it be what I called simply a ‘dependency hypothesis’. Let a full dependency hypothesis be a maximally specific proposition about how all things do and do not depend causally on the agent’s ­present actions. Then I agree completely with your observation on page 13 that a tendency proposition (an equivalence class under the relation of having the same tendencies) is, if anything, not a practical but a full dependency hypothesis. However this will not lead to further differences between the treatments if, as I think, I could just as well have formulated mine throughout in terms of full rather than practical dependency hypotheses. The difference in formulations won’t matter if, whenever K is a practical d.h. and H is a full d.h. compatible with – and hence implying – K, then V(AH) = V(AK). And that will be so if, for every value-level proposition V = v, C([V = v]/AH)= C([V = v]/AK). And how can that not be so if, indeed, K covers all respects of dependence that the agent cares about? Concerning agents who think they may have foreknowledge about the outcomes of chance processes. Sobel has nothing to say against Connection Thesis 1 except in cases of this sort; I take it – though of course I should not take Sobel to be committed to this – that he finds it plausible as applied to other cases. (Let me call these cases normal.) So do I. Sobel finds it doubtful in abnormal cases. So do I. Sobel doesn’t want to reject the possibility that a fairly reasonable agent might find himself in an abnormal case. Neither do I. So far, no disagreement. But we handle the problem differently. I impose the principle (restricted to the agent’s options) and accordingly agree to set aside ‘some very special cases – cases about which I, at least, have  no  firm views’. Sobel doesn’t impose the principle and doesn’t set aside the abnormal cases. But – unless Sobel has some other reason than he gave to avoid Connection Thesis 1 – we seem to be in agreement both (1) in our treatment of the normal cases, and (2) in our hesitancy to commit ourselves to much concerning the abnormal cases. Now, I don’t dismiss the abnormal cases for the reason you consider on page 18: that an agent would have to be irrational to be in such a case. As you say, I want the theory – so far as possible – to apply to imperfectly rational agents. Besides, I believe in the logical possibility of time travel, precognition, etc., and I see no reason

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why suitable evidence might not convince a perfectly rational agent that these pos­si­ bil­ities are realized, and in such a way as to bring him news from the future. My worry is a different one. It seems to me completely unclear what conduct would be rational for an agent in such a case. Maybe the very distinction between rational and irrational conduct presupposes something that fails in the abnormal case. You know that spending all you have on armour would greatly increase your chances of surviving the coming battle, but leave you a pauper if you do survive; but you also know, by news from the future that you have excellent reason to trust, that you will survive. (The news doesn’t say whether you will have bought the armour.) Now: is it rational to buy the armour? I have no idea – there are excellent reasons both ways. And I think that even those who have the correct two-boxist intuitions about Newcomb’s problem may still find this new problem puzzling. That is, I don’t think the appeal of not buying the armour is just a misguided revival of V-maximizing intuitions that we’ve elsewhere overcome. Concerning constraints on the tendency model. I found your Theorem 4 extremely interesting. The moral, I think, is that Sobel should have imposed a constraint on the tendency models that would rule out such models as you produce! This is not because the agent’s credences somehow limit the tendencies of the world – I’ll have none of such idealism – but because chance has more structure to it than Sobel’s treatment captures. So I put to him a dilemma. If we are to understand his primitive tendency function by way of the connections he establishes between it and our or­din­ary talk of chance, then we must have an additional constraint. (And if we do, this difficulty for L2.2 goes away.) If not, on the other hand, then how are we to understand what a tendency is? (In this case, indeed, Sobel’s treatment would diverge from my own.) The constraint I have in mind resembles the ‘chances aren’t chancy’ principle of my ‘Subjectivist’s Guide to Objective Chance’.2 In terms of tendency functions, it comes to this. It is never the case that world w has some nonzero tendency, given A, to wʹ such that wʹ differs from w itself in its tendencies given A. I find the following unintelligible, if ‘chance’ really means chance: this coin has 50% chance (or tendency) of falling heads if it is tossed now; but also, it has 50% chance, if it is tossed now, of having 100% chance of heads if it is tossed now; and likewise it has 50% chance, if it is tossed now, of having no chance of falling heads, if it is tossed now. If Sobel’s theory makes sense of that, so much the worse for Sobel’s theory, unless it gets further constrained in a way that accords with his talk of chance. And, as far as I can see, it very well could be further constrained.   (Lewis 1980c).

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676.  To Frank Jackson, 23 November 1982

437

Your four-world model illustrates the problem. Suppose that the coin is tossed at worlds w1 and w4; it falls heads at w1, tails at w4. Consider the situation from the standpoint of w2. If the coin were tossed, there would be equal chance of the two maximally similar toss-worlds, w1 with heads and w4 with tails. But w1 is the only maximally similar toss-world to w1, likewise w4 is the only maximally similar tossworld to w4. So (again from the standpoint of w2), if the coin had been tossed, it would have had equal chance of being such that, if tossed, it would have had 100% chance of heads (as at w1) and of being such that, if tossed, it would have had 0% chance of heads (as at w4). Now, I submit that so long as Sobel’s theory allows that, it admits of models that do not conform to his intention to speak of chance. Contrariwise, if we take him at his word we should regard such models as unintended. Again, thank you very much for a most instructive paper. I shall be interested to see Sobel’s comments, if any – doubtless you sent him your paper, and I shall send him a copy of this. Sincerely, David Lewis

676.  To Frank Jackson, 23 November 1982 Princeton University Princeton, NJ Dear Frank, Much to my annoyance, I’ve become worried about one part of what you say on behalf of the implicature-of-robustness theory of indicative conditionals. Let me state my worry, and say what change it suggests. The affected places are ‘Assertion . . .’, last paragraph of page 577, and ‘Conditionals . . .’, third and fourth paragraphs of page 135. Also affected, though not about conditionals, is ‘On a Challenge . . .’, bottom of page 180.1 Let A and B jointly imply C; let Pr(A) be high. Perhaps A is a conditional with antecedent B and consequent C; or perhaps A is a disjunction of not-B with C. Consider (1) If I were to learn B, I would be in a position to conclude C. We agree that a sufficient condition for (1) is that 1   ‘On Assertion and Indicative Conditionals’ (Jackson 1979); ‘Conditionals and Possibilia’ (Jackson 1980a); ‘On a Challenge by Anderson and Belnap’ (Jackson and Humberstone 1982).

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(2) If I were to learn B, I would still believe A (i.e. . . . would still give high probability to A.) At which point, given that we learn by conditionalizing, you move from (2) to (3) Pr(A/B) is high, or in other words, A is robustly probable with respect to B. Well, assuming conditionalizing, which I gladly will, I give you the interchangeability of (3) and (4) If (perhaps per impossibile) I were to learn exactly B, and nothing more, I would still believe A. But what if B isn’t the sort of thing I could learn without learning more at the same time? What if (5) If I were to learn B, I would learn B and also learn D and (6) If I were to learn B and D, I would cease to believe A, since (7) Pr(A/BD) is low? I say that (5)–(6)–(7) are compatible with (3)–(4); but that (3)–(6) imply – by a valid relative of the strengthening inference – (8) If I were to learn B, I would cease to believe A which, given the possibility of learning B, contradicts (2) and casts doubt on (1). You and Lloyd note parenthetically that (6) is a ‘separate question’ from (2). Well yes: taken by themselves, they’re logically independent. But (5) might hold; and the converse of (5) holds automatically; and, given both of those as auxiliary premises, we can interchange the antecedent of (2) and (6). The interchange principle is valid for all of Stalnaker, Lewis, and Pollock/Kratzer: P⁄Q, Q⁄P P⁄R iff Q⁄ R As an example of the problem, let B be ‘Reagan works for the KGB’; let C be ‘I’ll never learn that Reagan works for the KGB’; let A be the conditional from B to C; let D be not-C. My thought is that if the KGB have been so amazingly successful as to have their man as president, surely they’ve succeeded also in getting the news perfectly under their control. So the conditional ‘if Reagan works for the KGB, I’ll never



677.  To Bas van Fraassen and Calvin Normore, 26 November 1982

439

know it’ is assertible intuitively, assertible by Adams’s rule, and robust with respect to its antecedent by your definition. But it’s empathetically not so that if I were to learn the antecedent I would still believe the conditional to be true, and it’s not so that if I were to learn the antecedent I would be in a position to infer the consequent. For if I were to learn the antecedent, I would ipso facto learn what would be still more remarkable, that the KGB had failed to keep the secret. What to say? I offer you this. Our real interest is in robustness with respect to all that would be learned if the antecedent were learned. That’s the kind of robustness we really want if we’re to put the conditional in store for use in case the antecedent gets learned. But that’s sometimes a difficult thing to judge, in view of the variety of ways that something might get learned. And, for the most part, robustness with respect to the antecedent is a reasonable guide to the kind of robustness that really matters – a fallible guide, as we’ve seen, but pretty good most of the time. And it’s ever so much easier to figure whether we have robustness with respect to the antecedent than whether we have robustness with respect to all that would be learned if the antecedent were. So it’s unsurprising if what we have means to signal is the former, rather than the latter. And if this gets conventionalised, it should even be unsurprising that we signal robustness with respect to the antecedent when it clearly diverges from robustness with respect to all that would be learned if the antecedent were. That’s just what happens in the Reagan example. I don’t think the point does any harm to the point of ‘On a Challenge . . .’. For the requisite subjunctive can just be (1). Yours, David

677.  To Bas van Fraassen and Calvin Normore, 26 November 1982 [Princeton, NJ] Bas Calvin Let us suppose that ( 1) Determinism is false (2) As of the moment of his creation, Adam’s chance of sinning was 50% (3) Adam did sin

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ìis timelessly ü ý certain of all these things. (4) God í was at the moment of Adam’s creation î þ



The form of Miller’s Principle that I defend – the ‘principal principle’ as I call it – says ìtimelessly ü ý , C, comes from a reasonable that if God’s credence function í at the moment … î þ initial credence function by conditionalizing on none but evidence admissible at the moment . . ., then C((3 )/( 2 )) = .5 Contradicting C(3 ) = C( 2 ) = 1 according to (4). Then it is not so that C comes from a reasonable initial credence function by conditionalizing on none but evidence admissible at the moment of Adam’s creation. Then what? First hypothesis. God started out with a reasonable initial credence function, then He very soon conditionalized on evidence inadmissible at the moment of Adam’s creation, viz. evidence about how chance processes turned out therefore. (Thus God would be in the position of someone who gets news from the future by means of tachyon signals or the like.) This He could do because He sees all of time as if it were present. Second hypothesis. God’s credence is as if the first hypothesis were true; but the first hypothesis isn’t literally true, for it makes a change in God’s credence ìtimelessly ü ­from one time to another. Rather, God’s credence í ý is what according îat all times þ to the first hypothesis it would quickly become. Then there is no conditionalizing on evidence, admissible or otherwise. C is God’s initial credence function, although it is not a ‘reasonable initial credence function’. So God is unreasonable? Why not? I’ve heard of many divine virtues, but I don’t recall that inductive reason – specifically, cautious open-mindedness about outcomes of chance processes – was on the list. It’s perfectly fitting, nothing derogatory, that God should lack many human virtues. For many human virtues are a matter of acknowledging or coping with human limitations, vulnerabilities, weaknesses. Is He humble? Modest? Cautious? Prudent? Is He obedient? Cheerful? Thrifty? Brave? Clean? Reverent? Is He eager to learn? God needn’t have reasonable initial credences, i.e. a reasonable inductive method, when He’s got something so much better – omniscience. cc: Baysos1   ‘Baysos’ is Australian slang for ‘Bayesians’.

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678.  To Frank Jackson, 16 December 1982

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678.  To Frank Jackson, 16 December 1982 [Princeton, NJ] Dear Frank, Thank you for the reviews, and for the nice strengthening of the point against the moderate right,1 both of which I both like and agree with; and for the draft on conflict which I like but don’t agree with.2 First, I want to be an Assimilationist and claim ambiguity in my defence, though not in the way you consider. You wantPF (prima facie) to enjoy drinking the wine; you wantPF to lay off the wine and mark the exercises. That’s the conflict. You wantPF the wine and you wantPF the marking in the same sense, though on different grounds. You also wantOB (on balance) to mark, and you don’t wantOB to drink the wine. That’s why you don’t drink the wine, and that’s what you mean when you say ‘I don’t want any because I have to mark the exercises’. When you deliberated, you gave thought to your conflicting wantsPF, as a result of which you came to have a wantOB, namely against the wine. Maybe you had no wantOB one way or the other before deliberation; or maybe you had your wantOB against the wine (or the opposite ­wantOB, or indifferenceOB) without being aware of it. Anyway, what never happened – unless you were in a state of (relevant) fragmentation, which ex hypothesi you weren’t – was that you suffered a conflict between wantingOB the wine and wantingOB not to. That’s what doesn’t make sense. For the reasons you say. Right. What is wanting? It is definable in terms of wantingOB? – Maybe. But I don’t think I owe an analysis. I think the prima facie plausibility of Assimilationism – or of casual A’tionist remarks, ‘Oh how I wanted that wine!’ – is testimony enough that we have what concepts we must have to make A’ism OK. Still. Of course, I’d like to analyze wantingPF in terms of wanting. [Henceforth I retain the ‘PF’ and skip the ‘OB’, which fits your usage. Also I’ll try to speak as much as possible of preference rather than wanting, because ‘prefer’ seems unequivocally OB.] And you might fairly say that you’d prefer to analyze conflict not in terms of unanalyzed wantingPF but in better understood terms, and that’s what §4 does. OK; but I think that if the machinery of §4 can analyze conflict then it ought to be able to analyze wantingPF as well, seeing that conflict just is wantingPF contrary things. Before I turn to §4, let me say a little about Davidson and degrees.   ‘Two Theories of Indicative Conditionals: Reply to Brian Ellis’ (Jackson 1984a).   ‘Weakness of Will’ (Jackson 1984b).

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Davidson might – I never try to predict what he would say – agree with my A’ism so far as it goes, but propose an addition: wantsPF are wants relativized to factors. (That might become an attempted analysis of wantingPF in terms of wanting.) This is something I didn’t say; and I think that so far as I understand it, I don’t believe it, thanks to your box-of-cards example. Wanting and wantingPF both admit of degrees; and the wants depend partly on the degrees of the wantsPF; but just dragging in degrees without any PF/OB distinction doesn’t suffice, for the reasons you say. I think something along the lines of §4 probably is right, both as an analysis of conflict that bypasses wantsPF and as an analysis of wantsPF themselves. For indeed the central feature of the case is that your ranking is

1) 2) 3) 4)

Drink and somehow, per impossibile, get the exercises marked anyway Don’t drink and get them marked Drink and don’t get them marked Don’t drink and nevertheless don’t get them marked

so that you want your top-ranked option – (1) isn’t an option – and hence want not to drink, yet drinking would enhance, and not drinking does and would detract from, the cases of marking and not-marking alike. Is it this simple: that wanting is a matter of preference among (what you think are) options, whereas wantingPF involved preferences among options and nonoptions both? I don’t think so. For that would make it true that what you wantPF most, but false that what you want most, is the thing you can’t have: to drink the wine and mark the exercises anyway. That doesn’t sound right. (Still less should it sound right if you don’t even believe in wantsPF!) It ought to be true that you most want what isn’t an option, yet also you want your top-ranked option. Is there an unrestricted/ restricted-top-options ambiguity that crosscuts OB/PF? You might call this wishing/ wanting, but I don’t think language is firm on the point. Here we go, to make clear that it’s two crosscutting things. As before, except that it’s Sunday in Vic and you haven’t any wine. Then the following (idle) conflict is all about nonoptions. You wishPF to drink; you wishPF to decline the available wine and mark logic; you wishOB the latter. ----To continue. Something like what you say about detracting/enhancing looks right. But I’m worried about the way you develop it. To increase the worry, I’ll change the example. Jack has somehow roped you into a Jack-length bushwalk. About mile twelve, you’re going strong, but it’s getting to be an effort. The conflict (as I’d say) is between wantingPF to walk on and wantingPF to stop for a short rest. On balance, after



678.  To Frank Jackson, 16 December 1982

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­ eliberation, you want to go on; you don’t want to stop. But not resting does detract d from walking on. (Not going on would also have detracted from resting, had you wanted to do that and accordingly done it.) You didn’t want to stop. So the state of affairs you preferred and brought about – a  state of walking on – didn’t include stopping. Consider that state of affairs. The conflict consists in this: you want it – the state you brought about, a state of walking on – to include stopping. Is that right? It couldn’t have included stopping. It is essentially a walking, there can be no such thing as a walking-including-stopping! What is this, Canberra? Does the thing turn on your preferences regarding paraconsistent goings-on? (Milder case of the same worry. You decline the wine and mark. But what you prefer is that this very course of action include the pleasure of drinking! But would you prefer that? What would it be for this very course of action to include the pleasure of drinking? You decline, but find the wine coming down your throat anyway? Ugh – that’s no way to drink! You decline, but find yourself in a pleasant state, yet not incapacitated from marking? That’s nicer, but still disconcerting – do you really want such mysterious goings-on? Or would you rather have things cause what you’d expect them to?) Back to the bushwalk. It occurs to me that the preferred, unavailable possibility isn’t one in which you walk on but stop; rather it’s one in which you walk on but get reinvigorated as if from a short rest. But suppose it’s not that you want reinvigoration, and wantPF to stop as a means to reinvigoration. No; you want reinvigoration, but you think it’s out of reach. You think that a rest, far from being a means of reinvigoration, would leave you stiffened up. That’s why you want to go on. Nevertheless, despite the unwelcome consequences, you wantPF the stop for its own sake. ----Let me suggest this. I’ll do it Stalnaker-fashion; the adaptation to other treatments of counterfactuals should be routine. A would enhance/detract from world w iff the closest A-world to w is ranked above/below the closest not-A-world from w. (One of the other of these worlds is w itself, by centering.) A would uniformly enhance/detract from B iff A would enhance/detract from any B-world. A would expectedly enhance/detract from B iff there’s a subset Bʹ of the B worlds such that Pr(Bʹ) is most of Pr(B) and A would uniformly enhance/detract from Bʹ; or maybe if Pr(A would enhance/detract from the actual world/B) is sufficiently high. I once wrote a section of Counterfactuals with something like this in it as a def­in­ ition of intrinsic value;3 Warren Quinn showed me that it was no good for that, since 3   See Letter 12. To Lennart Åqvist, 9 March 1971 and Letter 16. To John  G.  Bennett, 12 May 1971, Volume 1: Part 1: Causation.

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the intrinsic comparisons were still entangled with instrumental value. I scrapped the section; but conceivably it could be resurrected for the present project. Thus, roughly, the idea is that for any world where you turn down the wine and mark exercises, the closest wine-world to it is better still; for any world where you walk on, the closest where you stop is better. What’s very clear is that this won’t be so under any closeness relation that’s right for non-backtracking, causal counterfactuals. Is there any closeness relation that would make it work? Don’t know. (Too much wine with dinner?) Yours, David

679.  To Frank Jackson, 13 January 1983 [Princeton, NJ] Dear Frank, The same point I was making in my letter about indicative conditionals is to be found in Bas’s review of Brian’s book, Canadian JΦ 10 (1980), page 503. See the clever Sally example, used by Rich Thomason some years ago against a one-stage theory connecting something about conditionals (truth or assertability? indicative or subjunctive? I don’t know) to what would be believed if the antecedent were believed. Yours,

680.  To Paul Horwich, 25 March 1983 [Princeton, NJ] Dear Paul, No, of course no injustice to me in your ‘Decision Theory . . .’.1 Thanks for sending it to me. Thanks also for the copy of your book which just arrived.

  ‘Decision Theory in Light of Newcomb’s Problem’ (Horwich 1985).

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Comment on pp. 9–12. Without defending Eells’ premise (3), might I suggest that (1) and (2) are even more unrealistic? Unless all they are is definition – definition of ‘deliberation’ in some idealized sense. My main objection to tickleism, even if in some sense it succeeds, is that it narrows the scope of decision theory to cases where there’s deliberation – worse still, to cases where there’s deliberation in some idealized sense. I want it to make sense to ask whether the rough-and-ready things we do under pressure when we can’t deliberate properly are rational; to which question any added news from tickles that would have appeared in deliberation seems irrelevant. One might say (maybe RCJ has?)2 that the theory of rational deliberation generalizes to the theory of rational decision thus: a decision made perhaps without de­lib­er­ ation is rational iff, if the agent had deliberated rationally, his deliberation would (might?) have resulted in that same decision. To which I say: sometimes, if the agent had deliberated, his decision problem would have been a totally different one. E.g. the fact that he’s under too much pressure to deliberate may be a crucial piece of evidence about his predicament. Or the thing he wants above all may be to have a chance for a bit of deliberation, so that if he were already deliberative he could turn to his secondary goals. Comment on page 16. What matters is simplicity of total theory, not simplicity of decision theory. If total theory has to pay for the concept of causal dependence anyway – which it does – decision theory gets the use of it for free. Comment on pages 17–18. On my account, or Stalnaker-Gibbard-Harper, there isn’t a built-in time bias: you’re out to optimize what counterfactually depends on what you do now, and what’s counterfactually independent cancels out. To which I expect you to say (cf. Horgan, recent J. Phil.):3 ‘Yes, but only if you use the right kind of counterfactuals; and the time-bias is built in there’. I agree to the only-if-you-usethe-right-kind part; but not to the time-bias-built-in part. Cf. my ‘. . . Time’s Arrow’.4 To which your next move might be: OK, it isn’t time-bias that’s built into your choice of the right kind of counterfactuals; but it’s another kind of arbitrary bias. To which I say: that’s just how it is. Yours, David

 Richard Jeffrey.   3  ‘Counterfactuals and Newcomb’s Problem’ (Horgan 1981).   ‘Counterfactual Dependence and Time’s Arrow’ (Lewis 1979b).

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681.  To Allen P. Hazen, 11 July 1983 [Princeton, NJ] Dear Allen, My plans are fairly settled: I’ll be in Melbourne from 2 August to 5 September, except for a brief side-trip to New Zealand starting 12 August, and the AAP week. Kidder willing, Steffi will join me 21 August. I’ll be staying variously at the Jacksons’, Ormond College, and Denis’s flat. I hope that at some point I’ll have time to take the XPT to Albury, coming on to Melbourne the following day. Would there be a lot to see at Albury? – Certainly. More than by dividing the same amount of time between Sydney and Melbourne? – Less clear. Richter. I agree with you that the Knower Paradox is more interesting than Moore’s Paradox; and the Hangman can be either, depending on how you tell it. I recommend a discussion of the Moore-style Hangman, with no pretensions to cover the Knower, by Frank Jackson; ‘The Easy Examination Paradox’, 1981, so far as I know unpublished.1 Of course you can get decision theory entangled with either sort of paradox, just as you can convert any old paradox into a proof of the existence of God. That’s what I suspect Richter of doing. But I doubt that you learn anything new either about the paradoxes or about decision theory (or theology) by doing so. You said that ‘if the person . . . is a Richterian, then the wrong’un, when the formulations in terms of your rational* are considered, would seem to be 2*’. Agreed; but what of it? I had a paradox about what’s true of a rational* agent; a Richterian isn’t rational*, so there’s no problem about him; but that doesn’t make the original paradox go away. It’s as if I had a paradox about what would be true of a knave in a certain predicament, and someone says the paradox wouldn’t arise if only he were a knight. Even if it’s better to be a knight than a knave (suppose!) it’s still bad news if what seems to be true about a knave is contradictory. Unless the idea is to prove that there can’t be a knave. But I don’t think Richter or anyone else wants to use the paradox as a reductio against the very possibility of being rational*.2 Yours,

  (Jackson 1985).   See David Lewis’s ‘Richter’s Problem’ (Janssen-Lauret and MacBride forthcoming).

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682.  To Ellery Eells, 30 November 1983

447

682.  To Ellery Eells, 30 November 1983 Princeton University Princeton, NJ Dear Ellery, Thank you for your draft on predictive accuracy.1 In a way, I accept all your points. And yet I end up less sceptical than you about measuring predictive accuracy. I think there’s a natural way, sufficiently closely tied to success rate, to sensitivity, and to the utility of employing the predictor to guide your choices. I think what you say splits into three problems for measuring accuracy by success rate. I grant your point on two of three, but don’t find them very damaging. I suggest a counter to your third. By ‘success’ I just mean truth of the biconditional: it rains iff it was predicted to, or what have you. By ‘success rate’ I mean an actual or expected frequency of success, either overall or conditionally on one or the other outcome. Your first point is that overall success rate measures not only the predictor’s intrinsic ability, but also his good or bad fortune in being situated in circumstances which help him do well or badly. If his success rate conditional on rain is better than his success rate conditional on not-rain, then he has a better success rate overall if there’s a lot of rain. Point taken. If we measure by success rate, we are evaluating predictor-in-context, not predictor-in-abstraction. Agreed, but I think not damaging. Your second point is that different kinds of success have different values; and that these differences reflect the customer’s interests, and so will differ for different customers. For me, successful prediction of rain produces twice the utility increment that successful prediction of non-rain does; for you it’s otherwise. For each of us, what’s closest to the decision whether to employ the predictor is a weighted success rate. This is so even for the special case of the Purely Epistemic chap whose weights are all equal. Point taken. Henceforth I’ll tacitly understand success rates as weighted averages of rates of different kinds of success, with equal rates only as one special case. Again, I think not damaging. It doesn’t result in a fragmented concept of ac­cur­ acy, only a parametrized one. Your third point was that an insensitive predictor, even one whose predictions are uncorrelated or negatively correlated with the outcome, may still enjoy a high success rate. Yet you wouldn’t call him an accurate predictor. Here I have a suggestion to offer. Let’s distinguish gross success rate, what we’ve hitherto been calling 1   ‘Ratifiability, Game Theory, and the Principle of Independence of Irrelevant Alternatives’ (Eells and Harper 1991, 6, 11).

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­simply ‘success rate’, from net success rate, which is gross success rate minus baseline. Baseline is the best gross success rate (under the given circumstances and weighting) which is available to a totally insensitive predictor. E.g. if it rains 80% of the time and the weights are equal, the best gross rate available to a totally insensitive predictor is the 80% available to the chap who predicts rains always. Then a sensitive predictor with a gross rate of 92% has a net rate of 12% out of a possible 20% (or if you normalize, a score of .60). An insensitive predictor can’t possibly have a positive net rate. So it’s not that sensitivity and success rate are independent dimensions of assessment. Rather, comparisons of gross rate are misleading because of differences in baseline, and the way to pay due respect to the importance of sensitivity while still going by success rate is to look at the net (weighted) success rate. Note that the circumstances and weighting enter twice over into net success rate: first via the gross success rate of this predictor, second via the baseline, that is the best gross success rate possible for an insensitive predictor. Sincerely, David Lewis cc: Jeffrey, van Fraassen, Skyrms

683.  To William J. Talbott, 22 June 1984 [Princeton, NJ] Dear Bill Talbott, Thank you for your paper.1 I found it interesting, but I disagree with you on a basic point. It seems to me that no matter how badly you are interfered with, no matter how disabled from deliberating you may be, there is still a perfectly good question: is it so that your behavior serves your desires according to your beliefs? (If you are literally a puppet, in the hand of your master, perhaps ‘behavior’ is the wrong word for your movements. Even so, provided you have beliefs and desires, we can still ask whether the movements your master puts you through serve your desires according to your beliefs.) Of course, you may not be able to consider the question properly – that depends on the extent of the interference with your thought. And bystanders may not, if they too are interfered with, or if they don’t know enough. Maybe nobody is in a position to consider it. But it’s no less a meaningful question for all that.   ‘Standard and Non-Standard Newcomb Problems’ (Talbott 1987).

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684.  To Frank Jackson, 30 January 1986

449

I think this question, what behavior (or what movement) best serves desires according to beliefs, is the question what it is (instrumentally) rational to do. For someone lucky enough to be able to deliberate properly, the question what it’s rational to do is considered in deliberation. But it might come up in other connections. Somebody who may have to fly by the seat of the pants might want to cultivate habits that will conduce to rational behavior when there’s no time to deliberate. The puppet might be curious whether he is in the hands of a benevolent ­puppet master who makes him move rationally, or a malevolent one who doesn’t. A believer in genetically hardwired decisions might wonder, as a topic in the theory of evolution, how rational such decisions are. I don’t mistake you for a Tickleist, but I do say the same to you as to him: that we can properly ask what choice would be rational for someone, regardless of whether that someone makes his choices by fully rational means. Indeed, regardless of whether they are, properly speaking, his choices at all! Cf. ‘Causal Decision Theory’, bottom of page 10. Yours, David Lewis

684.  To Frank Jackson, 30 January 1986 [Princeton, NJ] Dear Frank, I don’t believe the ‘Lemma’ that begins your letter of 16 December about ­conditionals. The Lemma says that P(A) = P(B) for all rational P only if A and B are logically equivalent. ‘Rational P’ is short for ‘probability function P that could represent a rational person’s system of beliefs’. ‘Logical’ equivalence presumably means ‘broadly logical’ equivalence, else there are obvious counterexamples in which A and B differ only by synonym substitution. If rationality just means coherence, of course the Lemma is provable if understood as follows. Whenever P(A) = P(B) for any rational P, then also W(A) = W(B) for any world W, where W(A) is 1 or 0 according as A is true or false at world W, likewise W(B). Proof: W is a coherent belief function. But a higher standard of rationality will include the Principal Principle, and perhaps also some special cases of the Principle of Indifference. I think either of

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these will lead to violations of the Lemma. My trouble is that I can’t make the thing water-tight without helping myself to some further conditions of rationality, which might be at least somewhat plausible. Here’s the sort of thing I have in mind. Let S (for ‘set-up’) be a proposition that provides background. It says, in part (S⎺) Some day in the very far future, some last surviving piece of automatic machinery will toss a coin for the very last time. The toss will be a genuine chance process, and the chance of heads and tails will be exactly equal. (For those who just can’t take seriously the supposition that a coin toss might be a genuine chance process, let it be replaced by something about a particle and a halfsilvered mirror.) Now the two propositions for the counterexamples are (A) S, and the coin will fall heads; (B) S, and the coin will fall tails. Certainly A and B are in no sense equivalent. But the Principal Principle says that if P comes from any rational initial belief function C (for short: from any c-function) by conditionalising on evidence E which is ‘admissible’ at the time of the toss and consistent with S, then P(A) = C(A/SE) × C(S/E ) = 1 2 C(S/E ) P(B) = C(B/SE) × C(S/E) = ½C(S/E) so that P(A) = P(B); and of course if P comes from a c-function by conditionalising on evidence inconsistent with S, then again P(A) = P(B), since both are zero. We can suppose – a standard idealisation – that any rational P comes from some c-function by conditionalising on the total evidence. So we have almost a counterexample, except that we have to eliminate one remaining case. What if P comes from a c-function by conditionalising on total evidence E, and E is consistent with S, and E is inadmissible at the time of the toss? To deal with this, we beef up S – I told you that S⎺ wasn’t all of it. We can add that the last coin toss takes place so far in the future that all life and all intelligence is extinct forevermore. We can add that there is no funny business with time machines or circular time that brings traces from the time of the toss back to the earlier times when there still were believers. Or, more simply, we can just write it into S that at no times does any believer possess any evidence which is inadmissible at the time of the toss. Does this do the job? I think so, but not in any clean way. The trouble is that S



685.  To Frank Jackson, 18 February 1986

451

doesn’t contradict the inadmissible E directly; rather, S and the inadmissibility of E (for short: not-AE) imply that nobody has E (for short: not-HE). We could close the gap if we assumed two things. The first is that E implies HE – this is a somewhat plausible closure condition for total evidence propositions. The second is that not-AE follows from S (with the aid of premises about what the subject matter of E is, which we needn’t count because they’re necessary). Then S  implies not-AE, S and not-AE imply not-HE, E implies HE, and so S and E are ­inconsistent – QED. I’d like to do better – can you see how? A counterexample based on some sort of restricted principle of indifference would work in much the same way. A and B would be two different extensions of a set-up proposition S, there would be the appropriate sort of symmetry between the two, and something would get written into S to exclude anybody having in­ad­mis­ sible evidence that would reveal directly whether it’s A or whether it’s B. All of this looks pretty irrelevant to the use you actually make of the Lemma. I suspect there’s some way your use of the Lemma could be reconstructed using a weaker premise. This should be right up Collins’ alley; I’m taking the liberty of showing him your letter along with this. Yours,

685.  To Frank Jackson, 18 February 1986 [Princeton, NJ] Dear Frank, When I discussed my 30 January letter to you with John Collins, he thought it was harder than I thought to wield the Principal Principle against your lemma. I took his point; but by the time I was done, I decided that really it was easier than I’d first thought. I needed to make sure that if E were inadmissible (at the time of the toss) then E would contradict the proposition S which describes the set-up. I provided for this in three steps. (1) S implies not-(not-AE & HE). S says inter alia then inadmissible evidence isn’t available to anybody. (2) S implies not-AE.

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Philosophical Letters of David K. Lewis S tells enough to settle that any proposition with the subject matter of E will be inadmissible. (3) E implies HE. E is a proposition about the course of one’s own experience; E is ‘I have experience that goes like so-and-so’, HE is ‘someone has experience that goes like so-and-so’.

Now you can’t fault (1); you can fault the combination of (2) and (3), as Collins did, but which one is bad depends on how you understand what sort of proposition E is supposed to be. If you look in ‘Subjectivist’s Guide . . .’ at the end of the section headed ‘The Initial Credence Function C’, you find a parenthetical paragraph which says that I’m omitting a complication – namely, that probabilities attach not only to de dicto propositions (= sets of worlds) but also to de se propositions, also known as properties (= sets of possible individuals). Now the omission has caught up with me. I wasn’t thinking straight about what E was. When I think of E as somebody’s total evidence, I ought to be thinking of it as de se: the proposition that one’s experience up to now has gone like so-and-so. Then (3) looks good. But (2) looks bad: a de se proposition doesn’t have a certain historical time as its subject matter, so what sense does it make to have it be inadmissible because its subject matter pertains to times after the toss? When I think of E as an inadmissible proposition about times after the toss, I ought to be thinking of it as a de dicto proposition: someone gets experience at suchand-such historical times, or information that traces causally from such-and-such historical times. Then (2) looks good. But (3) looks bad, which is in effect what Collins said. Couldn’t one get information originating at so-and-so historical times without knowing that one was doing so? (Here, you see, I’m still taking HE as de se.) So at this point it looks harder to attack the lemma. But I thought the thing to do was to go back and try to fix the omission in ‘Subjectivist’s Guide . . .’. One way is to make the dubious idealisation that every ideally rational subject knows who and when in the world he is. But that would be highly suspect! A better way is to try to take the Principal Principle as de se throughout, and make S also de se. Then I have to take your lemma as applying to de se as well as de dicto propositions, since otherwise my counterexample (in which A and B extend S and S is de se) won’t apply. But your application of it to conditionals will be limited unless it can apply when A and B are de se, since certainly conditionals and their negations can be de se. A de se form of the Principal Principle might say that if C is a c-function for de se propositions, x is a number in the unit interval, t is a temporal distance, Y is the de se proposition that a chance process at time now+t will give a certain outcome, X is the de se proposition that the chance at time now+t of Y will be x, and Z is a de se proposition



686.  To Jordan Howard Sobel, 19 May 1986

453

admissible at now+t (for instance by being entirely about history before now+t), then C(Y/XZ) = x. Somewhere there needs to be a dismissal of time travel and the like; this can be written into X. Then I think the admissibility at now+t of a de se proposition about the course of one’s experience up to now is automatic; and a total evidence will be such a proposition. So all the rigmarole in my previous letter of making sure that an inadmissible total evidence E will contradict S can just be bypassed. ------[. . .] See you almost certainly at the AAP, perhaps also in Canberra before or after. Yours, cc: Collins

686.  To Jordan Howard Sobel, 19 May 1986 Princeton University Princeton, NJ Dear Howard, I owe many people comments on many things – I’ve fallen way behind in reading and correspondence, and I’m only just beginning to catch up. One of the longeststanding debts has to do with ‘Not Every Prisoner’s Dilemma is a Newcomb Problem’1 which you’ve sent me more than once, and which I now have in the CampbellSowden book. Despite our clash of titles, it seems to me we have no real disagreement. It’s an issue of terminology only, and I’m certainly not wedded to the terminology chosen in my paper! Mixing your notation and mine, we’ve got payoff matrices of the form: C

-C

A: I confess

A

r

1+r

-A

0

1

or I take the transparent box C: You confess or The opaque box is empty

where r is positive, where A and -A are my alternative actions, and where C and -C are causally independent of whether A or -A. So causal decision theory, in any version, says to do A. Evidential decision theory disagrees, saying to do -A, if and only if (*)  [1 + r] less than [P(D/A) + P(D/-A)],   (Sobel 1985).

1

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where D (for ‘diagonal’) is [(A & C) ∨ (-A & -C)]. In my paper, I put this by saying that ‘average estimated reliability exceeds (1+ r )/2’. In the extreme Newcomb problems, for instance the original story about the wonderful Martian or the Prisoners’ dilemma between ‘psychological twins’, we even have (*!)  [1+r] much less than[P(D/A) + P(D/-A)] = almost 2 but that’s an extra; it may add to the dramatic effect (and detract from plausibility), but isn’t needed to make the divergence between causal and evidential decision theory. We note that (*) is not implied by (**)  1/2 less than P(D) or even by (**!)  1/2 much less than P ( D ) = almost 1 because of cases like this: P(D/A)=1, P( D/-A ) = 0, P(A)= .99, P(D)= .99. Now we can divide Prisoners’ dilemmas into two sorts: the ones that satisfy (*) and the ones that don’t. I say that every Prisoners’ dilemma at least has the shape of a Newcomb problem: it meets conditions (1), (2), (3ʺ) of my paper. That is to say that it has the right matrix, the agent regards C as causally independent of A, and the agent regards C as to some extent potentially predictive of A. By the last, I mean nothing more than just that the agent regards his fellow prisoner as being to some extent – perhaps a very limited extent – similar to himself, and in a similar predicament. That was the point of my paper. So far, I trust that you agree. You say that not every Prisoners’ dilemma does what Newcomb problems characteristically do: namely, present us with a divergence between rival conceptions of rationality. Only the ones that satisfy (*) do that, and not every Prisoners’ dilemma satisfies (*). If I regard the fellow-prisoner as a very poor predictor of me (or as a good predictor only if I do A), or if r is rather large, or both, then (*) will not hold. That was the point of your paper. Of course I agree. Now, what shall we call a Prisoners’ dilemma that fails to satisfy (*)? – One thing to call it is: easy. Because in such a case all hands agree that A is the thing to do. So says offhand common sense, so say both evidential and causal decision theory. What else to call it? We might call it a Newcomb problem because it has the right shape, while noting that it is an uncommonly unproblematic one. (Call this the broad construal.) Or we might say that it is no Newcomb problem at all, because it doesn’t present us with the characteristic divergence. (Call this the narrow construal.) We might call it a Newcomb non-problem. We might do without any settled policy about what to call it.



686.  To Jordan Howard Sobel, 19 May 1986

455

(Mold some butter so that it has the shape and size of a chair. What to call it? Is it a chair, but an uncommonly useless one? Or is it no chair at all, because it’s no good at doing what chairs characteristically do, namely supporting us? Who knows? Who cares? Who needs an official position on this issue? Who needs even to standardize his usage from one day to the next?) My footnote 6 said of a non-(*) Prisoners’ dilemma that ‘even this non-problem might legitimately be called a version of Newcomb’s problem’ because, as I’m ­putting it in this letter, at least it has the right shape. That was an endorsement – an exceedingly feeble one – of the broad construal. You decline to call it a Newcomb Problem, because it doesn’t present the characteristic perplexing divergence. By writing condition (4) into your definition, you had opted for the narrow construal. No worries – I’m happy to construe the term either way. This is not an issue between us. The broad construal does enjoy a certain amount of currency, as you noted in your footnote 12. But I must say that it’s currency in circles I wouldn’t care to be part of. You have Levi and others, people who are really one-boxers but don’t want to just say so. What they want to say is that we crude two-boxers are missing all sorts of distinctions; whereas they with their subtle minds have observed that Newcomb’s problem comes in many versions, in some of which – the non-(*) ones – it’s right to take two boxes, whereas in others – the (*) ones – it’s right to take only one. To make their careful distinctions, or (as I would rather say) to drag in their red herrings, of course they have to adopt the broad construal; else they’d have not the many problems, but the one. (They drag in other red herring non-problems as well, notably the non-problem of what you ought to do ahead of time, before the Martian shows up, to make yourself the sort of person who’s going to win.) If there is any vestige of real disagreement between us, it comes from your doubt about my statement that Prisoners’ dilemmas that are Newcomb problems (on the narrow construal) are ‘deplorably common in real life’. My reason for saying so was that all you need is (*), not (*!). Given a low value of r, (*) is very undemanding. It can be satisfied when P(D/A) and P(D/-A) are only very slightly more than 50% – there’s no need at all to think that my fellow prisoner and I are ‘psychological twins’, no need for what you call the case of ‘near certainty’. An afterthought. Just as we might say that a non-(*) ‘Newcomb problem’ doesn’t deserve to be so called, so we might also say that a non-(*) ‘Prisoners’ dilemma’ doesn’t deserve to be so called. It has the shape of a Prisoners’ dilemma, sure enough; but it doesn’t present the characteristic perplexity of more problematic Prisoners’ dilemmas. It’s easy to see that it’s rational to confess. It’s a Prisoners’ non-dilemma. To this a reply, but a less than conclusive reply, is that Prisoners’ dilemmas present two different characteristic puzzles: one is the problem about what it’s rational to do, one

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is the social misfortune that widespread rationality can make us all worse off. The non-(*) ‘Prisoners’ dilemma’ does the second of these characteristic things, if not the first. (It’s as if you molded some hard cheese into the shape of a chair. Would it deserve the name? Not only does it have the right shape – also it does some of what you’d expect a chair to do. You couldn’t sit in it yourself, but you might get away with stacking a few papers on it.) So it has some claim to its name – an imperfect claim, but a stronger claim than the non-(*) ‘Newcomb problem’ has. Yours, David

687.  To Robert Aumann, 30 June 1986 Princeton University Princeton, NJ Dear Professor Aumann, Thank you very much for your letter of 12 June. I’m much relieved to learn that in 1976 you simply didn’t know of my discussion of common knowledge, and that now you do know of it and have been citing it. Therefore I have no cause whatever for complaint. My only suggestion is that Schiffer should be mentioned along with me. Sonnenschein urged me that it wasn’t enough to send you a copy of my letter to Werlang, also I should write to you directly at your California summer address. I did; but since the California address I used turns out to be all wrong, it may never reach you. Copy enclosed, but it’s now superseded. Why did I call ‘common knowledge’ a ‘joky’ name? – just because I don’t think the everyday meaning implies any ‘higher-order’ knowledge about others’ knowledge. (Similarly, I don’t see anything about higher-order knowledge in Harsanyi’s stipulation in the 1967 article that the hypothetical observer should have information common to the players.)1 But certainly it’s only to be expected that if X is common knowledge in the everyday sense, then normally X will be common knowledge in our special sense; because normally we’re moderately well informed about what things other people can be expected to know about. I agree with you: our hitting on the same name is a surprising coincidence, but not so surprising as to be unbelievable.

  ‘Games with Incomplete Information Played by “Bayesian” Players’ (Harsanyi 1967).

1



687.  To Robert Aumann, 30 June 1986

457

Why did I agree with Werlang that the meet-of-partitions formalization is ‘faulty’? – because it is applicable only given a very hefty assumption of ideal rationality. In a less-than-ideal case, the players may not even have information partitions; then the MOP formalization doesn’t apply; yet the informal notion, and also the reachability formalization that you give in the middle of page 1237,2 apply as well as ever. Whatever idealizations might be introduced later on in a theory – and I certainly don’t oppose idealizations per se – surely the definitions ought to apply as generally as possible. I’ve changed my mind somewhat since I wrote the 27 May letter to Werlang. I then thought he was right to complain that the generality of the MOP formalization was limited by the ‘implicit assumption that the information partitions . . . are themselves common knowledge’. But when I tried harder to understand your reason for saying that ‘actually, this constitutes no loss of generality’, I saw that you had given a perfectly good reason why ‘the information sets P1(w) and P2(w) are indeed defined unambiguously as functions of w, and these functions are known to both players’. But what you don’t defend, and what I can’t defend without a hefty idealization, and what therefore does seem to me to involve a serious loss of generality, is the assumption that these information functions are going to be generated by information partitions. If they are, then indeed the partitions are common knowledge and all is well; if they aren’t, all talk of a meet of information partitions rests on a false presupposition. Take one player: me. We have, I’ll grant you with no relevant reservations, the well-defined function that assigns to each possible world w the set of worlds P(w) such that, at w, I know all and only those propositions that hold throughout all the worlds in the set P(w). (Maybe I ought to say: . . . throughout all worlds in P(w) except perhaps a set of probability zero that doesn’t include w itself. And maybe I ought to say that this is ‘knowledge’ in a sense more stringent than that of everyday usage. Let’s forget these complications.) Since what is known at w must at least be true at w, we have that w always belongs to P(w). This implies that the P(w)’s jointly exhaust the worlds. If the P(w)’s are to comprise a partition – this would then be the information partition that generates the information function P – we must have in addition that the P(w)’s are mutually exclusive: whenever P(u) ≠ P(v), P(u) and P(v) are disjoint. That would mean it couldn’t happen, for instance, that P(u) was a proper subset of P(v), so that at u I knew all that I knew at v and more besides. Why not? I think that could happen, and in two different ways. Let’s imagine that I get information through two channels: video and audio. World u is a world where both channels give me accurate information: the   ‘Agreeing to Disagree’ (Aumann 1976).

2

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video channel tells me that the world I live in is in class V, the audio channel tells me that the world I live in is in class A, so P(u) is the intersection of V and A. At world v I get exactly the same accurate information from the video channel that I do at world u, but I get no accurate information whatever from the audio channel. So P(v) = V, of which P(u) is a proper subset. What’s the matter with the audio at world v? – two alternatives. Case 1: silence. Maybe v is a world where the audio channel is silent and gives me no information at all. Someone might object that this can’t be right: won’t I also get the information that the world I live in is in the class S of worlds where the audio is silent, so that P(v) is the intersection of V and S, a class disjoint from P(u)? Well, maybe. I would be prepared to agree, nay insist, that if I am an ideal learner, that must be so. But an ordinary sensible chap might just not notice the silence of the audio channel, might pick up only the video information and no audio information whatever, not even the information that he’s not getting any (other) information. Case 2: error. Maybe instead v is a world where the audio channel gives me the misinformation that the world I live in is in the class M of worlds, a class which is disjoint from A and S, and which does not contain v. Then again P(v) = V. The misinformation M should not be included as part of what I know in world v; I think I know it, but I don’t really know it because it’s false. Only the true part of my information should count. Someone might object that this can’t be right: in the last analysis, my sensory information concerns nothing but my own present experience, and on that subject I am infallible. Well, maybe. I would be prepared to agree, nay insist, that if I am an ideal learner, that must be so. But an ordinary reasonable chap isn’t like that: what registers, and what acts as evidence for revision of the rest of his belief system, is fallible information about the external world, not infallible information about his own experience. Attention to one’s own experience is a difficult skill, cultivated by impressionist painters and old-fashioned introspective psychologists. When you get good at it, you get some surprises; it turns out that you’ve been making a lot of mistakes about your own experience. Or so they say; but maybe what’s true is rather that the attention transforms the experience. ‘Foundationalism’ is philosophers’ jargon for the idea that there’s a certain basic subject matter – my own present experience, perhaps – about which I can’t possibly be wrong and can’t possibly know less than the whole truth; and that this basic knowledge provides a foundation for all the rest of my knowledge and reasonable belief. Foundationalism is controversial, to say the least; or maybe nowadays it’s so very widely rejected that there’s not much controversy left. (I suppose I count as a bit of a reactionary for saying that foundationalism is at least part of ideal rationality, even when I go straight on to insist that the ideal learner therefore differs from the  ordinary reasonable chap much more than might have been expected.) My



688.  To Brian Skyrms, 26 September 1986

459

c­ omplaint, in a nutshell, is that the MOP formalization of common knowledge is faulty because it presupposes foundationalism, and therefore doesn’t apply to or­din­ ary people. (Or even to halfway-idealized ones.) The reachability formalization – no less formal! – should have been preferred as the definition, even if you then went on to study the foundationalist special case where the MOP formalization applies. I’d be very glad to meet you in September. I’ll be in Australia for most of the (northern) summer, but back in Princeton after 3 September. Classes start in the ­middle of September, but the period before that should be a bit of a lull. I should warn you, though, that my interests have changed a lot since the Convention book. More recently, my work has centered on the analysis of causation and the metaphysics of possible worlds – it’s a long time since I thought much about common knowledge, social coordination, and so forth. There’s someone else around here whom you might also like to meet: Margaret Gilbert, a good philosopher who has much more to say about common knowledge nowadays than I do. She teaches at the University of Connecticut, Storrs; but she’s married to a colleague in my department, so lives much of the time in Princeton. I  don’t know where she is now (maybe Jerusalem, in fact), or where she’ll be in September. But if she’s in Princeton or in Storrs, it’s easy range of New York either way. Sincerely, David Lewis cc: Sonnenschein

688.  To Brian Skyrms, 26 September 1986 [Princeton, NJ] Dear Brian, I’ve suggested to Robert Aumann (Institute of Mathematics, Hebrew University, 91904 Jerusalem) that he send you his paper ‘Correlated Equilibrium as an Expression of Bayesian Rationality’.1 I suggest to you that you send him your stuff on dynamics of deliberation. I think the two fit together in a nice way. We’ve noticed various special cases of what I’ll call ‘non-coexistence theorems’. On pain of contradiction, an agent in such-and-such game cannot both (1) have soand-so pattern of subjective probabilities, and (2) be a utility maximizer. That is what   (Aumann 1987).

1

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several of us took to be the lesson of Richter’s problem, once we set aside the red herring about rival conceptions of rationality. More simply it’s the lesson also of ­puzzles about penny-matching between clones and the like. What Aumann has, I take it, is the general non-coexistence theorem of which these things are special cases. Non-coexistence theorems are paradoxical – something can’t happen, but what stops it? If you stick a maximizer into a certain game, do you thereby somehow peg his beliefs, maybe in defiance of any amount of evidence you might also give him? Or if you stick somebody into a certain game and give him a lot evidence (e.g. that he and the other player are clones) do you thereby somehow convert him into a non-maximizer? How could either thing happen? What you have, I take it, is a satisfying answer to this dilemma. The second horn is right: he stops being a maximizer. But not because you somehow auto­mat­ic­ al­ly render him irrational, or change his notion of what rational decision is. He remains a resolute would-be maximizer. His trouble is just that he never finishes his  deliberation because he keeps getting hit with new evidence when he’s partway through. It occurs to me that there’s also a connection with an old thing of mine, with Jane Richardson, that you may or may not have seen. We know that clone puzzles and predictor-avoider puzzles are much alike, as witness the case that the predictor does his predicting by getting hold of a clone and seeing what it does. Long ago, Jane and I suggested getting out of a predictor-avoider paradox by questioning whether the predictor and avoider could both finish their calculations – you can stipulate that the predictor has all the time he needs, else his failure is uninteresting; you can stipulate that the avoider has all the time he needs, else maybe the predictor succeeds; but you can’t stipulate both together if the time each one needs is a fast-enough increasing function of the time the other one uses. I enclose a copy. Gil Harman said much the same thing at much the same time about a self-prediction puzzle: ‘Scriven on the Unknowability of Psychological Laws’, Philosophical Studies 18 (1967) 61–63. Gil doesn’t say, but makes obvious, that his version just borrows the standard proof of the unsolvability of the halting problem. Jane and I didn’t see that connection at the time. I’ve become interested in Ayer on verifiability. Do you have anything on ­verifiability and ‘metaphysics’ beyond what’s in P&E?2 Yours, cc: Aumann

  Pragmatics and Empiricism (Skyrms 1984).

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689.  To Frank Jackson and Philip Pettit, 23 June 1987

461

689.  To Frank Jackson and Philip Pettit, 23 June 1987 [Princeton, NJ] Dear Frank and Philip, When I rewrote ‘Desire as Belief’1 to be more explicit, inter alia, about how the kinematic rule for value was derived, I saw that the anti-Humean had the move suggested in your (Frank’s) letter. He needn’t question probability kinematics; he needn’t question the formula that tells us that the value of A is the probability-weighted average of the values of the AEi’s (where the Ei’s comprise a partition); he should only question the invariance premise which says that the values of the AEi’s are unchanged in kinematics that originates in the partition of Ei’s. Just as you say; except you don’t stop at the AEi’s but partition all the way down to individual worlds. A reply would be to get a reductio without using the invariance premise. I can do it, after a fashion. But the trouble is, I need to strengthen the desire-as-belief thesis to do it – or at least, to do it in the only way I’ve found yet. Then the anti-Humean’s next move is to say that he didn’t need to be committed to the thesis in such a strong form. (Compare the opponent in ‘Probabilities of Conditionals . . . ΙΙ’.)2 Suppose for reductio that the d-a-b thesis holds throughout a class of probability functions closed under conditionalising. Let C be any function in the class; let A be any proposition; let I be the necessary proposition; let O be the impossible propos­ition. By d-a-b and additivity of probabilities, 





(1) V( A ) = C( A ) = C( A /A)C( A ) + C( A /A )C( A ). Let CA and CA ̄ come from C by conditionalising on A and A respectively, and let VA and VA ̄ be the corresponding value functions. By definition of conditionalising; then by d-a-b for CA and VA, or CA ̄ and VA ; then by the fact that VA, or VA , can’t distinguish between propositions that differ only on a region to which CA, or C A , gives probability zero; then by d-a-b again; then by definition of conditionalising again: 











(2) C( A/A)=C A (A)= VA (A)= VA (I)=C A (I)=C(I/A), 



(3) C(A/A)= C A (A)= VA (A)= VA (O)=C A (O)= C(O/A). Plugging (2) and (3) into (1) we get 







(4) V( A )=C(I/A )C( A ) +C(O/A )C( A )=C(IA ) +C(OA ).

  (Lewis 1988a).   ‘Probabilities of Conditionals and Conditional Probabilities II’ (Lewis 1986d).

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This is already either an interesting result or else a sign of trouble coming. I think it looks pretty fishy. But let’s go on. Next, by definition of expected value applied to the case of I we have (5) V(I) = V(A)C(A) + V(A)C(A). All this has been general; so pick B such that C(B) = ½ = C(B ). Then (6) V(I) = ½ V(B) + ½ V(B). Now apply (4) three times: first with A as I, then with A as B, then with A as B. The second and third times, multiply through by ½. 





(7) V(I )=C(II ) +C(OO )=C(I ), 







(8) ½V( B)=½C(IB) +½C(OB ), (9) ½V( B )= ½C(IB ) +½C(OB). Also, by additivity, we have 





(10) C(I )=C(IB) +C(IB ), 





(11) C(O)=C(OB)+ C(OB). By (6)–(11) we have 



(12) C(I )=C(O ). But this is so for any C in a class closed under conditionalising. So as instances of (12) under conditionalising we have 







(13) C(I/O )=C(O/O )=1, 



 

(14) C(O/I )=C(I/I )=1. 



So O is the same as I (except maybe for a difference of probability zero under our original C); so we can substitute, and (4) simplifies to 





(15) V( A )=C(IA ) +C(IA )=C(I ). So for any C and V in the class, it turns out that all propositions have equal value! This completes the reductio. But I’ve gone all around Robin Hood’s barn in a disgusting fashion; I’ve conditionalised on some propositions that are highly unlikely to be evidence propositions; and I’ve used the value of the impossible proposition, something that ought by rights to be undefined or arbitrary. I don’t like it much.



689.  To Frank Jackson and Philip Pettit, 23 June 1987

463

Still, for what it’s worth, I didn’t use the invariance premise. There’s gotta be a better way. Yours, cc: Burgess, Jeffrey, Tappenden, Collins 23 June 1987 (evening) Dear Frank and Philip, Too right there’s a better way. Suppose for reductio that we have the d-a-b thesis for any probability function that comes from C by conditionalising. (Anti-Humean still gets to complain that this is stronger than he needs.) As in the typed letter, get as far as 



(4) V( A ) = C(IA ) + C(OA ) and skip the rubbish that follows. Three cases.  

(a ) I O has positive probability. Partition it into two disjoint propositions A1 and A2 with equal positive probability. By (4) we have that 

V(A1 ) = C(A1 ) + C(O ) 

V(A 2 ) = C(A 2 ) + C(O ) 



V(A1 Ú A 2 ) =C(A1 Ú A 2 ) + C(O ) = C(A1 ) + C(A1 ) + C(O ) Since C(A1 ) = C(A 2 ), V(A1 ) = V(A 2 ); since V(A1 Ú A 2 ) is a weighted average of V(A1) and V(A2), it equals them both; so C(A1 ) = C(A1 )+ C(A 2 ) = C(A 2 ); so C(A1 ) = C(A 2 ) = 0. Contradiction.  

( b ) IO has positive probability. Partition it into two disjoint propositions A1 and A2 with equal positive probability. By (4) we have that 



V(A1 ) = C(OA1 ) = C(O) – C(A1 ) 



V(A 2 ) = C(OA 2 ) = C(O) – C(A 2 ) 



V(A1 Ú A 2 ) = C(O(A1 Ú A 2 )) = C(O ) – C(A1 ) – C(A 2 ) Since C(A1 )= C(A 2 ), V(A1 )= V(A 2 ); so again V(A1 ∨ A2) equals them both; so again C(A1 )= C(A1 ) + C(A 2 )= C(A 2 ); so C(A1 )=(A 2 )=0. Contradiction. 



(g ) Neither a nor b . I and O coincide except on a set of probability zero. Then (4)    reduces to V(A)= C(IA ) + C(IA ) = C(I ). All propositions have equal value – a trivial case.

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690.  To Bas van Fraassen, 14 March 1988 [Princeton, NJ] Bas Re: ‘Rationality Does Not Require Conditionalisation’1 Right: my diachronic Dutch book was meant as a dilemma. If you know how you’ll respond to evidence (not just that you’ll respond by sitting down and thinking, but that you’ll come out with so-and-so posterior distribution), and if you won’t ­conditionalise on your total evidence, then you’re irrational because the bookie can beat you, and not by taking advantage of better knowledge of you than you have yourself; whereas (*)   if you don’t know how you’ll respond to evidence, that failure of selfknowledge is itself a departure from ideal rationality. In defence of (*), I ask: why should an ideally rational agent do without knowledge of the future that he can have for free? Why shouldn’t he ‘deliberate and think and engage in theoretical activity’, exercising ‘creativity, audacity, spontaneity’, and harvesting all the ‘(unpredictable) insights and decisions [he] shall reach during the theoretical deliberation on the evidence’ beforehand, as contingency planning for what to do in case the evidence turns out to be so-and-so? That way, he’s better informed about what will and won’t happen in the future: he knows he won’t give such-andsuch response to so-and-so evidence. Why not know such things, if knowledge costs him nothing? I know why I don’t like to cross bridges before I come to them – I don’t like to think hard about 25 candidates before I know which of them my colleagues might possibly support, I don’t like to dream up new theories that would fit surprising evidence until and unless that evidence actually shows up, etc. It’s because, for me, thinking things through is not a free good. It takes quite a lot of time and effort, and so the advantage of getting it done beforehand doesn’t begin to make up for the waste of thinking through a zillion hypothetical cases that never really arise. Sometimes, also, I can’t think things through very well so long as they’re hypothetical – I have to know the case is for real in order to take it seriously enough to do a good job. But the ideally rational agent, marvellous fellow that he is, has no such shortcomings. For him, thought is a free good. He can think things through even when they’re hypothetical. He does it thoroughly, instantaneously, and effortlessly. For

  ‘Rationality Does Not Require Conditionalization’ (van Fraassen 1993).

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691.  To Huw Price, 17 May 1988

465

him it’s no waste, and it is a source of possibly useful information, to plan in the cradle for all the epistemic lives he might turn out to live. So why doesn’t he do it? Investigating the ways of ideal rationality is a long way from thinking about how we do, and should, proceed. We should not imitate ideal rationality in every way we can. Because we cannot imitate ideal rationality in thinking through everything in the cradle, therefore we should not imitate ideal rationality in conditionalising along through later life and never stopping to catch up on the creative, audacious, . . ., thinking-through that we failed to do beforehand. Have we any disagreement, except maybe a trivial terminological one about how much to idealise before we may speak of ‘ideal rationality’? I think not. c: Broome, Harman, Jeffrey, Johnston, Skyrms

691.  To Huw Price, 17 May 1988 [Princeton, NJ] Dear Huw Price, I wrote just before your letter arrived to say that I’d be glad to do two seminars: ‘Parts of Classes’ on Monday 25 July, ‘Dispositional Theories of Value’ with Michael Smith on Tuesday 26. The ‘Submitted . . . 18 November 1987’ version of ‘Desire as Belief’ is final except for the first two footnotes. Those have been changed to give a fuller citation of the Michael-Philip-Michael exchange and the Collins paper. It’s not clear when my paper will appear. July 1988, most likely; but if so I should have had proofs by now and I haven’t. My own view of Decision Theory is not that it describes reasoning, whether conscious or whether unconscious. Rather, it amounts to a definition of the notion ‘behaviour that most effectively serves one’s desires according to one’s beliefs’; and thereby it plays a constitutive role since, roughly, the right way to interpret a total brain state as a system of belief and desire is to interpret the state so that the behaviour to which it typically disposes one is the behaviour that best serves the imputed desire according to the imputed belief. So understood, beliefs about one’s desires (and about one’s expected values) needn’t enter into it. They might be there, if the agent is blessed with self-knowledge; they might not. The notion of serving one’s desires according to one’s beliefs applies either way.

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Still: suppose one does have beliefs about one’s desires, and suppose those are complete and correct. Given the correspondence between desire and belief-aboutdesire, then behaviour that serves desire according to belief can also be described as serving* belief-about-desire according to belief, where the notion of serving* is defined in terms of serving. (One serves* BaD according to B iff one serves D according to B and BaD is the system of belief-about-desire that accurately represents D.) Your case of the perfect servant is a nice way of showing this. But, as you say, this doesn’t equate degree of desire to degree of belief that something is good. It equates degree of desire to certainty that the thing is desired to that degree. I don’t grant that one could be motivated by one’s certainties about what one’s desires are, instead of by those desires. Decision Theory is constitutive, so to be mo­tiv­ ated to behave in such a way as to serve such-and-such desires is, ceteris paribus, to have and be motivated by such-and-such desires. But your idea needn’t be that the desires are missing or idle; rather, that a desire is identical to one’s certain belief that one has that very desire. So what do I think of that? – Well, my first reaction is that it’s just an interesting loophole in the definition of a non-Humean. That wasn’t meant to be the idea! But how to formulate the idea properly to exclude the case? Yours, David

692.  To Philip Pettit and Michael Smith, 29 July 1988 Sydney, Australia Dear Philip & Michael, On the ‘Backgrounding Desire’ draft,1 § 3.2, I agree that anyone out to dodge my anti-DAB argument ought not to let me formulate DAB as 

V(A)= C ( A) or as 

V(A)= åC(A j )g j j



1   Cf. ‘The Humean Theory of Motivation’ (Smith 1987a); ‘Humeans, Anti-Humeans, and Motivation’ (Pettit 1987); ‘On Humeans, Anti-Humeans, and Motivation: A Reply to Pettit’ (Smith 1988); ‘Reason and Desire’ (Smith 1987b).



692.  To Philip Pettit and Michael Smith, 29 July 1988

467

°

where Aj is the proposition that A would be good to degree gj. I find it not at all obvious that different formulations couldn’t be recognisably DABs. (For instance I’m un clear what I ought to think about Huw’s V(A)= C(A/A).) But I don’t see how judging versus credence can help. We have that judging doesn’t admit of degree, so we can write ì1 if B is judged true J(B) = í î0 otherwise for any proposition B. Then shall we say 

J(A)= V(A)? No – that doesn’t allow desire to admit of degree. Better 

V(A) = g j iff J(A j )=1 Equivalently 

V(A) = åJ(A j )g j

° where we presuppose that only one of the A j’s may be judged true. ° But isn’t it possible for us to be uncertain about the A j’s? If they are propos­ itions about how good it would be if A, that had better be possible, for we very often are uncertain how good something would be. Surely being almost certain – ° or judging oneself almost certain – that A j ought to have nearly the motivating ° ° ° effect of simply judging that Aj; dividing credence 50-50 between A j and A j', or judging that one does so, ought to have a motivating effect intermediate between ° ° that of judging that Aj and that of judging that A j', and so on. How /to/ work this into your picture? The clue seems to be in the sentence starting at the bottom of p. 15, which says that to ‘register a probability as a premise’ of deliberation I have to judge it. That ° would go for distributions of credence over A j’s as much as for any other distributions of credence. (Fn 20 warns that there’s a rigidification here: the judgement is not the same thing as credence 1 in a contingent proposition about my own credence.) So I take it there’s such a thing as judged (or misjudged?) or registered credence. j

CJ(B)= x iff J(C(B)= x)=1 And the idea is that it’s CJ’s, rather than C’s, that figure as premises in deliberation. This strikes me as foregrounding credence unduly, but never mind. (Likewise I suppose there might – but needn’t – be such a thing as judged or registered desire. VJ(B)= x iff J(V(B)= x)=1

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But since desire is backgrounded, VJ’s are dispensable and we can get by with V’s.) Now it seems that if desire and goodness and the credences of goodnesspropositions are to admit of degree, as they all should if they’re to deserve their names, the new DAB thesis – or DAJ if you’d rather – will look like 

V(A)= åCJ( A j )g j

which is like (the more complicated one of) mine expect that judged credences replace plain ones. But Frederic might be, and might remain under any change within a certain large range, an excellent judge of credences. If so, his judged credences will equal his plain credence, both before and after change by Jeffrey conditionalizing. But then the replacement of plain by judged credences makes no difference in his case and the anti-DAB argument goes forward as before. ------Do you admit degrees of desire, of goodness, of belief in goodness-propositions? If so how, if not as I just did? If not, how can you justify denying that these things admit of degree and that their degrees are relevant to the strength of motivation by judgement? Yours, David c: Collins j

693.  To Henry Krips, 24 August 1988 Auckland, New Zealand Dear Henry, When I was in Melbourne I was frantically working on a paper against a deadline, so unfortunately I didn’t read ‘Subjunctive Conditionals . . .’1 in time to talk to you about it. Just how unfortunate, I’ve now found out. For I’ve found it very interesting, and also related to something I once tried. The reference is §8 of ‘Counterfactuals and Comparative Possibility’ Journal of Philosophical Logic 2 (1973), approx. p. 437; or my Philosophical Papers Vol ΙΙ (oup, 1986) p. 22. What you’ll find there looks like (ii)' on your ms page 4 except that (1) for no

  Cf. ‘Irreducible Probabilities and Indeterminism’ (Krips 1989).

1



693.  To Henry Krips, 24 August 1988

469

good reason I specify that m is somebody’s present subjective probability (which yields spurious arguments that my example sentence couldn’t be analysed any other way), and (2) I don’t there suggest, though I had it in my mind at some time in the early 70’s, that objective probability ought to be ‘counterfactual probability’ conditional on the necessary proposition. I saw myself as adapting Dick Jeffrey’s idea of objectified subjective probability: Logic of Decision §12.7, pp. 202 ff in the 2nd edition. Roughly: subjective probability conditional on the truth is objective probability. How much of the truth? Not quite the whole truth – a single world – else all objective probabilities would be zero, one, or undefined. But a lot of it: something strong enough that conditionalising on something else true would be highly unlikely to make any difference. (Skyrms’ ‘resilience’.) The trouble was that a strong enough truth would most likely have probability zero. Dick’s solution was to take ‘the truth’ to be the true cell of a partition, and then to pass to a limit in a sequence of finer and finer partitions. I thought – as have you – that my machinery for counterfactuals gave me a way to imitate Jeffrey while making fewer burdensome assumptions. (1) If a sphere around i is the i-containing cell of a Jeffrey partition, that means that if S is a sphere around i and j ∈ s, then also S must be a sphere around j. Need we assume that? (2) If S is a sphere around i and Sʹ is a sphere around iʹ, Jeffrey’s approach makes sense of the question: do S and Sʹ correspond to equally stringent standards for similarity? I.e. are they generated by the same partition in the sequence? It’s not obvious that the question does make sense, hence preferable to use apparatus that doesn’t auto­mat­ ic­al­ly give it sense. (Your numerical indexing of spheres also makes unwanted sense of this correspondence, however in your case, unlike Jeffrey’s, it looks clear that the numerical indexing is a superficial feature of the presentation, readily abandoned without cost to the real idea.) Well, I went sour on the idea. By the time of ‘Subjectivist’s Guide’, though I still liked the idea of objectification as conditioning on (a great deal of) the truth, I no longer liked the idea of passing to a limit to solve the problem of conditioning on a proposition of probability zero. Why not? First, because I thought I knew a better way: work in the setting of nonstandard analysis and let the relevant probabilities be not zero but infinitesimal. This is still my choice. But at first I liked it better than I was entitled to, because I didn’t understand one of the drawbacks. I thought the probability distribution over propositions was given entirely by the distribution of (infinitesimal) probabilities over the worlds, analogously to the finite case. I didn’t understand at first that the set-function of nonstandard summation wasn’t unequivocally given once and for all, but might bear part of the burden of encoding the probabilities of sets of worlds. I hope this didn’t lead me to say anything plain false, but it did lead me to overestimate the extent to

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which using infinitesimals was neater than passing to limits. Still, I think that even if rightly understood it does remain neater. Second, because I got bothered by the fact that if I passed to limits, whether in your way with spheres or in Jeffrey’s way with refinements of partitions, there was no guarantee the limits would always exist. And laws like P(A/B) = P(AB)/P(B) P(C Ú D) = P(C) + P(D) – P(DC) would be buggered up: because the limits P(A/B) and P(C ∨ D) might exist even if P(AB), P(B), P(C), P(D), P(DC) didn’t. Maybe I overreacted to the problem, especially because I thought the infinitesimals a superior method anyhow. Here’s the sort of pathology I had in mind: For any n, m( Sn+1 ) = 1/10 m( Sn ) A = (S1 – S2 ) È (S3 – S4 ) È (S5 – S6 ) È… ì >90% for odd n m(Sn ⋅ A)/m(Sn) í x!? The catch is that x isn’t fixed. It should have been 1) The other has 2x and x is a smallish quantity versus 2) The other has ½ x and x is a largish quantity. I think the spurious argument that you should treat the shooting room as a 90% risk of death trades on the same confusion of fixed and unfixed. Yours, David c: Alan H., Denis R., et al.

700.  To John Leslie, 4 September 1989 [Melbourne, Australia] Dear John, More – when I heed (what I take to be) the lesson of the shooting room, I come away with a much firmer opinion about the question left open in my June letter. The lesson is that despite distracting oddities about relative frequencies in expanding populations, and despite the comparative unfamiliarity of probability distributions over possible people rather than over possible worlds – probability de se – still  we should hold fast to what we know best. Which is: if I’m certain that (or if

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I conditionalize on the hypothesis that) I face a definite objective chance x of a certain future event, then whatever else I may or may not know, barring news from the future, my present degree of belief (or conditional degree of belief) should be x. The question left open was whether the (initial, subjective) probability of turning out to be one of the inhabitants of possible world w ought to be proportional to the population of w. Answer: other things being equal, yes. However there should be a second factor to reflect, inter alia, the chances involved in the history of w. (So you’ll have a combination of what happened in the first case in my June letter with what happened in the third and fourth cases – if I’ve remembered the numbering properly without a copy to hand.) Here we have two worlds, exactly alike until the year 2000, at which time – for the first and only time in history – a chance event takes place. With 90% objective probability this event results in Doomsday – no more people thereafter – and it’s w1. But with 10% objective probability it’s w2: no Doomsday, and population growth for a long time after that, so that the total population of w2 is 100 times the total population of w1. You know for certain (or you conditionalize on the hypothesis that) either you’re j1 in w1 or you’re j2 in w2.



700.  To John Leslie, 4 September 1989

485

Finding out that you’re either j1 or j2 shouldn’t alter the ratio of their de se ­ robabilities. If P0 is the initial distribution and PN is your present, conditionalized p distribution PN ( j1 ) P0 ( j1 ) = PN ( j2 ) P0 ( j2 ) I still say that the total de se initial probability of a world ought to be divided equally between the inhabitants of that world. If #1 and #2 are the total populations of w1 and w2, # 2 = #1 ´100, P0 ( j1 ) = P0 ( w 1 ) / #1

P0 ( j2 ) = P0 ( w 2 ) / # 2

Your present degree of belief that Doomsday will come, i.e. that you’re in w1, i.e. that you are j1, ought to equal the objective chance (common to both worlds) of 90%. Likewise your present degree of belief that Doomsday won’t come, i.e. that you’re j2, ought to equal the chance of 10%. PN ( j1 ) = 90%, PN ( j2 ) = 10%. So we have 90% P0 ( w 1)/ #1 = 10% P0 ( w 2 )/ # 2

.09 =

90% 10%

#1 P0 ( w 1 ) = # 2 P0 ( w 2 )



In the ratio of total de se initial probabilities of worlds, the chance factor favours by 9 to 1 the world that develops in the less unlikely way, w1; but the population factor favours by 100 to 1 the more populous world, w2. This, I now claim, is the right way to calculate de se probability ratios of worlds, in the case where they start out alike and differ only in how some chance event turns out. If you had to bet, from behind a veil of ignorance about who in the world you are and which world you’re in, you ought to think you’re only 9% as likely to be someone or other in w1 as you are to be someone or other in w2, just because the population factor favours w2 a lot and partially counteracts the chance factor. If this seems strange – as it certainly does to me – bear in mind that we more or less never are behind that kind of veil of ignorance. Once you know who in the world you are – ‘if this is w1 I’m j1, if this is w2 I’m j2’ – then the population factor conditionalizes away altogether and only the chance factor remains. And you do, in anything remotely resembling normal life, know who in the world you are. (And even if you were in the situation of the characters in stock examples of de se ignorance – ‘if this is w1 I’m either j1 or k1, if this is w2 I’m either j2 or k2’ – you’d still know enough about who in the world you are for the population factor to conditionalize away altogether.) Whereas if a population factor hadn’t been built into the initial ratio P0 ( w 1 )/P0 ( w 2 ) , then it would have appeared after conditionalizing on ‘if w1 I’m j1, if

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486

w2 I’m j2’ and it would have appeared the wrong way round, favouring the hypothesis that you’re in the less populous world! If we had the chance factor alone

P0 (w 1 ) 90% = P0 (w 2 ) 10%



we’d get that

PN ( j1 ) P0 ( w 1 )/ #1 90% = = PN ( j2 ) P0 ( w 2 )/ # 2 10%

#2 = 900 #1



so that PN ( j1 ) = 99.9%, a pessimism far out of proportion to the known chance of Doomsday. In short: if you’re doing de se probability, you can’t help having a population factor somewhere – and if so, you’d rather have it in the initial probabilities, where it soon disappears as a result of conditionalizing on an almost inescapable modicum of self-knowledge. Yours, David c: as before

701.  To Richard Cartwright, 4 September 1989 as from: Princeton University Princeton, NJ [Melbourne, Australia] Dear Prof. Cartwright, I’ve been reading the introduction to your Ф Essays.1 I think we may disagree less than you think – let me try on a couple of irenic additions to what I said. (Thank you for the second sentence of footnote 1. But even without it, there’s no fear I would have taken what you say as an attack.) We probably disagree about how often an apparently ultimate impasse really is one – how likely it is that yet-to-be-discovered arguments, distinctions, and counterexamples could break, or at least transform, the deadlock. I don’t know what to say about this. For I think that (as often happens) I’ve formed an opinion under the   (Cartwright 1987).

1



701.  To Richard Cartwright, 4 September 1989

487

impact of evidence but not retained a record of what the evidence was. So let’s pass on to the question: what if an impasse is ultimate? I say that we’re left with a difference of opinion. You are ‘left uncomfortable’. But let me say more. 1) As already said, it may well be a disagreement between a true opinion and a false one. (Or both sides’ opinions may be false, if the opinions are contraries.) OK; but not yet enough. 2) I don’t claim that when I think one of my opinions is caught in a philosophers’ impasse, I should respond by being less sure of it than before. Not if it’s the opinion that I have hands, that many things move, or that contradictions never are true! I should remain very sure of these opinions whatever philosophers’ impasses they may be part of; and further, I have reason to be sure of them. For 3) Philosophers’ impasses are, typically, disagreements between reasonable and unreasonable opinions. That doesn’t alter the fact of deadlock; because part of what’s in dispute is what it is to be reasonable. If one side is right and the other is wrong – point #1 – then one side is right, and the other wrong, inter alia about what’s reasonable. I think that if ever there was an ultimate impasse, my disagreement with Graham Priest about whether there are true contradictions is one. I don’t think there’s anything I can say against him that doesn’t beg the question in favor of consistency. Begging the question means using what’s been called into question, and it’s he who does the calling into question. Does this make me more open-minded about contradictions? – Not on your life! Am I being unreasonable in insisting dogmatically on noncontradiction when I can’t defend it without begging the ­question? – No; on the contrary, rejecting contradictions is a central part of being reasonable. So say I. Graham, on the other hand, says that open-mindedness about logic (and all else) is a central part of being reasonable. That’s part of what our ­difference of opinion is all about. I can no more call Graham’s position reasonable than I can call it consistent. He should no more call my position reasonable than he can call it open-minded. I’m right, he’s wrong. One thing I’m right about is that I’m the one who’s being reasonable. But saying this in no way breaks the impasse, true though it be. I think the same goes, mutatis mutandis, for a deadlocked dispute with an in­duct­ ive sceptic who thinks we have no reason to believe we have hands. And so on for other philosophers’ impasses. 4) Subject to a qualification, I also say that the one who’s right in a philosophers’ impasse typically knows that he’s right: I know I have hands, know that things move, know that contradictions are never true.

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The qualification is that the knowledge may temporarily vanish in the course of ­philosophical discussion because ‘alternatives’ are made ‘relevant’ that normally are  not. (See my ‘Scorekeeping in a Language Game’, Ф Papers I, comment on the ‘commonsense epistemologist’.)2 Maybe I cannot truly say, in the midst of a discussion of far-fetched sceptical hypotheses, that I know that I have hands. Attending to these hypotheses temporarily raises the standards for what may be called know­ ledge. But I can truly say, even then, that under more ordinary circumstances I can truly say that I know that I have hands. So I still say that ultimate impasses, when and if there are any, are differences of opinion. Have I yet said enough to distinguish them from some other sorts of difference of opinion? Best regards, David Lewis

702.  To Graham Oddie, 4 October 1989 [Princeton, NJ] Dear Graham, OK; I said that an ethically significant sense of rightness had better not make what’s right to do turn on a split-second difference of timing, and I’d better agree that if it’s a split-second difference between a time just before and a time just after my state of information changes, that can matter. As you say, that should be common ground. But I still can’t believe that what’s right (in an ethically significant sense) could turn just on whether my choice comes a split second before or a split second after a distant chance event. Not if that’s the only difference between the two cases, unaccompanied by any difference in my state of information at the time of choice. Small comment: I don’t think it’s quite right to say that the agent treats sub­ject­ ive expected value as ‘his best (though fallible) guide’ to what maximizes objective expected value. Because sometimes what maximizes SEV definitely doesn’t maximize OEV, namely when you hedge your bets. You sometimes maximize SEV by ­giving up all hope of doing the OEV-right thing in order to make sure of doing a nottoo-far-from-OEV-right thing. Frank made this point in his talk at ChCh. I once illustrated it this way: there’s an epidemic, all the antitoxin is locked in your safe, and you’ve lost the combination. You maximize SEV by sending for a safecracker at once.   Philosophical Papers I (Lewis 1983c).

2



703.  To Daniel M. Farrell, 28 March 1990

489

Time is precious – don’t waste it trying out combinations and hoping to be lucky! But this definitely doesn’t maximize OEV, due to the time lost before the safecracker turns up. There is a certain combination – the correct one, whichever that might be – such that what maximizes OEV is to dial it immediately. Yours, c: Mellor, Jackson, Pettit

703.  To Daniel M. Farrell, 28 March 1990 [Princeton, NJ] Dear Professor Farrell, Thank you for ‘Intention, Reason & Action’.1 Two big reservations. First, I disagree with your footnote eight. I think the paper is mistargeted. 1) Where did I say I was talking about what an ‘ideally rational individual’ should or could do, as opposed to what it would be rational for real people to do? Rationality is a matter of degree, and the IRI is a very peculiar character indeed. But you don’t have to be the IRI before it makes sense to talk about what it’s rational for you to do. Many things that are rational for us real people to do are ways of compensating for the fact that we are not IRIs. And many things that are possible for us, and may on occasion be rational for us, are impossible by definition for the IRI. 2) Where did I say that I was talking about direct actions of intention-forming, as opposed to actions that lead indirectly, but foreseeably, to intention-forming (perhaps by also leading to diminished rationality)? In the first paragraph, immediately after I spoke of ­intention-forming, I glossed it thus: ‘You may have to do something that would indeed leave you disposed to retaliate. . .’. That’s what I mean by an action of ­intention-forming. Nothing there about directness, nothing there about how the ‘something’ leads to the disposition! The more one resembles the IRI, I suppose, the more indirect an action of intention-forming will have to be. Second, as you know from ‘Devil’s Bargains’,2 I think it’s unwise and perhaps even dangerous to use ‘paradoxical’ nuclear deterrence as a philosophical example. Here’s a parallel. What if someone writing about consequentialism versus deontology, and whether official acts are a special case, used this example:

  (Farrell 1989).   ‘Devil’s Bargains and the Real World’ (Lewis 1984).

1 2

490

Philosophical Letters of David K. Lewis Suppose it’s known for certain that the only way to stop AIDS from spreading by heterosexual transmission and killing 70% of us is to set up a system of high-security prison camps, and a ruthless secret police force to catch and imprison all those who test positive, and all those who fall under the slightest suspicion of having had sexual contact with anyone who later tested positive, and all those who. . . . Now, what should the president do?

A fascinating example, I’m sure, and we could have a lot of fun writing philosophy papers about it. But we shouldn’t. There’s just too much risk that by talking about this example as if we took it seriously, we’d help spread false and dangerous ideas, and perhaps help bring about evil policies. Just saying in passing ‘of course it’s only a hypothetical case’ isn’t enough of a safeguard. Any philosophical point we want to make can be made with safer examples. Well, I think the same goes for examples about paradoxical nuclear deterrence. Despite the two reservations, I liked the paper very much, and I’m inclined to agree with you. Sincerely, David Lewis

704.  To Daniel M. Farrell, 24 September 1990 [Princeton, NJ] Dear Professor Farrell, Thank you for your letter; and for your new paper which accompanied it, and which I look forward to reading.1 My second paper on deterrence is called ‘Finite Counterforce’.2 I’ve sent you a copy separately. The enclosed ‘Buy like a MADman, use like a NUT’ is a very abridged version of it.3 As you’ll see, it’s a policy paper; there’s scarcely any philosophy in it. I still don’t see that the phrase ‘the action of adopting the intention’, on page 143 of ‘Devil’s Bargains . . .’, suggests an action that’s simple and direct and ‘just like that’. But if it does, may I suggest that your complaint be re-addressed to David Gauthier? For at that point I’m replying to him, so I’m discussing his case as he presents it, and he says the deterring agent ‘chooses’ or ‘forms’ or ‘adopts’ an intention.

  ‘On Some Alleged Paradoxes of Deterrence’ (Farrell 1992).      (Lewis 1986a).

1 3

  (Lewis 1989b).

2



705.  To Alexander Rosenberg, 31 December 1990

491

I agree with you that there are people around who would have no problem supporting MAD, and would willingly make themselves wicked – probably not ‘just like that’ but in gradual and self-deceptive ways – in a good cause. Not just thoughtless people, either; George Quester, for instance, is anything but thoughtless. It’s im­port­ ant to insist that these people are wrong about what deterrence requires. (And not just wrong about what deterrence of the Soviet Union requires in 1990 – next to nothing, I suppose – but wrong about what it required when I wrote in 1983, and wrong about what deterrence required in Stalin’s time.) We don’t disagree about why people with MAD intentions would be, among other things, wicked. Wicked is one thing, dangerous is another. Automatic re­tali­ ation machines would be even more dangerous, I dare say, but not at all wicked. People with MAD intentions would be no less wicked if, unbeknownst to them, all the warheads were duds; but not at all dangerous. Sincerely, David Lewis

705.  To Alexander Rosenberg, 31 December 1990 [Princeton, NJ] Dear Alex, Some comments on the paper you sent me about the monarchy.1 [. . .] Page 21, top, ‘this is just what it cannot do’; and page 22, middle, ‘Lewis draws a pessimistic conclusion about Humean supervenience’; page 23, top, ‘this [Humean supervenience of chances] is an outcome of which Lewis despairs’. This seems to me to be distorted. I don’t, in the end, draw any conclusion one way or another about Humean supervenience of chances. I say there’s trouble all around: bad trouble for various sorts of theories on which chances do supervene, bad trouble also for the­or­ ies on which they do not. Yet not all these bad troubles can be conclusive refutations, because after all some theory has to be right! Therefore I can’t claim to have refuted any of the alternatives. Is there any way that a Humean magnitude could fill the chance-role? Is there any way that an unHumean magnitude could? What I fear is that the answer is ‘no’ both times! Yet how can I reject the very idea of chance . . . (Papers II, p. xvi.)2   ‘Causation, Probability and the Monarchy’ (Rosenberg 1992).   

1

  (Lewis 1986c).

2

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It’s an unsolved problem. The threat to Humean supervenience is that the unknown solution might turn out to be one that somehow removes the trouble for the unHumean alternative. Or instead the unknown solution might turn out to somehow remove the trouble for one of the Humean alternatives. So long as it’s unknown, who can tell which alternative it will rescue? Yours, David Lewis

706.  To Dorothy Edgington, 11 June 1991 [Princeton, NJ] Dear Dorothy, Thank you for your paper on conditionals.1 Now that the work of the semester is over, I’ve read it. It’s quite interesting. Comments. Propositions not existing. You sometimes speak of conditional propositions ‘not existing’. But surely a three-valued ‘proposition’ (or as I’d rather say, random variable) that takes the value 1 if A & C, 0 if A & ¬C, and some intermediate value X if ¬A is just a function. It still exists regardless of what subjective and objective probability distributions there may be. What it doesn’t do, when and if X ≠ P(C/A), is get expressed by an arrow sentence. A complaint against Adams, due to John Collins. To some extent, we can see how P(C/A) measures assertability of the conditional: when P(C/A) is quite high, that makes it right to assert the conditional. But we shouldn’t think that lower values of P(C/A) correspond to lower degrees of assertability. In what sense is ‘If this fair coin were tossed twice, it would fall heads both times’ 25% assertable? In what sense is it more assertable than ‘If it were tossed three times, it would fall heads all three times’? It seems that neither conditional is assertable to any degree whatever! You don’t speak of assertability; and neither does Adams, anymore. But you do speak of conditionals being accepted or rejected with varying degrees of uncertainty, and I think Collins’ point applies. At the extremes of P(C/A) yes, there is acceptance or rejection; and yes, it admits of degree. But over a vast stretch in the middle, I think, there’s no acceptance or rejection at all, of any degree.

  ‘Matter-of-Fact Conditionals’ (Edgington 1991).

1



706.  To Dorothy Edgington, 11 June 1991

493

Terminology. Examples like the two Oswald sentences still show that we have two kinds of conditionals (at least two), though not whether their difference is a matter of semantics, pragmatics, or even syntax. We’ve long known (and it didn’t take Dudman to tell us!) that indicative versus subjunctive syntax was no infallible mark of what kind of conditional we’ve got. We’ve also long known that the same kind of conditional we typically use when the antecedent is presupposed to be known to be false can be used also without that presupposition. We have managed for a long time not to be misled by the customary terminology, and I don’t see that there’s any reason to start fussing about it now. Embeddings. It seems to me that sentences with conditionals in the antecedents of other conditionals always turn out to work fine on the hypothesis that the embedded conditional is counterfactual. (Even if it isn’t marked by subjunctive syntax, and even if its antecedent isn’t presupposed to be known to be false.) The connection between counterfactuals and past conditional chances can be explained without going for a unified theory. Yesterday, just before noon, the conditional chance of C in the evening given A at noon was high. We’d have said then (if we’d known the chances): ‘if A, then very probably C’. But A didn’t happen; and today, looking back, we say that if it had been that A, it would very probably have been that C. We get this connection by supposing that if it had been that A, the chance distribution beforehand would have been just as it actually was; and that’s something we could very easily take for granted. Indeed, it will follow whenever our counterfactual works by the usual last-minute divergence (whether by fiat, as in Jackson, or whether by rigging the respects of similarity to make it come out that way). Had it been that A, the history up to just before noon yesterday would have been no different; the history-to-chance conditionals (and the probabilistic laws they follow from) would have been no different; and so the chance distribution just before noon would have been no different. It’s hard to stop taking this counterfactual independence of history for granted, but we can do it, I think, in two ways. One way is to go for the backtracking reso­ lution of vagueness of similarity: if A, things would have been different long before, so as to give A more than the negligible chance it actually had. That said, it’s natural to follow by saying that in that case, the chance of C given A well might have been different; so that although we still know that the actual chance of C given A was high, we may not conclude that if A had happened, it would very probably have been that C. The other, harder, way is to go for something that disrupts the usual de facto asymmetries of time: if A, a time traveler would have been at work. Then the way is open, given a suitable story, to reason that C might well have prevented the subsequent departure of that time traveler; and so to doubt that C would have happened if A, even though we still know that the actual chance (and maybe even the counterfactual

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chance!) of C given A was high. In short: we want a connection between counterfactuals and past conditional chances, sure enough; but we also want that connection to be defeasible. I fear a unified theory may give us the connection without the de­feas­ ibil­ity. The main problem I have with Jeffrey’s proposal, and equally with your objective revision of it, is that I don’t see any reason to regard the third value as a truth value in any sense whatever. Failing that, I don’t see any reason to regard the expected value of this so-called truth value as measuring the probability of a proposition. So I don’t really see what Jeffrey has got that Adams hasn’t already got: a sentence ‘if A then C’ that has no truth conditions and expresses no proposition (or at best has partial truth conditions, going undefined when A is false, and expresses a partial proposition); and then a way of associating the quantity P(C/A) with this sentence. Yours, David Lewis c: Jeffrey PS I’ll be away from Princeton almost the whole time until mid-September. For part of the time, Princeton will forward my mail. But of course I won’t be able to refer to copies of earlier correspondence.

707.  To Philip Pettit, 14 August 1991 [Melbourne, Australia] Dear Philip, If there’d been an opportunity, I’d have liked to talk with you about something you said in discussion of Rae Langton’s paper.1 Failing that, a letter. As best I can remember it, you said that the difference between consequentialists and deontologists is not that they value different sorts of properties, but that they disagree about what you do when you value a property. The consequentialist tries to get it instantiated as widely as possible; the deontologist tries to instantiate it. So consequentialist Maria, valuing an ideal of openness and non-manipulation, would have carried on with her lie (or at least silence) in order to preserve a patch of imperfect but good openness; whereas deontologist Maria served that very same ideal in her different way by telling the whole truth then and there, regardless of the cost to (among other things) the future prevalence of openness.   ‘Duty and Desolation’ (Langton 1992), read at a conference at Monash University, August 1991.

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I say what’s in part the same and in part different. And in part the difference is substantive, in part it’s what Mark calls a mere difference in styles of bookkeeping. I say that the consequentialist and the deontologist value different kinds of properties. The consequentialist tries to get the world to instantiate valued properties; whereas the deontologist tries to get himself to instantiate valued properties. The properties will be different just because the sort of valued properties the world could instantiate are not the sort an agent could instantiate. (Translations to connect this to what I say in my Swansea paper. Valued property that the world could instantiate = valued proposition = value de dicto. Valued property that the agent could instantiate = valued egocentric proposition = value [irreducibly] de se.) Preliminary comment. I hope you’ll agree that we can’t hope to capture any pre-existing sharp distinction, either in philosophical jargon or ordinary language, between consequentialists and deontologists. Rather, we know well enough what the prototypical consequentialist and deontologist look like: Bentham and Anscombe. The object is to put a finger on one of the differences between Bentham-like and Anscombe-like moralists. Other, cross-cutting differences. A typical consequentialist is fairly happy about trading off conflicting values according to more or less determinate exchange rates, and maximizing the weighted sum. A typical deontologist doesn’t like this, and may vacillate between lexical ordering and incommensurability, perfectionism and satisficing. (And may vacillate between incommensurability-therefore-no-choice-iswrong and incommensurability-therefore-no-choice-is-right.) A typical consequentialist values properties intrinsic to the time when they’re instantiated – contemplation of beauty, friendship, happiness. Deontologists may be more likely to value properties involving relations to the past, near or distant – keeping promises, getting revenge, historical knowledge, acting from a sense of duty, acting without ‘one thought too many’. Set aside these other differences and get back to the difference that in our different ways we’re both looking at. Consider first the sort of case where there’s nothing but a difference in styles of bookkeeping. Let FA be a property that agents (on particular occasions) instantiate – say, truthfulness. Let FW be a corresponding property that the world as a whole instantiates, or might instantiate – being a world wherein FA is widely instantiated. I say, and so do you, that the deontologist who values FA pursues FA by trying to see to it that he himself instantiates FA. You say that the consequentialist who values this same property FA promotes FA by trying to see to it that FA is widely instantiated. Whereas I say that this same consequentialist values FW and pursues FW by trying to see to it that the world instantiates FW. (Of course, it’s nonsense that the world could

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instantiate FA, or that the agent could instantiate FW.) So far, no issue between us, right? – Equivalent descriptions. But sometimes the consequentialist may value and promote a different kind of property of the world. He may try to get the world to instantiate GW, where GW is not equivalent – or not in any obvious way – to the widespread instantiation in the world of any property GA of agents. GW might be beauty, or diversity, or equal distribution of wealth, or progress over time. Then it’s not true that the consequentialist is trying to get some valued property of agents instantiated as widely as possible. So my way of keeping the books seems more generally applicable. A red herring. To the property GW of the world, there corresponds a property of agents: being aware of living in a GW-world. If the world instantiates GW, the agents in it will instantiate GA. So isn’t the consequentialist really trying to promote the widespread instantiation of GA? – Well, not necessarily! He might value GW per se regardless of whether anybody was aware of it; might think they probably wouldn’t be aware of it; might think it would be best if they were not. GW is one thing, ­widespread awareness of GW is another thing. We could well imagine that a ­consequentialist turns out to value both, but he needn’t, and if he does it’s still two different values. A better reply: leave out the awareness. Let G*A be just the property of living in a GW-world. Then indeed the world instantiating GW is equivalent to widespread (in fact, universal) instantiation of G*A. (At least, on the assumption that there are inhabitants. But what if GW is the property of being a world devoid of life? – Not the most likely thing for a consequentialist to value.) So why can’t you say that the consequentialist values, and tries to promote widespread instantiation of, G*A? Well, you can. It’s hokey, but not wrong. However, I want to say that if we’re willing to be that hokey, we can go on to unify everything under the ‘deontologist’ heading. (No longer an appropriate name if we do unify everything under it!) For now we can equivalently represent the consequentialist as trying to see to it that he himself instantiates G*A! In fact, given that I inhabit the world, the following are equivalent, for any property P: 1 )  Trying to see to it that the world instantiates P, 2)  Trying to see to it that I instantiate the property of inhabiting a P-world, 3)  Trying to see to it that the property of inhabiting a P-world is instantiated as widely as possible among inhabitants of the world. Returning to the first case, promoting widespread truthfulness is the same as trying to see to it that I myself instantiate the property F*A: inhabiting a world where truthfulness is widespread. So both our deontologist and our consequentialist turn out to



708.  To Philip Pettit, 23 September 1991

497

be trying to instantiate properties themselves. But the one tries for FA (truthfulness) and the other goes for F*A. I do think this hokey way of putting things serves one purpose: it allows us to talk about trading off values without a categorial difference either between the values pursued or a difference in what it means to pursue them. But for the most part I’d revert to saying that the typical deontologist is concerned about how he himself is, whereas the typical consequentialist is concerned about how the world is. And I suppose any ordinary sensible person, except when the stakes for the world become overwhelming, is concerned about some of each. Yours, David c: Frank

708.  To Philip Pettit, 23 September 1991 [Princeton, NJ] Dear Philip, Thank you for your letter and offprint.1 They bring a third thing into the ­picture – honouring a value by keeping clean hands. (1) There is pursuing a value V by trying to instantiate it, where V is a value that you can instantiate, namely a value de se. (2A) There is promoting a value V by trying to make V be widely instantiated in the world; equivalently, trying to see to it that the world instantiates the property Vʹ of being a world wherein V is widely instantiated; equivalently, trying to instantiate the property Vʺ of living in a world wherein V is widely instantiated. In this case it’s a mere ‘bookkeeping’ matter whether you say that the value in question is V or Vʹ or Vʺ. (2B) There is promoting a value U by trying to make the world instantiate it (equivalently, by trying to instantiate the property of living in a world that instantiates U) where, unlike case (2A), U is not the property of being a world wherein some other property is widespread. (3) There is ‘honouring’ a value by trying to have clean hands with respect to it. The value so honoured could be the same value that might be promoted in the fashion of case (2A), as in the case you consider; or it could be the same value that might   ‘Consequentialism’ (Pettit 1991).

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be promoted in the fashion of case (2B); or it could be the same value that might be pursued in the fashion of case (1). My reaction is that (3) does not belong in the same list as (1) and (2). Honouringby-pursuing, case (1), shouldn’t be lumped together with honouring-by-keepinghands-clean. Rather, I’d say that having clean hands with respect to a value V is a putative value in its own right, different from the value V; and if indeed it’s a value in its own right, it is itself something that may be pursued, promoted, or both. Cleanhands values are themselves subject to the (1)-versus-(2A/B) division. You can try to keep your own hands clean; or you can try to promote widespread cleanliness of hands, or you can try to promote various kinds of collective cleanliness of hands that don’t reduce to widespread individual cleanliness. I think ‘deontologist’ and ‘consequentialist’ are cluster concepts. I can agree that an interest in pursuing, as opposed to promoting, values may tend to correlate with a valuing of clean hands. The prototypical consequentialist promotes happiness, and cares nothing about either pursuing or promoting clean hands. But sometimes it happens that people who are mostly consequentialist also care about pursuing clean hands, at least in the following way: when harm is overdetermined, and it makes no difference at all to the harm if one more person joins in to help overdetermine it, they will avoid joining in for the sake of their clean hands; and they will do so even if their joining in would promote some sort of good. If you want to say that these mostly-consequentialist people are showing a deontological streak, I’ll agree; but I’ll say that that’s not because they value clean hands, rather it’s because they are pursuing instead of (or as well as) promoting the putative value of clean hands. [. . .] Yours, David Lewis c: Frank, Michael

709.  To Paul Benacerraf, 14 January 1992 [Princeton, NJ] Paul, The part of my letter to Cartwright1 about temporarily losing knowledge while involved in debate with a sceptic was too brief to make much sense by itself. Sorry.   Letter 701. To Richard Cartwright, 4 September 1989.

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709.  To Paul Benacerraf, 14 January 1992

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Sure, there are circumstances in which I might accept, or have reason to accept, the hypothesis that I don’t have hands. (Say, if I’d just had them chopped off as punishment for thieving.) But those weren’t the circumstances I had in mind. I had in mind that my having of hands, my evidence about whether I had hands, and my high degree of belief that I have hands might all remain unchanged; and yet it might temporarily become false for me to describe this unchanged state as one in which I know that I have hands. ‘I know I have hands’ means, roughly, that every possibility (psst – except for those possibilities I’m now justifiedly ignoring) is either one in which I have hands or else one that is decisively ruled out by my present evidence. Most of the time, I can truly say that I know I have hands; because most of the time I’m justifiedly ignoring such far-fetched possibilities as that I’m the handless victim of a deceiving demon. But when I debate with a sceptic – more generally, whenever I think about epis­tem­ol­ogy – I’m no longer justifiedly ignoring those possibilities, because I’m not ignoring them at all. (In jargon: a possibility explicitly under consideration is automatically a ‘relevant alternative’.) To think about epistemology is ipso facto to think about how I normally ignore various far-fetched possibilities. I can’t do that and still go on ignoring them, because to think about my ignoring of them is ipso facto not to ignore them. I can only think about how I ignore them the rest of the time. So when doing epis­tem­ol­ogy, as I now am, I can’t truly say that I know I have hands. Well, can I say now (when doing epistemology) that I knew yesterday (when not doing epistemology) that I had hands? – This is a general question about indexicals: when in circumstance X you speak about circumstance Y, is it X or Y that governs the reference of the indexical? If Y, call the indexical shifty, if X call it rigid. For instance ‘present’ tends to be shifty, ‘today’ tends to be rigid. That’s why (1) is a better thing than (2) to say on Tuesday:

(1) Yesterday, the present day was Monday. (2) Yesterday, today was Monday.

I suppose it’s a matter of tendencies only; I doubt that any indexical utterly refuses to be shifty, or utterly refuses to be rigid. I think that in circumstances of epis­tem­ol­ ogy – i.e. of not ignoring the far-fetched possibilities – I can go either way. I can take the indexical as rigid, and so deny that I knew yesterday that I had hands. Or I can take it as shifty, and so say that I knew yesterday that I had hands. But it’s clearer to say something quotational instead: I can say that yesterday I was in a position to say truly ‘I know I have hands’ just as I can say that yesterday I was in a position to say truly ‘Today is Monday’. Your question: can I know today (when doing epistemology and not ignoring far-fetched possibilities) that I was yesterday in a position to truly say ‘I know I have

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hands’? No; I don’t even know today that I did have hands yesterday. But I can opine today just as well as I ever can, and so I think I’m entitled to assert today, that yesterday I had hands, and further I was in a position to say truly ‘I know I have hands’. --‘Proof isn’t everything’. Don’t take it back, but gloss it thus. ‘Proof from incontrovertible premises, proof without begging the question, isn’t everything’. Seldom can one avoid begging the question against a resolute opponent who understands the move-tree of the game and stands ready to controvert whatever he must controvert to force a stalemate. I think one should be willing and ready to beg questions (in an open and above-board way, of course). Whether what you’ve given is a proof from true premises, or from known premises, or from reasonably believed premises – those are, as you say, among the questions over which there’s an impasse. Whoever’s on the right side of the rest of the impasse will presumably be in the right about these questions too.

710.  To Nicholas Denyer, 10 March 1992 [Princeton, NJ] Dear Nicholas Denyer, Thank you for your paper on ease and difficulty,1 which I’ve now read with a good deal of interest. I have three comments. First, I doubt the connection with Altham’s plurality. Your ‘It’s easy’ seems to mean ‘it can happen in many different ways’ (where the ways are worlds accessible for me). Often, what can happen in many different ways is therefore easy: if there are a fixed number of tickets altogether in a lottery, the more tickets are winning tickets, the easier it is to win. But not always. It may be that it can happen in many ways that P, but every one of these ways is very difficult to achieve; while it can happen in only one way that Q, but that one way is very easy to achieve. So I would have looked not to the number of worlds, but rather to degrees of accessibility of single worlds. Second, whichever way you do it, ease and difficulty should admit of degree; or at least of comparison. It ought to make sense to say that it’s easier (for me) that P than that Q.  More P-worlds than Q-worlds, in your set-up; or in my set-up, some P-world is more accessible (for me) than is any Q-world. This would lead to something

  ‘Ease and Difficulty: A Modal Logic with Deontic Applications’ (Denyer 1990).

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710.  To Nicholas Denyer, 10 March 1992

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like my ‘comparative possibility’ in Counterfactuals, with the added feature of rela­tiv­ iza­tion to person. Third, for part of your treatment – the part before you raise questions of competition – the framework Geach suggested to you, with sentential operators subscripted with terms, is unnecessarily complicated. A nice alternative would be Prior’s egocentric logic. Probably you know it – your choice of notation suggests that you’re a Prior fan – but if not, see Worlds, Times and Selves.2 A sentential expression expresses an egocentric proposition: one that is true not only with respect to a time and a world, but also with respect to a person. An egocentric proposition true of a person at a time at a world is, to my mind, indistinguishable from a property had by a person at a time at a world; it doesn’t matter which we call it. You can read an egocentric sentential expression with a first person sentence, or with a gerund, or with an infinitive. Example: there’s a famous story of Prior at a crowded party waiting outside the occupied loo and writing on the door: ‘CLpLq’. To make good sense of this, the ‘p’ and ‘q’ should be egocentric; and what he wrote could be read as any of: If it’s necessary that I pee, it’s necessary that I queue; If peeing is necessary, queuing is necessary; If it’s necessary to pee, it’s necessary to queue. (And the whole sentence is egocentric: it’s true of him then at this world, but not true of the next-door-neighbours; not true of him after he’s gone home from the party; not true of him at the party in a world where the party house had many more loos.) Then your ‘easy’ and ‘difficult’ as well as your ‘necessary’ and ‘possible’, unsubscripted, can be taken as operators which attach to egocentric sentences to yield egocentric sentences. If it’s easy for you to Φ and not easy for me to Φ, that’s covered (without a term subscript) by the egocentricity of EΦ. Yours, David Lewis

  (Prior and Fine 1977).

2

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711.  To Nicholas Denyer, 1 April 1992 [Princeton, NJ] Dear Nicholas Denyer, Agreed: even if you explain being easy in terms of accessibility, you’d better not also say that accessibility is just closeness (in the sense of similarity). We’d better say, as you suggest, that a world is not necessarily highly accessible from itself. I also agree that the disjunction of many difficult possibilities may be an easy possibility. So just using degrees of accessibility doesn’t do the trick, because if we use degrees of accessibility, any disjunction will turn out to be exactly as easy as its easiest disjunct and the other disjuncts won’t enter into it. (This is how my comparative possibility system worked.) But also I think that just using plurality of ways of succeeding doesn’t do the trick. Yes, it’s easy to score at darts because there are many ways of scoring, many targets you can hit to score, and in most cases, a near miss on one target will be a hit on another. But sometimes multiplicity of targets doesn’t make the task easier: im­agine that the dartboard is cut up into little scraps, one right in front of you, one behind you, one overhead, . . . . Now, hitting the dartboard is no easier than hitting the easiest one of all the little scattered scraps of it. And sometimes being easy or difficult has little to do with the number of different ways of succeeding: for instance, when it’s easier to tie your shoelace than to thread a needle. So we have two different aspects of being easy or difficult: 1) there are many or few specific ways to succeed, and 2) these specific ways, taken one by one, are easy or difficult to achieve. I don’t know whether the two aspects can be merged by looking at less-than-maximally-specific possibilities. (By the way, I recommend a paper by Lloyd Humberstone to anyone interested in such a line: ‘From Worlds to Possibilities’, Journal of Philosophical Logic 1981.) If not, maybe it’s best not to merge the two aspects at all. This reminds me a bit of a problem about the truthlikeness of false theories. In the space of worlds – which, for this purpose, you needn’t take too seriously – the truth is given by a point. And the theory is given by a region, consisting of all the worlds that conform to that theory. One way for the region to resemble the point – for the theory to be close to the truth – is for the region to be small and thus pointlike. Another way is for the region to be close to the point; and we could explain this in terms of how close to the point the closest part of the region is, never mind the rest of the region. I think analyses of truthlikeness have been hindered by trying to merge these two respects of truthlikeness into one single combined virtue of theories.



712.  To Keith DeRose, 9 April 1992

503

Similarly, mutatis mutandis for the two aspects of being easy or difficult. The analogy’s not perfect – it’s backward in that the first aspect of being truthlike is being small,  whereas the first aspect of being easy is being large – but maybe it’s good for something. Yours, David Lewis

712.  To Keith DeRose, 9 April 1992 [Princeton, NJ] Dear Keith DeRose, I’m inclined to agree that you have an example of an epistemic ‘might’ counterfactual. However, I think maybe instead of a ‘would’ counterfactual preceded by an epistemic possibility operator, it’s one of my ‘mights’ – that is, a not-would-not – preceded by an epistemic possibility operator. The reason is that if I change the example, so that I know afterward that if there’d been a penny there I’d have had only 50% chance of finding it, then I think I know afterward that the ‘would’ counterfactual is false, but I don’t know afterward whether the not-would-not counterfactual is true or not. So, writing the epistemic possibility operator as ‘for all I know’, in this revised example For all I know, if I’d looked, I’d have found is false, but For all I know, not: if I’d looked, I’d have not found is true. But (B)1 sounds at least as good as it did in your original example. Or at least it sounds good if suitably followed; but what should follow to make it sound good should be changed, because in the revised example the final sentence of (C)2 is false. If we had an epistemic ‘might’ that attaches to sentences, and also we had my not-would-not ‘might’ counterfactuals, then something true in your example, and the only relevant thing true in my example, is: It might be that: if I’d looked I might have found.   ‘(B) If I had looked in my pocket, I might have found a penny’ (DeRose 1994, 413).   ‘(C) If I had looked, I might have found a penny. But I might not have. To be honest, I don’t know whether I would have’ (DeRose 1994, 416). 1 2

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That’s clumsy; and there’s no way to work the epistemic ‘might’ into the verb phrase of the clause it modifies, as we’d normally do. * If I’d looked, I might have might have found. It would be no wonder then if we let just one ‘might’ do double duty, signalling both the epistemic possibility and also the not-would-not character of the conditional! So I don’t resist granting you your epistemic reading; and I’ve already granted Stalnaker his reading with a possibility operator in the consequent of a ‘would’ counterfactual. (Pages 63–5 of my Philosophical Papers, Volume II.) But however many different readings may proliferate, I do want to insist at least that the not-would-not reading is still one of them. It isn’t all epistemic. I think I can argue for this using your own example. One of the things I can appropriately and truly say afterward, not knowing whether there was a penny in my pocket at the time, but knowing that if there had been one and I’d looked I would have found it for sure, is For all I know, I might have found a penny if I’d looked. To be honest, I don’t know whether I might have or not. That is, I can appropriately and truly claim to be ignorant of the truth value of some sort of ‘might’ conditional. Could this be an epistemic ‘might’ conditional? No; then I’d be claiming to be ignorant about some aspect of my own epistemic situation, and we can now suppose (consistent with the rest of what’s stipulated about the example) that I have no relevant ignorance about my epistemic situation. So I think what I’m saying is that I don’t know whether a not-would-not ‘might’ conditional is true. Thank you for the paper.3 I liked it. I hope to see it in print. Yours,

713.  To Stephen Hetherington, 2 August 1992 University of Melbourne Melbourne, Australia Dear Stephen Hetherington, There is a paper I’ve not been getting around to writing for years. My title for it is ‘Elusive Knowledge’, but the title ‘Lacking Knowledge by Theorizing About It’   ‘Lewis on “Might” and “Would” Counterfactual Conditionals’ (DeRose 1994).

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713.  To Stephen Hetherington, 2 August 1992

505

would suit it equally well. So when I saw the announcement of your 14 August ­seminar1 I was much interested, and wondered whether we’d both hit upon the same idea. Nice if so. Let’s compare notes. (My unwritten paper is an expression of some very brief remarks I made in ‘Scorekeeping in a Language Game’, JPL 8 (1979), p. 355; and those in turn are a ­‘contextualist’ response to Peter Unger, Ignorance.)2 Here’s how it goes. In the first place, the infallibility analysis of knowledge: ‘S knows that P’ means that there is no possibility of not-P that is not eliminated by S’s evidence. Next a sotto voce qualification: no possibility – psst, except for possibilities that we’re now justifiedly ignoring. The rest of epistemology is the story of when we are justified in ignoring genuine possibilities – in jargon, when they are ‘irrelevant alternatives’. This is the place to use all the things we’ve learned from post-Gettier epistemology, and it won’t be a short story. For one thing, the true alternative, and other alternatives saliently like it, are never justifiedly ignored. (Loose ends. 1) Knowledge of non-contingent truths. 2) Knowledge without belief – the timid student problem.) However that may be, we’re not justifiedly ignoring a certain possibility if we’re not ignoring it at all! And we can’t attend to our ignoring of x without thereby attending to – that is, no longer ignoring – x itself. But when we theorize about knowledge, at least if our theorizing is any good, we have to attend to our justified ignoring of genuine possibilities. So when we theorize, normally ignored possibilities are no longer ignored. The range of relevant alternatives expands. So knowledge vanishes. That sotto voce ‘psst’ is a bogus and futile attempt to have it both ways at once: to call attention to our ignoring of possibilities while still ignoring them. It can’t work, but it gets the idea across. (Bumf about kicking away ladders, whistling what we can’t say, not begrudging a pinch of salt . . . .) Moore was right – in normal life, we know plenty. But when thinking about epistemology leads us inexorably into scepticism – mainly because as Unger rightly insists it seems unacceptable to say ‘I know that P but it’s possible that I’m wrong’ – that’s right too. Doing epistemology makes scepticism true. Only temporarily, ­fortunately. But I’m doing epistemology right now, so how can I truly say what I just did say – that in normal life, outside the special context of epistemology, we know plenty?

1   ‘Lacking Knowledge and Justification by Theorising about Them’ (lecture at the University of New South Wales, August 1992). See ‘Elusive Epistemological Justification’ (Hetherington 2010). 2   Ignorance: A Case for Scepticism (Unger 1975).

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Philosophical Letters of David K. Lewis

Well . . . (more bumf about ladders, etc.). Or appeal to the overriding rule of pragmatics: by hook or crook, interpret what’s said so as to give it a chance of being right! So, I’ll be very interested to know how much this has in common, if anything, with what you’re saying. Best regards, David Lewis PS Somewhat similar things may be said about belief (in the sense in which it’s an allor-nothing matter) or about justified belief. But I guess you’d drop the rule that the true alternative is never justifiedly ignored.

714.  To Krister Segerberg, 26 January 1993 [Princeton, NJ] Dear Krister, When you sent me your Tonga paper, you also wrote me a letter which I didn’t answer because I didn’t quite understand what you were asking. You said that doing an action is like running a program. So perhaps in order properly to define a decision situation we really need something like a program (to make sure what the problem really is). Even so there is a problem: what programming language? One would of course want a definition of ‘decision problem’ that was not relative to a programming language. Now that I have your new paper1 – thank you! – I see better what you had in mind. OK; I can agree that in some sense of ‘action’, doing an action is like running a program. What’s called one action is a longish stretch of activity, punctuated by new choices and by the arrival of new information about nature or other players. But I don’t think that’s the best sense of ‘action’ to use when we also say that a decision problem is a choice of actions. I’d rather think of a decision problem as momentary: you choose between the things you might do at that moment. Some outcomes of a decision problem then confront you with new decision problems. So I wouldn’t describe Savage’s example as you do. Instead:

  ‘Perspectives on Decisions’ (Segerberg 1993).

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714.  To Krister Segerberg, 26 January 1993

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Decision problem 1: Add the sixth egg to the omelette? Throw away the sixth egg? Break the sixth egg in the saucer? And if you choose the third action, you then find out whether the egg was bad, and also you are then confronted with Decision problem 2: Pour what’s in the saucer into the omelette? Throw away what’s in the saucer? So for me, defining a decision problem amounts to specifying the agent’s mo­ment­ ary options at a given moment. What I’ve said about how to do that doesn’t appear in anything of my own, but Jeffrey reports my proposal in his paper ‘Preferences among Preferences’, Journal of Philosophy 1974, 387–8. I then identified options as sentences; I’d prefer now to take them as properties of an agent at a time. (Properties of timeslices, or relations of agents to times.) Step 1: A partition is a partition of options [for an agent at a moment] iff the following holds for each member: if it were preferred to every other member [by the given agent at the given moment] it would be true [of the agent at the moment]. Step 2: a basic option is any member of any such partition. Step 3: an option is anything implied by a basic option. Then the agent’s (momentary) decision problem is given by the partition of options. The reason I don’t think decision theory applies directly to prolonged ­program-like actions – ‘contingency plans’ or ‘strategies’ – is that this ignores problems of credibility and deterrence. You have a winning strategy at the game of chicken: just charge straight ahead and don’t stop no matter what! And so does every other player, likewise. So why doesn’t every player win every game? Because partway through ‘running the program’ there come new decisions, whether to keep on or whether to play it safe and turn chicken and lose. It shouldn’t be denied that you have the choice whether to turn chicken midway, or whether to keep on. Then if you’re timid, is the prolonged action of keeping on no matter what not really an option for you? Well, yes and no. If you start, you won’t really follow through. But that’s not from inability; it’s because, midway, you’ll no longer choose to. So I think that to concentrate on the choice between prolonged actions, instead of the choices both at the beginning and midway between momentary actions, lands you in a dilemma about which prolonged actions really are options. By sticking to momentary decision problems, which may have other momentary decision problems as outcomes, we dodge that issue. Yours, David Lewis

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715.  To Michael McDermott, 6 December 1993 [Princeton, NJ] Dear Michael, My target in ‘Desire as Belief’ was only one specified sort of anti-Humean. (The paper is explicit on that point, though one reader, Broome, has militantly missed it.) A different, and more traditional, sort of anti-Humean thinks that a certain goal G necessarily attracts us, so that our motivation to do any act A depends on A’s believed conduciveness to G; this conduciveness might then be explained in terms of a conditional probability C(G/A) or, better, in terms of the probability of a suitable conditional. (Or there might be a bundle of different goals G1, G2, that necessarily attract to different degrees, so that motivation is given by a weighted sum g1C(G1/A) + g2C(G2/A) + . . ., or the same with probabilities of conditionals.) My paper says nothing against that sort of anti-Humeanism. I don’t accept it, but I consider it coherent. However, I don’t think it’s a desire-as-belief theory; rather, the basic desire for G is necessary and  independent of belief; belief enters into the derivative desire for A in the way that  belief enters into the derivation of derivative desire from basic desire by ­anybody’s lights. I enclose a draft from 1988 about this. Yours, David Lewis

716.  To Stephen Hetherington, 9 February 1994 [Princeton, NJ] Dear Stephen Hetherington, Non-sceptical epistemology? You ask me to consider a context in which we are thinking about knowledge, presumably in a general and philosophical way, without at all attending to far-fetched and normally ignored possibilities of error. OK, I grant there might be such a context; OK, it might even be rightly called ‘epistemology’. But I think it would be a far cry from the activity of epistemology as we mostly know it. It seems to me that the far-fetched possibilities and the ignoring of them, even when they go unmentioned, are seldom far below the surface. They motivate the very discussions (analyses of knowledge in terms of information flow, as it might be) wherein we take such pains to leave them unmentioned.



717.  To Barry Stroud, 9 February 1994

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Selectively sceptical epistemology? A context in which we attend to some far-fetched possibilities of error and completely ignore others seems to me even stranger. I wonder whether we wouldn’t be implicitly attending to far-fetched possibilities of error in general, regardless of which examples we chose to mention. But I’m not sure. Maybe such a context is possible. And if it were, I suppose it would indeed make some ascriptions of knowledge go false and leave others unscathed. --Disappearing knowledge. If S is doing epistemology with an eye to scepticism – and I think that’s at least the usual way of it – then I do think that S’s standard everyday knowledge disappears not just in the sense of being put ‘on hold’ and stowed away out of sight and out of mind, but in the stronger sense that this knowledge cannot, for the duration, truly be ascribed to S either by S himself or by a bystander who is attentive to S’s state of mind. --Your paper mostly was about losing justification by theorizing about it, then added that knowledge was lost in an analogous way. I think I went wrong by over­esti­ mat­ing just how alike you meant the two analogous cases to be. I supposed without adequate reason that your epistemic principles P, P1, . . . were meant to be principles requiring justification. That’s how I mistook your regress of epistemic principles for a supposed demand for an endless foundation of justifying reasons. You and Barry Stroud have both questioned the way I reported your views. I do want to talk about a position which says that knowledge is context-dependent because standards of justification are (so as to distinguish that from what I’m saying myself), but plainly I shouldn’t be ascribing that position to either of you. So here’s the relevant page as revised. Thank you very much for your letter, Yours, David Lewis

717.  To Barry Stroud, 9 February 1994 [Princeton, NJ] Dear Barry, You and Hetherington both questioned the way I reported your views.1 I do want to talk about a position which says that knowledge is context-dependent   See for instance ‘Understanding Human Knowledge in General’ (Stroud 1989).

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because standards of justification are (so as to distinguish that from what I’m saying myself), but plainly I shouldn’t be ascribing that position to either of you. So here’s the relevant page as revised. Thanks! --A context in which we attend to tiny bumps, or a context in which we attend to far-fetched and normally ignored possibilities of error, is a context in which we can’t truly ascribe flatness to much of anything, or knowledge to much of anyone. I can’t truly and literally say, in that context, ‘Well, it was flat yesterday, because yesterday I was ignoring tiny bumps’. Nor can Fred truly and literally say ‘I knew Ortcutt’s whereabouts yesterday, because yesterday I was ignoring far-fetched possibilities of being fooled by Ortcutt’s look-alikes’. So it isn’t just present-tense first-person ascriptions of flatness or knowledge that go false in the special context of epistemology. In the midst of epistemology, Fred can’t truly and literally say that he now knows that Ortcutt went into the bank on Monday; and no more can Fred truly and literally say that he did know on Monday, or that a bystander untainted by sceptical epistemology knows today. If Fred wants to say something true and literal about how he used to be epi­ stem­ic­al­ly better off, he has to resort to semantic ascent. Thus: ‘I used to be in a pos­ ition where I could say, truly relative to the context that then obtained, “I know that Ortcutt went into the bank” ’. So in your story, the relevant change of context – of course, context is always changing in ever so many other ways as well – comes only on Wednesday, when the police get Fred to attend to the possibility that he was fooled by a look-alike. But this change (so long as it lasts) makes a difference not only to what Fred can truly and literally say about his knowledge after the change, but also to what he can truly and literally say about his previous knowledge, and about others’ knowledge. So it isn’t true and literal for Fred to say ‘I used to have knowledge until the police robbed me of it by getting me not to ignore far-fetched possibilities of error’; or for me, as a bystander, to say this about Fred. Still and all, I think that’s quite a good non-literal way to describe Fred’s misfortune, so I’m unrepentant about describing it that way. Yours, David Lewis



718.  To Stephen Hetherington, 9 March 1994

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718.  To Stephen Hetherington, 9 March 1994 [Princeton, NJ] Dear Stephen, Thank you for the new version of ‘Lacking Justification by Theorising About Having It’.1 I think I’ve misunderstood you very badly hitherto, through trying to read in more resemblance to my own line than there really is. To put it briefly: for me, the epistemologist’s problem is that he’s insatiably fastidious. His job is to discover when he ignores far-fetched possibilities of error, or he neglects negligible prob­abil­ ities of error, or he relies on justifying principles that cannot themselves be justified in turn, or . . . . And somehow, when he discovers these things he’s doing, he’s no longer willing and able to go on doing them. On my own approach, that happens very simply: to attend to his ignoring of something is ipso facto not to ignore it. But something parallel might somehow happen on other approaches. I kept trying to fit what you were saying into that same pattern, and it kept not fitting. But now I think I see how very different what you’re saying really is. For you, the epistemologist’s problem is that he’s insatiably reflective – he thinks about every aspect of his epistemic life, and so has an unlimited amount of thinking to do. To bring out the difference between problems of fastidiousness and problems of reflectiveness, consider a companion argument titled ‘Lacking Unjustification by Theorising About Having It’. An epistemologist who thinks only about his epistemic successes and never about his failures would be a strangely one-sided epistemologist. A two-sided epistemologist thinks about both. Then: EFJ For any epistemic principle P, time t, and two-sided epistemological ­subject x (of P at t), x fails to have justification via P at t only if at t, he is thinking about P. If your way of setting up a regress is right, it seems to me that EFJ (or rather EFJ*) should set up a parallel regress.2 But this time it’s obvious that fastidiousness is not the problem. If the two-sided epistemologist can have neither justification nor unjustification via any principle without completing an impossible infinite task of thinking, what should we conclude? Not, I think, that the two-sided epistemologist ends up

  See (Hetherington 2010).   EFJ is the rough equivalent, for justification failure, of Hetherington’s EJ: ‘For any putatively sufficient epistemic principle P, time t, and epistemological epistemic subject x: x has justification for her belief that p, via P at t, only if at t she is thinking about P—including P’s applying to her at t’ (Hetherington 2010, 320). 1 2

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neither justified nor unjustified! Rather, that there can be no such thing as the twosided epistemologist – the effort to be one must inevitably break down. However, I don’t accept that your way of setting up a regress is right, and ­neither do I accept the parallel regress for unjustification. I agree with the ‘typical reaction’ on pages 21–22. But I’ll say more. Preliminary definition: someone is an epistemologist at a certain time iff he thinks, at that time, about all the principles whereby he himself, at that very time, gains justification. (Or fails to gain it; I’ll skip this henceforth.) ‘Epistemologist’ is here a term of art. You’re not an epistemologist in the relevant sense if you think about only some of those principles, or you think only about the principles whereby you gain justification at other times, or only about the principles whereby other people gain justification. Take a principle: it says that you’re justified when you satisfy some condition; say, the condition of believing your eyes. (No need to be careful in stating the condition, it’s just an example.) You say, if I now understand: OK, maybe you’re justified as a standard subject when you believe your eyes, but you’re not justified as an epistemologist. The condition for justification as an epistemologist must be something stronger. So we’ll have to switch to a second, stronger principle; but it will have the same problem; and so ad infinitum. Distinguo. ‘A sufficient condition for being justified as an epistemologist’ might mean, (1) a condition such that, necessarily, even if you’re an epistemologist, if you satisfy it, then you’re justified. Or it might mean, (2) a condition such that, necessarily, if you satisfy it, then you’re both justified and an epistemologist. The difference is that under (2) but not (1), it has to be a sufficient condition for being an epistemologist as well as for justification. If you mean (1), then I understand and I accept your argument that if an epistemologist is to be justified, he needs to satisfy a condition for being justified as an epistemologist. And if you mean (2), then I understand your argument that we’ll have to switch to a second, stronger principle; and so ad infinitum. But neither way, it seems to me, do I get both halves of your argument together. That’s my main disagreement. But I have a lesser one. It seems to me that you could mean (2), and still not end up requiring an infinite sequence of principles. Because I wonder whether one self-referential principle could do the job. Like this, for example: SRP Necessarily, if you believe your eyes and you think about this very principle (and that’s all you do), then you are thereby both justified and an epistemologist. I can certainly think about SRP despite its self-referential character. (For instance, I can think about its self-referential character.) Suppose for the sake of the argument that



719.  To Trenton Merricks, 14 July 1994

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believing your eyes is sufficient for justification as a standard subject (which it isn’t really – we’re still taking a simple toy example). If so, then I think the condition stated in SRP is equally sufficient for justification as an epistemologist, in both senses (1) and (2). Yours, David Lewis

719.  To Trenton Merricks, 14 July 1994 as from: Princeton University Princeton, NJ [Canberra, Australia] Dear Trenton Merricks, Thank you for your ‘Dilemma . . .’ paper.1 As you know, I accept that what I know now depends on future contingencies. One reason for this, besides what you mention, is my Humeanism: what causes what, what causal processes are re­li­ able, . . . now and in the past depend on the laws of nature. These supervene on all of history, including future history, but not on an initial segment of history. Any epis­ tem­ol­ogy that is to any degree and in any way causalist or reliabilist – as mine is – will say that if Humeanism is true, then knowledge depends on the future. [. . .] Best regards, David Lewis

720.  To Stewart Cohen, 11 August 1994 University of Melbourne Melbourne, Australia Dear Stew, Thank you very much for the comments on ‘Elusive Knowledge’1 that you sent me earlier in the year. I’ve certainly learnt from them – though I doubt it’s the lessons you meant for me to learn.   ‘A Dilemma for Any Theory of Knowledge’ (Merricks 1995).

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  ‘Elusive Knowledge’ (Lewis 1996a).

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The lesson of your versions of the Bill-at-the-races case and the Ford case seems to me to be that the rule of Resemblance can work in an additive way. Suppose we have two possibilities that can’t properly be ignored. They might for instance be the actual possibility, A, and a different possibility B that is, or ought to be, believed to obtain (or at least, believed to a sufficient degree – which might happen even in a case of suspension of judgement). A third possibility, C, resembles A in some salient ways and B in others. The resemblance to A isn’t quite strong enough to make C a relevant alternative (or not definitely so). Neither is the resemblance to B. But maybe the two resemblances can work together. If A and B join forces to render C relevant, and if C is uneliminated, then C can serve as a counterexample to an ascription of knowledge. --In actuality, A, Bill lost at the races, was mistaken about whether he’d lost, thought he’d won, was dishonest and afraid of his creditors and so said that he’d lost. In B, relevant by the rule of Belief, he lost, he was correctly informed about whether he’d won or lost, he thought he’d lost and he honestly said so. In C, he won. In C, as in B, he was correctly informed; so, as in A, he thought he’d won. In C, as in A, he was dishonest and afraid of his creditors and so, as in A, he said he’d lost. C is relevant in virtue of its resemblance partly to A and partly to B. --In A, Nogot drives a Ford he doesn’t own, whereas Havit drives a Ford he does own. In B, which is one – but only one – of the possibilities to which you give a substantial degree of belief, Nogot drives a Ford he owns and Havit neither owns nor drives a Ford. In C, as in A, Nogot drives a Ford he doesn’t own. In C, as in B, Havit neither owns nor drives a Ford. In C, as in both A and B, the correlation between driving and owning holds good at least in Havit’s case. C is relevant in virtue of its resemblance partly to A and partly to B. --The more respects of resemblance I have to drag in – whether Bill is wellinformed, whether Bill is honest – the more it matters which ones are salient. Take away salience restrictions and there are resemblances every which way! You asked me whether our judgement of a Gettier case could be reversed by monkeying with what’s salient. Well, maybe, I wouldn’t be at all surprised to see it done, however I have no example to show you. If it can’t be done, what does that show? – Maybe not much. Maybe just that you can’t say all the things you have to say to make clear that you have a genuine Gettier example without thereby setting up the saliences needed to provide a diagnosis of the example. ---



720.  To Stewart Cohen, 11 August 1994

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Before I go on, an afterthought about the Ford case. You modified it so as to cut down the resemblance of C to A. But let’s return to the case as I told it in the paper: in Aoriginal, Havit owns a Ford but never drives it. C and B are the same as in our modified version. Well, I can still say all I originally said about resemblances between Aoriginal and C. But also I can note that C resembles B – and this time B gets an even higher degree of belief than in your modified version. C resembles B perfectly so far as Havit is concerned, and C resembles B in one significant way so far as Nogot is concerned. So maybe I should have said that in my original example, resemblance of C to Aoriginal and resemblance of C to B worked together to make C relevant. (Maybe their combined effect was more than enough – maybe not.) --Turning to what you say in the fixed lottery case, I fear I don’t understand you. Originally, in the case of the fair lottery, the possibility of winning was a relevant alternative because of its resemblance to the actual case in which someone else wins. So you don’t know you’ll lose (no matter how bad the probabilities against you). Then in the new case you’re told that it’s fixed against you. Now, you say, you know you’ll lose. This is supposed to show that justification ‘must play a role in the rule of resemblance’. I don’t get it. Case 1. Despite the actual or intended fixing, you win. Then you didn’t know you’d lost because, since actuality is always a relevant alternative, you can’t know what’s false. Case 2a. Despite what you were told, there’s no actual or intended fixing. You were misled. It doesn’t seem right that because you were misled, you knew you’d lose. You only thought you knew it. Possibilities with no actual or intended fixing in which you win saliently resemble actuality and are not properly ignored. Case 2b. There’s an intention to fix, but there’s no actual fixing. Same response to this case as to 2a. Case 3. The warning is true: the lottery actually is fixed against you. But you found the warning incredible and thought or should have thought you might well be in case 2a or 2b. Possibilities with no actual or intended fixing in which you win saliently resemble a possibility to which you do or should give a substantial degree of belief, so you again don’t know you’ll lose. Case 4: The warning is true: the lottery actually is fixed against you. What’s more, you find the warning convincing. Now at last I can agree that you knew you’d lose. But I explain that without adding any new wrinkle to my story. Possibilities in which the lottery isn’t fixed, or in which you win despite the fixing, aren’t actual and don’t much resemble actuality; they don’t and shouldn’t get much degree of belief nor do they much resemble possibilities that do or should get much degree of belief.

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So (unless some pest of a sceptic insists on calling them to your attention) what is there to make them relevant? --If the bogus barns around never have red doors, but the real barn before you does have red doors, that detracts from the resemblance between actuality and the possibility C that you’re seeing one of the many bogus barns and it has red doors. If in addition you give and should give no substantial degree of belief to possibilities with bogus barns that have red doors even compared to other possibilities with bogus barns then there’s no additional resemblance of C to a possibility to which you do or should give a substantial degree of belief. If indeed you can then know you see a barn – I’m not fully convinced – this may do as an explanation. --I agree that after attending to far-fetched and normally-irrelevant possibilities of error – perhaps at the behest of some troublesome sceptic – we can revert to our normal and sensible ignorings. But I don’t think it happens entirely smoothly. The machinery creaks. Rules are bent. The insistent desire to get on with serious business, and the principle of making the message make sense, dominate. The ob­struct­ ive get scolded. Likewise in other cases, e.g. of flatness and tiny bumps. I agree that your story of the hiking club is an exception to what I say happens generally. Without claiming to give you a general theory of how exceptions happen, I note two things. (1) It’s especially obvious that there were meant to be understood restrictions on the quantifier. If the leader had said ‘Everyone who started out made it’, that would have been just a bit less obvious, and it seems to be that the reversion to the smaller domain might well have gone just a bit less smoothly. (2) It’s pretty clear that Smith wasn’t trying to expand the domain; he was just making a mistake about whether the guy turning back was in the original, unexpanded domain. Once that mistake has been corrected, Smith has every reason to want it to be as if his remark had never been said. And nobody else in the conversation has any reason to want anything different. Reverting without a fuss is the obviously cooperative thing to do. Again, thanks! Yours, David



721.  To Peter Unger, 26 September 1994

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721.  To Peter Unger, 26 September 1994 [Princeton, NJ] Dear Peter, Keith had sent me his paper earlier; I share your admiration for it, and I’m very pleased to see now that it’s going to be in the Phil. Review.1 Here’s a paper2 taking a line somewhat, but only somewhat, similar to Keith’s. I may have shown you an earlier version of it – I forget. It all goes back to ‘Scorekeeping . . .’3 and to some discussions you and I had several years ago about ‘invariantists’ versus ‘contextualists’. Yours,

722.  To Robert Nola, 2 October 1994 [Princeton, NJ] Dear Robert, Thanks for your 12 September letter about ‘Elusive Knowledge’. Comments on your two points. (1) I don’t want to require that S have P in mind. Sure, usually when we say that S knows that P, we presuppose that S does have P in mind – but I think not always. Holmes teases Watson, or the teacher encourages the student: ‘Just think a little more! Put two and two together! You have this evidence, you have that evidence, . . . so you know the answer’. Such things are sometimes said. I say they can be literally true, though certainly they’re conversationally peculiar. In dealing with a compartmentalised subject, I think there’s an ambiguity. We can say that he knows iff he has some compartment that knows. Or iff all compartments know. Or iff the compartments collectively know, even if they haven’t pooled their knowledge. So there’s a sense (or two) in which compartmentalised Watson doesn’t know who done it, but also there’s a sense in which he does. Here’s another case. We fear that our secret has leaked, the enemy knows it. No one person in the enemy camp knows it yet, fortunately, but at any moment, the one who knows this will talk to the one who knows that, and then. . . . But collectively,   ‘Solving the Skeptical Problem’ (DeRose 1995).      ‘Scorekeeping in a Language Game’ (Lewis 1979d).

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  ‘Elusive Knowledge’ (Lewis 1996a).

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they have the knowledge already; though just for now it’s in dispersed, unusable form, and none of them yet has it in mind. Likewise I’d say that a library or data bank contains knowledge (though not that it knows) even though some of the knowledge it contains is in dispersed form, not written all together in any one place. (2) If my evidence eliminates every possibility in which not-P (psst . . .), and if previously some such possibilities were uneliminated and had non-zero total probability, then indeed my evidence raises the probability of P. And if in addition the ignored possibilities have low total probability – which they’d better, else pre­sum­ ably not all of them were properly ignored – then the probability of P ends up high. Right. And I do think of justification probabilistically (though admitting that there’s some idealisation here). But does this make my definition ‘justificationist’? I still say not, since justification per se didn’t get mentioned (except in the ‘Rule of Belief’). But what I will say is this: elimination of not-P possibilities is a common ingredient: essential alike to my account and to a justificationist account. That said, I hope no real disagreement remains. Thanks, Yours, 2 October 1994 Dear Robert, Postscript to what I said in my other letter today about your second point. Somebody – not me! – might have a radically subjectivist position according to which there is no such thing as a justified prior possibility distribution. Anything goes. (Except incoherence, of course.) S has eliminated all possibilities in which notP, except for a class of I possibilities that S is properly ignoring. S gives low total subjective probability to I, and since anything goes, it cannot be said that S ought to give higher total probability to I. So the Rule of Belief doesn’t object to S’s ignoring of I. But since anything goes, it also cannot be said that S is justified in giving low total probability to I. So it cannot be said that S is justified in believing P to a high degree. My analysis says that S knows that P. But a justificationist analysis, combined with this sort of radical subjectivism, cannot say that S knows that P. (There’s very little it can say, in fact!) So here’s another way to make my case that, despite the common ingredient, my analysis isn’t justificationist. Yours,



723.  To Keith DeRose, 28 November 1994

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723.  To Keith DeRose, 28 November 1994 [Princeton, NJ] Dear Keith, Thank you for your letter of 21 October about ‘Elusive Knowledge’. *** Your first worry was that I might make it too hard to eliminate possibilities. You’re at the zoo, you take a look, your experience is just such as it would be if you were seeing a zebra under normal conditions (a zebra standing out in the open, in good light, etc.). So, I say, you know there’s a zebra there. You don’t have to eliminate painted mules – that possibility is properly ignored. (At least it is in the present context, though contexts bedevilled by sceptics would be another story.) But you do have to eliminate gazelles. However, ‘the mundane alternative that yonder animal is a gazelle seems to entail little about [your] sensory experiences and memories’. I agree: it’s possible that (1) It’s a gazelle and you’re hallucinating. (2) It’s a gazelle behind a screen on which a zebra is painted. (3) It’s a gazelle behind a mirror which reflects the zebra behind you. (4) It’s a freak gazelle shaped and striped just like a zebra. etc. What importantly is eliminated by your experience is a possibility that’s hard to describe in watertight detail, but easy to describe in a summary way: (0) It’s a gazelle viewed with no funny business of any kind. So what happened to the possibility that it was a gazelle? Taken as a whole, it was neither eliminated nor irrelevant. But it divides into more specific subcases. Subcase (0) was eliminated (so too were some other more peculiar subcases). Subcases (1), (2), (3), (4) etc., on the other hand, were irrelevant alternatives (at least, in the ordinary and unbedevilled context we were in before beginning this discussion). So I say that the possibility that yonder animal was a gazelle was partly eliminated and partly irrelevant; so indeed there was no uneliminated possibility, except possibilities I was properly ignoring, in which it was a gazelle. So my attribution of knowledge to you comes out true, as it should. You knew that the animal was a zebra. You worry that if I say – as I do say – that the eliminated and irrelevant possibilities need to be divided specifically enough, that will get in the way of your knowing

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something so unspecific as that it’s a zebra. Why? However finely I subdivide the eliminated and irrelevant alternatives, it’s still true that the unspecific proposition that it’s a zebra holds throughout all the uneliminated relevant alternatives. The propositional object of knowledge doesn’t have to be at the same level of specificity as the eliminated and irrelevant alternatives. *** Your second worry is that the belief condition on knowledge is unaccounted for. I didn’t want to account for it, but rather to reject it. At least, I wanted to reject it in all but its weakest version. I’m convinced by the timid student counterexample: the student is far from certain of his answer, he regards it as nothing better than a guess, yet it turns out he knows the answer. But I do want to hold on to the weakest version of the belief condition: you cannot know that P if you are firmly convinced that not-P.  That was supposed to be accounted for by what I called the Rule of Belief: if S gives sufficient credence to a possibility, that makes it a relevant alternative. (And the standard of sufficiency was supposed to be adjusted to the degree of specificity of the possibility in question.) I  suppose that if you’re firmly convinced that not-P, that should mean that some ­uneliminated possibility of not-P gets enough credence to qualify under the Rule of Belief as a relevant alternative. How could that fail to be so? Well, maybe subject S is incoherent: although no uneliminated case of not-P gets enough credence to be deemed relevant according to the Rule of Belief, yet the subject is convinced of not-P anyway. My general treatment for incoherent subjects is to treat them as compartmentalised thinkers with disagreeing compartments. Credences, relevance, eliminations, and knowledge all may differ from compartment to compartment. My initial summary description of S’s incoherence is patched together out of partial descriptions of his two compartments. Separating the compartments we have: S1:

Credence in P is high Credence in not-P is low No case of not-P gets sufficient credence to qualify as relevant under Rule of Belief Nor do any of them qualify under other rules S1 knows that P

S2:

Credence in P is low Credence in not-P is high Some cases of not-P get sufficient credence to qualify as relevant under Rule of Belief (what happens under other rules doesn’t matter) S2 doesn’t know that P

What if S is so hopelessly incoherent that you can’t even divide his total state of mind into two coherent compartments? – Then I become doubtful that he’s a clear



724.  To Jonathan Vogel, 21 February 1995

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example of anything. It isn’t clear what, if anything, he believes; what, if anything, he knows; etc. Hence he can’t be used as a test case. Yours, David Lewis

724.  To Jonathan Vogel, 21 February 1995 [Princeton, NJ] Dear Jonathan, TRUDY AND JUDY Ed doesn’t know (after the tree limb) that it’s Trudy he’s seeing because, though he is ignoring the case that it’s Judy who has the mole and Trudy who doesn’t, he isn’t ignoring this case properly, and neither is it eliminated. Why isn’t it properly ignored? – because of its resemblance to actuality. Ned, on the other hand, does know that it’s Trudy he’s seeing. He may or may not be ignoring the case that it’s Judy who has the mole, but it would be as improper for Ned to ignore this case as it is for Ed, and for the same reason. However, Ned doesn’t have to ignore the case in order to know that it’s Trudy he’s seeing, because . . . Roughly speaking, because Ned’s perceptual and memory evidence eliminates it. But, less roughly, the case that it’s Judy who has the mole subdivides. Subcase 1: it’s Judy who has the mole, and there’s no funny business: Trudy and Judy give their right names when introducing themselves, Ned notices the mole and the correlation with the name given, he remembers all this correctly, etc., etc. Ned’s perceptual and memory evidence eliminates this subcase. But there’s also Subcase 2: it’s Judy who has the mole and there is funny business: she often gives a false name, or Ned misperceives or misremembers. Ned’s evidence doesn’t eliminate this subcase, but this subcase (for Ned and Ed alike) is properly ignored. So far, so good? But at this point you say that Ed’s evidence, like Ned’s, elim­in­ ates subcase 1. Ed didn’t notice the mole, a fortiori he didn’t remember noticing it, but if Ed played back in his head the ‘videotape’ of his past percepts, then since the percepts were the same for Ed as for Ned, ‘so too will the memories be the same’. Well, I think these inner ‘videotapes’ (1) are most likely mythical; and (2) if not mythical, they aren’t what we normally call ‘memory’, and so may do more eliminating than memory properly speaking can be said to do. (To focus on this issue: suppose I do have videotapes; I still don’t know what unnoticed events may be recorded on my

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videotapes.) And (3) if I granted that unnoticed events recorded on my videotapes were rightly called ‘memories’, then I think it would indeed follow that I know more than I think I do. (Note that it’s OK to say by way of metaphor: I don’t yet know what you’ve been up to – but my hidden camera knows.) At this point you say that if I treat memory in the same way that I treat ­perceptual evidence, then I’m not in a position to exclude the videotapes. And here your crucial premise is that I ‘use a “thin”, nonpropositional notion of perceptual evidence (p. 20)’.1 But I think you’ve misunderstood something. I don’t deny that perceptual evidence (and memory) have propositional content (provided of course that we admit egocentric, de se propositions). And I don’t deny that sameness of perceptual (and memory) evidence between two possibilities boils down to sameness of propos­ ition­al content. (But neither do I assert it. Rather, I treat it as an open question.) What I do deny on p. 20 is that perceptual evidence (or memory) eliminates exactly those possibilities that conflict with its propositional content. Suppose I have perceptual experience (or memory) with content P. And suppose for the sake of the argument that this content does characterize the experience (or memory) completely. Which alternative possibilities are thereby eliminated? Those where P is false? Or those where I have different perceptual experience (or memory) with content different from P? I say the latter, not the former; and that’s the point of my second remark on page 20. That way, it can sometimes be an uneliminated and unignored possibility that perception or memory is deceiving me. Right, my apparent perception that P, and likewise my apparent memory that P, do not entail knowledge that F, because they do not automatically eliminate pos­si­ bil­ities in which not-P.  What they do eliminate is possibilities in which I lack the apparent perception or memory that P. NOTICING AND BELIEVING When Watson fails to make inferences, then the modal notion of knowledge breaks down to some extent. Watson is compartmentalized. The modal notion applies to each of the separate compartments of Watson’s mind, but not to Watson as a whole. There’s one compartment of Watson’s mind that eliminates all relevant possibilities in which not-P; there’s another compartment that eliminates all relevant possibilities in which not-Q; the first compartment knows P and the second compartment knows Q. But maybe neither compartment knows P & Q, and if R follows from P and Q together but not from either one by itself, maybe there’s no compartment of Watson’s mind that knows R. I’m willing to say that Watson knows P if he has a compartment

  Cf. ‘The New Relevant Alternatives Theory’ (Vogel 1999).

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724.  To Jonathan Vogel, 21 February 1995

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that knows P; Q if he has a compartment that knows Q; but that doesn’t yet give us any sense in which Watson knows R. Maybe Watson eventually gets around to putting P and Q together in one compartment; and thereby coming to know P & Q, and also R. Following Stalnaker, I like to think of inference as a process of overcoming compartmentalization, merging fragments of knowledge out of hitherto separate compartments. Holmes, of course, is much better than Watson at merging his compartments and bringing together all he knows. If Holmes is not at all compartmentalized, to take the ideal case, Holmes’s knowledge is closed under all manner of implication. So maybe one of Watson’s compartments knows that the culprit is a brilliant mathematician, another of Watson’s compartments knows that the culprit escaped on the 12:12 from Paddington, and yet another knows that Moriarty was the only mathematician on the 12:12. Then for lack of a merging of compartments – for lack of an inference – Watson might not know, not in any compartment, that Moriarty was the culprit. Whereas Holmes . . . Noticing is a different case. (Maybe there’s compartmentalization in visual experience, but I don’t think that’s going on in your example.) The visual percept is not determinate. My amblyopia is unhelpful in daily life, but it’s beneficial in doing philosophy of perception. With my bad eye, I can have visual experience according to which there are several whiskers on the cat, but for no number n is it so that according to my visual experience there are n whiskers on the cat. No amount of effort to stare at the whiskers and count them will change that. The content of visual experience in my amblyopic eye is indeterminate in the same way that the content of imagination, memory, and verbal description often are. I’ve convinced myself that the same indeterminacy happens sometimes with my good – normal – eye, just not in such an extreme and obvious way. I don’t know who ‘Rainman’ is, but if he can immediately recognize how many objects are present, even if the number is large, then his percepts and mine with the bad eye certainly differ a whole lot, and I should guess that his and yours also differ. They differ exactly in the extent of their determinacy. Noticing is a way to make the percept more determinate than it was before, and hence it’s a way to change the percept. What is eliminated by the changed percept may well be different from what was eliminated by the previous percept. Whether a change of belief about the scene before the eyes accompanies this change of percept is neither here nor there. It won’t if, for example, the subject believes all along that he’s totally hallucinating. Noticing isn’t believing. I can guess there’s a swastika hidden in the puzzle ­picture, because the picture appears in Nazi News. I can even know for certain there’s a swastika hidden there, because you notice it and tell me so. The swastika

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still  isn’t part of my percept, it isn’t part of the content of my visual experience, until I notice it. KNOWLEDGE OF ONE’S OWN MENTAL STATES I’m happy to regard introspection as ‘inner sense’. A GETTIER CASE? Possibilities de se are possible individuals; so there’s no problem finding the subject in an unactualized de se possibility even if he’s no good counterpart of the actual subject. Even if, for example, the actual subject is essentially made of protein (an unlikely story, I think) and the unactualized possibility inhabits a protein-free world. (See ‘Individuation by Acquaintance and by Stipulation’, ΦR 1983, on the problem of finding the subject.) Yours, David Lewis

725.  To Stewart Cohen, 1 March 1995 Princeton University Princeton, NJ Dear Stew, This is a response to just one thing that’s in your letters of March and December 1994. I passed over it in my reply in August, maybe because I didn’t understand you. Maybe I still don’t, but let’s try. Suppose I properly ignore the possibility that I’m a brain in a vat. More precisely: I properly ignore every sufficiently specific possibility in which I’m a brain in a vat. Accordingly, on my account, I know I’m not a brain in a vat. What I know is true for the usual reason: I couldn’t be properly ignoring the actual case. And what I know is contingent. You say this knowledge of mine is a priori. Why? I suppose, because I could have properly ignored all those very same pos­si­bil­ ities no matter what my perceptual and memory evidence had been. I think I agree that if that were so, there would indeed be a good sense in which my knowledge was a priori. I would find that conclusion an amusing surprise, but not clearly unacceptable. However, I don’t think it’s true that I could have ignored those very same ­possibilities no matter what my evidence had been. For my evidence could have been such as to prevent me from properly ignoring possibilities in which I’m a brain in a vat.



726.  To Michael Strevens, 19 May 1995

525

It seems to me just as if I meet a man who comes up to me and says: ‘Hi, I’m the Vat Master. Let me show you my collection’. He takes me to see his vats, which extend for miles in every direction. He convinces me that indeed many have been his victims. Then he tells me ‘I very nearly got you once, and one of these days I’ll have another try’. And then he tells me how the first thing he does to any newly envatted brain is to give it a simulated tour of the vats, so that it will have exactly the sort of experience I’m having right now. At some point in all this, I can no longer properly ignore the possibility that I now am a brain in a vat. The Rules of Belief, Attention, and Resemblance are all working together to that effect. If my evidence were like that, whether or not I was a brain in a vat, whether or not my experience of meeting the Vat Master was veridical, I could not properly ignore the possibility that I was now a brain in a vat, and so could not know that I wasn’t. So if I do properly ignore all possibilities in which I’m a brain in a vat, and accordingly I know I’m not just in virtue of my proper ignorings, I think my know­ ledge depends on my not having such experience as I’ve just described. Hence my knowledge is a posteriori. Yours, David Lewis

726.  To Michael Strevens, 19 May 1995 [England] Dear Michael Strevens, I’ve had a closer look at your ‘closer look’ paper.1 While it would certainly be nice if the new principle were always available as a consequence of the old, I’m afraid I think it’s too good to be true. For the sake of comparability, let’s stick to the case considered in ‘Humean Supervenience Debugged’.2 Two things to emphasize. (1) H is not arbitrary ­‘background’; rather H is a complete history up to a certain time (such that P gives chances at this same time). I think this guarantees admissibility of H. You disagree. We’ll return to the question later. (2) A conditional probability C(X/Y) or P(X/Y) is defined not as the probability of some sort of special proposition X/Y, but rather as a ­quotient   ‘A Closer Look at the “New” Principle’ (Strevens 1995).   

1

2

  (Lewis 1994a).

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C(XY) or P(XY) C(Y) P(Y) (For well-known reasons it cannot be both at once.) That means that ‘X/Y’ is an incomplete symbol, meaningless in isolation. Again I think you disagree. [. . .] Now the postponed question about admissibility of H, or of lesser matters of historical fact. You said: suppose an infallible crystal ball predicted the chance event A. Wouldn’t that be inadmissible relative to A? – I agree. (And by the way, it needn’t be infallible. Fairly reliable is good enough. In fact, rather unreliable but still not utterly random is good enough to make the point.) But I say that although the message in the ball is part of history, the infallibility (or reliability, or . . .) of the ball is not part of history.* And it takes both together to have something that’s inadmissible relative to A. So what’s inadmissible isn’t entirely part of history; what’s part of history isn’t inadmissible. Yours, David Lewis c: Thau, Hall, Loewer

727.  To Graham Oddie, 4 August 1995 [Melbourne, Australia] Dear Graham, I’ve looked through your chapters 3 and 4 on Harmony and Flux.1 I get a clearer picture than I did from the paper in Mind,2 but I fear it’s a picture of a big misunderstanding. All the anti-DAB proofs – my old one, my new one, Arló Costa-Collins-LeviHájek – show the same sort of thing: trivial cases aside, it cannot happen that DAB holds throughout a class of credence functions closed under all revisions of so-andso kind. (The kind in question varies from one proof to another.) For all your talk of ‘failure’ and ‘fallacy’ and ‘counterexample’, it in no way impugns the correctness of any such proof if you show that

*   It involves the intrinsic and relational character of the ball; and the laws of nature which, according to Humeans, supervene on a pattern throughout all of space and time.

  Value, Reality, and Desire (Oddie 2005).   

1

  ‘Harmony, Purity, Truth’ (Oddie 1994).

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728.  To John Bigelow, 7 December 1995

527

1) DAB holds throughout a class closed under some but not all revisions of the specified kind. or 2) . . . throughout a class closed under certain revisions not of the specified kind. or 3) . . . throughout a class closed under some but not all revisions of the s­ pecified kind and also under certain revisions not of the specified kind. The best way to make the case you want to make would be to question not the ­validity but the applicability of the anti-DAB proofs. I think you think that the range of revisions to which a harmonious rational agent is susceptible is (1) a different range, and (2) not a more inclusive range, than any of the ranges featured in the various antiDAB proofs. For instance, take the anti-DAB proof you have mainly in mind: the proof that DAB can’t hold (trivial cases apart) throughout a class of credence func­ tions closed under all revisions by conditionalizing. If you want to attack the ap­plic­ abil­ity – not the validity! – of that proof, it’s useless to show that a harmonious rational agent is susceptible to revisions not by conditionalizing. (You almost certainly have shown that, most quickly by your example of tensed propositions about the rain.) What you need instead is to show that there’s some revision that is by conditionalizing to which the harmonious rational agent is not susceptible. That would show that the proof might not be applicable. Then to clinch your case, you’d need to show that all harmony-wrecking revisions fall outside the range to which the agent was susceptible. Could you show that? I don’t know. (Does the agent change his mind not only in response to new sensory evidence but also in response to new moral arguments – parables, etc?) I only say it’s unlike anything you have tried to show. Yours,   David c: John Collins, Alan Hájek, Frank Jackson

728.  To John Bigelow, 7 December 1995 Princeton University Princeton, NJ Dear John, I found your ‘Gettier Rules OK’ paper1 enormously interesting. (That may be an  understatement.) I have several comments. Mostly, by way of restating your ­argument and generalizing it still further. But also I complain that something   ‘Gettier’s Theorem’ (Bigelow 2006).

1

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­crucial to understanding – though you do state it fair and square – is confusingly played down. Let K(A) mean that the subject knows that A; let K⎺(A) mean that the subject has whatever it takes to know that A except maybe for truth of A.  So K⎺ means ­knowledge minus truth. I don’t mean that K⎺(A) implies that A isn’t true; only that K⎺(A) is noncommittal about whether A is true. Sufficiency now takes the form: K⎺(A) & A entail K(A). Fallibility takes the form: K⎺(A) doesn’t entail A. Closure takes the form: if A entails B, K⎺(A) entails K⎺(B). The reductio takes the form: suppose K⎺(P) but not-P: that’s possible by Fallibility. Suppose also that T. K⎺(P ∨ T) by Closure. So K(P ∨ T) by Sufficiency. But in many cases that conclusion will be absurd. Comments about K⎺. Like you, I don’t say whether K⎺ is an internal matter of good evidence or reasons to believe, or an external matter of reliable tracking, or some of each, or something else altogether. Unlike you, I don’t say whether K⎺ is something disjunctive or something unitary. Unlike you, I don’t say whether K⎺ includes belief. (So this version of Gettier/Bigelow hits even those who buy the ‘timid student argument’ that knowledge doesn’t require belief.) If there were a general notion of ‘logical subtraction’, K⎺ really would be knowledge minus truth. Maybe the general notion of logical subtraction is in trouble; but that doesn’t mean that this example of logical subtraction is in trouble. Lloyd Humberstone has an excellent (unpublished?) paper2 about logical subtraction which I long ago lent to a colleague who never gave it back: anyway, it would be well worth your while to consult Lloyd about this aspect of the matter. As well as other aspects, of course. Comments about Fallibility. (1) It would be closer to what you said if Fallibility instead took the form: K⎺(A) doesn’t entail K(A). But, given Sufficiency and the converse of Sufficiency, the two versions of Fallibility are equivalent. So I prefer the version that makes it more immediately obvious what’s going on. (2) In a way it’s true that denying Fallibility lands you in Scepticism. My line in ‘Elusive Knowledge’ is that insofar as this is true, the sort of Scepticism you land in – temporary Scepticism in special contexts – is not so very nasty. Comments about Closure. (1) It’s important that you’re using an unfamiliar principle, closure of K⎺ (or, in your version, closure of each of the several R’s) rather than the more familiar principle of closure of K. You say this, fair and square, when you state the principle formally; and again when you use it in the reductio. But before

  ‘Parts and Partitions’ (Humberstone 2000).

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729.  To Bredo Johnsen, 21 January 1997

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that, you’ve alluded to familiar debates about closure of K itself. I’m afraid that gave me a bum steer, only set right after rereading. (2) I’ve idealized from deduction carried out by the subject to entailment; you didn’t; that’s a matter of taste. But it’s anyway a matter orthogonal to the generalized Gettier problem. And when the entailment is very obvious – from disjunct to disjunction – then it matters very ­little  which we say. (3) The familiar closure principle for K covers many-premise inferences. It’s of some interest that all we need is closure of K⎺ under one-premise inferences. ---[. . .] Yours, David PS I’d rather you not cite ‘Elusive Knowledge’ until it’s forthcoming, but I hope you won’t have long to wait. I submitted it to AJP some while ago, saying that I knew it was way over their length limit and I’d understand perfectly if they didn’t want to consider it. I thought it would be in character for Robert to stick to his principles. But no, he said he did want to consider it.

729.  To Bredo Johnsen, 21 January 1997 [Princeton, NJ] Dear Bredo, Thank you for the two papers, both of which I’ve now read. I’ll comment just on the shorter one, though of course some of the comments will be relevant to the longer one as well.1 You say your purpose ‘is to show that [Lewis’s theory] provides no defense whatever against scepticism’. Was I trying to provide a defense against scepticism? So you say (in the first line of your second paragraph). But you could just as well say that I was trying to support scepticism, by providing a theory according to which sceptical denials of knowledge are true on any occasion when a sceptic argues for them by pointing out uneliminated possibilities of error. This view is rather more friendly toward scepticism than is the mainstream of epistemology!

1   The longer one is, presumably, ‘Contextualist Swords, Skeptical Plowshares’ (Johnsen 2001). The shorter one does not seem to have been published.

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However, we need a distinction. There are (1) sceptics who deny that we have knowledge; and then there are (2) sceptics who deny that our beliefs are justified. (Who say, in your word, that our beliefs are ‘arbitrary’.) And of course there are sceptics who do both. The two denials are different. It would be perfectly possible to insist that our beliefs are, by and large, justified and reasonable and non-arbitrary; but that, thanks to their fallibility, none of them really deserves the name ‘know­ ledge’. Or it would be possible for an extreme externalist to say that if we have the good luck to be tracking the truth, then we have plenty of knowledge; and yet to doubt that we are justified in believing that we’re so lucky, and indeed to doubt that we’re justified in believing much of anything. It’s the sceptical denial of knowledge that I was, within limits, befriending. As for the other sort of scepticism, the denial of justified belief, I think that’s an absurd view. But I have nothing new to say against it, it’s a separate topic from the one I was writing about, and so my paper said nothing at all about it. At one point, you imagine a sceptic who first points out, rightly, that everyday attributions of knowledge in everyday contexts are mostly false if this is an evil demon world; and who then claims that it is ‘entirely arbitrary’ to presuppose that this is not an evil demon world. All of a sudden, your sceptic is denying not just knowledge but also justification; and at that point I, in common with most of us, disagree. This is not to say that I propose to ‘defeat’ the sceptic’s false claim that every­ day beliefs are arbitrary – such a debate would foreseeably become deadlocked, so why begin it? But deadlocked debates are no excuse to become excessively openminded; I am not about to become open-minded about whether this is an evil demon world; and I am not going to write as if I were open-minded about it! This isn’t an evil demon world, so I can truly say in everyday contexts that I know a lot; so I do say it. ‘It bears emphasizing’, you say, ‘that the “properness” of a presupposition has nothing to do with its “conversational acceptability” ’. That’s exaggerated. Many of the considerations governing propriety of presuppositions have nothing to do with conversational acceptability, to be sure. But when my conversational partner refuses to ignore a certain possibility, and I nevertheless carry on ignoring it – in other words, presupposing that it doesn’t obtain – that’s not (fully) acceptable. Here we may disagree. Your story about the sceptical juror suggests that it is conversationally acceptable to carry on with everyday presuppositions despite his refusal to go along. I think not. I will grant you a number of things, but not that. (1) I will grant you that the sceptical juror was himself doing something conversationally unacceptable when he refused to ignore the possibility that the world was created ten  minutes ago. (2) I will grant you that the other jurors would have been doing something wrong – maybe even conversationally wrong – if they had followed his lead and dropped their presupposition that the world had existed for more than ten



729.  To Bredo Johnsen, 21 January 1997

531

minutes. (3) I think the uncooperative juror puts the other jurors in a dilemma, where nothing they can do is fully right; and (4) maybe the best of the unsatisfactory ­alternatives available to them is to flout the rules of cooperative conversation. Nevertheless, they would be flouting the rules. You contemplate a sceptical position according to which everyday knowledge claims are false, but none the worse for that; they nevertheless are conversationally OK and serve their communicative purpose. (Unger once took just such a line.) The position is that there’s some other property ‘schmuth’ that is aimed at in cooperative conversation involving knowledge claims; and that hearers trust speakers to have aimed at, and mostly to have achieved; but that ‘truth’ is something different, and something that everyday knowledge claims seldom or never have. I ask: wherefore is schmuth not better called ‘truth’? Imagine the following view: the truth-conditions of almost all English sentences are not what we usually think. Rather, each English sentence is true if and only if pigs fly. But there is one false sentence that we customarily say only when we think it’s cold out, and that we use for the conversational purpose of informing others that it’s cold out; and there’s another false sentence that we say only when we think it’s lunchtime . . .; and so on, and so forth. What would you say was wrong with this  view? Well, I think the same thing is wrong with the less extreme view that you consider. You then contemplate a different ‘sceptical’ position according to which every­ day knowledge claims are tacitly restricted to a framework of relevant alternatives, and so are true. This is, of course, my position – minus the part which says that the framework changes whenever a speaker calls attention to hitherto ignored pos­si­bil­ ities. Is it really a sceptical view? Well, yes and no. It doesn’t say that everyday know­ ledge claims, in their everyday contexts, are false. Yet it does acknowledge that there are (almost) always uneliminated alternatives. Indexical object-language sentences do express propositions; it’s just that they express different propositions in different contexts. And these propositions are either true or not. So what’s the problem about my lacking the means to confront (or agree with) the sceptic? I have to take account of the context in which the sceptic uttered his sentences, and indeed of the context in which I utter my comments, before I can confront (or agree with) him, but what’s so hard about that? Thanks again. See you next month. Yours,

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730.  To Robert Black, 27 February 1997 [Princeton, NJ] Dear Robert Black, One thing I’m doing in this sabbatical semester is working through an overwhelming backlog of papers people have sent me in the last year or so. I’ve just read your ‘Chance, Supervenience and the Principal Principle’.1 You ask whether you’ve correctly interpreted me: yes. Whether I’ve changed my views since 1994: no. Whether my account of fit is stipulative: yes. What is my response? Well, I’m Humean in more ways than one. I never expected to justify induction; or, to say the same in Bayesian terms, I never expected to justify the constraints that distinguish rational from irrational prior credence functions. (I call them rational, because after all that is the name they go by; but in calling them that, I do not mean to suggest that there are reasons to be given in their favour.) How, you ask, can Lewis justify this constraint on credence functions? How, I ask, can anybody justify any constraint on credence functions? Rational credence functions are where you find them. There’s no justifying, only describing. Well, maybe sometimes we can justify derivative constraints by subsuming them under broader constraints. That’s what I had in mind when I said ‘I think I can see dimly . . . how knowledge of frequencies and symmetries and best systems could constrain rational credence’.2 But justification soon comes to an end. When your ‘realist’ (I’d rather say ‘primitivist’) ‘just helps himself’ to the old Principal Principle, it appears that his justification has come to an end. So to your challenge I say tu quoque. But if we give away justifying and stick to describing, then what you’ve done to relate the Humean’s credence function to the primitivist’s is very interesting and helpful. We do have offhand inclinations favouring both primitivism and the old Principle. Your ‘as if’ derivation of the constraint I need hooks it up to those in­clin­ ations. Thereby justifying the constraint? – I think not. Thereby helping to explain the inclinations? – Maybe. Thank you very much for the paper. Yours, David Lewis

  ‘Chance, Credence, and the Principal Principle’ (Black 1998).   ‘Humean Supervenience Debugged’ (Lewis 1994a, 484).

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731.  To Fred Feldman, 12 June 1997

533

731.  To Fred Feldman, 12 June 1997 [Princeton, NJ] Dear Fred, Peter Unger sent me a draft of your critical study of Living High and Letting Die.1 I’m writing mostly to say that I liked it very much, and that I agree with you that there’s a big puzzle about how Chapter 7 goes together with the rest of the book. As you know, when I reviewed the book,2 I ignored Chapter 7; and now I’d like to tell you why I think that was OK to do. (But first let me say that, whatever the editors of Noûs may think, I don’t approve of the idea that a review should be subject to negotiation between reviewer and author – or between reviewer and friends of the author. Anyway, I like your review the way it is. So this letter of comment is not meant to urge, or even to suggest, any changes in what you’ve written.) I’m fairly sure that Chapter  7 was not meant to undermine significantly the case made by the rest of the book. I reject the hypothesis that it was all a sham. I also reject the hypothesis of compartmentalization. So the first six chapters are still there:  the case is being made, not just displayed for the sake of example. And it’s being made wholeheartedly by Peter, not just by one compartment of his divided mind. How this could be true remains to be seen; but I’m pretty sure it is true, and that’s what I assumed in reviewing the book the way I did. How do I know? If the book had come out of thin air, written by a total stranger, I’m not at all sure I could reject the all-a-sham hypothesis and the compartmentalization hypothesis. After all, one can’t reject either of these hypotheses on the basis of scattered passages: any one passage, or any few passages, could be part of the sham, displayed for the sake of example rather than asserted. Likewise, any one passage, or  any few, could be just one compartment talking. But Peter isn’t a stranger; I’ve known him for many years, and talked with him a lot about these and related m ­ atters. And I think I can trust him not to be playing tricks on us, and not to be compartmentalized. In fact, I think I could reject these hypotheses even if I had no alternative hypothesis. But I do have an alternative hypothesis. Here it is. Insofar as Peter accepts ­context-dependent semantics, he is a reluctant contextualist. Yes, he grants that in some contexts it’s true to say that the table with a plate glass top is flat, whereas in other contexts it’s true to deny it. He grants that in some contexts it’s true to say that I know   ‘Living High and Letting Die: Our Illusion of Innocence by Peter Unger’ (Feldman 1998).   ‘ “Illusory Innocence?”; Review of Peter Unger, Living High and Letting Die’ (Lewis 1996b).

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I have hands, whereas in other contexts it’s true to deny it. He grants that in some contexts it’s true to say that it’s morally permissible to throw away the envelope, whereas in other contexts it’s true to deny it. But in each case, I think he thinks that the context in which the denial is true is in some sense a privileged context (and the context in which the affirmation is true is unprivileged). And I think he thinks that: being true in a privileged context is somehow closer to being just plain true in a ­context-independent (‘invariant’) way than being true in an unprivileged context is. For short: his contextualism is inegalitarian. Contexts aren’t all on an equal footing; and therefore in cases like the three just considered, the denial and the affirmation are likewise not on an equal footing. As you show, this stuff about privileged contexts would be idle if it turned out that calling a context privileged was itself a context-dependent matter. (Yeah, sure, a context is privileged if what’s true in it is true; so the contexts where it’s true that the table is flat are the same as the contexts where it’s true that the privileged contexts are the ones where it’s true that the table is flat; likewise the contexts where it’s true that the table isn’t flat . . ..) But I think Peter may think, or he may at least hope, that some contexts are privileged in an invariant way. I’m influenced by my memory of the discussions I had with Peter that led up to his Philosophical Relativity book.3 As I recall it, the course of the discussion went something like this. First, Peter held the ‘invariantist’ view on which it’s just plain false, independent of context, that the table (or anything else) is flat. Yet there was this much of a concession to common sense: some falsehoods are conventionally permissible to say, others aren’t, and we have a practice of communicating effectively by saying what we know perfectly well to be permissible falsehoods. But if saying ‘the table is flat’ is a permissible falsehood, why shouldn’t saying ‘it’s true that the table is flat’ be a permissible falsehood in just the same way? And if saying ‘it’s true that the table is flat’ is permissible as an isolated remark, why shouldn’t it be equally permissible when built into systematic semantics? And then won’t ‘It’s true that the table is flat’, and ‘it’s true that it’s true that the table is flat’, and ‘It’s true that it’s true that it’s true . . .’, and so on, all be equally permissible? And likewise their direct-quotational counterparts? And if so, should we still be calling all these things falsehoods? – But now the original invariantist view has turned into a contextualist view. (Permissibility was of course context-dependent all along.) But at this point, Peter considered the original permissible-falsehood story and the contextual-truth story to be equivalent descriptions, compatible, terminological variants. So Peter’s contextualist story was said to be equivalent to an invariantist story that was emphatically inegalitarian – a story on which the denial of flatness and the affirmation of flatness were not on an  (Unger 1984).   

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731.  To Fred Feldman, 12 June 1997

535

equal footing. But if so, the contextualist story too should be somehow inegalitarian. I surmise – none too confidently – that Peter’s contextualism has been inegalitarian ever since, including the contextualism of Chapter 7 of Living High . . .4 What could it mean that a context is (invariantly) privileged? Maybe this. Being in some contexts involves a pretense. When the bumps are small, we make believe there are no bumps at all, though we know better. We make believe there are no uneliminated possibilities of error, though we know better. And maybe Peter would say (though here I’m putting words in his mouth much more than before) that when you’re in a context where it’s true to say that it’s morally permissible to throw away the envelope, you make believe there are no cogent moral reasons to send UNICEF any money, though you know better. What’s said in an unprivileged context is true in its context, granted, but being in that unprivileged context involves a false pretense. That’s how the things that are true in unprivileged contexts are tainted with falsehood. Not so for the things that are true in privileged contexts. That’s one story that I think might be to Peter’s liking in the cases of flatness and of knowledge, and maybe it could be adapted to the case of moral judgements as well. Here’s a different – but compatible – story of how contexts are privileged, taken from my paper ‘Elusive Knowledge’. When all parties to a conversation acquiesce, we can be in any of various contexts. But what happens when there’s a conflict, when one party to the conversation wants to be in a context in which it’s true to say that the table is flat while another party to the same conversation wants to be in a context in which it’s true to deny that the table is flat? I’m inclined to think that in such a case of conflict, we almost automatically get into a context where the denial is true. The context where the denial is true is privileged in the sense that it’s the one that prevails in case of conflict; it’s the default choice. And likewise for the context where all uneliminated alternatives are relevant and we know next to nothing; and likewise, Peter might perhaps want to say, for the context where it’s true to say that we’re under very stringent moral requirements. I say that in case of conflict we almost automatically get into the privileged context. Maybe this is a tendency that can be resisted, especially by those with forceful personalities or those in positions of authority; but I think of this successful resistance, when it happens, as something that flouts our normal mutual expectations about the pragmatic workings of the language. I can envisage two sorts of misgiving about what I’ve just said. One is familiar to me from audience responses to ‘Elusive Knowledge’; the other is not familiar, but I’d sympathize with it all the same. The first misgiving comes from contextualists of

  Living High and Letting Die: Our Illusion of Innocence (Unger 1996).

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a more egalitarian sort: they don’t like the idea that the sceptic has a winning hand, and it isn’t sufficient consolation that the sceptic’s victory is only temporary. They’d rather say nothing much one way or the other about which sort of context prevails in cases of conflict. Accordingly, they don’t like it when I say that a context in which it’s true to say that the table is flat, or that I know I have hands, is a context in which bumps or uneliminated alternatives are ignored. You can’t continue to ignore  something while attending to your ignoring of it; you can’t continue to ignore something while engaged in conflict with someone else about whether to ignore it. So by describing the irrelevant bumps or alternatives as ‘ignored’, I build in a prediction that attention to these bumps or alternatives, for instance the attention that will take place if there’s a conflict over what sort of context to be in, will render them relevant. The other misgiving, the one I haven’t heard but nevertheless take seriously, is that I don’t give any reason why some contexts prevail in cases of conflict and others don’t. Is this just an arbitrary convention, could it just as well have been the other way round? Or is it rather that some contexts are privileged in the sense that they prevail in case of conflict because they are privileged in some other and more fundamental sense? (As it might be: because they don’t involve pretense and so aren’t tainted with falsehood. That is, at this point the first account of privilege I considered might combine with, and support, the second.) You might think I’ve already answered the question: the unprivileged contexts involve ignoring, you can’t continue to ignore while attending to your ignoring, and that’s why the unprivileged contexts don’t prevail in conflict. But that just gets us back to the prior question: why is it right to describe the differences between contexts in terms of ignoring rather than in some more neutral way? Enough. As an answer to your question how Chapter 7 was meant to coexist with the rest, all this stuff about privileged contexts strikes me as rather speculative. (Whereas my conviction that Chapter 7 isn’t meant to undermine the rest is not at all speculative.) Let’s see what Peter thinks of it. Yours, David Lewis c: Peter Unger



732.  To Stewart Cohen, 3 June 1998

537

732.  To Stewart Cohen, 3 June 1998 [Princeton, NJ] Dear Stew, Thank you for your paper ‘. . . Gettier and the Lottery’.1 There’s a lot we agree about, including the desirability of making the rule of resemblance speaker-sensitive in order to deal with the case of poor Bill; and also including the desirability of not making the rules of belief and actuality speaker-sensitive. I’m also inclined to like your suggestion that a speaker-sensitive salience restriction on resemblance might be used as a way of refusing to heed all the resemblances of an evidential situation. That would have the consequence that there is a new way to make skepticism temporarily true: namely by making resemblances of evidential situation temporarily salient. However this consequence seems not to be a problem. So all I have left to do is to find a way of keeping out of trouble with your case of bystander A and the Gettier victim, pages 14ff of your paper. Here’s what I suggest. There are these two possibilities: P1: S sees a sheep-shaped rock, which he mistakes for a sheep, on a sheepless hill; P2: S sees a sheep-shaped rock, which he mistakes for a sheep; and behind it is hidden the only sheep on the hill. I say that the resemblance between P1 and P2 is salient for more or less anyone, in more or less any context, and in particular may be presumed to be salient for A. What A doesn’t know is that P2 is actual – but A doesn’t have to know that. (The Rule of Actuality is not speaker-sensitive.) So P2 is a relevant alternative, by the Rule of Actuality; and P1 saliently resembles P2 (saliently relative to A) so P2 is also a relevant alternative by the Rule of Resemblance; and P2 is uneliminated; so A speaks falsely when he says that S knows there’s a sheep. When you say at the bottom of p. 14 that ‘The resemblance between [P1] and actuality is not salient for A’ I disagree (at least under the proper disambiguation). The resemblance in question is salient; it’s just that A doesn’t know that it’s a resemblance to actuality. OK? Yours, David Lewis

1  ‘Contextualist Solutions to Epistemological Problems: Scepticism, Gettier, and the Lottery’ (Cohen 1998).

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733.  To Keith DeRose, 19 August 1998 [Princeton, NJ] Dear Keith, It’s OK to say ‘if the warhead were triggered, the chance of an explosion would be 100%’ when what’s strictly and literally true is that the chance would be negligibly less than 100%. Nobody will be misled. It’s common knowledge between speaker and hearer that we can, and we often do, neglect what’s negligible. That’s all I really want to say. You’re having trouble discerning my position on the further question whether this statement is true – just plain true, as opposed to strictly and literally true – in a context where we’re ignoring negligible differences. That’s as it should be. I don’t think this is a question on which I ought to have a ‘position’. Rather, it’s a pretty-mucharbitrary choice between alternative styles of bookkeeping. The same goes more generally. It doesn’t matter that the value that the counterfactual chance differs negligibly from is 100%; it could as well be 43%. It doesn’t matter that it’s a counterfactual, as opposed to an actual, chance. It doesn’t matter that it’s a chance, as opposed to some other magnitude, say someone’s height. (I’m somewhere between 5ʹ 11¼ʺ and 5ʹ 11½ʺ. Is it just plain true to say, in a lax context, that I’m 6ʹ?) It doesn’t even matter that it’s a magnitude, as opposed to some other property which can differ negligibly from some precise and simple specification. Compare Austin’s ‘inclination to play Old Harry with . . . the true/false fetish’ and his insistence that ‘France is hexagonal’ ‘is a rough description; it is not a true or false one’. (How to Do Things with Words, pages 150 and 142.) I applaud his impatience with the question whether ‘France is hexagonal’ is true or false; but instead of saying as he does that it’s neither, I say it’s OK to call it whichever you please. The case of the negligibly small bumps, or of the ignored possibilities of error, is something of an exception: here there’s a real advantage to the ‘contextualist’ style of bookkeeping that doesn’t generalize smoothly to other cases of blameless roughness. The advantage is that contextualist bookkeeping exploits the idea that quantifiers have context-dependent restricted domains; that’s something we’d want to believe anyway; it would be a waste to believe in it and then not use it to support contextualist bookkeeping. So in this case I do have a ‘position’: ‘The table is flat, and Keith knows that it is’ is often just plain true. Imagine yourself in a context where height differences of less than an inch are being (properly) ignored; now consider whether, in this context, the difference between my height and 6ʹ makes false the statement that I’m 6ʹ tall. – These instructions demand doublethink: ignore the difference and don’t ignore it. I don’t say that



734.  To Bredo Johnsen, 15 April 1999

539

the question whether the statement is just plain true in this context is therefore ­nonsensical; I only say you shouldn’t expect a clear-cut and reliable answer. Yours, David Lewis c: Peter Unger

734.  To Bredo Johnsen, 15 April 1999 [Princeton, NJ] Dear Bredo, After some months working toward a lecture deadline, and before some weeks of proof-reading to meet another deadline, at last I have enough of a lull to catch up on a backlog of correspondence, including your February/March letter. You mentioned surgery. I hope all is well? Anyway, best wishes! Actuality and the demon-world resemble each other very little overall, and indeed it’s resemblance of entire worlds that I had in mind. But the one respect of resemblance that there is will be a very salient one, at least in the context of a scep­ tic­al challenge to my knowledge that I had hands. Hence the ad hoc exception. But now I’m thinking: why bother? That resemblance is indeed very salient in the context of a sceptical challenge – but in that context it does no harm to trigger the Rule of Resemblance. That would make the demon-world a relevant alternative, sure enough; but in the context of a sceptical challenge the demon-world is a relevant alternative anyway by the Rule of Attention! To make trouble, the resemblance would have to be salient in any context, and I don’t think it really is. I think I must not have been distinguishing salience in a normal context from salience in the context of a sceptical challenge (or in the context of an epistemological discussion, which of course was the context in which I said that the resemblance was salient). You point to various respects of resemblance between the actual no-bogusbarns world and the world where you’re looking at the one and only bogus barn. Agreed, some of the resemblances you point to are not evidential resemblances. And of course there are yet other resemblances you could have mentioned: in respect of the population of China, in respect of the distance to the nearest star, and so ad infinitum. What I’m not convinced of is that any of the resemblances you mentioned, any more than those you rightly didn’t mention, are salient in a normal context – as opposed to the contexts of a sceptical challenge or an epistemological discussion.

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You may be thinking, rightly, that some of them are resemblances in virtue of salient features of the scene: the bales of hay, the tractor-tire ruts, etc. But, absent scep­ tic­al challenge or epistemological discussion, it would be not at all likely to cross your mind, or a bystander’s mind, to notice how similar the scene you take yourself to be seeing is to a scene which is otherwise similar except that the barn is bogus. Let W1 be the no-bogus-barns world, let W2 be the one-bogus-barn-andyou’re-looking-at-it world, let W3 be the mostly-bogus-barns-but-you’re-lookingat-a-real-one world, and let W4 be the mostly-bogus-barns-and-you’re-lookingat-one-of-them world.* You ask how I can get (B) and yet deny (A). (A) If you’re in W1, you can’t properly ignore W2. (B) If you’re in W3, you can’t properly ignore W4. (Your (b) is my (B); your (a) is the denial of my (A).) Special contexts aside, the resemblance between W1 and W2 would not be salient to someone who pays attention to W1, though it would be salient to someone who pays attention to W2. Even without a special context, the resemblance between W3 and W4 would, I think, be salient to anyone who pays attention either to W3 or to W4 – it’s the resemblance between a hit and a near miss. This is not to say that the resemblance between W3 and W4 is automatically salient to anyone who is in W3. Most likely, no thought either of W3 or of W4, still less of their resemblance, crosses his mind. But I proceed in two steps, using first the Rule of Actuality and then the Rule of Resemblance. (B1) If you’re in W3, you can’t properly ignore W3. (B2) If you don’t ignore W3, you can’t properly ignore W4. So if you’re in W3, and you don’t do any improper ignoring, you don’t ignore W4 – quod erat demonstrandum. Now if we try the same two-step procedure on (A), appealing to the same two rules, it doesn’t work. We’d need (A1) If you’re in W1, you can’t properly ignore W1. (A2) If you don’t ignore W1, you can’t properly ignore W2. Here (A1) is true, but (A2) is false, so we can’t get to (A).

*   You say that there are two, three, four . . . bogus barns. I've changed this so as to suggest, as I did in the paper, that the genuine barns are few by comparison with the bogus barns; so that seeing a genuine barn in the land of bogus barns would be a piece of improbable luck. I think that’s important in making the case convincing.



735.  To Timothy Williamson, 21 May 1999

541

I hope this helps. Of course this goes way beyond what’s in my paper, or anything I had in mind when I wrote it. Thanks very much for helping me work it out! Yours, David Lewis

735.  To Timothy Williamson, 21 May 1999 [Princeton, NJ] Dear Tim, ‘Elusive Knowledge’, evidence, and luminosity When we talked after the Rutgers conference, I doubted that I’d even mentioned evidence in ‘Elusive Knowledge’. I was wrong about that, as you’ve probably seen for yourself. Sorry! But what I was remembering, and what I did get right, was that the notion of evidence was not a load-bearing part of my account. For no sooner did I talk of possibilities uneliminated by one’s evidence than I pinned down what I meant by stipulative definition: So next we need to say what it means for a possibility to be eliminated or not.  Here I say that the uneliminated possibilities are those in which the ­subject’s entire perceptual experience and memory are just the same as they actually are. (I contemplated also including ‘evidence of our extrasensory faculties’, ‘innate dis­ posi­tions to believe’, and spontaneous kinesthetic judgements without benefit of sense experience – if there were any such things, which I was inclined to doubt. I would have done well to make explicit that ‘memory’ wasn’t meant factively.) So, in the sense I specified, it’s clear that the subject’s ‘evidence’ is indeed the same in the bad case and the good. (Now that you mention it, I’m strongly inclined to agree with you that ‘evidence’, when not pinned down by such a stipulation, is used much more inclusively. Roughly: all knowledge is evidence. Less roughly: whatever can in some context truly be called knowledge can in some context truly be called evidence. Not in every context: in a context in which we’ve conceded that you somehow know that P, and we’re asking how you know, we mustn’t say that your evidence for P is P itself.)

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One of the things I was trying to do in ‘Elusive Knowledge’ was to set things up so that knowledge of ‘evidence’ comes out as a trivial truth, not a risky psychological hypothesis. This requires two controversial moves. The first of these moves is to ­conflate knowing with being in a position to know. Thus what I try to make trivial is  exactly what you call luminosity: whenever one has experience of so-and-so ­(suitable) kind, one is in a position to know that one does, in other words one knows that one does. (I shall sometimes call this epistemic luminosity.) My second move is to distance being in a position to know from being disposed to believe upon reflection. Therefore epistemic luminosity, on my preferred notion of knowledge, doesn’t include what I’ll call psychological luminosity: the thesis that whenever one has experience of so-and-so (suitable) kind, one is disposed to believe that one does. I’m inclined to distinguish two varieties of psychological ­luminosity, reject one, and accept the other. More on that below. I think I’m within my linguistic rights in both of these moves, though I dare say I’m holding on to one aspect of usage at the expense of others. For I’m struck by the fact that we can encourage a student to figure something out by saying ‘You know the answer’; and when he does figure it out, if he does, we can say ‘See – you knew it all along’. I’m also struck by how unrelated knowledge and belief can be in a context in which we’re worrying that a secret has got out. The enemy had a spy in the Pentagon, so we fear they know our plans for the invasion. Whether they’re disposed to believe what their spy has told them is neither here nor there. However, a linguistic right is not a linguistic duty. I’m willing to be flexible. I don’t mind switching to a notion of knowledge that’s more psychological than my officially preferred notion – a notion on which being in a position to know does include being disposed to believe, and therefore a notion on which epistemic luminosity does include psychological luminosity. I’ll make that switch later in order to agree with something you say in your 1996 JΦ paper.1 The argument in your Rutgers paper I think the argument in your Rutgers paper2 is not a successful refutation of any kind of luminosity. Rather it’s a sorites, and goes wrong in very much the same way that other sorites arguments do. My line on the original sorites is just the standard supervaluationist line. I’ll go through it quickly so as to introduce some terminology. There’s some point at which a non-heap turns into a heap. That’s supertrue: true on every precisification. But whichever particular point you may pick is, near enough, not the transition point. That’s near enough supertrue: it’s true on almost every precisification. Near enough is good enough, so it’s no wonder that we take all

  ‘Cognitive Homelessness’ (Williamson 1996).   

1

2

  ‘Scepticism and Evidence’ (Williamson 2000).



735.  To Timothy Williamson, 21 May 1999

543

the induction steps to be just plain true. Yet it’s supertrue that some one of the ­induction steps is false. (There might also, or instead, be a Kamp effect: the point [or points, provided there aren’t too many of them] that you focus your attention on becomes de­ter­min­ ate­ly not the transition point. By focusing your attention on a point, you create a context in which some precisifications are made inadmissible, namely those which put the transition right at the point[s] you’re focusing on. The transition is determinately elsewhere than where you’re looking, which creates the illusion that it’s nowhere. A neat idea; but I’m not fully convinced of it, so I’ll stay with the simpler and more standard supervaluationist idea that for each point, it’s almost supertrue that the transition is elsewhere.) Now here’s what I say about the case of watching it gradually go from night to day. There are many points at which your perceptual experience changes, at which your evidence in my stipulative sense changes, at which your evidence in a more ordinary sense changes, at which your knowledge changes, and at which the class of possibilities uneliminated by your evidence or by your knowledge changes. The transition points for all these things are the same. There are many of these transition points, though far less than one per microsecond. It’s supertrue that there are many such transition points: true on every precisification. But different admissible precisifications put the transitions at different points. So whichever particular point you may pick is, near enough, not one of the transition points. That’s near enough supertrue: it’s true on almost every precisification. Near enough is good enough, so it’s no wonder that we take all the induction steps to be just plain true. Nevertheless, it’s supertrue that some of the induction steps are false. (I’ll again ignore the possibility of a Kamp effect.) At the Rutgers conference, I constructed various parodies of your argument, designed to render the counterpart of the luminosity premise incontrovertible and thereby force you to doubt some instances of the induction step. You thought that some but not others of my parodies succeeded in this. I forget just which parody arguments I tried out on you. Anyway, the induction steps in three of my parody arguments are It is consistent with what’s entailed by the whole truth about the relevant ­properties of one’s experience in ai that one is in ai-1. It is consistent with what’s entailed by one’s total evidence in ai that one is in ai-1. It is consistent with what one knows in ai that one knows one is in ai-1. It seemed to me that my parody arguments, and your original argument as well, were all somehow failing in just the same way. Now I can put that more precisely. I think

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your induction step, and likewise all my parody induction steps, go false at just those steps, under just those precisifications, where we hit one of the transition points. The argument in your JΦ paper My supervaluationist line predicts that if, per impossibile, we could fix on a single precisification, some precisifications would make the induction step clearly false. In your JΦ paper, you argue that ‘sharpening has the opposite effect . . . [each induction step] becomes more not less plausible’. I think I can agree with that for the argument in your JΦ paper, but the lesson does not carry over to the slightly different argument in your Rutgers paper. Here’s how I think the case in the JΦ paper might work. It’s supertrue that there’s a transition point where one begins to feel hot; it’s also supertrue that there’s a transition point where one begins to be in a position to know that one feels hot. But it’s also supertrue that the first transition point comes before the second: no admissible precisification puts the two transition points in the opposite order, or makes them the same. (Maybe this is more than I need to claim to make my point, but I’m inclined to think it’s true.) So each induction step (1)  If in ai one is in a position to know that one feels hot, then in ai-1 one feels hot. is supertrue. Accordingly, some instances of the luminosity premise (2)  If in ai one feels hot, then in ai one is in a position to know that one feels hot. must not be supertrue. Sure enough, (2) is false on any precisification that puts ai after the transition point for feeling hot, but before the later transition point for being in a position to know that one feels hot. You might agree that someone could take the line I’ve just offered, but you might fairly wonder how I could take it. For, as I said earlier, didn’t I try to set things up so that luminosity comes out trivially true? On my account, don’t I have to say that the point at which my experience begins to eliminate the possibility that I don’t feel hot is exactly the point at which I begin to feel hot? – Well, as I said, I’m perfectly willing to depart from my official notion of knowledge (and of being in a position to know) and switch to a more psychological notion. On that notion, being in a pos­ ition to know includes being disposed to believe; so epistemic luminosity includes psychological luminosity. And the variety of psychological luminosity that’s targeted in your JΦ paper, at least on one plausible reading, is a variety I’m willing to reject. So what I’m proposing is that the transition point for feeling hot, on any admissible precisification, comes before the transition point for being disposed to believe that I’m feeling hot; and at any step, under any precisification, where we’re in between the two transition points, the relevant kind of luminosity does indeed fail.



735.  To Timothy Williamson, 21 May 1999

545

What’s the difference? Before I can say why the lesson of your JΦ paper doesn’t carry over to the argument in your Rutgers paper, I need to distinguish two varieties of psychological luminosity. Before I can do that, I need to make a preliminary point about belief ascriptions, following Steven Rieber, ‘A Test for Quotation’, Φ Studies 68 (1992): 83–94. Even when they’re in indirect quotation, belief ascriptions can have a quotational character; but it can be ambiguous whether they do or not. Rieber’s example: a man knows perfectly well that he has a home and it isn’t made of mud-brick; but he’s mixed up the English words ‘abode’ and ‘adobe’. Does he believe that he has an abode? You can say yes, or you can say no. Likewise if the man rather thinks that ‘abode’ means ‘home’, but he isn’t quite sure. If you’re quite sure just how the beer you’re drinking tastes, but you aren’t quite sure whether that taste is called ‘hoppy’, do you believe that your beer tastes hoppy? Same ambiguity. If you’re quite sure just how you feel but you’re not sure whether that feeling is called ‘feeling hot’, are you disposed to believe that you’re feeling hot? Same ambiguity. (I suppose what you’re unsure of is whether it’s near enough supertrue that you’re feeling hot. Notice that if, per impossibile, you could settle on one precisification of ‘feeling hot’, that wouldn’t help. What you need is a precisification of ‘near enough supertrue’.) So just as we can distinguish quotational and non-quotational senses of ‘believe that one feels hot’, likewise we can distinguish quotational and non-quotational varieties of psychological luminosity. Feeling hot might dispose you to believe that your feeling is rightly called ‘feeling hot’; or it might dispose you to believe that your experience has a certain property which, whether you know it or not, is in fact rightly called ‘feeling hot’. In your JΦ argument, the psychological luminosity that failed seemed as if it well might be quotational, or at least not unambiguously not quotational. I’m quite prepared to doubt psychological luminosity, so long as it’s quotational. But I’m not so prepared to doubt non-quotational psychological luminosity. I rather think that an experience of a certain (suitable) kind and a belief that one is having an experience of that kind are one and the same thing; or at least, as a fallback, that part of the constitutive functional role of a (suitable) kind of experience is that it’s a basis for a disposition to believe that one’s having an experience of that kind. The argument in your JΦ paper can plausibly be read as targeted against quotational psychological luminosity. So understood, I think it succeeds. The argument in your Rutgers paper is different. Instead of giving an example of a relevant descriptive property of belief – feeling hot – you quantify over such properties. That makes it impossible for a quotational reading of belief ascriptions, or of psychological luminosity, to gain a foothold. There’s nothing there to quote. The argument in your Rutgers paper has to be read as targeted against non-quotational luminosity. The induction steps in your Rutgers argument have the form:

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(3i)  It is consistent with what one knows in ai that one is in ai-1. What happens to (3i) at a step, and under a precisification, at which we hit a transition point? – That depends on what kind of transition point it is. The step from ai-1 to ai might be a transition point simultaneously for one’s experience and for one’s knowledge (of the relevant properties of one’s experience). Call that a total transition point. At a step, and under a precisification, at which we hit a total transition point, (3i) goes false. Thus the right precisification and the right choice of ai would indeed make (3i) less plausible – totally implausible, in fact. Or instead the step from ai-1 to ai might be a transition point for one’s experience, but not for one’s knowledge. Call that a partial transition point. At a step, and under a precisification, at which we hit a partial transition point, (3i) does not go false. Rather, there is a failure of luminosity. For one’s knowledge in ai is ex hypothesi the same as one’s knowledge in ai-1, and that certainly didn’t eliminate the possibility that one was in ai-1. So that choice of step and precisification would make (3i) more plausible not less. This would be a failure of epistemic luminosity, brought on by a failure of non-quotational psychological luminosity. Since I doubt that there are any such failures, I doubt that there are any partial transition points. All the transition points are total. And the existence of total transition points means that instances of (3i) are not quite supertrue, though they may well be near enough supertrue that they’re assertable and seem as if they’re just plain true. Thus the argument fails in the usual sorites way. And that’s the difference between the JΦ argument and the Rutgers argument. In the JΦ argument, read as targeted against quotational luminosity, there is a partial transition point, where luminosity fails. But there are no total transition points, so the induction steps are supertrue. And, as you say, fixing on a particular precisification would make the induction steps more plausible, not less. Defence of supervaluationism Having taken a supervaluationist line about the sorites arguments in the two epis­ tem­ol­ogy papers, I owe you some comments about Chapter V of the vagueness book.3 I agree with much of what you say, but I don’t think it adds up to a successful attack on supervaluationism. Section V.3. I don’t think I need to choose once and for all what shall be my official notion of logical validity, in other words of truth-preservation. I can speak both of local and of global validity, provided that (when it matters) I don’t mix them up. Indeed, I can attend to still other conceptions of truth-preservation as well. In ‘Logic for Equivocators’ (reprinted in my Papers in Philosophical Logic, CUP 1998)4 I took an   Vagueness (Williamson 1994).   

3

  (Lewis 1998).

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interest in ‘truth-osd’, short for ‘truth on some disambiguation’. I explicitly included vagueness as a form of intractable ambiguity, in which case truth-osd becomes truth under some precisification – in other words, nonsuperfalsity of the negation. I considered also ‘truth-osd only’, in other words truth-osd without falsity-osd, in other words supertruth. The ‘logics for equivocators’ that preserve truth-osd, or that preserve both truth-osd and truth-osd only, turn out to be fragments of well-known relevant logics. A different point about V.3. I’m not altogether comfortable saying that for vague sentences, supertruth is truth. I’d rather say, as I once did (Papers in Metaphysics and Epistemology [CUP 1999], page 172),5 Super-truth, with respect to a language interpreted in an imperfectly decisive way, replaces truth simpliciter as the goal of a cooperative speaker attempting to impart information. I’d have done still better to say ‘Supertruth, or getting near enough to supertruth, . . .’. Section V.4. Little to say: I can only agree that sometimes an existential quantification is assertable because supertrue, and none of its instances is assertable because supertrue. I even agree that each instance is deniable because near enough, though not quite, superfalse. Maybe this took some getting used to, but I don’t remember that it did. I can’t now recapture a state in which I’m intuitively uncomfortable with it. See the first objection and reply, Papers in M&E, 173. Section  V.5: on comparatives. Point (a). Might the vague comparative ‘She is more intelligent than he is’ match the vagueness of ‘The class of precisifications on which he’s intelligent is a small subclass of the class on which she’s intelligent’? Point (b). ‘Saul is brave, but David is braver than Saul’ can’t be supertrue, but it can be near enough supertrue to be assertable. Point (c). I wouldn’t much mind admitting that the ‘truer than’ theory doesn’t work for comparatives of precise predicates. But I’m not convinced by the example you give. I’m somewhat inclined to think there’s a precise ‘acute’ that means ‘less than 90°’ and doesn’t admit degrees or comparatives; and there’s a vague ‘acute’ that means ‘significantly less than 90°’ and does admit degrees and comparatives. Point (d). Once we have comparatives, we have another line we can take on ‘very’: something is very dark blue if it’s darker blue than most dark blue things. – Mind you, I don’t at all object to your suggestion that admissibility of precisifications is itself vague and context-dependent. Section  V.6. I agree about the need to extend the higher-order vagueness of ‘admissible’ ad infinitum. I attach equal importance to the higher-order vagueness of ‘near enough supertrue’, or in other words ‘true on almost all admissible precisifications’.   (Lewis 1999).

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Let a borderline* case of something be either a borderline case, or a borderline case of a borderline case or . . . . Something I want to insist on, and something that meets resistance, is that you can’t draw a sharp line between cases that are borderline* and those that are not; but not because ‘borderline*’ is itself vague. Rather, because every case is borderline*. Those who think otherwise are lazily thinking that borderline* is a special variety of borderline, which it isn’t. That parallels your second alternative suggestion that perhaps no man is definitely* tall. Section V.7. I think there’s something very importantly right about deflationism (or ‘redundancy’ or ‘disquotationalism’ or . . .) about truth. But I think deflationism applies in the first instance to propositions; and those aren’t vague, however much semantic indecision there may be about how to express them in language. For any proposition P, the proposition that P is true is the same proposition as P. So whether disquotation carries over to sentences which are vague by reason of indecision about which proposition they express, or to sentences that don’t succeed in expressing propositions at all, is neither here nor there. Also, this is another point where I need to insist that I don’t want to ‘identify ordinary truth with supertruth’; as I said before, I prefer to regard supertruth as a conversational substitute for truth simpliciter when semantic indecision makes truth simpliciter go undefined. It’s not the only such substitute; truth-osd is another, which may be easier to come by in especially hard cases. Well – all this is much longer than I meant it to be. Sorry! I hope you won’t mind if I share this letter with a few interested Princeton colleagues who came to your seminar, and with Jonathan Schaffer (Rutgers), and Kit Fine (NYU). Yours, David Lewis PS [. . .]

736.  To Timothy Williamson, 19 June 1999 [Princeton, NJ] Dear Tim, Thank you for your letter of 31 May. Quick replies to some of the points raised. The enemy had a spy in the Pentagon, though we hope they don’t believe what he’s told them. So they probably know, though we hope they don’t ­believe, that we have a contingency plan for an amphibious landing at 6 am on 19 August.



736.  To Timothy Williamson, 19 June 1999

549

Acquaintance wasn’t what I had in mind. Belief ascriptions, unless explicitly quotational, are never unambiguously quotational. In the case of the Babylonian, a quotational disambiguation of ‘believes that he’s feeling hot’ involving English would be so obviously false that we’d ignore it. Believes that he’s in neural state STU isn’t right either, being obviously false unless he knows a lot of neurology. But I think there’s a way of believing that one is feeling hot that anyone can do, without knowing either English or neurology. I’m not sure there’s any good way to capture its content with a ‘that’-clause, unless we quantify in so that the clause contains a bound pronoun. (The property of feeling hot is such that he believes he has it.) And I’m inclined to think that this sort of believing, or at least being disposed to it, is an automatic consequence of feeling hot. ‘If s means in c that Harry is bald, then s is true in c iff Harry is bald’. True on all precisifications of ‘bald’, so feel free to say it. ‘ “Harry is bald” means in the current context’ – pretend we have a suitable current context – ‘that Harry is bald’. Well, strictly speaking, ‘Harry is bald’ means slightly different things on different precisifications of ‘bald’. Maybe we could say it’s true on all admissible joint precisifications of ‘bald’ and ‘means’? But I’m not sure of that. ‘If s means in c that Harry went to the bank, then s is true in c iff Harry went to the bank’. True on all disambiguations (if we set aside mixed disambiguations, that disambiguate the two occurrences of ‘bank’ differently). So feel free to say it. ‘ “Harry went to the bank” means in the current context that Harry went to the bank’. Well, not really; it doesn’t unambiguously mean anything, and this is a peculiar context that doesn’t help disambiguate it. (The speaker is just repeating what he was told, and doesn’t know what his informant meant by ‘bank’.) It’s not very plausible to say that it’s true on all admissible joint disambiguations of ‘bank’ and ‘means’. ‘ “Harry went to the bank” is true in the current context iff Harry went to the bank’. A mess, suffering both from ambiguity and from a false presupposition that the sentence has a definite meaning! I’m not sure what else to say about it. Likewise I’m not sure what to say about the T-biconditional in the previous case. ‘Unless supervaluationists identify truth with supertruth, it’s unclear how they explain failures of bivalence’. – An ambiguous sentence isn’t, strictly speaking, true or false; rather, it’s true or false on one or another disambiguation. Likewise a vague sentence isn’t, strictly speaking, true or false; rather, it’s true or false on one or another precisification. (If true on all precisifications, or almost all, it’s near enough to being just plain true for all practical purposes, apart from induction steps in sorites arguments. Then it’s blameless to call it true, as we mostly do.) That’s what I want to say. Is it a denial of bivalence? – You tell me. Yours,

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737.  To Robert Fogelin, 13 October 1999 [Princeton, NJ] Dear Bob, If I’ve understood you properly, ‘urbane’ Pyrrhonism1 seems to be something that I’ve taken for granted ever since my student days, so not at all something I’d try to refute. In particular, ‘Elusive Knowledge’ is not a rejoinder to it, and contains nothing that even pretends to satisfy Ernest’s yearnings. We have our ordinary ways of arriving at beliefs. Roughly: perception, testimony, and induction. (Somewhat less roughly: perception, testimony, inference to the best explanation, and some degree of tenacity in sticking to what we’ve believed hitherto. A little less roughly still: approximately Bayesian learning, starting with ­priors that have dispositions to favour best explanations and dispositions toward trust of others and tenacity built in.) These ordinary ways of believing can be called into question, either because they are fallible or by those who favour different ways. (As it might be, the ‘belief in God is properly basic’ crowd.) When they are, there is no way to reinstate them by argument without begging the question. In case of debate, a competent opponent can easily force a stalemate. If Ernest Yearner has called them into question, and yearns for someone to cure his condition by means of some fair, non-circular argument, I have no idea how what he yearns for could possibly be provided. If a justification means a non-circular argument, no justification of our beliefs (or our ways of forming them) can be given. It does not follow that we ought to give up believing things. It does not follow even that we ought to believe things a little less firmly than we usually do. Myself, I don’t think we should give up our believing, not even a little bit. Our usual levels of caution strike me as sometimes too low and sometimes too high, but mostly about right. Neither does it follow that our beliefs are unjustified (or unreasonable). I followed Strawson on the justification of induction, long ago. ‘Justified’ (or ‘reasonable’) just are our names for beliefs that are formed in such ways – and wherefore should we not call things by their right names? But these names are empty compliments. When I truly say that my belief that trees shed their leaves in October is justified, I do not mean to say that I have the sort of justification that Ernest yearns for – a nonquestion-begging argument that will reinstate this belief even after it, and the method whereby it was formed, have been called into question. (Likewise when I call this

 See Pyrrhonian Reflections on Knowledge and Justification (Fogelin 1994).

1



738.  To Adam Elga, 15 September 2000

551

belief reasonable, I do not mean that reasons for it can be given beyond those in­duct­ ive reasons that Ernest has called into question.) So my advice to Ernest is: your yearnings cannot possibly be satisfied. You might as well carry on believing things nevertheless. Pointless advice! You will, so it’s idle to worry about whether you should. Call things by the names they conventionally deserve according to your beliefs: in particular, feel free to carry on calling most of your beliefs ‘justified’ or ‘reasonable’. Likewise, go on speaking in the ordinary way of ‘knowledge’. But I take it that the ordinary way of speaking of knowledge is vulnerable to Cartesian, as opposed to Pyrrhonian, scepticism. This is not just a philosophical phenomenon; a mild version of it is the stock in trade of defence attorneys and conspiracy theorists. The point of contextualism is that this vulnerability is undeniable, but temporary. This discussion of attributions of knowledge and their context-dependence can all take place against a background of urbane Pyrrhonism. Indeed, I think there isn’t really any intelligible alternative setting for it. Yours, David Lewis c: Tim Oakley

738.  To Adam Elga, 15 September 2000 [Princeton, NJ] Dear Adam, I’ve decided that I don’t agree with you about Sleeping Beauty,1 and consequently there are some things in the Dr. Evil draft2 that I don’t agree with either. Your present total evidence eliminates some centered worlds and not others. There are two principles of indifference we might consider. There’s the principle that you state and defend, and I accept it too. INDIFFERENCE: given some uneliminated centered worlds that are located in the same uncentered world, assign them equal credence. Let the credence P(W) of an uncentered world be the sum of the credences of  all  the uneliminated centered worlds located therein. Then the credence of an

  ‘Self-Locating Belief and the Sleeping Beauty Problem’ (Elga 2000).   ‘Defeating Dr. Evil with Self-Locating Belief’ (Elga 2004).

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­uneliminated centered world located in W is given by P(W)/N(W), where N(W) is the number of uneliminated centered worlds within W. We’re not saying what P(W) is. There’s a stronger principle. You don’t defend it, and I don’t either, but you do defend some instances of it, namely those instances where the different centered worlds are in uncentered worlds that differ by the outcome of a fair coin toss. For instance, it would yield the second answer to the Sleeping Beauty problem, and there I disagree. INDIFFERENCE+: given some uneliminated centered worlds, whether or not they’re located in the same uncentered world, assign them equal credence. (The Dr. Evil draft had me misled for a while about whether you accepted INDIFFERENCE+. ‘Similar’ centered worlds well might have meant centered worlds that match with respect to the subject’s total evidence, whether or not they’re in the same uncentered world. You say fair and square that it doesn’t mean that; but I was careless, and I guess I was expecting you to defend INDIFFERENCE+ because you’d been defending an instance of it in the Sleeping Beauty paper. May I strongly suggest some different wording? ‘Collocated’, say?) Let’s look at your two-part argument in the Sleeping Beauty paper. INDIFFERENCE means that P(T1) = P(T2), just as you say in the first half of your argument. So far, so good. My disagreement is with the second half of your argument. I say that since P(WH) = P(WT ) = 1/2, P(H1) = 1/2 and P(T1) = P(T2) = 1/4. That means that P(H1/H1 or T1) is not 1/2 as you say it is, and as INDIFFERENCE+ would have it, but rather 2/3. You say (concerning the case that the coin will be tossed after the Monday awakening): ‘But your credence that the coin will land heads (after learning that it is Monday) ought to be the same as the conditional credence P(H1/H1 or T1)’. I agree: when you’re told that it’s Monday, that amounts to being told not-T2, and conditionalizing on not-T2 leaves you giving credence 2/3 to H1. You say: ‘Your credence that you are in H1 would then be your credence that a fair coin, soon to be tossed, will land heads’. Again I agree. Your credence that the coin will land heads should also be 2/3. But isn’t this a violation of the Principal Principle, which I take it you’re im­pli­ cit­ly invoking? The toss hasn’t happened yet, you know that the chance of heads will be 1/2, yet the credence you give to heads is 2/3! How come? Well, the Principal Principle had a proviso: ‘Let E be any proposition com­pat­ ible with [the assignment of chance] that is admissible at [present]’. In the expected applications, E (as its name suggests) was meant to be the subject’s present total evidence. An inadmissible proposition was meant to be one that brought news from the future; or in other words carried information, perhaps probabilistic information, about the outcome of the chance event. The proviso was originally meant to make the Principle fall silent about cases of time travel, credible prophecy, etc. Later (‘Humean Supervenience Debugged’) I came to think there were more inadmissible



739.  To Adam Elga, 4 October 2000

553

propositions than I’d first thought. It certainly never occurred to me before that the information that you’re not now in T2 should count as inadmissible! But I think that’s what I ought to say, given that I’ve already said that it’s evidence that the future coin toss will fall heads. I had various inconclusive ways to pump intuitions against INDIFFERENCE+, but since there’s no reason after all to think that you accept anything more than ­certain of its instances, I won’t mention most of them. I mention one only because when we were talking about Dr. Evil at dinner, I seemed to be tacitly assuming INDIFFERENCE+! Why did the PDF actually have to go to the trouble of constructing Dup? Why not do it the easy way? They could have just sent Dr. Evil a letter saying: ‘We remind you that there are lots of uneliminated centered worlds out there in logical space where the subject will escape torture only if he surrenders’. (For a while at dinner I managed to persuade myself that the easy way would have been just as good!) Dr. Evil will of course think: ‘Yeah, and there are lots of others where the subject will escape torture only if he doesn’t surrender’. (Maybe the cardinalities of the two sorts of uneliminated centered worlds are equal; or maybe there are proper-class many of both.) Dr. Evil can think that anyway, when he knows that Dup has been constructed. Why is it a less effective response when Dup is thisworldly than when he isn’t? Answer: because what’s true is INDIFFERENCE, not INDIFFERENCE+. Yours, c: Bob Stalnaker PS [. . .]

739.  To Adam Elga, 4 October 2000 [Princeton, NJ] Dear Adam, Before I reply to what you say about Chancy Duplication, let me recall (what I take it was) your strategy in the Analysis paper.1 There were two cases: Late and Early. In Late, the fair coin is tossed after the Monday awakening; in Early it’s tossed before. You first say that the difference between Late and Early shouldn’t matter; then you give an argument which applies to Late but doesn’t appear to apply to Early.

  ‘Self-Locating Belief and the Sleeping Beauty Problem’ (Elga 2000).

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(Somebody might conclude that after all it does matter which it is, but neither of us wants to say that.) At the end of the Monday awakening, after Beauty is told it’s Monday (alternatively, after she’s awakened by a shout of ‘Monday’), the coin toss is still in the future. So a rule of setting credences equal to known future chances prima facie requires her to give equal credence to heads and tails. What I had to do was to argue that this prima facie requirement is overridden because at that point she has inadmissible evidence. But there’s not even a presumptive rule that calls for equating credences to known past chances. Of course the credences which you previously equated to known chances that were then future can subsequently change under the impact of new evidence. I took it that was the reason why you considered Late rather than Early; and I took it that indeed Late was a harder case for me than Early, since in Late but not Early I had to find something inadmissible to override the equating of credences to known future chances. I took it that Early was no problem for me. But Chancy Duplication is like Early rather than Late. The coin toss takes place before Fred awakens on Earth. So his previous credences about what was previously a future chance event can change under the impact of new evidence. There’s no need to find something that can override the equating of credence to known future chances, because by the time of the awakening on Earth the chances in question are not future. In particular, there’s no need to find something that inadmissibly brings news from after the time of the awakening; news from after the time of the coin toss is all we need. On indifference. Unfortunately I do want to take seriously the infinite case, perhaps even the case where all the possibilities in question contain proper-class many centered worlds. I take your point that the ‘peculiarity’ does matter in the in­fin­ ite case. So I need to say something different from what’s in my present draft. Changing to P(T1) less than 1 loses contact with the paper I’m replying to. Maybe I should just say that there is a principle of indifference which applies to colocated possibilities and tells us that P(T1) = P(T2) – but not that P(H1) = P(T1) = P(T2) – without trying to spell the principle out properly. Or maybe I should pretend we’re in the finite case, which amounts to coarse-graining.2 Yours, David

  See ‘Sleeping Beauty: Reply to Elga’ (Lewis 2001).

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740.  To Keith DeRose, 9 November 2000

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740.  To Keith DeRose, 9 November 2000 [Princeton, NJ] Dear Keith, I read ‘Now You Know It . . .’1 with interest, but I disagree. So far as the issue taken up in this paper goes, of course, we don’t disagree about epistemology. But we do disagree about the flexibility of ordinary language, the competence and the responsibilities of readers, and the responsibilities of writers. Competent readers know (except perhaps when they’re in a philosophy sem­ inar) that they’re expected to interpret what’s said in such a way as to make the message make sense. So when they read (outside the seminar) that genes are selfish, they know to take it as a metaphor. And when they read (outside the seminar) that France is hexagonal, they know that what’s meant is not that France is a perfect hexagon. And when they read (outside the seminar) that tomorrow never comes, because when it comes it will no longer be tomorrow, again they understand perfectly well. And so on. Authors are entitled to rely on readers to exercise just this kind of interpretative competence. But all too many philosophers seem to abandon their interpretative competence when they enter the philosophy room. They turn themselves into literalists and simpletons – or, more likely, they pretend to be literalists and simpletons when really they know better. I think that if this silly habit leads them to misunderstand – or, more likely, pretend to misunderstand – that’s their problem. Instead of pandering to such silliness, and reproaching those who refuse to do ­likewise, you might better reproach the silliness itself. Yours,

741.  To Bradley Monton, 12 February 2001 Princeton University Princeton, NJ Dear Brad, When we have centered possibilities as objects of belief and as items of evidence, there comes to be an ambiguity in what it means to gain and lose evidence. Except in very peculiar circumstances – the two gods, or the amnesiac, in my stories in   ‘Now You Know It, Now You Don’t’ (DeRose 2000).

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‘Attitudes . . . De Se’ – we are always gaining and losing centered evidence. The p ­ ossessor of evidence is, in the first instance, a stage: a more-or-less momentary t­ emporal part of a person. (If you’re one of those who reject ‘the crazy metaphysic of temporal parts’, or if you’re one of those who think of a person as stretched across many worlds, you might replace worldbound person-stages with world-person-time triples; but this replacement is not my project, and I wouldn’t care to guarantee that it will be free of trouble.) Suppose that when the alarm goes off, Fred does not throw the clock out the window: rather, he sits there staring at the clock, watching as the hands move. One of his stages has the centered evidence: the clock I’m now watching reads 9:06:24. Another of his stages, a little while later, does not have that centered evidence, but instead has the centered evidence: the clock I’m now watching reads 9:07:18. . . . Exactly the same thing happens if Fred keeps track of a biological clock, say by counting heartbeats. The same thing happens if Fred keeps track of a mental clock: it seems as if I now am 6 minutes after the alarm went off. Then, a little later: it seems as if I now am 7 minutes after the alarm went off. . . . The same thing happens if Fred keeps track of an extremely imprecise mental clock: it seems as if I now am an hour, give or take thirty minutes, after the alarm went off; it seems as if I now am two hours, give or take thirty minutes, after the alarm went off; . . . (I distinguish this from Fred’s stages’ changing self-ascriptions of locations in time. Maybe one of Fred’s stages will self-ascribe being located roughly at 10am, another will self-ascribe being located roughly at 11; . . . That’s what happens if Fred is sure – and doesn’t forget – that the alarm was set for 9am. But if Fred isn’t sure when the alarm was set for – maybe he doesn’t remember whether he reset it after getting home from Lebanon – then there will be changing self-ascriptions of being various (precise or rough) intervals after the clock went off, but no self-ascriptions of location in time.) That’s the sense in which gaining and losing evidence is an (almost) inevitable concomitant of having centered evidence. There’s another sense in which Fred in my stories, and in your story likewise, doesn’t gain or lose evidence; but in which if he forgot, he would lose evidence, and if he observed anything unexpected, he would gain evidence. In the story so far, his change of centered evidence happens entirely by a systematic process of updating. His experience of seeing the clock read 9:06:24 and expecting to see it soon reading 9:07:18 is followed a little later by the experience of seeing the clock read 9:07:18 and remembering seeing it read 9:06:24; and likewise in the case of biological or mental or imprecise mental clocks. If Fred forgets, or if he unexpectedly hears a bird singing, his change of centered evidence does not happen entirely by this systematic process of updating. If we distinguish between an old evidential state updated and a novel evidential state, then Fred in my stories and yours never gets into a novel state, but does undergo constant updating of his old state. In the no-novelty sense, Fred doesn’t gain or lose evidence. Nevertheless the centered



742.  To Bradley Monton, 9 April 2001

557

possibilities that he can tell by experience are actualised keep changing from one moment to the next. For you, it’s important that Fred’s mental clock is imprecise. That’s why his credence that the light is on doesn’t jump from zero to one, but rises gradually. OK, his updating is rough. But I don’t think that affects the distinction between change by updating and change by forgetting or by novelty. So I want to grant that Beauty gains new evidence when she’s awakened: the evidence that H1 ∨ T1 ∨ T2, which she didn’t have on Sunday when she was being told how the experiment would work. This new evidence isn’t new information in Adam’s sense. That is, it isn’t new uncentered evidence. It’s a change of centered evidence, and it’s a change by updating. She’s less capable of updating than most of us, because of the possible memory erasure. (And because, so far as I told the story, she wasn’t told just when the Monday and Tuesday awakenings were to be.) But she’s good enough at updating to go from ‘It will be that: H1 ∨ T1 ∨ T2’ to ‘(H1 ∨ T1 ∨ T2) & I remember being told that it would be that H1 ∨ T1 ∨ T2’. On this I take it that Adam and I agree. So the issue between us is whether it’s evidence relevant to HEADS versus TAILS. I haven’t thought about what this constant updating of centered evidence (without forgetting and without novel evidence) does to the Reflection Principle. I’d expect it to alter the letter of the Principle but leave the spirit unscathed. But that’s an affair I’d rather leave to Bas. Latest news: Adam will be joining us next fall. As will Hendrik Lorentz, in Classical Philosophy; and Hans Halvorson, in Philosophy of Physics. Yours, c: Adam, Bas

742.  To Bradley Monton, 9 April 2001 Princeton University Princeton, NJ Dear Brad, Beauty has not forgotten what day it is. True, she used to know that it was Sunday; and later she doesn’t, because it no longer is. But that’s not a loss of know­ ledge; it’s a loss of outdated ex-knowledge. The same is true of someone who’s functioning perfectly, and has an excellent mental clock (or access to an excellent external clock): when it’s no longer Sunday, one no longer believes that it is.

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There is indeed something Beauty is not doing. She isn’t updating her beliefs about what time it is in the way that a rational person under sufficiently favourable circumstances does. Nothing wrong with her rationality, of course. (Not at this point. The memory erasure comes later.) It’s just that the circumstances are unhelpful. She hasn’t retained the belief that it’s Sunday, as of course she shouldn’t have done. But had her circumstances been more favourable, as ours often but not always are, she would have been able to replace it with the correct updated belief that it’s Monday. As it was, she couldn’t. Bas does forget eating the croissant. Fred does forget what the clock read before he dropped it. Someone could forget where he was, or even who he was. But Beauty is a different case. The Reflection Principle as stated should not apply to having a belief about when it is. You should be certain that you will next year give credence very nearly 1 to the proposition that it’s 2002, but you ought now to give credence very nearly 0 to the proposition that it’s 2002. (If, as is in all probability true, favourable circumstances will permit you to update your beliefs.) Presumably the original Reflection Principle was never meant to apply to tensed propositions, and presumably there’s some correct generalization of the Principle. However, it had better not be a generalization that presupposes that everyone always must be in favourable circumstances to permit the updating of tensed beliefs. Your belief about who you are is like your non-indexical beliefs: it never needs updating because the truth stays always the same. Your beliefs about where you are are an intermediate case: they need updating only when you travel. (And again, circumstances may or may not permit correct updating.) Your beliefs about when it is, on the other hand, need constant updating. It’s an interesting question whether (in the case of an ideally rational and perfectly determinate thinker) changing your mind about when it is works by conditionalizing. I’m inclined to think that the part where you lose your outdated belief doesn’t, the part where you gain a new belief to replace it does. You constantly revert to your priors and conditionalize anew. Or put it this way: your many time-slices are alike in their priors, different in their total evidence. Your evidence might consist of a glance at the clock on the wall, or might be introspective evidence prominently including memory, or most likely some of each. Yours, c: Bas

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I NDEX OF TERMS AND NAMES ability hypothesis  xiv, 41, 160–1, 174; see also qualia aboutness 254 abstract entities, see abstractness abstraction operators  247, 255–6, 268 abstractness 44 accessibility relations  287, 302–3, 333, 363, 500–1, 502 accidental vs. lawlike generalisations, see lawlikeness Accommodation, Rule of  351 acquaintance: with mental states  40, 155–6, 159, 182–3, 213, 322 relations of  60, 81, 94–7, 106, 120–1, 124–5, 129, 132–3, 135–6, 137, 150, 151, 167, 179–81, 182–3, 206, 292, 296, 306 actions  392–3, 506–7 rational 393; see also decision theory unpredictability of  10–11 ‘actual’/‘actually’  22, 206, 316–17, 320–1 actualism, see worlds, ersatz actuality 274 Actuality, Rule of, see Rules of Actuality, Attention, Belief, Resemblance Adams, Ernest  xix, 407, 407 n. 2, 409, 410, 410 n. 1, 412, 439, 492, 494, 550–1 Adams, Robert Merrihew  97, 175 Adelson, Edward H.  116–17 admissibility, see evidence, admissible adverbs of quantification, see quantification, adverbs of Ajdukiewicz, Kazimierz  227–8, 233 alien properties  128, 131 aliens, space  160, 168; see also Martians Altham, J.E.J.  500 ambiguity  276, 298–9, 312–13, 314–15, 549 analyticity  xiii, xv, 15–16, 55, 63, 75, 84, 99–100, 127, 164–6, 217 anger at machines  169–70 Anscombe, G.E.M.  114, 114 n. 1, 495 anthropic explanations/principle/reasoning  132 anti-realism, see phenomenalism Åqvist, Lennart  283, 443 n. 3 Arló-Costa, Horacio  526 Armstrong, D.M.  xii–xiii, 23–5, 50, 50 n. 2, 52–3, 53 n. 2, 54, 54 n. 1, 77, 97, 99, 101, 110, 123, 145, 155, 160, 177, 199

artificial intelligence  5 assertability, see conditionals, assertability of Attention, Rule of, see Rules of Actuality, Attention, Belief, Resemblance attitudes de dicto/de re/de se, see beliefs de dicto/de re/ de se; propositional attitudes attributes  8–9, 12, 15, 26 Aumann, Robert  366, 457, 457 n. 2, 459–60, 459 n. 1 Austin, J.L.  5, 217, 218, 538 Ayer, A.J.  460 Bar-Hillel, Yehoshua  228 barns, bogus  516, 539–40 Bayesian confirmation theory/rationality  xix, 23, 395, 396; see also confirmation theory Bayes’ Theorem  386, 388, 389 Bealer, George  55, 55 n. 1, 203 behaviourism  xii, xiii, 37, 53, 57–9, 135, 154, 172, 194–5, 474 beliefs  123–5, 179, 358–9, 548–9, 550–1 compartmentalisation of  182, 533; see also beliefs, fragmentation of; doublethink; knowledge, compartmentalised de dicto/de re/de se  81–2, 87–8, 97, 104–8, 112–15, 124, 129, 133–4, 143, 149–52, 153, 161–2, 167, 179–81, 304, 452–3; see also acquaintance, relations of; propositional attitudes degrees of  385–6, 411; see also confirmation theory; credence; probability, subjective about desires  465–6; see also tickle defence fragmentation of  302, 429–30; see also fragmentation inconsistent, see beliefs, fragmentation of revision of, see conditionalising; confirmation theory see also content (mental); functionalism; identity theory of mind; propositional attitudes Belief, Rule of, see Rules of Actuality, Attention, Belief, Resemblance Belnap, Nuel  259, 283, 283 n. 1, 298, 300, 300 n. 1 Belzer, Marvin  324, 324 n. 1 Benacerraf, Paul  xx, 56, 120 Bennett, John G.  282, 443 n. 3 Bennett, Jonathan  xv, 218, 253 n. 1, 310 Bentham, Jeremy  495 Beth’s Theorem  281–2

574

Index of  Terms and Names

Bigelow, John  77, 84, 90, 91, 91 n. 1, 108, 125, 527, 527 n. 1 Black, Robert  532, 532 n. 1 Blackburn, Simon  138, 138 n. 1, 358, 368, 373, 378 Block, Ned  134–5, 134 n. 1, 144 Boër, Steven E.  87, 87 n. 1 Boghossian, Paul A.  145, 145 n. 2 Bohnert, H.G.  281, 281 n. 1 Boolos, George  356, 358 Braddon-Mitchell, David  xvi Bradley, M.C.  8, 12, 12 n. 1, 166 brain: processes  xii, 3, 53 states  xii–xiii, 3, 12, 57, 123, 135–6, 465; see also neural states see also functionalism; identity theory of mind brains in a vat  524–5 Brandom, Robert B.  301–2, 301 n. 1, 305, 317 Brooks, David  134, 134 n. 1 Broome, John  465, 508 Burge, Tyler  xvi, 268 n. 1 Burgess, John  297, 327–8, 463 Burnyeat, Myles  169 Campbell, Keith  20, 20 n. 1, 20 n. 2, 24–5, 160, 166 Carnap, Rudolf  xviii, 163, 214, 222–3, 225, 233, 237, 361–2, 361 n. 2, 362 n. 3, 363, 387, 394–5, 394 n. 2, 395 n. 4, 395 n. 5, 395 n. 6, 413 Carnap sentences  xvi, 223, 237; see also Ramsey sentences; theoretical roles/terms Cartwright, Richard  xx, 420, 486, 486 n. 1, 498, 498 n. 1 Castañeda, Hector-Neri  48 n. 2 causal: chains 79–80 dependence  80, 414–15, 418, 421, 428; see also causation, redundant processes, see causal chains relevance and efficacy  110–11, 144, 147; see also functionalism and causation/causal explanation roles  15–16, 20, 23–6, 28, 35, 37, 40, 41, 45, 46, 47, 51, 52–3, 57, 73, 98–9, 100, 123, 124, 136, 138, 145–7, 157–8, 174, 186, 241–2; see also colour; functional states; theoretical roles/ terms causation  111, 123, 275, 425 backward, see time travel counterfactual analysis of  16, 39, 414–15 as an intrinsic relation  98 mental 15–17; see also causation, redundant; functionalism and causation/causal explanation overdetermination, see causation, redundant pre-emption 80 programme vs. process, see functionalism and causation/causal explanation

redundant  172, 197–8, 204; see also causation, mental in vision, see experience, visual; vision Cavell, Stanley  217, 218 centering, see worlds, centred Chalmers, David J.  xv, 170, 170 n. 1, 171, 172, 175, 175 n. 4, 184, 190, 190 n. 1, 206, 209, 209 n. 1, 209 n. 2, 213–14, 213 n. 1 chance  80, 422, 434–7, 471–2; see also Principal Principle; probability, objective; probability as propensity Humean supervenience of  471–2, 491–2 Charity, Principle of  154 Chastain, Charles  245, 273, 292, 364 Cheng, Chung-ying  22, 22 n. 2, 237 n. 3 Chisholm, Roderick  148 Chomsky, Noam  9–10, 9 n. 4, 10 n. 5, 236, 236 n. 2, 269 Church, Alonzo  279 Churchland, Paul  152, 176 Clark, Ralph W.  319, 319 n. 1 closeness of worlds, see worlds, similarity of closest antecedent-worlds, see Limit Assumption Cohen, Stewart  xxi, 537, 537 n. 1 coin-tossing  411, 413, 423, 434, 436–7, 450, 478–9, 492, 552–3, 554 Collins, J.  451, 451–3, 463, 465, 468, 473, 492, 526–7 colours  7–9, 11–12, 15, 18–19, 20–1, 23–6, 28, 69–71, 76, 101, 103, 109, 145, 155–60, 161, 162–6, 177–8, 185–8, 197–8, 200–1, 204; see also identity of properties common knowledge  456–9 common sense/opinion  200–2 commonsense psychology  17, 18, 176; see also folk psychology community: linguistic  xv, xvi, 163, 165, 166, 270, 280, 375–6 of origin (of fiction)  317–18, 334, 335–6 scientific 119 comparatives  318, 319–23, 547 conceivability and possibility  41, 190–2, 208–9, 349 conceiving 345–50 conceptual: analysis  163, 381, 391 priority  88, 90, 95 Conditional Excluded Middle  309–10 conditionalising  396, 397–401, 402, 430–1, 551–4, 555–8; see also probability, ­conditional; rationality conditionals 492–4 assertability of  407, 409–10, 425–7, 437–9, 444, 492; see also conditionals, probabilities of counterfactual, see counterfactuals indicative 162



Index of  Terms and Names

probabilities of  397–401, 402–7, 410–11, 415–16, 437–9; see also conditionals, assertability of Conee, Earl  155–6, 155 n. 1 confirmation theory  xviii–xix, 23, 385–9, 394–5 consequentialism 494–8 content (mental)  xiii–xiv, 205 of attitudes, see propositional attitudes; beliefs de dicto/de re/de se fine-grained vs. coarse-grained  123–5 horizontal vs. diagonal, see semantics, two-dimensional narrow vs. broad/wide  112, 120–2, 124, 132–4, 161, 167; see also beliefs de dicto/de re/de se contradictions 487; see also fragmentation; impossibilities; logic, paraconsistent; worlds, impossible conventions  xv, 248–50, 251–2, 253–4, 270–2, 315, 365–7, 459 of truthfulness  221–2, 229–30, 243, 252–3, 270, 280, 353, 359 see also language and convention conversation  62, 129, 159, 198, 276, 343, 516, 517, 530–1, 535, 548 conversational implicature  122, 142, 230, 437 Cooper, John M.  187 coordination problems  xv, 253–4, 315, 365–7; see also conventions counterfactual dependence, see causal dependence counterfactuals  16, 62, 296–7, 354–5, 493–4 backtracking 493 chancy  493–4, 538–9 in decision theory, see decision theory, causal probabilistic, see counterfactuals, chancy vagueness of  309–10, 493 counterpart: relations  43, 230–1, 233–4 theory 27 credence  xix, 416–17, 422, 423, 425, 429, 436, 440, 452, 467–8, 471–2, 482, 520, 526–7, 532, 551–2, 554, 557, 558; see also beliefs, degrees of; Principal Principle; probability, subjective Cresswell, Max  104, 104 n. 1, 106–7, 112, 112 n. 1, 115, 125, 179, 205, 238–9, 297, 323 Currie, Gregory  332–4, 332 n. 1 Danto, Arthur C.  393, 393 n. 1 dark, seeing in the  84, 91 Davidson, Donald  xiii–xiv, 29, 29 n. 1, 63, 66, 128, 154, 162, 225, 226, 284–5, 379, 441–2 Davies, Martin  70–1 Davis, Lawrence H.  421 n. 2 decision, rational, see decision theory; rationality decision theory  xiv, xv, xix, 66–7, 162, 395, 423–4, 431–3, 445, 465, 466, 472–3, 507 causal  414–15, 418–21, 422–3, 424–5, 428, 434–7

575

evidential 453–4; see also tickle defence see also Newcomb’s problem; Prisoners’ Dilemma De Finetti, Bruno  394, 473 definite descriptions  8–9, 102, 134, 151, 237, 279, 349–50, 350–2 deliberation  441–3, 445, 448–9, 459, 464 De Marneffe, Peter  169 De Molina, Luis  309 demonstratives  68, 321–2 Dennett, Daniel  206 n. 2 denotation, see reference Denyer, Nicholas  500–1, 500 n. 1 deontic logic/modality/operators/sentences  230 n. *, 296, 301, 325–6; see also permission/ permissibility deontology 494–8 depravity 474 DeRose, Keith  xxi, 503 n. 1, 503 n. 2, 504, 504 n. 3, 517, 517 n. 1, 555, 555 n. 1 Descartes, René  148 de se attitudes, see beliefs de dicto/de re/de se; propositional attitudes desire 441–4 as belief  461–3, 465–8, 473, 508, 526–7 deterrence, nuclear  xv, 489–90 Devitt, Michael  xvi, 275, 275 n. 1, 364 diagonal content, see semantics, two-dimensional disjunctive syllogism  298, 300 dispositions  197–8, 204 Doomsday Argument  475–9, 481–6 double indexing  316–17 doublethink  182, 196, 538 dualism  15, 16–17, 99, 174; see also materialism; physicalism Dummett, Michael  202 Dunn, J. Michael  300, 300 n. 1 duplicates  125, 168 physical  98–9, 109, 128 worlds  60, 67, 95–7 Dutch books  xix, 399, 464 Eberhard, P.H.  309 Edgington, Dorothy  303, 492–4, 492 n. 1 Eells, Ellery  431–2, 431 n. 1, 431 n. 2, 445, 447–8, 447 n. 1 egocentricity  43, 97, 105–6, 107, 108, 121, 130–1, 132, 133, 153, 189, 207, 210, 311, 475–6, 495, 501, 522; see also beliefs de dicto/de re/de se; content, narrow vs. broad/wide; propositional attitudes Elga, Adam  551–3, 551 n. 1, 551 n. 2, 553–4, 553 n. 1, 557 Ellis, Brian  87, 89, 89 n. 1, 89 n. 2, 291, 406, 406 n. 2 Elugardo, Reinaldo  135–6, 135 n. 1 emotions  169–70, 303

576

Index of  Terms and Names

epiphenomenalism  14, 16, 39; see also qualia, epiphenomenal epistemology  xviii–xxi, 499, 505, 508–9, 510, 511–12, 513, 529, 555 contextualist xx–xxi; see also knowledge, contextualism about; knowledge as elimination of relevant alternatives ersatzism, see worlds, ersatz essences  9, 88, 132, 133, 144, 156, 173, 183, 229, 287, 387, 443, 524 essentialism  9, 88, 200, 247 ethics, see moral; morality Evans, Gareth  xvii–xviii, 71, 293–5, 293 n. 1, 338–9, 339 n. 2, 339–41, 342 events  29, 39 mental  38–9, 57; see also functionalism; identity theory of mind Everett, Hugh  19, 132, 192 evidence 541–2 admissible  440, 450–3, 526, 552–4 existence 272–3 expected utility, see decision theory experience  8, 12, 15, 29, 32, 122–3, 143–4 causal role of  15–17 phenomenal character of, see qualia visual  30–2, 194–5, 202–3, 205–6, 207–8, 523–4; see also vision explanation  80, 189–90, 193; see also functionalism and causation/causal explanation Farrell, Daniel M.  489–90, 489 n. 1, 490, 490 n. 1 Farrell, Robert  87 fear of slime  169–70 Feldman, Fred  533–4, 533 n. 1, 536 Fetzer, James H.  73 n. 1 fiction, see make-believe; truth in fiction fictional characters  272–3, 274–5, 282, 290, 318, 335 fictionalism, see moral fictionalism Field, Hartry  43–4, 43 n. 1, 123, 123 n. 1, 123 n. 2, 125, 278 Fine, Kit  256, 256 n. 1, 316, 316 n. 2, 501 n. 2, 548 Firth, Roderick  5, 5 n. 5, 31 Fisher, Ronald A.  415, 418 Fitch, Frederic  303 Fodor, Jerry A.  10, 17, 82 n. 1, 154, 154 n. 1, 224, 380 Fogelin, Robert  550 n. 1 folk: psychology xiii, 17–18, 36, 40, 52, 55, 77, 99–100, 134–5, 152, 157, 160, 164, 167–8, 176–7, 179, 428 psychophysics  157, 164–6, 201–2 Føllesdal, Dagfinn  200 n. 3 Foot, Philippa  433 Forbes, Graeme  352, 352 n. 1 Forrest, Peter  214 foundationalism 458–9

fragmentation  xvii, 288, 290, 299, 300, 301, 302–3, 304–5, 306, 317, 319, 323–4, 333; see also beliefs, compartmentalisation of; beliefs, fragmentation of; knowledge, compartmentalised; truth in fiction; logic, paraconsistent functionalism  xiii, xv, 34–41, 45–7, 49–59, 97, 99–100, 134–5, 172 and causation/causal explanation  138–9, 144, 146–8, 197–8, 199, 204 see also functional states; identity, psychophysical; identity theory of mind; theoretical roles/terms functional states  8, 12, 51, 122–3, 138–9, 172–3, 174, 199; see also colour; functionalism Gaifman, Haim  228 games/game theory  xv, 365–7, 424, 459–60, 479, 480–1, 507; see also decision theory; Prisoners’ Dilemma Gans, Carl  334–5 Gardner, Martin  119, 119 n. 1 Gauthier, David  490 Geach, Peter  227–8, 232, 255–6, 260, 368, 501 Gettier, Edmund  17, 17 n. 5, 505, 514, 524, 528–9, 537 Gettier cases  514–15, 524, 527–9, 537 Gibbard, Allan  415–16, 415 n. 1 Giere, R.N.  416–17, 417 n. 1, 422 n. 2 Gilbert, Margaret  xvi, 315, 315 n. 1, 459 God/gods 439–40; see also problem of evil Goodman, Nelson  4, 7, 7 n. 1, 9, 9 n. 4, 13, 187, 320, 387, 389 Graff (Fara), Delia  205 n. 1, 207, 207 n. 1 grammar  xi, xvi, 26, 226–9, 231, 239–40, 243–4, 246, 299, 358–9 Ajdukiewicz/categorial  227–8, 233 innate 9–10 Montague  227, 228, 254 transformational  74, 226, 227, 228–9, 230, 236, 254 Green, Josh  376 Grice, H.P.  5, 217, 218 Gricean effects/implicature, see conversational implicature grue  13, 386–7, 394 Gunderson, Keith  22, 224, 226 Hacking, Ian  115, 115 n. 1, 412 haecceitism  42–3, 60–2, 67, 77–8, 94, 96–7, 113–14 Hájek, Alan  483, 486, 526–7 Hall, Ned  526 hallucination  83, 212–13, 519, 523 Hardin, C.L.  126–7, 126 n. 1, 166 Harman, Gilbert  203, 262, 272, 376, 378, 460, 465 Harper, William L.  xix, 66, 379, 403, 403 n. 1, 405, 405 n. 1, 415, 415 n. 1, 447 n. 1 Harrison, Andrew  23, 81, 81 n. 1



Index of  Terms and Names

Harsanyi, John C.  456, 456 n. 1 Hart, W.D.  270 Hawthorne, John  xvi, 353, 358–9, 358 n. 1 Hazen, Allen P.  xvii–xviii, 47, 48 n. 2, 317, 339, 339 n. 3 Heil, John  199, 199 n. 1 Hellman, Geoffrey  235, 235 n. 2 Hempel, Carl G.  13, 23, 39, 395 Hetherington, Stephen  xx–xxi, 505, 505 n. 1, 509, 511, 511 n. 1, 511 n. 2 Hilbert, David  187, 187 n. 2 Hill, Christopher S.  175, 175 n. 1 Hinckfuss, I.C.  19, 19 n. 3 Hintikka, Jaakko  42, 94, 107, 113, 121, 231, 233, 362–3, 362 n. 4, 394–5, 394 n. 1 Hodgson, D.H.  250 holes 26 Horgan, Terence  xiv, 37–9, 37 n. 1, 122, 122 n. 2, 125, 125 n. 1, 127–8, 127 n. 1, 130, 197, 197 n. 1, 197 n. 2, 199, 199 n. 2, 336, 336 n. 1, 359, 359 n. 1, 445, 445 n. 3 Horwich, Paul  444–5, 444 n. 1 Humberstone, Lloyd, 70–1, 78, 302, 302 n. 1, 428, 437 n. 1, 502, 528, 528 n. 2 Hume, David  39 Humeanism and anti-Humeanism: about causation/laws  39, 123, 513, 526 n. * about induction  532 about motivation  461, 463, 466, 471–2, 508; see also desire as belief see also necessary connections; supervenience, Humean Hunter, Daniel  67, 424 hyperintensionality  205, 329 ‘I’  73, 151 identity 72 of bodies and persons, see personal identity contingent  5–6, 8, 12, 39, 54, 186, 245; see also identity of properties; identity of states of indiscernibles, see Leibniz’s Law mind-body, see materialism; physicalism of properties  25, 54, 69–72, 74–6, 101–4; see also colours; identity, psychophysical psychophysical  9, 38–40, 145; see also functionalism; identity theory of mind of states  8–9, 12 transworld 233–4; see also counterpart relations identity theory of mind  xii–xiii, 3, 14–15, 17, 29, 53, 160, 167–8 type-type  xiii, 34–6, 53, 98–100 see also functional states; functionalism; identity of properties; identity, psychophysical; identity of states ‘If I were you’, see McCawley sentence imaging  400, 402, 405, 434–5 imagining, see conceivability and possibility; conceiving

577

imperatives 235–6 implicature, see conversational implicature impossibilities  190–2, 200, 208–9, 233, 301–2 belief in  184–5, 196, 371 conceiving of, see conceivability and possibility wanting 184–5 see also impossible worlds incommensurability, see scientific theory-change indeterminacy: of interpretation  63–4, 65; see also indeterminacy of reference of reference  332 semantic  63–4, 65–6, 127–8 of translation  29 see also vagueness indeterminism 238; see also chance; probability, objective; probability as propensity indexicals  73–4, 499, 531; see also ‘actual’/‘actuality’; ‘I’; propositional attitudes indices  244, 256, 276, 280 induction  358, 388, 394, 550 justification of  532 new riddle of, see grue see also confirmation theory; logic, inductive intensional contexts  237–8, 240–1, 328–9 intensions, see semantics primary vs. secondary, see semantics, two-dimensional interpretation: indeterminacy of, see indeterminacy radical xiii–xiv introspection  14, 524 intuition, see common sense/opinion; linguistic intuition inverted spectra  37, 41 Ishiguro, Hidé  30–2, 30 n. 1 Jackson, Frank  66, 68–72, 68 n. 1, 70 n. 2, 70 n. 3, 74–5, 74 n. 1, 74 n. 2, 74 n. 3, 101–4, 101 n. 1, 108–11, 108 n. 1, 125–6, 138–9, 142, 146, 146 n. 1, 148, 155–6, 160, 163, 171, 175, 177–8, 177 n. 1, 184, 197–8, 197 n. 3, 197 n. 4, 204, 205, 205 n. 1, 206, 206 n. 1, 214, 331–2, 331 n. 3, 367–71, 367 n. 1, 423, 423–4, 425–8, 437, 437 n. 1, 441–3, 441 n. 1, 441 n. 2, 446, 446 n. 1, 461, 471, 471 n. 1, 481, 488–9, 493, 497, 498, 527 Jacobs, R.A.  236, 236 n. 2 Janssen-Lauret, Frederique  xix n. 2, 354 n. 2, 395 n. 3, 446 n. 2 Jaśkowski, Stanisław  305 Jeffrey, Richard C.  xviii, 225, 238, 238 n. 5, 310, 367, 388, 388 n. 4, 411, 413, 413 n. 2, 413 n. 3, 415, 415–16, 417, 420, 423, 425, 429, 431, 432, 445, 445 n. 2, 448, 463, 465, 469–70, 473, 494, 507 Jennings, Ray  305

578

Index of  Terms and Names

Johansson, Ingebrigt  299 Johnsen, Bredo  529–31, 529 n. 1 Johnston, Mark  90, 94, 97, 151, 160, 321, 323, 371, 376, 378, 379, 465, 495 justification  509–10, 511–13, 518, 530, 550–1 Kamp, Hans  239, 297 Kanger, Stig  363, 363 n. 6 Kaplan, David  48, 48 n. 3, 70–1, 77, 81, 371, 391 Katz, Jerrold A.  10, 152 Kavka, Gregory  429 Keenan, Edward L.  258, 258 n. 1, 261, 261 n. 1, 261 n. 2, 401 n. 4 Kim, Jaegwon  5, 39 Kitcher, Patricia  xiv, xvii, 45–7, 45 n. 1, 290, 290 n. 1, 292, 292 n. 2 Kitcher, Philip  xiii, xvii, 193, 290, 290 n. 1, 291–2, 291 n. 1, 310–13, 310 n. 1, 315 knowledge  195–6, 391–2, 513, 527–9 a priori  191, 195–6, 524–5 closure of  528–9 collective/dispersed 517–18 compartmentalised  517, 520–1, 522–3 contextualism about  xx–xxi, 551, 555 as elimination of relevant alternatives  488, 498–500, 504–6, 508–10, 513–25, 529–31, 537, 539–46 see also acquaintance; epistemology; justification; Rules of Actuality, Attention, Beliefs, Resemblance; scepticism knowledge argument  136–7; see also Mary, black-and-white; qualia Kochen, Simon  300 Kratzer, Angelika  62, 90, 164–5, 296, 296 n. 2, 428, 438 Kripke, Saul A.  xvii, 38, 38 n. 2, 54, 71, 75, 87–8, 120, 132, 132 n. 1, 159, 166, 173, 186–7, 200, 200 n. 1, 200 n. 2, 214, 263–4, 263 n. 2, 265, 266, 279–80, 282, 332, 360, 360 n. 1, 364–5 Krips, Henry  468–71, 468 n. 1 Kuhn, Thomas S.  7, 7 n. 2, 119, 310–13, 310 n. 1, 313 n. 2, 314–15, 314 n. 1 Kutschera, Franz  296, 410 n. 1 Kyburg, Henry E., Jr.  388, 388 n. 5 Lakatos, Imre  297 Lakoff, George  230–2, 230 n. 1, 232 n. 2, 232 n. 3, 233–4, 234 n. 1 Langton, Rae  494, 494 n. 1 language xv–xvi and convention  217, 220–2, 226–7, 229–30, 268–70, 328–30, 358–9, 369–70; see also coordination problems; conventions extensional vs. intensional  223 observational 292 of thought  44–5, 143, 162, 168, 173 see also pragmatics

Lavoisier, Antoine, 212, 311–12 lawlikeness 193 laws of nature  14, 19, 39, 98, 123, 513, 526 n. * Leibniz, Gottfried Wilhelm  214 Leibniz’s Law  294, 341 Lepore, Ernest  154 n. 1 Leslie, John  132, 475 n. 1 Levi, Isaac  455, 526 Lewis, D.K.: biographical information  4, 7, 17, 18, 54, 218–20, 238, 330 employment 236 intellectual  xii–xxi, 4, 7, 194, 200, 217 personal  18, 64 Lewis, Harry A.  254, 254 n. 1 Lewis, Stephanie R.  7, 18, 21, 22, 26, 26 n. 9, 29, 32, 47, 49, 54, 64, 65, 84, 87, 90, 113, 139, 200, 219, 222, 238, 239, 251, 279, 279 n. 1, 283, 283 n. 2, 288, 330, 354, 397, 402, 416, 674, 446 Limit Assumption  62, 286, 428 linguistic intuition  409, 427 Loar, Brian  191 Loewer, Barry  526 logic: inductive  385, 387; see also confirmation theory; induction modal  27, 200, 231, 257–8, 340 paraconsistent  xvii, 200, 297–302, 304–6, 327–8; see also fragmentation relevant  299–302, 305–6 logical space  42, 553 Lubow, Neil  xiii, 34–6, 34 n. 1 luminosity 541–6 Lumsden, David  42, 42 n. 1, 128–9 Lycan, William G.  87, 87 n. 1, 142–3, 142 n. 2, 144 MacBride, Fraser  xix n. 2, 354 n. 2, 395 n. 3, 446 n. 2 McCawley sentence  231, 234 McDermott, Michael  xiv McGinn, Colin xvii, 56–8, 56 n. 1 McKay, Thomas  120–2, 120 n. 1, 120 n. 2, 355–6, 355 n. *, 355 n. 1 Mackie, John  39, 357, 370 McManus, Denis  380, 380 n. 1 McMullen, Carolyn  128–31, 128 n. 1 mad pain  49–50, 52–3, 98–9 Mahoney, Michael S.  120 make-believe  169, 308, 317, 333, 371, 535 Martians  37, 50, 53, 86, 98, 135, 168 Mary, black-and-white  125–6, 130, 155–6, 160–1, 175, 182–4; see also qualia mass  44, 174 mass nouns  247–8, 239 materialism xii-xv, 5, 35, 45, 63, 98–9, 100–1, 128, 131, 142, 174, 181 type-B  xv, 191 see also dualism; physicalism



Index of  Terms and Names

mathematics  299–300, 305–6; see also numbers Maxwell, Grover  xvi, 224 n. 2 Meinong, Alexius  267, 341 Meinongianism  290, 341 Meinongian propositions  346–7, 349 Mellor, D.H.  429, 429 n. 1, 432, 432 n. 1, 479, 479 n. 2, 489 memory  32–3, 143–4, 171–2, 521–2, 541 mentalese  152, 168 mental states  xiii, 3; see also experience; events, mental; functionalism; identity theory of mind; qualia; sensations Menzies, Peter  479, 479 n. 1 Merricks, Trenton  513, 513 n. 1 Merrill, G.H.  263–4, 263 n. 1, 266 n. 1, 286–7, 286 n. 1, 287 n. 2 meta-ethics, see moral; morality meta-philosophy, see philosophical method metaphors  116, 117, 522, 555 metaphysics  19, 138, 148–9, 337, 357, 460 Michael, Michaelis  178, 359 Mill, John Stuart  39 Miller, David  413, 413 n. 1 Miller, S.R.  xvi, 328–9, 328 n. 1 modal actualism, see worlds, ersatz modality: de dicto/de re  25–6, 247, 263–4, 266; see also names knowledge of, see conceivability and possibility modal realism  97–9, 132; see also worlds Montague, Richard  xvi, 227, 227 n. 3, 228, 231, 236, 238, 238 n. 2, 238 n. 3, 247, 254, 363, 363 n. 5, 363 n. 1 Montgomery, Hugh  293, 340 moods of sentences  230, 236 Moore, G.E.  505 Moorean facts  201 moral: error theory  373–6 expressivism  367–71, 371–3 fictionalism  370–1, 374 quasi-realism 377–80 realism 379–80 reasons 374–8 subjectivism  373, 378 value/rightness  481, 488 morality  367–80, 433–4, 489–91, 535; see also consequentialism; deontology; moral; prescriptive judgements; utilitarianism; value folk 357 Moran, Richard  170 Morgenbesser, Sidney  388, 396 Morgenstern, Oskar  366, 366 n. 1, 473 Mortensen, Chris  299, 302 Morton, Adam  81 n. 1, 174 motion  138, 331–2 Müller, Anselm  114–15, 218

579

Nagel, Thomas  100, 109, 148, 351 names  48, 166, 186–7, 248, 263–4, 275–80, 360–3 proper  239, 244, 245–6, 264–6, 276–81, 306, 360–5 see also colours; reference; theoretical roles/terms Nash equilibria  365–7 natural kinds  178, 241 necessary connections  97, 181, 508; see also supervenience, Humean necessity 257–8; see also possibility negation 371–3 Nelson, David  299 Nemirow, Laurence  100–1, 100 n. 1, 101 n. 2, 122, 136–7, 156, 184 neural states  14–15, 50–1, 172, 197–8, 199, 549; see also brain; functionalism Newcomb’s Paradox, see Newcomb’s problem Newcomb’s problem  414, 415, 418, 420–2, 429, 430, 436, 447–8, 453–6 Nicod’s criterion/rule  385, 388 Nola, Robert  xvi Nolan, Daniel  xviii, 376, 376 n. 5 Normore, Calvin  309–10, 310 Nozick, Robert  420, 420 n. 1 nuclear arms race/deterrence  4, 489–91 numbers  26, 44, 74, 360 Nute, Donald  73, 73 n. 1 Oakley, Tim  80, 88, 551 Oddie, Graham  479, 479 n. 1, 481, 526–7, 526 n. 1, 526 n. 2 O’Grady, Jane  xii ontological commitment  58, 273, 274 opinion, see common sense/opinion Oppenheim, Paul  xiii, 189–90, 189 n. 1, 193 Oppenheimer, Paul  118, 120 Over, David E.  339–41, 339 n. 1 overdetermination, see causation, redundant pain  xiii, 3, 9, 15, 17, 35, 36, 38–40, 41, 44, 45–7, 49–50, 51–5, 57, 75, 98–100, 101, 102, 104, 108–9, 124, 138, 186–7, 199; see also functionalism; identity theory of mind Paradox of the Stone  389–90 Parfit, Derek  148 Pargetter, Robert  101–4, 101 n. 1, 160, 197–8, 197 n. 3, 204, 331–2, 331 n. 3 parsimony, ontological  xiii Parsons, Terence  xvi, 226, 226 n. 1, 227–8, 231, 234, 234 n. 1, 267, 267 n. 1 Partee, Barbara  xvi, 231, 254, 258, 261 Paul, L.A.  204 Peacocke, Christopher  80, 80 n. 2, 86, 86 n. 2 Pelletier, F. Jeffry  247–8 perception, see experience; vision percepts 207–8 performatives 235

580

Index of  Terms and Names

permissibility/permission 324–6 Perry, John  xiv, 42, 42 n. 1, 47, 72, 88, 130 personal identity  5–6, 22, 148–52 Peters, P. Stanley  236, 236 n. 1, 269 Peterson, Sandra  225, 395 Pettit, Philip  138, 146, 146 n. 1, 160, 163, 367–71, 367 n. 1, 465, 466–8, 466 n. 1, 489, 497, 497 n. 1 phenomenal information  142; see also qualia phenomenalism  57–9, 474 philosophical method  xvi–xvii, xx, 13, 34, 127, 341, 380–1, 486–8, 489–90, 500, 555; see also common sense/opinion; conceptual analysis phlogiston  225, 239, 291–2, 311–14, 373–4, 378 physicalism  75, 108–10; see also materialism; qualia physics  63–4, 65–6, 108, 110, 131, 138, 305; see also quantum mechanics Plantinga, Alvin  214, 246, 246 n. 1, 248, 309, 347–8, 348 n. 2 platitudes  35, 40, 99–100, 154, 163, 164 Pollock, John L.  416, 438 Popper, Karl  395, 413 population, see community possibilia  26, 97–8, 109–10 possibilities de se 524 possibility 191–2 combinatorial 174 epistemic  75, 214, 503–4 logical 75 metaphysical 75 possible worlds, see modal realism; worlds Postal, Paul M.  236 pragmatics  159, 166, 283, 354, 408, 409, 493, 535; see also conversation; conversational implicature prediction  389–90, 447–8 of actions  10–11 see also confirmation theory pre-emption 80 prescriptive judgements  370 Price, Huw  467 Priest, Graham  xx, 122, 190, 191, 191 n. 1, 196, 200, 209, 297–9, 297 n. 1, 327–8, 327 n. 1, 328 n. 3, 345–7, 345 n. 1, 347–8, 348–50, 371, 487 Priestley, Joseph  311–13, 14 primary/secondary: content, see semantics, two-dimensional qualities, see qualities, primary/secondary Principal Principle  xix, 411–13, 416–17, 422, 439–40, 449–53, 525–6, 532, 552–3 principle of indifference  387, 394, 449–50, 451, 471–2, 551–3, 554 Prior, A.N.  101–4, 101 n. 1, 197–8, 197 n. 3, 204, 254, 501, 501 n. 2 priority, conceptual, see conceptual priority Prisoners’ Dilemma  420–1, 453–6 probability  xix, 237–8, 406–7, 468–71

axioms of  396, 406 conditional  397–401, 403–7; see also conditionalising; conditionals, assertability of of conditionals, see conditionals, probabilities of as frequency  411 objective  411–12, 469–70 prior/antecedent  386–7, 388–9, 518 as propensity  411, 416 semantics  400–1, 402–7 subjective  411, 469–70 see also beliefs, degrees of; chance; credence; Principal Principle problem of evil  341 projectibility  10, 387, 391 properties 26 abundant and sparse  102 alien, see alien properties as classes, see properties, nominalism about differential  387, 389, 391; see also properties, natural disjunctive  20–1, 23, 24, 53, 197–8 essential and accidental, see essences; essentialism haecceistic, see haecceitism identity of, see identity of properties intrinsic and extrinsic  24–5, 98, 122–3 natural  128, 198, 388 nominalism about  24, 102, 199 projectible, see projectibility; properties, differential as tropes, see tropes as universals, see universals see also attributes propositional attitudes  xiv, 42–5, 48–9, 60–2, 64, 67–8, 73–4, 77, 89, 104–8, 123–5, 129–31, 132–4, 135–6, 153, 233; see also acquaintance, relations of; beliefs de dicto/ de re/de se propositions  43–5, 48 n. 2, 61–2, 67–8, 73–4, 90, 133–4, 451–3 egocentric, see egocentricity see also propositional attitudes, statements prosthetic eyes, see vision, prosthetic psychology, folk/commonsense, see folk psychology psychophysical identifications, see identity theory of mind psychophysics, folk, see folk psychophysics Putnam, Hilary  xiii, 4, 5, 8–10, 9 n. 4, 12, 12 n. 2, 57, 161, 167, 172–3, 189–90, 189 n. 1, 193, 218, 219, 220, 239, 332, 396 qualia  14, 36–7, 40, 45–7, 100–1, 128, 142, 159, 170–2, 175, 181–4 epiphenomenal  108–11, 136–7 see also ability hypothesis; experience, phenomenal character of; Mary, black-andwhite; Vegemite, taste of



Index of  Terms and Names

qualities, primary/secondary  7, 8, 12, 14, 18–19, 28, 161, 163, 177, 185–6 quantification: adverbs of  257, 258–61, 262–3, 401 plural  355–6, 357–8 tensed 257 quantum mechanics  422 Everettian/no-collapse interpretation of  19, 132, 192 Quester, George  491 quidditism 174 Quine, W.V.  xv, 4, 7, 9, 25–6, 29, 43, 43 n. 3, 62, 66, 97, 200, 201, 225, 228, 232, 337–8, 341 Quinn, Warren  443 Rabinowicz, Wlodek  xix, 434–7, 434 n. 1 Ramsey, F.P.  58, 163, 292, 473 Ramsey sentences  xiii, xvi–xvii, 13, 17–18, 58, 134, 223, 357; see also Carnap sentences; theoretical roles/terms rationality  xix, 162, 167, 196, 315, 396, 407–8, 431–2, 433–4, 445, 446, 448–9, 449–50, 465, 489 ideal  195–6, 271, 396, 429, 430, 431, 433, 445, 452, 457, 458–9, 464–5, 489, 558 see also conditionalizing; decision theory realism and anti-realism, see phenomenalism; reductionism reasons  374–8, 472–3 Recombination, Principle of  191–2; see also worlds, cardinality of reductionism  14, 15, 189–90, 192–3, 224, 226 reference  243–4, 245, 246, 284–6; see also indeterminacy of reference; names; semantics, referential; theoretical roles/terms Reichenbach, Hans  xviii, 395 Reid, Jasper  207 Reimer, Marga  350–2, 350 n. 1, 352 relations 44–5; see also properties representation, mental  43–5 Rescher, Nicholas  301–2, 301 n. 1, 305, 317 resemblance, see similarity Resemblance, Rule of, see Rules of Actuality, Attention, Belief, Resemblance Restall, Greg  376, 376 n. 5 Rey, Georges  172–3, 172 n. 1, 173 n. 2 Richardson, Jane Shelby  10, 10 n. 2, 460 Richter, Reed  67, 424, 446, 460 Richter’s problem  446, 459–60 Rieber, Steven  545 rigid designators, see identity of properties; names Ritchie, R.W.  236, 236 n. 1 Robb, David  198, 198 n. 3, 199, 199 n. 3, 204 Robinson, Denis  481, 483, 486 role occupancy, see functionalism; theoretical roles/terms Rosen, Gideon  371 Rosenbaum, P.S.  236, 236 n. 2

581

Rosenberg, Alexander  491, 491 n. 1 Routley (Sylvan), Richard  293, 299, 327, 327 n. 1, 327 n. 2, 340 Rovane, Carol  148–9, 148 n. 1, 152, 152 n. 1 Rules of Actuality, Attention, Belief, Resemblance  514–16, 518, 520, 525, 537, 539–40 Russell, Bertrand  225, 237, 261, 341 Sainsbury, R.M.  338–9, 338 n. 1 Sartorius, Rolf  xvi, 248–50, 248 n. 1 Savage, C. Wade  390, 390 n. 2, 473, 506 scepticism  xx, 359, 392, 488, 498–500, 505, 508–9, 524–5, 529–31, 539–41, 550–1 inductive 487 Scheffler, Israel  xvi, 4, 58, 58 n. 1, 218, 388 Schelling, Thomas C.  xv, 219 n. 2, 315 Schaffer, Jonathan  548 Schiffer, Stephen  229, 252, 353, 358, 456 Schilpp, Paul A.  4, 4 n. 4, 362 Schotch, Peter  305 Schuyler, William M., Jr.  272–3, 274 n. 1 Sciama, Dennis W.  132 science, unity/disunity of xiii, 19, 189–90, 192–3 scientific method  34, 118–19, 126–7 theories  14, 15 theory-change  291–2, 310–15 Scott, Dana  237, 237 n. 4, 257, 257 n. 2 Scriven, Michael A.  4, 10–11, 10 n. 7, 389–90, 389 n. 1 Seager, William  175 secondary qualities, see qualities, primary/ secondary seeing-as 30–2 Segerberg, Krister  506, 506 n. 1 Sellars, Wilfrid  17 semantics  226–9, 239–46, 246–8, 254–63, 306–7 contextualist  533–6, 538–9, 555 possible-world 230–4 referential  220–1, 226–7, 351; see also grammar; reference two-dimensional  36, 61, 68, 71, 77, 191, 195, 205, 206–7, 209–12, 214 sensations  15–16, 28, 37; see also experience; qualia sense data  5 Shaffer, Jerome A.  xii, 3, 3 n. 1, 4, 4 n. 2, 5–6, 5 n. 6, 6 n. 7, 6 n. 8, 15 n. 1, 231 Shimony, Abner  19, 385, 387 Shoemaker, Sydney  6, 36–7, 36 n. 1, 97–100, 97 n. 1 similarity 188; see also properties; tropes; universals of counterparts, see counterpart relations of worlds, see worlds, similarity of Simon, Herbert  118 Skinner, B.F.  10

582

Index of  Terms and Names

Skyrms, Brian  132, 366, 415, 418–20, 418 n. 1, 422–3, 422 n. 1, 429, 444, 448, 460, 460 n. 2, 465, 469 Sleeping Beauty problem  551–4, 555–8 Sleigh, Robert C., Jr.  389 Slote, Michael A.  229, 385, 385 n. 1, 387, 387 n. 3 Smart, J.J.C.  xii–xiii, 19, 19 n. 1, 20–1, 22–6, 22 n. 6, 23 n. 7, 29, 54, 58, 58 n. 3, 63–4, 63 n. 1, 65 n. 1, 66, 156–7, 156 n. 1, 161 n. 1, 162–3, 162 n. 1, 249, 249 n. 2, 313 n. 2, 330 Smith, Michael  162–6, 373, 465, 466–8, 466 n. 1, 498 Smokler, Howard E.  388 Soames, Scott  365 Sobel, Jordan Howard  434–7, 453–6, 453 n. 1 Sonnenschein, Hugo  456, 459 Sosa, David  364–5, 364 n. 1 Sosa, Ernest  178 space, logical, see logical space spacetime, branching  139–41; see also quantum mechanics, Everettian/no-collapse interpretation of Stalnaker, Robert C.  xiv, xix, 43, 65, 70, 77, 77 n. 1, 93–7, 104, 112, 132, 132 n. 4, 184–5, 206, 210, 214, 247, 289, 297, 326, 397–401, 397 n. 1, 402–3, 403 n. 1, 404–5, 407, 414–15, 415–16, 430, 438, 443, 471, 471 n. 3, 504, 523, 553 Stapp, Henry  309 states of affairs  204, 213, 214, 304, 443 Stegmüller, Wolfgang  394, 394 n. 1 Stenius, Erik  226–7 Sterelny, Kim  108–11 Stoutland, Frederick  393, 393 n. 1 Strawson, P.F.  550 Strevens, Michael  525–6, 525 n. 1 Stroud, Barry  xxi, 29, 509, 509–10, 509 n. 1 supervenience  108, 125, 127–8, 171, 181, 189, 199, 205, 370, 425 Humean  513, 526 n. *; see also chance, Humean supervenience of survival, see personal identity Talbott, William J.  448, 448 n. 1 Tappenden, James  463 Tarski, Alfred  220 Teller, Paul  xix, 131, 131 n. 1, 156, 156 n. 2 temporal parts  5–6, 149–52, 555–6; see also personal identity; time travel tense operators  257 Thau, Michael  526 theoretical: entities 222–3 roles/terms xi-xvii, 55–6, 57–9, 157–60, 192–3, 222–6, 237–8, 241–3, 244–5, 250–1, 281–2, 291–2, 313, 315; see also colours; ­functionalism; Ramsey sentences

virtues 13; see also philosophical method Thomason, Neil  207 Thomason, Richmond  247, 318, 397, 444 thought experiments  66, 419–20 tickle defence  419–20, 429, 430–1, 445, 449 time travel  139–41 Tooley, Michael  203–4, 203 n. 1 topic-neutrality  xii–xiii, 17–18, 57, 76 trains  49, 74, 113, 188 triviality results  410, 471 tropes  198, 199, 204 truth  221, 378–9, 548 bearers  89–90, 89 n. 2 in fiction  xvii, 267–8, 286–7, 288–90, 307–8, 317–19, 323–4, 332–6, 370–1; see also community of origin; fragmentation -telling, see conventions of truthfulness truthlikeness 502–3 truthmakers  133–4, 146, 147, 356, 402, 505 truth-value gaps  165, 298, 319 Twin Earth  161; see also XYZ underdetermination of theories by evidence  63–4, 65 Unger, Peter  xx, 17, 17 n. 4, 36, 391–2, 391 n. 1, 392 n. 2, 505, 505 n. 2, 531, 533–6, 534 n. 3, 535 n. 4, 539 universals  29, 53, 57, 97, 110, 128, 199 utilitarianism  184, 249 vagueness  xvii–xviii, 164–5, 308–9, 359–60 higher-order 547–8 of identity  293–5, 338–9, 342–4 of objects  293–5, 337–44 supervaluationism about  197, 331–2, 359, 542–9 see also counterfactuals, vagueness of value/valuing  443–4, 473–4, 479–81, 488–9, 494–8 Vanderschraaf, Peter  365, 366 van Fraassen, Bas  309–10, 331, 444, 448, 464, 464 n. 1, 557, 558 van Inwagen, Peter  290–1, 290 n. 2 Vegemite, taste of  136–7, 143–4, 155–6, 173 Velikovsky, Immanuel  13, 13 n. 1 Velleman, David  145, 145 n. 2 velocity, see motion Veltman, Frank  66, 296–7 verificationism 63 verisimilitude  100, 289 Vermazen, Bruce  226 vision  84–7, 91–3, 115–17 censored  78–80, 82–5 objects of  212–13 prosthetic  78, 85, 116 see also experience, visual



Index of  Terms and Names

Vogel, Jonathan  522, 522 n. 1 von Neumann, John  366, 366 n. 1, 473 von Stechow, Arnim  104, 104 n. 1, 106–7, 112, 112 n. 1, 113–15, 125, 316, 316 n. 1, 323, 323 n. 1 Walton, Kendall  xvii, 169, 169 n. 1, 290, 290 n. 2, 317 West, Caroline  376, 376 n. 5 Wheeler, John  19, 19 n. 2, 132 ‘whether’ 283–4 Williams, Donald C.  xii, 4, 7, 14–15, 14 n. 2 Williamson, Timothy  xviii, 542–8, 542 n. 1, 542 n. 2, 546 n. 3 Wilson, N.L.  25, 25 n. 8 Winnie, John  222, 222 n. 1, 222 n. 2, 223, 223 n. 1, 244–5 Wittgenstein, Ludwig  217, 218 world-bound individuals, see counterpart relations; counterpart theory worlds  22, 214, 233 branching 274 cardinality of  47

583

centred  43, 67, 94–5, 97, 205, 210, 214, 296, 297, 434–5, 443, 471, 551–2, 553, 554, 555–7 closeness of, see worlds, similarity of as concrete entities  78 duplicate, see duplicate worlds ersatz 233 impossible  233, 288; see also impossibilities indiscernible, see haecceitism knowledge of, see modality, knowledge of similarity of  16, 354–5, 443–4; see also counterfactuals spheres of  469–70; see also accessibility relations see also modal realism; semantics, ­ possible-world XYZ  167, 206–7 Zaragoza, Kevin  368 zombies  40, 170–2, 182

I NDEX OF LEWIS’S WORK S CI TED ‘Adverbs of Quantification’  263 n. 3, 401, 401 n. 4 ‘Analog and Digital’  234–5, 234 n. 1 ‘An Argument for the Identity Theory’  xii–xiii, 14, 14 n. 2, 20, 29, 29 n. 3, 35, 170, 170 n. 2, 178 ‘Are We Free to Break the Laws?’  145, 145 n. 1 ‘Attitudes De Dicto and De Se’  xiv, 47, 47 n. 3, 60–2, 60 n. 1, 64, 66, 66 n. 1, 73, 73 n. 2, 89 n. 1, 104–6, 104 n. 2, 120–1, 120 n. 3, 124, 132, 132 n. 2, 149, 296, 475, 475 n. 2, 555 ‘Buy Like a MADman, Use Like a NUT’  490, 490 n. 3

‘How to Define Theoretical Terms’  xiii, xvi, 22, 22 n. 3, 28, 28 n. 2, 35, 39, 39 n. 3, 56, 58, 178, 224–5, 224 n. 1, 237, 237 n. 2, 239, 239 n. 1, 243, 244, 281, 360–1, 373, 373 n. 3 ‘Humean Supervenience Debugged’  525, 525 n. 2, 532 n. 2, 552 ‘Illusory Innocence’ (Review of Peter Unger, Living High and Letting Die)  533, 533 n. 2 ‘Index, Context and Content’  77, 77 n. 2, 178 ‘Individuation by Acquaintance and by Stipulation’  94, 94 n. 1, 142, 524

‘Causal Decision Theory’  xix, 310 n. 1, 415, 415 n. 1, 430, 432, 449 ‘Causation’ 415 ‘Causal Explanation’  144 Convention: A Philosophical Study  xv–xvi, 18, 18 n. 2, 22, 22 n. 5, 219. 219 n. 1, 220, 226 n. 2, 227, 236, 248–9, 269–70, 329, 366, 369, 395, 459 Conventions of Language (dissertation)  xv, 17, 385, 385 n. 2 ‘Could a Time Traveler Change the Past?’  243 ‘Counterfactual Dependence and Time’s Arrow’  354, 412, 412 n. 3, 421, 421 n. 3, 445, 445 n. 4 Counterfactuals  xvii, 274, 282, 297, 351–2, 443, 501 ‘Counterfactuals and Comparative Possibility’  316, 416, 468 ‘Counterpart Theory and Quantified Modal Logic’  22, 22 n. 4, 27, 27 n. 1, 28–9, 200

‘Languages and Language’  xv–xvi, 152, 152 n. 2, 227, 227 n. 2, 229–30, 229 n. 1, 242–3, 269–70, 277, 329 ‘Logic for Equivocators’  301, 301 n. 2, 306, 306 n. 1, 317, 429–30, 431, 546

‘Desire as Belief’  461, 461 n. 1, 465, 508 ‘Devil’s Bargain’s and the Real World’  489, 489 n. 2 ‘Dispositional Theories of Value’  356, 356 n. 1, 373, 373 n. 2, 473

‘On Causality and Natural Laws’  16, 16 n. 2 On the Plurality of Worlds  136, 174, 330, 330 n. 2, 344 ‘Ordering Semantics and Premise Semantics for Counterfactuals’  62 n. 2, 66 n. 2, 90, 90 n. 3, 296, 296 n. 1, 428, 428 n. 1

‘Elusive Knowledge’  xx–xxi, 504–5, 513–14, 513 n. 1, 517, 517 n. 2, 519–21, 529, 535, 541–2, 550 ‘Events’  144, 204 ‘Finite Counterforce’  490, 490 n. 2 ‘Finkish Dispositions’  198, 198 n. 6 ‘General Semantics’  xvi, 73–4, 152, 152 n. 1, 238, 238 n. 1, 242–3, 246, 254–5, 279, 279 n. 2, 306 ‘Holes’ (with S. Lewis)  26, 26 n. 9, 248 ‘How Many Lives has Schrödinger’s Cat?  191 n. 2

‘Mad Pain and Martian Pain’  47, 47 n. 2, 51–3, 51 n. 1 ‘Many but Almost One’  xviii ‘Meaning and Convention’  217 ‘Meaning Without Use: Reply to Hawthorne’  353, 353 n. 1 ‘The Monty Hall Problem’  354, 354 n. 2 ‘Naming the Colours’  77 n. 5, 145 n. 4, 160 n. 2, 161, 185, 185 n. 1, 197, 204 ‘New Work for a Theory of Universals’  125, 125 n. 2, 128, 132, 136

Papers in Metaphysics and Epistemology  395 n. 1, 547, 547 n. 5 Papers in Philosophical Logic  546, 546 n. 4 ‘Percepts and Color Mosaics in Visual Experience’  30, 30 n. 2 Philosophical Papers I  xx, 122, 123, 136, 149, 178, 317, 317 n. 1, 332 n. 2, 488, 488 n. 2 Philosophical Papers II  144, 149, 178, 204, 330, 330 n. 1, 354, 468, 470, 470 n. 2, 491, 491 n. 2, 504 ‘Postscripts to “Mad Pain and Martian Pain” ’  122



Index of Lewis’s Works Cited

‘Postscripts to “Truth in Fiction” ’  317–18, 317 n. 1, 332 n. 2 ‘Probabilities of Conditionals and Conditional Probabilities’  xix, 47, 47 n. 1, 406, 406 n. 1, 410–11, 410 n. 2, 461, 461 n. 2 ‘A Problem about Permission’  324 n. 2 ‘Psychophysical and Theoretical Identifications’  xiii, 22, 22 n. 1, 35, 39 n. 3, 56, 145, 145 n. 3, 152, 162, 176, 178, 237, 237 n. 1, 250, 250 n. 1

585

‘Should a Materialist Believe in Qualia?’  170, 170 n. 3, 175, 175 n. 2 ‘Sleeping Beauty: Reply to Elga’  554 n. 2 ‘A Subjectivist’s Guide to Objective Chance’  xix, 417 n. 2, 422, 422 n. 1, 425, 425 n. 1, 436, 436 n. 2, 452, 469–70 ‘Survival and Identity’  149 ‘Truth in Fiction’  xvii, 282, 282 n. 1, 289, 290, 290 n. 1, 317, 332, 334–6

‘Quasi-Realism is Fictionalism’  374 n. 4 ‘Radical Interpretation’  xiii-xiv, xv, 29 n. 2, 63, 63 n. 2, 63 n. 3, 65 n. 1, 136, 154 ‘Reduction of Mind’  xiv, 161, 161 n. 1, 164, 173, 174, 177, 177 n. 1 ‘Relevant Implication’  344, 344 n. 1 ‘Review of Olson and Paul, Contemporary Philosophy in Scandinavia’ (with Stephanie R. Lewis)  279, 279 n. 1, 283, 283 n. 2 ‘Richter’s Problem’  446 n. 2 ‘Scriven on Human Unpredictability’ (with Jane Shelby Richardson)  10 n. 6, 460 ‘Scorekeeping in a Language Game’  xx, 326, 352, 354, 354 n. 1, 488, 505, 517, 517 n. 3

‘Utilitarianism and Truthfulness’  250, 250 n. 3 ‘Vague Identity: Evans Misunderstood’  xvii-xviii, 295 n. 2 ‘Veridical Hallucination and Prosthetic Vision’  78, 78 n. 1, 84, 84 n. 1, 116, 116 n. 2 ‘What Experience Teaches’  xiv, 100–1, 122, 122 n. 1, 136, 236 n. 1, 141–2 ‘What Puzzling Pierre Does Not Believe’  132, 132 n. 3 ‘ “Whether” Report’  283–4, 283 n. 3 ‘Why Conditionalize?’  xix, 395 ‘The World Turned Upside Down’  194

I NDEX OF RECIPIEN TS Adams, Ernest  406–7, 410–12, 412–13 Adams, Robert  176–7 Armstrong, D.M.  51–4, 101–4, 185–8 Aumann, Robert  456–9 Austin, David  132–4 Bealer, George  55–6 Belnap, Nuel  283–4 Belzer, Marvin  324–6 Benacerraf, Paul  498–500 Bennett, Jonathan  251–3, 253–4 Bigelow, John  84–7, 91–3, 527–9 Black, Robert  532 Blackburn, Simon  138–9, 378–80 Block, Ned  144, 160–1, 167–8 Boër, Steven E.  87–8 Brandom, Robert B.  301–2 Brooks, David  134–5 Burge, Tyler  268–70, 270–2 Burnyeat, Myles  169–70 Campbell, Keith  20–1 Carwright, Richard  486–8 Chalmers, David J.  170–2, 174, 179–81, 181–3, 190–1, 191–2, 195–6, 208–9, 209–10, 210–11, 211–12, 213–14 Cohen, Stewart  513–16, 524–5, 537 Conee, Earl  155–6 Craig, W.L.  153 Cresswell, Max  104–7, 112–13, 353–4 Currie, Gregory  332–4 Davidson, Donald  29–30, 32–3 Davis, Lawrence H.  420–1 de Marneffe, Peter  169–70 Dennett, Daniel  152, 205–6 Denyer, Nicholas  500–1, 502–3 DeRose, Keith  503–4, 519–21, 538–9, 555 Devitt, Michael  275–8, 279–81 Dreier, Jamie  184–5 Driver, Julia  317–18, 319, 323–4 Dunn, J. Michael  297–9 Eells, Ellery  431–2, 447–8 Edgington, Dorothy  492–4 Elga, Adam  551–3, 553–4 Ellis, Brian  89–90 Elugardo, Reinaldo  135–6

Farrell, Daniel M.  489–90, 490–1 Feldman, Fred  533–6 Field, Hartry  43–5 Fine, Kit  256–8 Fodor, Jerry A.  82, 154 Fogelin, Robert  550–1 Forbes, Graeme  352 Gibbard, Allan  414–15, 428–9 Giere, R.N.  416–17, 422 Gilbert, Margaret  315 Goodman, Nelson  234–5 Gorman, Jonathan  451–3 Graff, Delia  202–3, 207–8 Hacking, Ian  115–16 Harper, William L.  402–3, 403–5 Hawthorne, John  358–9 Hazen, Allen P.  47–9, 200–2, 293–5, 299–300, 446 Heil, John  199 Hetherington, Stephen  504–6, 508–9, 511–13 Hill, Christopher S.  175 Horgan, Terence  37–9, 39–40, 41, 122–3, 125–6, 127–8, 197–8, 334–6, 336–8, 359–60 Horwich, Paul  444–5 Humbertstone, Lloyd  302–3 Ishiguro, Hidé  30–2 Jackson, Frank  68–72, 74–7, 78–80, 82–4, 108–11, 123–5, 136–7, 146–7, 177–8, 205, 206–7, 330–2, 357, 367–71, 437–9, 441–4, 444, 449–51, 451–3, 461–3, 471–2 Jeffrey, Richard  394–5, 407–8 Johnsen, Bredo  529–31, 539–41 Johnston, Mark  212–13 Joyce, Richard  373–6, 377–8 Kaplan, David  371–3 Kavka, Gregory  423–4 Keenan, Edward L.  258–61, 261–3 Kissling, Henry W.  34 Kitcher, Patricia  45–7, 54–5, 118–20, 288 Kitcher, Philip  118–20, 188–90, 192–3, 288, 291–2, 310–13 Kratzer, Angelika  296–7 Kripke, Saul  284–6, 309–10, 310 Krips, Henry  468–71



Index of Recipients

Kuhn, Thomas  310–13, 314–15 Kutschera, Franz  408–10 Lakoff, George  230–3 Lamarque, Peter  289–90 Leslie, John  475–9, 481–3, 483–6 Lewis, Harry A.  254–6 Lubow, Neil  34–6 Lycan, William G.  49–51, 87–8, 139–43, 183–4, 306–7 Maxwell, Grover  223–4 McDermott, Michael  161–2, 167, 508 McGinn, Colin  56–9 McKay, Thomas  120–2, 355–6, 357–8 McManus, Denis  380–1 McMullen, Carolyn  128–31 Mellor, D.H.  429–31, 432–4, 479–81 Merricks, Trenton  513 Merrill, G.H.  263–4, 265, 266, 286–7 Miller, S.R.  328–30 Mondadori, Fabrizio  239–41, 241–3, 243–5, 245–6 Montague, Richard  238–9 Monton, Bradley  555–7, 557–8 Morton, Adam  81 Nemirow, Laurence  100–1, 143–4 Nola, Robert  517–18 Normore, Calvin  439–40 Nute, Donald  73–4 Oddie, Graham  488–9, 526–7 Over, David E.  339–41, 344 Parsons, Terence  226–7, 227–30, 233–4, 267–8 Partee, Barbara  235–6 Pelletier, F. Jeffry  246–8, 308–9 Perry, John  42–3 Pettit, Philip  146–7, 147–8, 367–71, 461–3, 466–8, 494–7, 497–8 Pigden, Charles  473–4 Pollock, John  425–8 Price, Huw  465–6 Priest, Graham  327–8, 345–7, 347–8, 348–50 Quine, W.V.  217, 218, 219, 220–1, 221–2 Rabinowicz, Wlodek  434–7 Rainer, Valina  123–5 Reimer, Marga  350–2

587

Rescher, Nicholas  301–2 Rey, Georges  172–3 Richardson, Jane Shelby  389–90 Rosenberg, Alexander  491–2 Rovane, Carol  148–9, 149–52 Sainsbury, R.M.  338–9, 342–3 Sartorius, Rolf  248–50 Schelling, Thomas  219–20 Schuyler, William M. Jr.  272–3, 274–5 Segerberg, Krister  506–7 Shaffer, Jerome A.  3–4, 4–6, 15–17 Shoemaker, Sydney  36–7, 97–100 Skyrms, Brian  366–7, 418–20, 422–3, 424–5, 459–60 Slote, Michael A.  385–8, 388–9, 391 Smart, J.J.C.  7–11,  11–13, 13–15, 17–18, 18–19, 22–6, 27–9, 63–4, 65–6, 156–60, 224–6, 237–8, 281–2 Smith, Michael  162–6, 466–8 Soames, Scott  360–3, 363 Sobel, Jordan Howard  392–3, 415–16, 453–6 Solomon, Robert  303–6 Sorensen, Roy  354–5 Sosa, David  364–5 Stalnaker, Robert C.  60–2, 66–8, 77–8, 93–7, 194–5, 397–401, 405–6 Sterelny, Kim  108–11 Strevens, Michael  525–6 Stroud, Barry  509–10 Talbott, William J.  448–9 Teller, Paul  131, 396–7 Tichý, Pavel  250–1 Tooley, Michael  203–4 Unger, Peter  391–2, 517 Vanderschraaf, Peter  365–6 van Fraassen, Bas  439–40, 464–5 van Inwagen, Peter  290–1 Velleman, David  145 Vogel, Jonathan  521–4 von Stechow, Arnim  104–7, 113–15, 316–17, 319–21, 321–3 Walton, Kendall  116–17, 282, 307–8 Williamson, Timothy  541–8, 548–9 Winnie, John  222–3 Ziolkowski, Ted  126–7