Locke’s Ideas of Mind and Body 9781138241794, 9781315279770

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Locke’s Ideas of Mind and Body

Locke’s Ideas of Mind and Body offers a provocative and highly original interpretation of Locke’s position on the mind-body problem. The book makes a significant contribution to our understanding of Locke’s metaphysics that will be of great interest to specialists and students alike. —Nicholas Jolley, University of California, Irvine, USA

This book begins with a survey of various readings of Locke as a materialist, as a substance dualist, and as a property dualist, and demonstrates that these inconsistent interpretations result from a general failure of modern commentators to notice the significance of Locke’s ‘mind-body nominalism’. By illuminating this largely overlooked aspect of Locke’s philosophy, this book reveals a common mistake of previous interpretations: that of treating what Locke conceives to be ‘nominal’ as real. The nominal symmetry that Locke posits between mind and body is distinct from any form of metaphysical dualism, whether substance dualism or property dualism. It is a brand of naturalism, but does not insist that the material is ontologically more basic than the mental or that the former determines the latter. On this view, the material and the mental both relate solely to a certain set of functional roles, rather than to an intrinsic property that plays these roles. The term ‘matter’ is thus rendered vague, and materialism is conceived as a precariously grounded ontological doctrine. Elaborating on this interpretation of Locke’s Essay, this book examines the insightful readings of Locke developed by seventeenth- and eighteenth-century thinkers such as Richard Burthogge, William Carroll, and Joseph Priestley. This book also seeks to clarify what Locke’s position would look like in a modern setting by noting some significant parallels with the ideas of leading contemporary philosophers such as Donald Davidson, David Lewis, and Colin McGinn. Han-Kyul Kim earned his BA at Seoul National University (Korea) and his PhD at the University of York (UK). He taught at Temple University (USA) and is the author of several articles on the history of early modern philosophy.

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Locke’s Ideas of Mind and Body

Han-Kyul Kim

First published 2019 by Routledge 52 Vanderbilt Avenue, New York, NY 10017 and by Routledge 2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN Routledge is an imprint of the Taylor & Francis Group, an informa business © 2019 Taylor & Francis The right of Han-Kyul Kim to be identified as author of this work has been asserted by him in accordance with sections 77 and 78 of the Copyright, Designs and Patents Act 1988. All rights reserved. No part of this book may be reprinted or reproduced or utilised in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any information storage or retrieval system, without permission in writing from the publishers. Trademark notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data A catalog record for this book has been requested ISBN: 978-1-138-24179-4 (hbk) ISBN: 978-1-315-27977-0 (ebk) Typeset in Sabon by Apex CoVantage, LLC

In memory of Roger

Contents

Preface Abbreviations and Notes Introduction

viii xii 1

1

Locke and the Mind-Body Problem

14

2

Mind-Body Nominalism

34

3

Epistemic Humility

57

4

The Superadded Power of Thought

80

5

Burthogge, Carroll, and McGinn

99

6

A Functionalist Account of Substrata

116

7

Locke and Dynamic Realism

134

Bibliography Index

153 162

Preface

The embryo of this book was a six-page essay entitled ‘Was Locke a Secret Materialist?’ that I wrote for a tutorial in the spring of 1998 while studying for my MA at King’s College London. I was fortunate to have as my tutor John Milton, who led me into the wonderland of Locke’s Essay Concerning Human Understanding, teaching me how to appreciate this masterpiece of the seventeenth century and its historical significance. At the time, my answer to the question raised in the title of my essay was straightforwardly positive, but my views have evolved since then. Now, in this book, I offer a subtler answer. My next debt is to the late Roger Woolhouse, who supervised my doctoral thesis, the basis of this book, at the University of York. His intellectual guidance is still evident on every page. At our first meeting, we had a conversation about my writing sample on Locke—an upgraded version of the six-page essay—as well as my MA dissertation on Spinoza’s account of the human mind. Roger alerted me to a neglected eighteenth-century work in which Locke was accused of being a Spinozist: William Carroll’s Dissertation Upon the Tenth Chapter of the Fourth Book of Mr. Locke’s ESSAY, Concerning Human Understanding (1706). I obtained a microfilm copy of this intriguing treatise from the British Library. Was Locke a Spinozist? If so, in what sense? My doctoral work started with these questions. This book begins with a survey of various readings of Locke as a materialist, as a substance dualist, and as a property dualist, and demonstrates that these inconsistent interpretations result from a general failure of modern commentators to notice the significance of Locke’s ‘mind-body nominalism’, as I call it, which is his view that the categories of materiality and mentality are both ideas or descriptions applied to things on the basis of how they operate or function. By illuminating this largely overlooked aspect of Locke’s philosophy, this book reveals a common mistake of previous interpretations: that of treating what Locke actually conceives to be ‘nominal’ as real. The nominal symmetry that he posits between mind and body is distinct from any form of metaphysical dualism, whether substance dualism or property dualism. On this view, the material and mental both relate solely to a certain set of functional

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ix

roles, rather than to an intrinsic property that plays these roles. With this point in mind, Locke’s epistemic humility can be seen as offering a critique of materialism. His mind-body nominalism is a brand of naturalism, but does not imply that the material is ontologically more basic than the mental or that the former determines the latter, for (like the category of mentality) the category of materiality acquires its meaning only through a set of functional roles. The term ‘matter’ is thus rendered vague, and materialism is conceived as a precariously grounded ontological doctrine. Elaborating on this interpretation of Locke’s Essay, this book examines the insightful readings of Locke developed by Carroll, Richard Burthogge (1678, 1694), and Joseph Priestley (1777). This book also seeks to clarify what Locke’s position would look like in a modern setting by noting some significant parallels with several leading contemporary philosophers. Through e-mail correspondence, Colin McGinn, Jaegwon Kim, David Papineau, and the late Donald Davidson offered me fruitful suggestions that helped me better understand their own views. McGinn kindly sent me his then-forthcoming article ‘What Constitutes the Mind-Body Problem?’ (now the first chapter of his book Consciousness and Its Objects), which was enormously useful to me in developing my view. After Roger’s retirement, I worked with Tom Stoneham for a year while writing my doctoral thesis. My debt to Tom is incalculable, particularly in terms of the contemporary issues and topics addressed in the thesis and in this book. Some historians of philosophy will be critical of this approach, but I believe it to be particularly effective in the case of Locke, whose philosophical insight, as I see it, transcends his own historical context. In his article ‘The Philosopher’s History and the History of Philosophy’, Anthony Kenny (2005, 19) describes one of the possible values that we derive from the history of philosophy as ‘resembl[ing] the enhanced appreciation of Shakespeare we may get by seeing a new, intelligent production of King Lear’. In keeping with this aim, it is my hope that this book will breathe life into Locke’s Essay by drawing readers’ attention to his insight into the mind-body problem and its significance for contemporary debates. In 80 Years of Locke Scholarship: A Bibliographical Guide, Roland Hall and Woolhouse (1983, 4) remarked that, despite the accusation that Locke is an inconsistent philosopher, ‘with further close study and interpretation, [Locke] may emerge as more interesting and more coherent’. This book is an attempt to show that Locke is not only a more ‘interesting’ and more ‘coherent’ philosopher than many suspect, but also a significant one even in the context of recent debates on the mind-body problem. For the publication of this book, I am indebted to many other scholars, colleagues, friends, and students. Upon the completion of my doctoral work, I returned to Korea to teach at Seoul National University for three years. Although my research remained stagnant during this short period, I was fortunate enough to be invited to Yale as a visiting scholar in the fall of 2006. During my time there, Michael Della Rocca kindly offered to see

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me every week to talk through my doctoral thesis. I immensely enjoyed my conversations with Michael, a leading Spinoza scholar, especially on Carroll’s account of Locke, which figures centrally in Chapter 5 of this book. Many thanks also go to Kenneth Winkler. I participated in two of his seminars: Causation in Early Modern Philosophy (co-taught by Michael) and Locke and Leibniz. I also wish to thank the insightful scholars—too numerous to list—whom I’ve met at conferences. Particular thanks go to Nicholas Jolley for his interest in this book project and his words of encouragement. At the California Conference on Early Modern Philosophy in Long Beach in 2007, I received helpful comments from Michael Ayers on a paper I read, which was an earlier draft of Chapter 2. He called my attention to Burthogge’s idealism and its relevance to Locke, which is now discussed in Chapter 5. At the Oxford Seminar in Early Modern Philosophy in 2010, where I delivered an earlier draft of Chapter 7, I had an illuminating conversation with Antonia LoLordo on Locke and dynamic realism. I also had the chance to speak with Martha Bolton about my research project during our train trip from St. Andrews, where we had been invited for the Locke Workshop, to York to attend the Memorial Conference for Roger Woolhouse in June 2012. Some of the material in Chapter 1 appeared as ‘Locke and the MindBody Problem: An Interpretation of his Agnosticism’ (Philosophy 83, 2008). Chapter 2 is a revised version of ‘What Kind of Philosopher was Locke on Mind and Body?’ (Pacific Philosophical Quarterly 91, 2010). Part of Chapter 3 derives from ‘Lockean Humility’ (Philosophy 89, 2014). Part of Chapter 4 was included in ‘A System of Matter Fitly Disposed: Locke’s Thinking Matter Revisited’ (American Catholic Philosophical Quarterly 90, 2016). Part of Chapter 6 appeared as ‘The Supposed but Unknown: A Functionalist Account of Locke’s Substratum’ (in Locke and Leibniz on Substance, Routledge, 2015). Many thanks to the journals and publishers for allowing me to use this material here. I also wish to thank the philosophy department at Temple University, where I’ve taught over the last ten years, for giving me the opportunity to teach such excellent students. Their questions and our engaging conversations were a source of inspiration and energy to me while working on this book. I also thank my former colleagues, Jerry Vision and David Wolfsdorf, for their support, advice, and encouragement. I owe very special mention to Ben White for reading the entire manuscript. Ben attended a graduate seminar on British empiricism that I taught at Temple and is now my mentor on contemporary metaphysics. He saved me from many errors in the early stages of this book. I would also like to express my appreciation to the anonymous referees at Routledge for their many helpful comments, suggestions, and criticisms, as well as Andrew Weckenmann for his interest in this project and his patience with the delayed completion of the final version.

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Finally, my deepest appreciation goes to my parents for their endless support, to my wife, Sang-Eun, for her selfless help, and to my three daughters—Daseul, Dahae, and Daham—for their beautiful smiles. I am so happy to be able to spend more time with the girls now. The youngest was jealous of Locke, as he took me from her for years. She will soon learn, though, about the worth of writing a book on him. February 28, 2019 Wynnewood, Pennsylvania

Abbreviations and Notes

Locke’s Essay Concerning Human Understanding is referred to as the ‘Essay’. I refer to Nidditch’s Oxford edition (1975). When passages are quoted from the Essay, only their book, chapter, and section numbers are specified. Thus, ‘IV.iii.6’, e.g., refers to the Essay, Book IV, Chapter iii, Section 6. References to Locke’s letters to Stillingfleet are to he reprint in The Works of John Locke, vol. 4 (London: printed and sold by Thomas Tegg, 1823). References to Stillingfleet’s letters to Locke and to his Discourse in Vindication of the Doctrine of the Trinity, Chapter X, are to the reprint contained in Three Criticisms of Locke (Hildesheim, Zürich, New York: Georg Olms Verlag, 1987). Locke’s first letter and second reply to Stillingfleet1 are referred to as follows: First Letter:

Second Reply:

A Letter to the Right Reverend Edward, Lord Bishop of Worcester, Concerning Some Passages Relating to Mr. Locke’s Essay of Human Understanding, in a late Discourse of his Lordship’s in Vindication of the Trinity. (January 7, 1697) Mr. Locke’s Reply to the Right Reverend the Lord Bishop of Worcester’s Answer to his Second Letter. (May 4, 1698)

Each letter is referred to by its title and page number: e.g. ‘First Letter, 33’ or ‘Second Reply, 478’. Stillingfleet’s book and two letters to Locke are abbreviated as follows: Discourse: First Answer:

A Discourse in Vindication of the Doctrine of the Trinity. (1697) The Bishop of Worcester’s Answer to Mr. Locke’s Letter, Concerning Some Passages Relating to his Essay of Human Understanding, Mention’d in the late Discourse in Vindication of the Trinity. (April 26, 1697)

Abbreviations and Notes Second Answer:

xiii

The Bishop of Worcester’s Answer to Mr. Locke’s Second Letter; Wherein his Notion of Ideas Is prov’d to be Inconsistent with itself, And with the Articles of the Christian Faith. (September 22, 1697)

Other authors’ works are abbreviated as follows: Dissertation:

William Carroll, A Dissertation Upon the Tenth Chapter of the Fourth Book of Mr. Locke’s ESSAY, Concerning Human Understanding. OVN: Richard Burthogge, Organum Vetus et Novum, or A Discourse on Reason and Truth. ERS: Richard Burthogge, An Essay upon Reason, and the Nature of Spirit. Disquisitions: Joseph Priestley, Disquisitions relating to Matter and Spirit. Free Discussion: Joseph Priestley and Richard Price, A Free Discussion of the Doctrine of Materialism and Philosophical Necessity. NE: Leibniz, New Essays on Human Understanding. Trans. by Peter Remnant and Jonathan Bennett. (‘NE, IV.iii.6: 377’, e.g., refers to the New Essays, Book IV, Chapter iii, Section 6, page 377). CSM: The Philosophical Writings of Descartes. Ed. and Trans. by John Cottingham, Robert Stoothoff, and Dugald Murdoch. (‘CSM I’ refers to volume I, and ‘CSM II’ to volume II.) In the fourth edition of the Essay, Locke frequently italicizes words, phrases, and sentences, and uses capital letters. Nidditch’s edition, based on the fourth edition, preserves this notation. When I quote Locke’s words, phrases, passages, and chapter headings, I preserve their original notation. Hence, the italics used in quoted passages from the Essay in this book are Locke’s own, not mine. The same applies to other British authors quoted, such as Stillingfleet, Burthogge, and Priestley, who also frequently use italics. When I quote passages from Locke and other authors, I place them in single quotations. When a quoted passage contains a quotation or quotations, I place these in double quotations to avoid confusion. When I need to refer to a word instead of using it, I also use single quotations. Round brackets used in Locke’s text are his own. Square brackets in passages quoted from Locke and other authors are mine. For example, in the following passage, the phrase ‘[i.e. by reflection]’ has been inserted by me: ‘the other supposed (with a like ignorance of what it is) to be the Substratum to those Operations which we experiment in ourselves within [i.e. by reflection]’ (II.xxiii.5).

xiv

Abbreviations and Notes

Note 1. In 1697, a year after publication of the third edition of Locke’s Essay and four years before the fourth, Edward Stillingfleet published his book Discourse in Vindication of the Doctrine of the Trinity, in which he criticized Locke’s Essay as a threat to the immateriality of the mind. In the same year, Locke wrote a reply to the Discourse, titled A Letter to the Right Reverend Edward, Lord Bishop of Worcester, Concerning Some Passages Relating to Mr. Locke’s Essay of Human Understanding, in a late Discourse of his Lordship’s in Vindication of the Trinity (January 7, 1697). Just a few months later, Stillingfleet replied with The Bishop of Worcester’s Answer to Mr. Locke’s Letter, Concerning Some Passages Relating to his Essay of Human Understanding, Mention’d in the late Discourse in Vindication of the Trinity (April 26, 1697). Almost at once, Locke wrote Mr. Locke’s Reply to the Right Reverend the Lord Bishop of Worcester’s Answer to his Letter, Concerning Some Passages relating to Mr. Locke’s Essay of Human Understanding, in a Late Discourse of his Lordship’s, in Vindication of the Trinity (June 29, 1697). Stillingfleet then immediately wrote The Bishop of Worcester’s Answer to Mr. Locke’s Second Letter; Wherein his Notion of Ideas Is prov’d to be Inconsistent with it self, And with the Articles of the Christian Faith (September 22, 1697). The final correspondence in this debate was Locke’s last reply with the following full title: Mr. Locke’s Reply to the Right Reverend the Lord Bishop of Worcester’s Answer to his Second Letter. Wherein, besides other incident Matters, what his Lordship has said concerning Certainty by Reason, Certainty by Ideas, and Certainty by Faith; the Resurrection of the Same Body; the Immateriality of the Soul; the Inconsistency of Mr. Locke’s Notions with the Articles of the Christian Faith, and their Tendency to Scepticism; is Examined (May 4, 1698). Stillingfleet died on March 27, 1699.

Introduction

Locke has continuously been branded the philosopher of mere commonsense. Otherwise he has frequently been dismissed as inconsistent. But with further close study and interpretation, he may emerge as more interesting and more coherent. (Hall and Woolhouse 1983, 4)

1.

Inconsistent Readings

The place of the human mind in the newly emergent mechanistic worldview was one of the main philosophical concerns of early modern philosophers. We are familiar with the ascription of ‘Reductive Materialism’ to Hobbes, of ‘Substance Dualism’ to Descartes, of ‘Occasionalism’ to Malebranche, of ‘Parallelism’ to Spinoza, and of ‘Pre-established Harmony’ to Leibniz as convenient labels for characterizing the views that these thinkers developed in responding to the mind-body problem. No such widely accepted label has yet been agreed upon, though, for Locke’s position on this issue. Although the lack of a label for a philosopher may amount to nothing more than the absence of a proper word or phrase, our lack of attention to Locke’s views on this subject is striking, considering that Locke’s contemporary readers regarded the mind-body problem as being ‘near the forefront’ of his philosophical concerns (Jolley 1999, 80). When first published in 1690, Locke’s Essay was considered radical and controversial mainly due to its treatment of the subject of the human mind. Its various editions span the seventeenth and eighteenth centuries: the six editions were published in 1690, 1694, 1695, 1700, 1706, and 1710, respectively. Between the third and fourth editions, Locke engaged in a series of debates with Edward Stillingfleet, the Bishop of Worcester. Their debates started with the publication of Stillingfleet’s Discourse in Vindication of the Doctrine of the Trinity (1697) wherein Locke’s Essay was accused of posing a threat to the doctrine of the immateriality of the soul. From 1697 to 1699, Stillingfleet wrote two long letters (154 and 178 pages in length) to Locke just before his death. Locke replied to both the Discourse and these letters. Taken together, these three replies totaled more than two hundred pages. All their correspondence was

2

Introduction

published. In their debates, Locke insisted that the doctrine ‘that the soul is immaterial . . . cannot be demonstrated’ (Second Reply, 474). In the Continent, Leibniz wrote a chapter-by-chapter criticism of Locke’s Essay, entitled New Essays Concerning Human Understanding. Leibniz finished this work in 1704 but withheld its publication, as Locke died in the same year. It was published sixty years later, long after Leibniz’s death. Leibniz seems to have been aware of the Locke-Stillingfleet debate and immediately ‘allied himself with Stillingfleet’s criticism’ (Adams 1994, 356). As Nicholas Jolley (1984) observes, Leibniz’s main purpose in the New Essays was to reveal and attack what he saw as Locke’s secret tendency to undermine the immateriality of the soul.1 Jolley claims that it is for this reason that Leibniz devoted so much space in the New Essays to defending the doctrine of innate ideas. In comparison with Locke’s contemporaries, modern readers have paid significantly less attention to Locke’s views on the nature of the mind and its relation to the body. In the midst of this relative decline in interest, modern commentators have produced a variety of conflicting readings of Locke’s theory of mind: he has been taken as a materialist (Yolton 1984; Jolley 1999), a substance dualist (Odegard 1970; Aaron 1971; Alexander 1991), and a property dualist (Bennett 1994b; Bermúdez 1996; Pyle 2013; Stuart 2013). Clearly, these readings stand in conflict with one another. At times, these inconsistencies on the part of the commentators have been imputed to Locke as his own, turning this issue into a puzzling problem. To make things worse, there has been no systematic attempt to resolve this interpretive predicament. In the past eighteen years, a series of book-length works on Locke have been published, including updated or advanced studies of his philosophy of action (Yaffe 2000), of language (Ott 2004), of personal identity (Forstrom 2010), of moral agency (LoLordo 2012), of consciousness (Weinberg 2016), of knowledge (Priselac 2017), and of his metaphysics (Stuart 2013). No book-length study has yet been published, though, on Locke’s philosophy of the mind per se—as the subject of consciousness, knowledge, and action. Representative examples of each of these inconsistent interpretations can be further described as follows. Jolley (1999) may be regarded as a modern spokesman for the late seventeenth- and early eighteenth-century critics of the Essay. His 1999 book on Locke contains a whole chapter on the mind-body problem. In comparison to other modern works on Locke, Jolley’s allocation of an entire chapter to the mind-body problem is noteworthy. Jolley (1999, 81) doggedly rejects the attribution of substance dualism to Locke: ‘[n]owhere in the Essay is Locke unequivocally committed to the truth of substantial dualism about the created world’. Sensing a tension ‘between the vein of agnosticism and a more positive thesis’ in the Essay, Jolley (1999, 81) holds that ‘[t]he main positive competitor to [Locke’s] agnostic stance is not substance dualism but a form of materialism’. While this observation of Jolley’s is grounded in the chapter ‘Of our Complex Ideas of Substances’

Introduction

3

(II.xxiii) of the Essay, Yolton (1984, 35–6) notes a materialistic tendency in the chapter on personal identity (II.xxvii) as follows: ‘[Locke] also discounts the notion that an immaterial substance is necessary for identity of person. He still pays lip-service to the two-substance view, but it is sameness of consciousness that holds an identity. He views consciousness as intimately related to the organized matter of the body’. These readings by Jolley and Yolton can be seen as modern versions of the StillingfleetLeibniz accusation: that Locke was a secret materialist. Although Locke was rarely regarded as a substance dualist during his own time, some twentieth-century readers, including Douglas Odegard (1970), Richard Aaron (1971), and Peter Alexander (1991), read Locke in this way. Odegard (1970, 88) claims that ‘John Locke is a dualist with respect to mind and body and, for the most part, his dualism falls into the first category sketched earlier [viz. substance dualism]’. Aaron (1971, 142) held that ‘[f]ollowing traditional ways of thinking, Locke regards mind as a substance which is immaterial. He accepts the usual dualism, the “two parts of nature”, active immaterial substance and passive material substance’. Here the phrase ‘two parts of nature’ suggests the orthodox type of duality, namely the ‘traditional’ view ‘accepted by the Church and upheld by Cartesianism’ (Aaron 1971, 143) in which the human mind is conceived as a nonphysical substance united with a physical body. Among those who regard Locke as a substance dualist, there is little agreement on what variety of substance dualism he is supposed to have endorsed. In contrast to the standard Cartesian form of substance dualism, according to which the respective essences of mental and corporeal substances are thought and extension, Alexander (1991) attributes to Locke a derivative version of substance dualism, in which the respective essences of mental and corporeal substances are instead constituted by sensation and solidity. Alexander (1991, 216) used the term ‘a two-substance theory’ to distinguish his dualistic reading of Locke from the orthodox type: ‘I am suggesting that, like Descartes, Locke is accepting a two-substance theory but characterizing the two substances differently’. The Odegard-AaronAlexander reading clearly contrasts with the materialist reading favored by Stillingfleet, Leibniz, Yolton, and Jolley. A third reading of Locke’s theory of mind has been offered by José Luis Bermúdez (1996, 226), who contends that Locke advocates only property dualism, not substance dualism: ‘Locke does not explicitly advocate metaphysical dualism, and nor is he implicitly committed to it . . . he is a property dualist’. Property dualism is more dualistic than materialism in that it takes the mental to be irreducible to the physical, yet less dualistic than substance dualism in that the irreducible entity that constitutes one’s mind is taken to be a property (or collection of properties), not a substance. Property dualism is in this respect a weaker version of dualism that insists only on ‘the impossibility of explaining mental properties in terms of physical properties (or physical ones in

4

Introduction

terms of mental ones)’ (Bermúdez 1996, 230).2 As the duality obtains only at the level of properties, property dualism allows for one substance to have both kinds of properties. By contrast, substance dualism (or metaphysical dualism) maintains that each kind of property must be attributed to a different substance. Jonathan Bennett (1994b, 89) also argues that ‘property dualism can be felt all through Locke’s Essay’. More recently, Andrew Pyle (2013) and Matthew Stuart (2013) have aligned themselves with the property dualist reading.

2.

Overlooked Topics to Be Illuminated

As I see it, the variety of conflicting readings of Locke’s theory of mind results from the general failure of modern commentators to notice that Locke took a multifaceted approach to the mind-body problem. In hopes of remedying this oversight, this book focuses particular attention on the following four overlooked topics: (1) Locke’s mind-body nominalism,3 (2) his epistemic humility,4 (3) his functionalist account of substrata,5 and (4) his naturalist approach to the human mind. While Locke’s adherence to these four positions in the Essay has garnered some attention from commentators, no comprehensive attempt has yet been made to see how they are related to one another within Locke’s account of mind and body. In fact, as we shall see, the conjunction of these four positions gives rise to a novel solution to the mind-body problem, which is not only historically interesting but also worth considering in regard to recent debates on the subject. In my reading, Locke’s nominal dualism does not drift toward substance dualism or property dualism. To Locke’s eyes, materialism, too, would appear to be a precariously grounded doctrine. As we shall see, what is novel about his treatment of materialism is the manner in which he criticizes it—viz. by taking the material to be a nominally basic category, rather than by adding immaterial items (whether substances or properties) to the physical world as dualists do. For Locke, the basic error of materialism lies in its failure to recognize that materiality is only a nominally basic category and thus cannot constitute the basic nature of reality. Thomas Reid’s awareness of this novel view in the Essay is perhaps what led him to characterize Locke as a proto-idealist. In his Essays on the Intellectual Powers of Man, Reid (1895, vol. 2, 286) writes that ‘[Locke] may lead one to conjecture that he had a glimpse of that system which Berkeley afterwards advanced, but thought it proper to suppress it within his own breast’. For this reading, Reid refers to a passage from IV.x.18 in the Essay, in which Locke mentions that the physical world might have been created in a different way than our ‘vulgar Notions’ of matter suggest. Here, Reid seems to have misconstrued Locke’s body-nominalism as an idealistic position.6 In my reading, Locke is a realist, but a humble realist, who confesses that the true nature of the world is inaccessible to us, and takes the categories of materiality and mentality as both equally

Introduction

5

nominal; neither truly represents the ‘true Nature of things’ (II.xxiii.32). As we shall examine, Locke’s insight is that not only materialism but also idealism misconceives one of the nominal essences as constituting the true nature of reality, whereas Cartesian dualism confused the nominal distinction as a real one. The remainder of this introduction explains each of the four views just mentioned. I will begin with Locke’s mind-body nominalism, as it is the central position among the four, and then proceed to show how the other three are related to it. While Locke’s account of nominal essences of ordinary natural kinds (e.g. water, gold, horses, and men) has been much discussed, his mindbody nominalism has been largely overlooked. The fact that Locke applies his account of nominal essence to the broader categories of mentality and materiality has rarely been acknowledged. Locke himself coined the term ‘nominal essence’ in the Essay, defining it as ‘nothing but the abstract Idea’ of a kind ‘to which the Name is annexed’—so that ‘every thing contained in that Idea, is essential to that Sort’ (III.vi.2). An individual substance of a particular sort has its own essence by virtue of which it is what it is. This individual essence is what Locke calls a ‘real essence’: ‘that particular constitution, which every Thing has within itself, without any relation to any thing without it’ (III.vi.6). However, an individual substance is also of a certain kind. Every member of a kind has something in common, viz. ‘the Essence of each Genus, or Sort’, which is nothing but an abstract idea. ‘[T]he nominal Essence of Gold’, for example, is thus ‘that complex Idea the word Gold stands for’ (III.vi.2). Significantly, Locke also seems to allow for the existence of nominal essences of a higher order, which correspond to higher-level abstract ideas, e.g. our ideas of mind and body, as we shall see in Chapter 2. Is a horse a purely material being? Does it have any mentality? Such questions are concerned with what Locke refers to as ‘[t]he primary Ideas we have peculiar to Body, as contradistinguished to Spirit’ (II. xxiii.17). It is consequently not only ordinary kinds that are associated with abstract ideas; the same holds likewise of higher-level kinds, e.g. materiality and mentality. For the consistent nominalist, it would be rather strange to apply the nominalist principle only to lower-level kinds without also applying it to higher-level kinds. An individual substance that is classified as the horse-kind is therefore further classified as material or mental, insofar as it satisfies the criteria of the more general categories specified by our abstract ideas of mind and body. That is, ‘mind’ and ‘body’ are also ‘sortal’ names attached to the abstract ideas of those kinds. The general contention of this book is that Locke’s mind-body nominalism, combined with the three views mentioned previously, presents a critical alternative to both Cartesian dualism and materialism (both of which Locke’s Essay has been wrongly interpreted as supporting). Locke’s nominal dualism, as we shall see, should be differentiated from property dualism as well.

6

Introduction

A nominal essence can be considered a semantic entity (rather than a physical or metaphysical one) that describes a set of characteristic roles that an individual substance must satisfy in order to be classified as a member of a certain kind. In contrast, ‘real essence’ can be taken as the intrinsic property of an extra-ideal entity that occupies and implements the roles associated with that kind. Locke holds that ‘as to the real Essence of Substances, we only suppose their Being, without precisely knowing what they are’ (III.vi.6). This quotation represents the position that I refer to as ‘epistemic humility’—an epistemologically moderate position on the intrinsic properties of things in themselves. In the Essay, there are several types of agnostic stances. Among them, the preceding is the main type, from which the others are derived, as we shall explore in Chapter 3. The combination of Locke’s epistemic humility with his mind-body nominalism can be better understood by invoking the notion of function. Although Locke did not use the term ‘function’ as a technical term in the Essay, the following passage from II.xiii.19 can justify my use of this term to characterize his views: ‘[s]o that of Substance, we have no Idea of what it is, but only a confused, obscure one of what it does’. Here, ‘what [a substance] does’ can be taken as its functional property while ‘what it is’ refers to its intrinsic property.7 Locke applies this functionalist account all the way down to the building blocks of the world, i.e. to the ‘insensible Corpuscles’ or ‘little atoms’ that serve as ‘the greatest Instruments of Nature’ (IV.iii.25).8 The advantage of this functionalist stance is that it is readily applicable to Locke’s epistemic humility. As he contends, we know what a substance does (i.e. its functional role) by observing its power or disposition, but not what it is (i.e. its intrinsic nature by virtue of which it plays the role that it does). Chapter 6 examines Locke’s view of substrata from this functionalist point of view. This book further contends that Locke’s epistemic humility is a view that he advances within his commitment to naturalism: that is, it is applicable only to those objects, the existence of which is confirmable by natural science. Here, my term ‘natural’, or ‘naturalist’, describes a property, substance, process, or event that is made of or depends on the ‘greatest Instruments of Nature’, i.e. the basic particles. The ‘naturalist approach’ is based upon the belief that God creates no more than such basic particles and ‘superadds’ a set of higher-level properties to the world, including the power of thought, merely by configuring or arranging the particles into a suitably disposed system. Although these higher-level properties can be described as a ‘new’ set of properties ‘over and above’, or ‘irreducible’ to, the physical properties of the suitably disposed systems that they are ‘superadded’ to, they still depend on the ‘greatest Instruments of Nature’ in that they cannot exist without the basic elements of the world. According to Locke’s mind-body nominalism, however, the irreducibility of the mental to the physical can be understood merely in terms of their nominal disparity, as we shall explore in Chapter 4.9

Introduction

3.

7

A Neglected Eighteenth-Century Criticism of Locke’s Essay

Given that most contemporary commentators have failed to acknowledge the symmetrical treatment of mind and body in Locke’s nominalism, William Carroll’s Dissertation Upon the Tenth Chapter of the Fourth Book of Mr. Locke’s Essay Concerning Human Understanding (1706) is a significant work worthy of consideration. This work was published six years after the fourth edition of Locke’s Essay. The main claim of this neglected eighteenth-century criticism is that Locke ‘copied’ Spinoza (Dissertation, iii). Carroll holds that Locke had ‘Spinoza’s Pattern before him’ and ‘improv’d it’ (Dissertation, iv) and even remarks that ‘Mr. Locke translates it very well’ (Dissertation, 32). Carroll expressed his intellectual sympathy with Stillingfleet on the doctrine of the immateriality of soul, and accused Locke’s Essay of being a ‘pernicious’ book ‘purposed writ, in order to spread and teach the Doctrine [i.e. Spinozism] established in it’ (Dissertation, 108). While Stillingfleet’s criticism of Locke was from the religious perspective, Carroll’s Dissertation is more philosophically oriented. Carroll held that: Mr. Locke, in the Essay upon Human Understanding, establishes Spinoza’s Hypothesis of One Only Extended Material Substance. . . . I hope Mr. Locke will give me leave to say here . . . that he borrow’d his Hypothesis from Spinoza. (Dissertation, 2) ‘Spinoza’s Hypothesis’, which Carroll attributes to Locke, has two aspects. Carroll begins the Epistle to the Reader of the Dissertation with the bold contention that Locke, following Spinoza, upholds the thesis of materialism. On some occasions, however, Carroll understands Locke rather differently—not as a materialist but as maintaining a symmetry between mind and body. Consider the following passage in which Carroll comments on Locke’s account of nominal essence: ‘’[t]is [Locke’s] Nominal Essence alone, and nothing else, that constitutes and determines particular Substances, such as Spirit and Matter, Man and Horse, &c. into Sorts, Kinds, or Species’ (Dissertation, 40–1). Here, Carroll maintains that Locke takes ‘spirit’ (or ‘mind’) and ‘body’ as natural kind terms that do not refer to reality but only to nominal essences. He summarizes Locke’s view in the following intriguing statement: I shall call [mind and body (as conceived by Locke)] hereafter, by the new Names of Nominal Substances, and shall afterwards assign a Reason for my doing so. (Dissertation, 37) Locke does not use the term ‘nominal substance’ in the Essay; he uses ‘nominal’ only in applying it to the term ‘essence’. Carroll, however, uses

8

Introduction

‘nominal substance’ and ‘nominal essence’ interchangeably. According to Carroll, Locke’s position can be expressed as the view that mind and body are ‘two Nominal, and not two Real Substances’ (Dissertation, 38). This interpretation of Locke’s philosophy of mind and body runs parallel to my own, although Carroll sometimes seems to confuse the symmetric view he attributes to Locke with materialism. Carroll’s confusion, however, is instructive, and his understanding is significant. Carroll is right to note that Locke ‘carefully divested [the term “idea”] of [its] originally settled Signification’, and that modern readers ‘were not accustomed to take’ the term ‘idea’ as Locke employed it in the Essay, since his use of the term differed from the ‘common Custom of the English Language’ (Dissertation, 2). But while Locke’s use of the term ‘idea’ might well have been unfamiliar to his contemporaries, the fact that he made such frequent and significant use of it points to the basic philosophical position underlying his view of mind and body—i.e. mindbody nominalism.10

4.

An Outline of the Book

This book’s title—Locke’s Ideas of Mind and Body—signifies that we will be exploring not merely Locke’s philosophy of mind but also his philosophy of body, as he treats both as equally nominal entities. The term ‘Ideas’ in the title thus serves as a reference to Locke’s mind-body nominalism. While most modern Locke scholars have failed to note his mind-body nominalism in the Essay, Carroll correctly noted, to some extent, the novel position in it. My proposed reading of the Essay on this issue nevertheless implies that Locke’s treatment of the mind-body problem was also misunderstood even by most of his contemporary readers. As I see it, Locke’s philosophy of mind has some originality that transcends his own century’s intellectual milieu. This book offers a Lockean solution to the mind-body problem and places his positions, newly interpreted, in dialogue with contemporary approaches to this problem, including Donald Davidson’s anomalous monism, David Lewis’ Ramseyan humility, and Colin McGinn’s cognitive closure.11 Chapter 1 starts with a sketch of the debate between Cartesianism and materialism. The phrase ‘the mind-body problem’ is sometimes used to refer to the problem of mind-body interaction that critics raise against Descartes, but more often it signifies a ‘difficulty’ that anyone might face—whether dualist, materialist, or idealist—when formulating a theory of the nature of the mind and its relationship to the body. For materialists, the problem is how to account for the nature of the mind in terms of matter alone. Idealists face the converse problem of accounting for the material world in terms of mental entities. For substance dualists, the problem lies in accounting for the interaction or union of mind and body, as both are conceived as separate substances. In this context, Locke

Introduction

9

occupies a distinctive position in the history of mind-body theories. Some commentators contend that he simply gave up on trying to solve the mind-body problem, referring to the fact that throughout the Essay, he claims that only ideas of the mind and body are available to us. Yet his mind-body nominalism makes a crucial point: what he explores is neither ‘reduction’ nor ‘interaction’ but rather a ‘confusion’—on our end—of ideas and reality. Chapter 2 examines the notion of nominality by investigating what Locke meant by claiming that we have clear ideas of the mind and body. As human perspectives are involved in the formation of the categories of mind and body, there is a sense in which the mind-body problem is a human-created problem. Locke conceives of the mental and physical not as properties that are irreducible to each other but as ideas or descriptions that are applied to things based on how they act or function, not what they are essentially made of. Inattention to this point has made the mindbody relationship seem like a hard problem. This chapter demonstrates that Locke is committed to nominal dualism but not substance dualism. The significance of mind-body nominalism is then illuminated by way of comparison with Davidson’s anomalous monism. For Davidson, too, there is a sense in which mentality and physicality are nominally symmetrical. The two philosophers differ, though, in that while Davidson’s more linguistically oriented mind-body nominalism seldom addresses the issue of the intrinsic nature of events themselves, Locke’s mind-body nominalism does, and is to this extent more sustainable and defensible than Davidson’s. Chapter 3 is concerned with epistemic humility. There I examine what it means for us to be incurably ignorant about the intrinsic nature of things in themselves. There are different types of epistemic humility expressed in the Essay. Among them, the main type is that which concerns the intrinsic nature of the basic particles of the world. Another thing to consider is the extent of Locke’s epistemic humility. When Locke maintains that ‘every day[’]s experience furnishes us with’ (II.xxiii.28) the ideas of mind and body, the phrase ‘every day[’]s experience’ might appear to imply that nominal essences are confined to ordinary natural kinds that feature in our folk theories, physical or psychological. For Locke, however, even the most advanced (human) sciences cannot reveal the true nature of things: we cannot possibly acquire ‘a perfect Science of natural Bodies, (not to mention spiritual Beings)’ (IV.iii.29). Accordingly, even the functional roles described in any future advanced scientific theory (whether physical or psychological) should be taken to be merely nominal essences. In making this point, this chapter casts light on the significance of Locke’s epistemic humility in more recent contexts by noting a parallel with Lewis’ Ramseyan humility. Chapter 4 investigates what Locke meant by claiming that ‘God, if he pleases, should superadd the power of thought to a system of matter fitly

10

Introduction

disposed’ (IV.iii.6). This chapter argues that the ‘superadded’ that Locke speaks of is a ‘natural’ property: God creates no more than the ‘greatest Instruments of Nature’, i.e. the basic particles, on which the so-called superadded depends in such a way that without the particles it would not be able to exist. In other words, God creates no properties or substances that cannot be made of those basic items; nonetheless, God ‘superadds’ the power of thought to the created world by letting it ‘emerge’ (in more modern terminology) out of a fitly disposed system of particles. On this reading, the disparity between the mental and physical only features in our nominally dualistic concepts. In that sense, the power of thought can be said to be ‘superadded’ to a material system from the perspective of human ideas. Chapter 5 explores the views of one contemporary Lockean, Colin McGinn, with the aim of clarifying what a position that combines mind-body nominalism with epistemic humility might look like in a more modern setting. Echoes of Lockean epistemic humility appear in McGinn’s account of ‘cognitive closure’ with regard to which he himself confessed his intellectual debt to Locke. Although the objects of McGinn’s and Locke’s epistemic humility may at first seem to differ, some significant parallels can also be found between them. For McGinn too, our objective approach to the brain and our subjective acquaintance with conscious states constitute two different ways of viewing the world. These two views of the world are, in Locke’s eyes, ‘equal’ (II.xxiii.15). Locke’s account of species with higher intelligence (III.vi.3; IV.iii.23) implies that the only way we can solve the mind-body problem is to acquire a duality-free concept of the true nature of reality. Our acquisition of such a concept, however, would imply our becoming a different cognitive species than we are now. Given this point, the mind-body problem cannot be solved by us, who sense it as a problem. In addition to illuminating this Lockean viewpoint by comparing it to McGinn’s treatment of the mind-body problem, this chapter considers Carroll’s and Richard Burthogge’s references to Locke. As mentioned earlier, Carroll’s reading of Locke contains the seed for the account of Locke’s theory of mind and body presented in this book. In his Essay Upon Reason, and the Nature of Spirit (1694), dedicated to Locke, Burthogge suggests that our epistemic features as observers are reflected in our understanding of the external world, including the distinction we make between mind and body. The relevance of Burthogge’s conceptualism to his mind-body nominalism will also be explored in relation to McGinn’s and Carroll’s references to Locke. Chapter 6 is concerned with Locke’s functionalist view of substrata. The world is occupied by many and varied things. What constitutes their thingness? Locke addresses this question in the chapter ‘Of our Complex Ideas of Substances’ (II.xxiii), which includes the much-contested definition of ‘substratum’ as ‘a supposed but unknown support of the Qualities’ (II.xxiii.2). Most significant in this definition are the dual qualifiers ‘supposed’ and ‘unknown’. For Locke, there are two components that

Introduction

11

constitute the thingness of any sort of thing, whether mental or physical (or macro or micro): first, a set of co-instantiated qualities, and second, a substratum that serves as the unifier of those qualities. This chapter examines the two qualifiers in Locke’s definition and illuminates their relevance to the mind-body issue. Chapter 7 examines the historical significance of Locke’s functionalist approach in relation to the dynamic realists of the eighteenth century, such as Baxter (1733), Knight (1748), Boscovich (1763), Priestley (1777), Nicholson (1782), Young (1788), and Hutton (1792, 1794). During the eighteenth century, a conflict arose between two competing conceptions of matter: the inert and the dynamic. The former is characteristic of the seventeenth-century Boylean notion of matter, whereas the latter represents a new account of matter that emerged in the eighteenth century. The dynamic realists of the eighteenth century referred to Locke as a forerunner of their active conception of matter. Their interpretation of Locke may seem justified, inasmuch as Locke had indeed remarked in the Essay that the insensible atoms or corpuscles are ‘active parts of Matter’ (IV.iii.25). This chapter considers the relevance of this remark to the functionalist account of substratum examined in Chapter 6.

Notes 1. Robert Adams (1994, 364) also offers a similar observation with regard to the primary aim of Leibniz’s New Essays, quoting the following passage from a letter dated April 28, 1704, from Leibniz to Isaac Jaquelot: ‘I devote myself above all to vindicating the immateriality of the soul, which M. Locke leaves doubtful’. 2. Bermúdez (1996, 229) also quotes Bennett’s (1984, 41) definition of property dualism as the view that ‘the properties of things can be cleanly split into two groups, mental and physical, with no property belonging at once to both groups; this being so understood as to rule out any defining of mental terms through physical ones’. Stuart (2013, 250) defines ‘property dualism’ as the view that ‘mental features and physical features form two closed sets, none of the members of either being ultimately explicable in terms of, or reducible to, members of the other’. 3. My term ‘mind-body nominalism’ has its ancestry. In a paper of mine (2010) examining Locke’s account of the mind and body, I used the term ‘nominal symmetry’ to describe the view that neither the mental nor physical are ontologically privileged over the other insofar as both are nominal categories. Chapter 2 is a development of this earlier work. One recent scholar has suggested something very similar to my account of ‘mind-body nominalism’. In proposing her ‘essentialist’ reading of superaddition, Downing (2007, 370–1) has noted Locke’s term ‘the idea of matter’ (her emphasis) (which he used in a passage on superaddition from Second Reply 460–1) and contended that ‘[t]he superaddition Locke writes of here . . . is with regard to the nominal essence’. Downing does not develop this point beyond its application to Locke’s account of superaddition. 4. The term ‘epistemic humility’ or ‘humility’ has been used by Langton (1998) in reference to Kant, and by Connolly (2015) and myself (2014) in reference to Locke.

12

Introduction

5. My use of the term ‘functionalist’ or ‘functionalism’ to characterize Locke’s conception of substratum derives from an article of mine (2015). 6. For more detailed discussions of Reid’s idealistic reading of IV.x.18, see Bennett and Remnant (1978) and Woolhouse (1982). 7. In the Essay, Locke often uses terms such as ‘capacity’, ‘force’, or ‘power’ interchangeably. We would now typically classify the intended referents of all of these terms as ‘dispositions’. While the term ‘disposition’ is often used exclusively in relation to substances of natural kinds, such as fire, water, diamond, and so on, the term ‘function’ can be applied to artificial objects as well, such as road signs, computers, and chairs. For example, a road sign can be said to have the function of pointing people in a certain direction. This function is established by social agreement on the sign’s use. It is not the sign’s property of being metallic, but rather the convention on which we agree, that enables the sign to serve the function of directing people. It would thus sound bizarre to say that the road sign has a ‘disposition’ to point people in a certain direction, since in its metallic nature, there is no such disposition to change the direction of a person’s movement. As this example indicates, things can have certain functions that are not identical with or reducible to any of their natural dispositions. We can nevertheless take a functionalist position on dispositions, given that ‘function’ is a wider category than ‘disposition’. This is the standpoint that Mumford (1998, Chapter 9) adopts in his ‘functionalist theory of dispositions’. In contrast to the property of being liquid or gaseous, the property of being metallic would at least seem to bestow on the sign the disposition to prevent people from, say, walking right through the space in which the sign is located. This might be construed as a kind of disposition to alter a person’s movement. In this case, though, the sign alters the walker’s movement, not as a sign but as a physical object. By virtue of its physical properties, including its mass and solidity, it physically prevents the walker from entering into the space it occupies. Due to the function it has been given through the social convention, however, the sign can also change the walker’s action by virtue of its representational content as a sign. It is this latter capacity that we ascribe to the sign when we say that it has the socially adopted function of pointing people in a certain direction. The functionalist theory of dispositions, however, enables us to ascribe a naturally established function to the sign as a physical object as well. 8. Locke used the term ‘atom’ in the Essay to refer to whatever particle was deemed to be fundamental by the natural philosophy of his time, whereas today, the term ‘atom’ is understood to refer to an entity that is composed of sub-particles, such as electrons, neutrons, and protons. Thus, used in Locke’s sense, the term ‘atom’ would today refer not to the composite entity that we now typically take it to refer to but rather to whatever particles are deemed fundamental by contemporary science. 9. This interpretation gives a support to Ayers (1981, 1991) in suggesting that the ‘superadded’ power of thought does not refer to non-natural properties. Ayers’ account differs from mine, however, in that his reading does not place sufficient weight on Locke’s nominal dualism. In that regard, my position is closer to Downing’s (2007), who mentions the idea of matter in her ‘essentialist’ reading of superaddition. Chapter 4 develops Downing’s insight from the perspective of mind-body nominalism and further advances the discussion of superaddition into a more modern account of emergentism. 10. Drawing on Carroll’s criticism of Locke’s Essay, Lennon (1993, 322) has associated Locke with a position he calls ‘dualism of epiphenomenal kinds’. Lennon defines this position as ‘the view that minds and bodies . . .

Introduction

13

are appearances of the real’. That is, mind and body are ‘epiphenomena’ of reality—if the mental is ‘epiphenomenal’, then so, too, is the physical. However, Lennon’s account of this alleged symmetry in Locke’s treatment of mind and body goes no further than this. To assess its applicability to Locke, Lennon would need to explore Locke’s nominalism in relation to mind and body, which is what this book seeks to accomplish. Locke might agree with Lennon’s observation insofar as mind-body symmetry is concerned, but he would likely prefer his own term, ‘nominal’, to the term ‘epiphenomenal’, which is vague and contentious. 11. Jolley (2015) has recently written a highly illuminating book on this subject, which examines Locke’s views on the human mind in the context of seventeenth-century Christian conceptions of personal identity, resurrection, and immortality. My treatment of Locke’s theories of mind and body is more extensive in terms of its philosophical scope: this book more directly addresses the interpretive predicament presented by his discussion of mind and body by exploring a set of fundamental components of his system, such as his discussions of nominal essence, substratum, intrinsic properties, and epistemic humility.

1

Locke and the Mind-Body Problem

This chapter begins by outlining the debate between Descartes and the French materialist Pierre Gassendi on the nature of mind. According to Gassendi, Descartes failed to establish the immateriality of the mind and succeeded only in identifying what it does. In this argument, Gassendi distinguishes the function of a substance from its intrinsic nature. This Gassendian type of distinction can also be found in the Essay. Locke would readily agree with Gassendi’s criticism of Descartes, but would not thereby subscribe to materialism. Instead, Locke would apply the same form of argument to materialism by pointing out that materialism likewise does not tell us what the stuff that it treats as the fundamental basis of reality (i.e. matter) is, but only what it does. This parallel criticism of the two rival doctrines of materialism and substance dualism defies easy categorization, but it may be aptly described as a humility-based functionalist ontology in which both mentality and materiality are conceived as only nominally dualistic categories. This chapter examines the novelty of this view by comparing it to the following major doctrines: materialism (Section 2), substance dualism (Section 3), and property dualism (Section 4).

1.

Background

The mind-body problem emerged as a fundamental topic of debate in the early seventeenth century with the rise of mechanical philosophy. This is why recent introductory books on the philosophy of mind tend to start with a survey of the early modern philosophers, such as Descartes, Hobbes, Leibniz, Spinoza, and Malebranche. The early seventeenth century brought with it a radical break from scholastic Aristotelianism. Why is a piece of gold shiny, yellow, malleable, and soluble in aqua regia? The scholastic Aristotelians answered this essence-related question by appealing to the ‘substantial form’ that is allegedly inherent in every individual substance of a given kind. The scholastics explained the actuality of an individual substance as consisting in an ontological union of the substantial form with materia prima, i.e. a pure potentiality for receiving the form. In

Locke and the Mind-Body Problem

15

contrast to the Aristotelian view, the mechanical philosophy sought to make all natural phenomena fully explainable in terms of ‘two grand principles’ (Boyle 1965a, 20)—namely, matter and motion. As an ardent proponent of this new mechanistic worldview, Descartes contended that ‘the nature of body consists . . . simply in extension’ (CSM I, 224), proclaiming that ‘the only principles which I accept, or require, in physics are those of geometry and pure mathematics’ (CSM I, 247). He even identifies extension with ‘extended substance itself—that is, body’ (CSM I, 215). This identification also indicates his rejection of the existence of the void (i.e. empty space with no matter): ‘[t]he extension constituting the nature of a body is exactly the same as that constituting the nature of a space’ (CSM I, 227); the difference between them simply ‘lies in our way of conceiving them’ (CSM I, 228). Cartesianism was, however, not the only way in which seventeenth-century mechanists sought to explain the nature of matter. Granting the existence of the void, atomists held that a single atom traveling in empty space is a concrete particle, specifically shaped and sized, though it is too infinitesimal to fall within the range of our ordinary capacities for observation. Gassendi (1972, 399), the prominent Continental atomist, writes that ‘atoms are the primary form of matter, which God created finite from the beginning, which he formed into this visible world, which, finally, he ordained and permitted to undergo transformation out of which, in short, all the bodies which exist in the universe are composed’.1 The English atomist Boyle (1965b, 211) maintains that ‘at the first production of mixt bodies, the universal matter whereof they among other parts of the universe consisted, was actually divided into little particles, of several sizes and shapes, variously moved’. The radical shift occasioned by the new mechanistic conceptions of matter, whether Cartesian or atomistic, led to the transformation of the mind-body problem into its modern form. The scholastics regarded the human soul, too, as a form. Accordingly, the scholastic mind-body problem was concerned with how the soul can be separated from matter after bodily death.2 By contrast, the modern form of the problem, as Daniel Garber (1998, 762) puts it, is concerned with ‘what can be established in terms of matter alone, and what, if anything, must be added to body’. Assuming that the mind can indeed be ‘established in terms of matter alone’, how exactly are we to account for the apparent difference between them? How is the dependence of the former on the latter to be explained? On the other hand, if the mind is a nonphysical substance added to a material body, how can it be combined with it? These are new questions raised in the debate between Cartesian dualists and materialists. Their debate on the nature of the human mind was a central topic of seventeenth-century metaphysics. In the course of this debate, Gassendi contends that Descartes failed to demonstrate the immateriality of soul: ‘[i]n saying that you [Descartes] are simply “a thing that thinks”, you mention an operation of which all

16

Locke and the Mind-Body Problem

of us were already well aware; but you tell us nothing of the substance which performs this operation—what kind of substance it is’ (CSM II, 185). Here, Gassendi argues that negative characterizations of the mind, such as ‘incorporeal’, ‘non-extended’, and ‘immaterial’, tell us nothing positive about its nature. That is, Descartes tells us only what the mind is not, never what it is. Given that a substance is identified by its principal property, it follows that if the mind is immaterial, then it must be identified by some immaterial property. Gassendi’s contention is that in regard to the mind, Descartes only refers to certain mental operations ‘of which all of us were already well aware’. Descartes sometimes uses the term ‘intellectual substance’ (CSM II, 54) to more positively qualify an immaterial substance, but Gassendi takes intellection, too, to be a functional characterization of a physical system: ‘why should you, who may be thought of as the noblest part of the soul, not be regarded as being, so to speak, the flower, or the most refined and pure and active part of [matter]?’ (CSM II, 185). The same sort of argument can also be found in Hobbes: ‘M. Descartes is identifying the thing which understands with intellection, which is an act of that which understands. Or at least he is identifying the thing which understands with the intellect, which is a power of that which understands’ (CSM II, 122). The Gassendi-Hobbes viewpoint appears in Locke’s Essay too: ‘thinking is the Action, and not the Essence of the Soul’ (II.xix.4). Locke’s term ‘action’ here lines up with Gassendi’s ‘operation’ and Hobbes’ ‘act’. Like these materialists, Locke is accusing Descartes of having confused the function of a substance with its intrinsic nature: ‘that actual thinking is essential to the [immaterial] Soul, and inseparable from it, is to beg, what is in Question, and not to prove it by Reason’ (II.i.10). These passages from the Essay show that Locke severs the link between thought and immateriality forged by Descartes. Locke’s criticism of Descartes on this point may be attributable to the influence of Gassendi. Gassendi’s influence on Locke’s thought is something that is, as Lennon (1993, 150) notes, ‘widely unexamined by the literature, [but] nonetheless widely acknowledged by it’. The following passage from the New Essays shows that Leibniz certainly saw a connection between the two: The author [Locke] is pretty much in agreement with M. Gassendi’s system, which is fundamentally that of Democritus: he supports vacuum and atoms, he believes that matter could think, that there are no innate ideas, that our mind is a tabula rasa, and that we do not think all the time; and he seems inclined to agree with most of M. Gassendi’s objections against M. Descartes. (NE, I.i: 70) Further signs of Locke’s agreement with the materialists might be found in his correspondence with Stillingfleet, where Locke maintains that the immateriality of soul ‘cannot be demonstrated by natural reason’ (Second

Locke and the Mind-Body Problem

17

Reply, 474). Consider also the following quotation: ‘parcels of matter, so endowed with a power of thinking and motion, might properly be called spirits’ (Second Reply, 483). In the Essay, Locke likewise held that he finds ‘no contradiction’ in the idea that God ‘should, if he pleased, give to certain Systems of created senseless matter, put together as he thinks fit, some degrees of sense, perception and thought’ (III.iii.6). In the following passage, too, Locke evidently affirms his belief that there is no repugnance between thought and matter: I know nobody, before Des Cartes, that ever pretended to show that there was any contradiction in it, [i.e. the idea that God can bestow on some parcels of matter a faculty of thinking]. So that, at worst, my not being able to see in matter any such incapacity as makes it impossible for Omnipotency to bestow on it a faculty of thinking, makes me opposite only to the Cartesians. For as far as I have seen or heard, the fathers of the Christian church never pretended to demonstrate that matter was incapable to receive a power of sensation, perception, and thinking, from the hand of the omnipotent Creator. (Second Reply, 469) Locke’s contention is that there is nothing in the nature of matter that precludes the power of thought. Whereas Descartes maintains that ‘thought and matter are not only different, but in some way opposite’ (CSM II, 9–10) (even though they nevertheless also ‘form a unit’ (CSM II, 56)), Locke does not presume that mind and body are metaphysically exclusive. The following passage from Chapter vi of Book III of the Essay thus suggests that the mental-material distinction consists merely in certain differences between the nominal essences of mind and matter, both of which ultimately fl ow from the same ‘Constitution’: For though, perhaps, voluntary Motion, with Sense and Reason, join’d to a Body of a certain shape, be the complex Idea, to which I, and others, annex the name Man; and so be the nominal Essence of the Species so called: yet no body will say, that that complex Idea is the real Essence and Source of all those Operations, which are to be found in any Individual of that Sort. The foundation of all those Qualities, which are the Ingredients of our complex Idea, is something quite different: And had we such a Knowledge of that Constitution of Man, from which his Faculties of Moving, Sensation, and Reasoning, and other Powers flow; and on which his so regular shape depends, as ’tis possible Angels have, and ’tis certain his Maker has, we should have a quite other Idea of his Essence, than what now is contained in our Definition of that Species [i.e. Man]. (III.vi.3)

18

Locke and the Mind-Body Problem

This passage presents a picture of Locke’s overall position as encapsulated in the following points. First, the name ‘man’ is annexed to the ‘nominal Essence of the Species so called’ that comprises the ideas of various mental and physical qualities. Second, those qualities that one classifies as being of a mental kind (e.g. ‘voluntary motion, with sense and reason’ and the ‘faculties of moving, sensation, and reasoning’) and those that one classifies as being of a corporeal kind (e.g. ‘shape’) ‘depend on’ the same ‘foundation’—i.e. ‘[the] Constitution of Man’ from which those mental and physical qualities ‘flow’. Here Locke seems to think that nothing prevents those dual features from being ascribed to a common substratum. The third point Locke makes in this passage is that if we could share in God’s knowledge of the real essence of man, then we would have ‘a quite other Idea of’ man’s real essence from ‘what now is contained in our definition of’ man. Our human idea of man, to which the name ‘man’ is attached, contains the mind-body distinction. An omniscient being, by contrast, would not view the world through such nominally dualistic categories of mentality and physicality, and would consequently not see the mind and body as really distinct. The ideal perceiver’s idea of reality, which we cannot apprehend since we cannot share that perspective, would not be influenced by our dualistic notions of materiality and mentality at all.

2.

Locke and Materialism

What are physical objects? If one replies that physical objects are those that exist in space and are thereby recognizable by and describable in the proprietary vocabulary of the physical sciences, Locke would further ask what the intrinsic nature of each physical object is by virtue of which it can be in space. He rejects the Cartesian identification of extension and body: ‘[t]here are some that would persuade us, that Body and Extension are the same thing’ (II.xiii.11). In his view, being extended is not sufficient for being a body. Rather he takes extension as the consequence of solidity, stating that ‘upon [solidity] depends [the material body’s] filling of Space’ along with ‘its Contact, Impulse, and Communication of Motion upon Impulse’ (II.xiii.11). Solidity is that property by virtue of which a material object ‘supports us’ when we sit on it and ‘hinders our farther sinking downwards’, so that ‘we always feel something under us’ (II.iv.1). Locke takes solidity as the most fundamental feature of material bodies, but refers to it in terms of the idea of solidity: ‘[t]here is no Idea, which we receive more constantly from Sensation, than Solidity’; and ‘[the Idea of Solidity] is most intimately connected with, and essential to Body’ (II.iv.1). Beyond the idea of solidity, Locke confesses, ‘there is something in solid substances . . . that we do not understand’ (Second Reply, 465).3 The ultimate source of the abstract idea of solidity is our observation of ‘the resistance which we find in Body, to entrance of any other Body into the Place it possesses, till it has left it’ (II.iv.1). The unknown property

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that plays the solidity-role is only functionally identifiable in terms of the observable role that it plays.4 This functionalist account of solidity only tells us how a body would respond when certain conditions are met.5 In Book III of the Essay, in which his theory of nominal essence appears, Locke states that ‘in marking the general Ideas [of kinds]’, one is ‘seeking more the convenience of Language and quick dispatch, by short and comprehensive signs, than the true and precise Nature of Things, as they exist’ (III.vi.32). The same is true in the case of ‘the complex Idea of Extension and Solidity’ (III.vi.33). Such nominal essences are often confused with ‘the true and precise Nature of Things’ (III.vi.32). For Locke, the statement ‘the essence of body is extension’ is only nominally true. As we saw, the materialist Gassendi relies on the distinction between role and role-player in his argument against the Cartesian soul. Now it seems as though Locke is applying the same distinction to the category of materiality in such a way as to make matter into a nominal entity that is identifiable only in terms of what material things do and not what they are intrinsically. In Gassendi’s argument against the immateriality of soul, Locke would simply replace ‘a thing that thinks’ with ‘a thing that is solid’ to turn it into an argument against materialists: in saying that you are simply ‘a thing that is solid’, you mention an operation of which all of us were already well aware; but you tell us nothing of the substance which performs this operation—what kind of substance it is. It is standardly said that physical objects are those entities that are recognizable by, and describable in the proprietary vocabulary of, the physical sciences, and that physicalism is the view that such entities are the only kinds of entities that exist in the world. Jaegwon Kim (2011, 11) distinguishes ‘physicalism’ from ‘materialism’ as follows: Materialism is the doctrine that all things that exist in the world are bits of matter or aggregates of bits of matter. There is no thing that isn’t a material thing—no transcendental beings, Hegelian ‘absolute’, or immaterial minds. Physicalism is the contemporary successor to materialism. The thought is that the traditional notion of material stuff was ill-suited to what we now know about the material world from contemporary physics. For example, the concept of a ‘field’ is widely used in physics, but it is unclear whether fields would count as material things in the traditional sense. Physicalism is the doctrine that all things that exist are entities recognized by the science of physics, or systems aggregated out of such entities. Here, Kim defines ‘physicalism’ in methodological terms as ‘the doctrine that all things that exist are entities recognized by the science of physics, or systems aggregated out of such entities’. Nevertheless, the ontological claim that everything is made of the same physical stuff is also a crucial part of modern physicalism. Kim (1997, 279) elsewhere defines ‘ontological

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physicalism’ as the view that everything in the world, including ‘any creature with mentality’, is ‘wholly constituted by the physical parts— ultimately basic physical particles’. The emphasis on the ontological doctrine is, as David Papineau (2000, 174) notes, ‘a striking contrast with the “unity of science” doctrines prevalent among logical positivists in the first half of the [twentieth] century’. In contrast to present-day physicalists, the logical positivists were mainly concerned with the more methodological question of ‘whether the different branches of science, from physics to psychology, should all use the same method of controlled observation and systematic generalization’ (Papineau 2000, 174). They paid little attention to the ontological question mentioned earlier. Despite this marked shift of emphasis from the logical positivists to present-day physicalists,6 one point of continuity between them is that neither offers a satisfactory account of the intrinsic nature of materiality. This was exactly the point Locke made in the Essay as early as the late seventeenth century. Modern physicalists contend not only that everything should be studied by the methods of physics and related special sciences, but also that everything is physically constituted. Locke would be comfortable with the claim that the world can be physically studied (through experimentation and the methods of physics) and physically describable (by an appeal to the theories and terms used in physics). For Locke, however, it would make no sense to say that the world is physically constituted.7 This ontological doctrine has faced mounting criticism from contemporary writers as well. Barbara Montero (1999, 183), e.g., contends that unless we have some understanding of what it means to be physical, ‘there is little use in arguing about whether the mind is physical, or whether mental properties are physical properties—questions many take to be central to the mind-body problem’.8 Montero refers to the preliminary task of clarifying what it means to call something ‘physical’ in the first place as the ‘body-problem’: Is the mind physical? Are mental properties, such as the property of being in pain or thinking about the higher orders of infinity, actually physical properties? Certainly many philosophers think that they are. For no matter how strange and remarkable consciousness and cognition may be, many hold that they are, nevertheless, entirely physical. While some take this view as a starting point in their discussion about the mind, others, well aware that there are dissenters among the ranks, argue for it strenuously. One wonders, however, just what is being assumed, argued for, or denied. In other words, one wonders, just what does it mean to be physical? This is the problem I call, ‘the body-problem’. (Montero 1999, 183) Montero argues that we cannot even say that the physical is a single property. Her examples involve neutrinos (which can pass through the

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earth without disturbing it), photons (which have no mass), and dark matter (which is arguably composed of different kinds of elementary particles than those constituting more standardly accepted physical objects). These examples indicate that traditionally acknowledged features such as impenetrability fail to serve as working criteria for physicality. Some physical objects are penetrable or massless; others are even composed of a different kind of stuff than that which constitutes the conventional type of physical object. These examples stand in tension with the ontological doctrine of physicalism that all matter is composed of the same (physical) kind of stuff. The foregoing challenge to this monistic, constitutional doctrine of physicalism, however, hardly gives support to Cartesian dualism, but is instead a critical reflection, emerging within physicalism, on the true nature of reality. In the face of the body-problem, physicalists might try to defend their thesis that everything that exists is physically constituted by appealing to the causal argument for physicalism, which runs as follows: (1) any physical effect is fully determined by a prior physical history in accordance with physical laws; (2) all mental occurrences have relevant physical effects; (3) their physical effects are not overdetermined; (4) therefore, mental occurrences must be identified with physical occurrences. But how are we to know what ‘physical’ causes, effects, and laws are if what counts as being physical has not yet been spelled out? The body-problem points out that we do not actually understand what property (or properties) is (or are) referred to when we use the term ‘physical’. If one defines ‘physics’ as the theory currently taught in university physics departments, then premise (1) of the causal argument is highly questionable, as our current physics is almost certainly not complete. If one defines it instead as some ideal future theory that will succeed our current physics, then, as Papineau (1993, 30) claims, one ‘seems to remove any significant content from the thesis of [causal] completeness, and thereby to make it doubtful that the thesis could have any substantial conclusions’. On this approach, physicalism would turn out to be an empty analyticity.9 (Granted, physicalism so-conceived would not be entirely vacuous, since it would at least claim that there is something real, but this claim is the bare minimum that any realist could make.) In reference to James Maxwell’s remark that our ignorance is a prelude to every real advance in knowledge, Galen Strawson (1994) coined the term ‘agnostic materialism’ to describe his position that our current ignorance of the nature of the physical is due solely to the fact that our current physics is not yet complete, in that some of the physical laws needed to explain certain physical events have yet to be discovered or fully understood. Agnostic materialism, however, would still not provide a satisfactory answer to Montero’s question. Although agnostic materialism concedes that our knowledge cannot explain all phenomena, it does not seriously address the question of what the intrinsic properties of things

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are. Agnostic materialists might admit that there are some features of the physical world of which we are presently ignorant, but they would not accept that this sort of ignorance poses a serious philosophical problem. Their agnosticism is an agnosticism of ‘width’—it is simply a confession of ignorance of certain empirical facts concerning the workings of the physical world. In the Essay, Locke sometimes discusses the width issue: e.g., ‘I doubt . . . whether we can come to the discovery of most of theses powers [of substances]’ (IV.iii.16). The main type of epistemic humility espoused by Locke, however, is an agnosticism of ‘depth’, which acknowledges a more basic and incurable ignorance of the fundamental nature that underlies the particular objects and qualities that make up the world. The following is an example of the depth type of epistemic humility with regard to power: ‘[w]e cannot by any means come to discover’ the ‘Subject’ or ‘Essence’ that ‘[the powers] are in’ and ‘the way of operating’ of the ‘Active and Passive Powers of Bodies’ (IV.iii.16). Increasing sensitivity to the depth issue has generated some critical reflections on the ontological doctrine of physicalism and the bodyproblem, even among present-day physicalists. As mentioned earlier in the Introduction, what is original about Locke’s treatment of materialism is his approach in criticizing the ontological doctrine that the world is physically constituted. He does not add any nonphysical entities to the world (whether substances or properties) but instead takes the physical to be only a nominally basic category. For him, the statement ‘x is solid and extended’ is only nominally true: what makes it true is x’s observable functional role of resisting the approach of other objects into its occupied space. Even in a possible world where the same role is realized by a different type of substratum, the statement ‘x is solid’ would still be true insofar as x plays the same role. The ground of materialism—as an ontological doctrine—thus turns out to be tenuous. For given that all one can know about physical objects are their functional roles, their true nature remains in principle inaccessible to us. We shall return to this point in Chapter 3 in which we explore Locke’s epistemic humility at length.

3.

Locke and Substance Dualism

Locke’s mind-body distinction is only nominal in that it applies only at the level of our ‘Ideas, the one of Body, the other of our Minds’ (II.xxiii.28). The ‘primary Ideas’ of body and spirit, ‘contradistinguished’ (II.xxiii.17), represent two distinct perspectives from which to view the world: The primary Ideas we have peculiar to Body, as contradistinguished to Spirit, are the cohesion of solid, and consequently separable parts, and a power of communicating motion by impulse. (II.xxiii.17) The Ideas we have belonging, and peculiar to Spirit, are Thinking, and Will, or a power of putting Body into motion by Thought, and, which is consequent to it, Liberty. (II.xxiii.18)

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The following passages from II.xxiii further exemplify Locke’s commitment to this strictly nominal form of dualism: ‘[w]e have as many, and clear Ideas belonging to Spirit, as we have belonging to Body’ (II.xxiii.5); ‘[w]e have as clear a Notion of the Substance of Spirit, as we have of Body’ (II. xxiii.28); ‘[t]he one is as clear and distinct an Idea, as the other: The Idea of Thinking, and moving a Body, being as clear and distinct Ideas, as the Ideas of Extension, Solidity, and being moved’ (II.xxiii.15); ‘[t]he Idea which belongs to Spirit, is at least as clear, as that that belongs to Body’ (II.xxiii.28); and ‘[t]hese Ideas, the one of Body, the other of our Minds, every day[’]s experience clearly furnishes us with’ (II.xxiii.28).10 The complex ideas of mind and body ultimately depend respectively on simple ideas of reflection and simple ideas of sensation. These two sorts of simple ideas are provided by the two disparate modes of experience, sensation and reflection: ‘[t]hese two, I say, viz. External, Material things, as the Objects of SENSATION; and the Operations of our own Minds within, as the Object of REFLECTION, are, to me, the only Originals, from whence all our Ideas take their beginnings’ (II.i.4). Here Locke distinguishes between the two disparate modes of experience by appeal to their ‘Objects’. The simple ideas of sensation (such as those of colors, smells, tastes, and sounds) are caused by ‘External, Material things’ (II.1.4) and ‘represent’ (IV.iv.4) them. In that way, sensation is about ‘External, Material things’, in that they are the ‘objects’ of sensation. As Locke puts it, such ideas of sensation ‘represent to us Things under those appearances which they are fitted to produce to us’ (IV.iv.4). ‘[S]imple Ideas [of sensation] are [thus] not fictions of our Fancies, but the natural and regular productions of Things without us, really operating upon us; and so carry with them all the conformity which is intended; or which our state requires’ (IV.iv.4). In this way, the simple ideas of sensation link us to external objects in the world by enabling us to identify material substances, ‘discern the states they are in’, ‘take them for our Necessities, and apply them to our Uses’ (IV.iv.4).11 In contrast, reflection is a faculty by which one perceives the operations of one’s own mind: ‘[t]he term Operations here, I use in a large sense, as comprehending not barely the Actions of the Mind about its Ideas, but some sort of Passions arising sometimes from them, such as is the satisfaction or uneasiness arising from any thought’ (II.1.4). The simple ideas of reflection do not represent the external word in the way that those of sensation do, ‘having nothing to do with external Objects’ (II.1.4). The main function of reflection is to observe the ‘manner’ (II.i.4) of the operation of the mind as well as the occurrence of some passion, such as satisfaction and uneasiness. With regard to reflection, Locke does not use the term ‘represent’ but ‘notice’—‘which the Mind takes of its own Operations, and the manner of them, by reason whereof, there come to be Ideas of these Operations in the Understanding’ (II.1.4). For this reason, Locke takes the ideas of reflection to be ‘distinct Ideas’ from those of sensation that ‘we [receive] from Bodies affecting our Senses’. Whereas the objects of sensation involve the ‘things’ or ‘substances’ that

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have causal power over the mind in the production of certain sensations in it, those of reflection involve the ‘manner’ of the operation of the mind, i.e. ‘actions of our own Minds’ such as ‘Perception, Thinking, Doubting, Believing, Reasoning, Knowing, Willing’ that ‘we [are] conscious of, and observ[e] in our selves’ (II.i.4). Thus, the meaning of ‘objects’ of reflection is different from those of sensation. For this reason, Locke holds that reflection provides ‘another set of Ideas’ (II.i.4). Although he does not further expound in this section upon the difference between these two types of simple ideas, his contention that reflection furnishes us with ‘another set of Ideas’ suggests that we derive from reflection an entirely new perspective that enables us to view another aspect of the world than its material aspect—namely, mental perspective. Each aspect is taken to be ‘an equal view of both parts of nature, the Corporeal and Spiritual’ (II.xxiii.15). Locke’s mind-body nominalism is the view that one acquires such a dualistic perspective on the world by forming the ‘primary Ideas’ of the distinct categories of mind and body. These ideas are ‘primary’ in that each represents a conceptually basic category; neither type of idea is explicable in terms of the other. Locke thus suggests that it may ‘be a Reason to prove, that Spirit is different from Body, [that] Thinking includes not the Idea of Extension in it’ (II.xiii.11).12 Locke also refers to the primary ideas of body and spirit as ‘superficial Ideas of things’ (II.xxiii.32), meaning that (like all abstract ideas) they involve an incomplete and partial consideration of the objects that they are ideas of, and thereby only represent a certain aspect of those things, not their ‘true Nature’ in its entirety. The ‘incomplete and partial’ nature of our primary ideas of body and spirit is, according to Locke, something [w]hich we are not at all to wonder at, since we having but some few superficial Ideas of things, discovered to us only by the Senses from without, or by the Mind, reflecting on what it experiments in it self within, have no Knowledge beyond that, much less of the internal Constitution, and true Nature of things, being destitute of Faculties to attain it. (II.xxiii.32) Thus, neither type of idea (of mind or of body) can represent the ‘true Nature of things’. In other words, under ‘the Idea of Body’, things are described using physical predicates, such as sized, shaped, solid, fragile, heavier than, faster than, longer than, etc., whereas under ‘the Idea of Spirit’, things are described using mental predicates, such as think, believe, hope, expect, and so on. No amount of knowledge about either set of predicates would enable us to be aware of the ‘true Nature of things’. This nominalistic form of dualism advocated by Locke contrasts sharply with Descartes’ account of ‘principal properties’ or ‘attributes’. According to Descartes, each substance has a principal property (either

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extension or thought) that (solely and wholly) constitutes its nature: ‘[t]o each substance there belongs one principal attribute; in the case of mind, this is thought, and in this case of body it is extension’ (CSM I, 210). Corporeal modes (e.g. shape, size, and motion) ‘presuppose’ the attribute of extension, and mental modes (e.g. sensation, imagination, and will) ‘presuppose’ the attribute of thought, so that ‘it is possible to understand extension without shape or movement, and thought without imagination or sensation, and so on’ (CSM I, 211), but it is impossible to understand a mode without presupposing its relevant attribute: e.g. ‘shape is unintelligible except in an extended thing; and motion is unintelligible except as motion in an extended space’; likewise, ‘imagination, sensation and will are intelligible only in a thinking thing’ (CSM I, 210–11). Descartes justifies the ascription of such a privileged status to the attributes by appeal to the clarity and distinctness of our (innate) idea of each attribute: ‘we can easily have two clear and distinct notions or ideas, one of created thinking substance, and the other of corporeal substance’ (CSM I, 211). From the clarity and distinctness of our understanding of the nature of the attributes, Descartes draws his substance dualism: ‘it is certain that I am really distinct from my body, and can exist without it’ (CSM II, 54). He ultimately identifies each attribute with a substance to which it belongs: ‘[t]hought and extension can be regarded as constituting the nature of intelligent substance and corporeal substance; they must then be considered as nothing else but thinking substance itself and extended substance itself—that is, as mind and body’ (CSM I, 215). By contrast, Locke takes a substance merely as a ‘thing’ that is ‘supposed always something’—‘though we know not what it is’. In the following passage, extension and thought are deprived of the privileged status that they enjoy in Descartes’ system: [W]hen we speak of any sort of Substance, we say it is a thing having such or such Qualities, as Body is a thing that is extended, figured, and capable of Motion; a Spirit is a thing capable of thinking; and so Hardness, Friability, and Power to draw Iron, we say, are Qualities to be found in a Loadstone. These, and the like fashions of speaking intimate, that the Substance is supposed always something besides the Extension, Figure, Solidity, Motion, Thinking, or other observable Ideas, though we know not what it is. (II.xxiii.3) Locke treats those qualities just listed—e.g. ‘Extension, Figure, Solidity, Motion, Thinking’—as equally apparent features of the substance, though there may be some conceptual entailments among some of them (e.g. the idea of solidity entails that of figure but not vice versa, as all solid bodies are figured but plane figures are not solid). Locke takes them to be predicates equally applicable to the supposed substance—‘though we know not what it is’—that he assumes can exist ‘besides’ any such

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qualities. In his statement that ‘Body is a thing that is extended, figured, and capable of Motion’, no privileged status is given to extension; the supposed thing is ‘extended’ insofar as it satisfies the idea of extension, not in the Cartesian sense that extension constitutes its entire nature. Locke even holds that the unknown substance is something ‘besides the Extension . . . [and] Thinking’ that it exemplifies. Bennett (1971) has suggested a bare substratum reading of Locke’s theory of substance, according to which the substance—‘besides’ extension and thought—is taken as a naked entity. On this reading, ‘x besides p’ would mean that x is deprived of p and thus a p-less entity. Given this account of ‘besides’, the substance ‘besides’ extension and thought would be an extension-less and thought-less entity that nevertheless underlies these two attributes. However, x’s being deprived of those qualities need not entail that it is bare or naked in nature. We shall hence discredit the bare substratum reading in Chapter 6. As an alternative to Bennett’s reading, Bermúdez (1996, 227) holds that Locke is here merely drawing attention to the tenuous basis for Cartesian references to thinking substance and material substance. This reading may be right, but Locke seems to me to be making a far more specific and positive point.13 In this regard, consider Ayers’ (1975, 12) observation on the preceding cited passage from II.xxiii.3: ‘[i]ndeed talk of such a support or thing having phenomenal properties can only be interpreted intelligibly as alluding to this unknown intrinsic nature which is causally responsible for the relational, phenomenal properties, i.e., for the effect of the substance upon us and on other things’. By alluding to the supposed (unknown) thing, Ayers notes, those predicated qualities ‘can only be interpreted intelligibly’ as properties that the supposed thing serves as the causal basis for. Though its true nature is unknown, the supposed thing that exists—‘besides’ extension and thought—is assigned a certain role in being made responsible for the instantiated qualities that are predicated of it. Building upon Ayers’ reading, I propose that the supposed substance—‘besides’ p—underlies p by virtue of its playing the p-ness role, where p-ness is taken to be the substance’s nominal essence. This unknown substance—which is posited as something ‘besides’ extension, e.g.—is observationally extended, insofar as it is observed as satisfying those descriptions that are grouped together under the idea of extension, but its nature is not identified with extension in the Cartesian manner; in other words, the unknown substance occupies the p-ness role but p-ness does not constitute its nature. By observing the role played, we can talk about the role-player, but only as the supposed something that plays it. To describe the situation ‘intelligibly’, we must say that the role is played by something. For without supposing a role-player, one cannot make the notion of ‘role’ intelligible. Yet we must confess that we do not know what the thing that plays the role is intrinsically, besides the role it plays.

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In the preceding cited passage from II.xxiii.3, Locke discusses individual substances of certain kinds (i.e. iron and loadstone) and more general kinds (i.e. minds and bodies). The examples listed include both physical and mental predicates: extended, figured, capable of Motion, capable of thinking, putting a body in motion, and so on. Whatever counts as of the body-kind does so by virtue of satisfying the set of descriptions spelled out in the ‘primary Ideas’ of the body. Consequently, to say that x is a body is to say simply that when acted upon, x would resist the approach of other bodies into the space it already occupies and would be moved when the approaching body’s force is greater than that which it has. Likewise, a thing counts as of a spirit-kind by virtue of satisfying the set of descriptions spelled out in the ‘primary Ideas’ of the spirit. To say that x is a spirit is therefore to say simply that x is capable of thinking, willing, and putting the body into motion by thought. It follows from these nominal definitions that when one says ‘x is physical’, the predicate ‘physical’ refers solely to the manner in which x acts or functions. The same holds likewise for the predicate ‘thinking’; when one says that ‘x is thinking’, the predicate ‘thinking’ is also concerned only with how x acts or functions. These functional statements remain true regardless of whatever (unknown) constitution satisfies the relevant functions, as they take no account of the intrinsic nature of the entities that satisfy the relevant functions. Accordingly, when one says ‘the mind is physical’, the logical structure of this statement implies that x is both mental and physical, since both ‘mind’ and ‘physical’ characterize how the thing referred to functions. The ‘is’ here can be said to link the two distinctive nominal realms of mentality and materiality, and is thus not intended to specify the real nature of any substance. Since nominal essence, whether mental or physical, involves no reference to reality, we are here presented only with a statement linking the two types of ‘superficial Ideas’ of the ‘true Nature’ of things.

4.

Locke and Property Dualism

In recent times, property dualism has emerged as a popular alternative to physicalism. It differs from both physicalism and substance dualism in that it allows for the existence of nonphysical properties within the physical world without invoking nonphysical substances. Frank Jackson’s (1982) thought experiment involving the scientist Mary presents a classic argument for the view. In his thought experiment, Mary is a hypothetical person who has complete knowledge of color in its theoretical (physical) dimension, but not in terms of the phenomenal or qualitative content of perception. Mary is a neurophysiologist, raised and educated in a perceptually isolated world—namely, a black-and-white room, where she is not allowed to perceive real colors and can only view the world through a black-and-white monitor: her body has been dyed gray, and she

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is given only black-and-white clothes to wear. One day, Mary is released from the room and perceives real colors. What will happen to Mary, then, when she first encounters a red tomato? According to Jackson, Mary will learn something new that was not contained in her complete physical knowledge. When she perceives a tomato after her release, the phenomenal character of her experience of its color is not something that she could have expected on the basis of her physical knowledge. Jackson’s claim is that these new perceptual items—i.e. qualia—that Mary encounters do not essentially belong to the physical world. He concludes that there are consequently certain nonphysical items in the physical world, and that physicalism is therefore false. In the Essay, Locke describes a case parallel to that of Jackson’s Mary. His example is a ‘Child kept in a place, where he never saw any other but Black and White’: Light, and Colour, are busie at hand every where, when the Eye is but open: Sounds, and some tangible Qualities fail not to solicite their proper Senses, and force an entrance to the Mind; but yet, I think, it will be granted easily, That if a Child were kept in a place, where he never saw any other but Black and White, till he were a Man, he would have no more Ideas of Scarlet or Green, than he that from his Childhood never tasted an Oyster, or a Pine-Apple, has of those particular Relishes. (II.i.6) This passage is about simple ideas of sensation, which we typically identify by the phenomenal character of our sensory experience. Locke, however, does not take simple ideas of sensation or the case of the child to pose a counterexample to materialism in the way that Jackson does. In places where Locke discusses simple ideas of sensation, he only takes them as materials of knowledge about the external world, not as items that might trouble us in regard to their relation to physical states or properties. The reading of Locke as a property dualist has a long history. The ancestry of this interpretation can be traced to Leibniz’s critique of what Locke refers to as the ‘superadded’ power of thought: ‘[t]o speak of sheerly “giving” or “granting” powers is to return to the bare faculties of the Scholastics, and to entertain a picture of little subsistent beings which can fly in and out like pigeons with a dovecote’ (NE, IV.iii.6: 379). Leibniz conceives of the ‘superadded’ powers of thought as ‘accidents which are not “ways of being” or modifications arising from substances’ (NE, IV.iii.6: 379). Leibniz has Philalethes (Locke’s spokesman in the New Essays) state that ‘we are not naturally sensible, thinking and immortal’ but ‘only through a miracle’ (NE, IV.iii.6: 380).14 Margaret Wilson’s (1979) reading of Locke’s stance on this issue can be viewed as a modern descendent of the Leibnizian interpretation. Wilson (1979, 144) argues that there is a conflict between Locke’s account of superaddition and his ‘official’ Boylean hypothesis that all the powers of a body flow from the primary

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qualities of its insensible particles: ‘I will argue that, his official position notwithstanding, Locke does not consistently maintain that all a body’s properties stand in comprehensible or conceivable relations to its Boylean “primary qualities”, or can be said to flow from them’. Wilson’s reading of Locke is premised on the following two claims: (1) the superadded properties Locke refers to cannot be conceived as natural consequences of the Boylean primary qualities; and (2) the superadded properties cannot be such consequences. Wilson contends that Locke is committed to (2), which is equivalent to ‘the irreducibility of the mental’, a thesis recently elaborated and attributed to Locke by Pyle (2013) and Stuart (2013). We shall examine these property dualist readings in Chapter 4. In the opening sections of Book I of the Essay, Locke proclaims that the aim of the Essay is ‘to enquire into the Original, Certainty, and Extent of human Knowledge; together, with the Grounds and Degrees of Belief, Opinion, and Assent’ (I.i.2). In the same section, he mentions the ‘Physical Consideration of the Mind’ as follows: I shall not at present meddle with the Physical Constitution of the Mind; or trouble my self to examine, wherein its Essence consists, or by what Motions of our Spirits, or Alternations of our Bodies, we come to have any Sensation by our Organs, or any Idea in our Understandings; and whether those Ideas do in their Formation, any, or all of them, depend on Matter, or no. These are Speculations, which, however curious and entertaining, I shall decline, as lying out of my Way, in the Design I am now upon. (I.i.2) Here Locke is addressing what we nowadays call the ‘hard problem’ of consciousness, i.e. the fact that while ‘[i]t is widely agreed that experience arises from a physical basis, . . . we [nevertheless] have no good explanation of why and how it so arises’ (Chalmers 1995, 201). In the preceding quotation, however, Locke ‘decline[s]’ to examine the problem of the ‘Physical Constitution of the Mind’ or investigate why and how conscious experience arises from a physical basis, on the grounds that it lies ‘out of [his] Way’. Locke’s mind-body nominalism entails that the duality of mind and body is a product of their nominal essences. This may be why Locke sees no reason to ‘trouble [himself] to examine’ the mind-body problem. For him, it is more productive to ‘enquire into the Original’ of the ideas of mind and body. That is, the resolution of the mind-body problem should be part of a general enquiry into the origins or grounds of human knowledge, beliefs, and opinions.15 From this point of view, we shall explore Locke’s nominal dualism, as distinguished from property dualism, in the following chapter. Locke’s distinction between nominal and real essence, as applied to ordinary natural kinds, can be viewed as one of the most systematic criticisms of scholastic essentialism. When applied to the categories

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of materiality and mentality, however, this distinction can be seen as presenting a trenchant criticism of the contemporary mechanical doctrines of Cartesianism and materialism as well. There are thus two ways in which Locke’s theory of nominal essence can be evaluated: first, as one of the mechanist theories developed in reaction to scholastic essentialism, and second, as an original and novel critique of other contemporary mechanist doctrines. Whereas the first of these two readings of Locke’s theory of nominal essence is fairly familiar, the second has been relatively underappreciated thus far. It is this latter aspect of Locke’s theory of nominal essence that provides the basis for the novel response to the mind-body problem, referred to as ‘mind-body nominalism’ in this book. The next chapter examines this neglected aspect of Locke’s Essay in greater detail.

Notes 1. See Lennon (1993) for a comparative study of Descartes’ and Gassendi’s mechanical conceptions of matter and related topics. 2. Aquinas (1949, 30) wrote that ‘form and matter are found in composite substance, for example, soul and body in man. It cannot be said, however, that either one of them alone is called essence’. Although Aquinas divided substances into divine, spiritual, and material kinds, he admitted that the soul was still not completely free from matter, but bound to it. 3. In the chapter on solidity in the Essay, Locke further remarks that: ‘[t]he two flat sides of two pieces of Marble, will more easily approach each other, between which there is nothing but Water or Air, than if there be a Diamond between them; yet it is not, that the parts of the Diamond are more solid than those of Water, or resist more’ (II.iv.4). The reason the two pieces of marble can more easily approach each other is simply that ‘the parts of water’ are more easily separable and thus more easily removed. But if the water were still positioned between them, the two pieces of marble could not possibly touch each other completely. The drops of water would ‘eternally hinder the approach of these two pieces of Marble, as much as the Diamond’; and it would be ‘as impossible by any force, to surmount their Resistance, as to surmount the Resistance of the parts of a Diamond’ (II.iv.4). What makes a material body ‘eternally hinder’ the approach of other bodies into the place it occupies? Ultimately, what makes each particle exert the power of resistance when approached by other bodies? Locke takes solidity as the most fundamental feature of materiality. But according to his epistemic humility, one can only know about its functional role, not the intrinsic property of the occupant of that role. We know that every physical object acts so, but not what makes them so. 4. Locke even contrasts physical bodies and empty space in terms of their ideas: ‘[the Idea of solidity] belongs to Body, whereby we conceive it to fill space. The Idea of which filling of space, is, That where we imagine any space taken up by a solid Substance’ (II.iv.2) and ‘our Idea of Solidity is distinguished . . . from pure space, which is capable neither of Resistance nor Motion’ (II. iv.3). The following statement evidently shows that the distinction between body and space is, for Locke, strictly nominal: ‘Space is not Body, because it includes not the Idea of Solidity in it’ (II.xiii.11). We shall examine these passages in Chapter 3.

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5. If, however, the property that plays the solidity-role is forever unknown to us, how does this square with Locke’s view that since solidity is a primary quality, our idea of solidity must ‘resemble’ (II.viii.15) the actual quality of solidity as it exists in objects? For Locke, there are two different types of ideas of solidity, as we shall explore in Chapter 7. First, we observe the solidity of ordinary-sized objects by touch. That is, we have the simple idea of solidity when we perceive them. Yet when it comes to the insensible atoms beyond the scope of ordinary observation, one can no longer rely on sensory ideas in order to identify their solidity. As regards ordinary-sized objects, one can say that what one sees as being square, e.g., really exists outside of one’s mind as being square. However, this pictorial type of resemblance that obtains between ordinary-sized objects and our sensory ideas does not also apply to minute particles. In Book IV of the Essay, Locke takes a more moderate stance on the primary qualities of the basic particles: ‘our want of precise distinct Ideas of their [the insensible Corpuscles’] primary Qualities, keeps us in an incurable Ignorance of what we desire to know about them’ (IV. iii.25). Given this dual treatment of primary qualities as possessed by micro and macro objects, the meaning of ‘resemblance’ in relation to our ideas of such qualities must depend upon what kind of objects (macro or micro) we are applying these ideas to. The way in which our idea of the solidity of a minute particle corresponds with that particle will thus be different from the way in which our idea of the solidity of a macroscopic object corresponds with that object. As we shall see in Chapter 7, typical examples of the primary qualities such as shape and size are no longer applicable to the active atoms postulated by eighteenth-century dynamic theories of matter. Priestley (1777) regards Locke as a forerunner of the new movement in the century’s natural philosophy, in which the distinction between primary and secondary qualities is eliminated, as the fundamental objects are taken to be inherently dispositional. Assessing the dynamic realists’ commentary on Locke, Chapter 7 investigates his distinction between primary and secondary qualities, as well as its relevance to the functionalist view of solidity that I attribute to him. 6. For a brief history of this shift in the 1950s and 60s, see Papineau (2000, 175–7). 7. Mind-brain identity theorists of the twentieth century, such as Place (1956) and Smart (1959), also elaborated upon the constitutional doctrine of materialism. When they say that the mind is the brain, their use of ‘is’ is in terms of the ‘is’ of composition, as in the following examples used by Place (1956, 45): ‘her hat is a bundle of straw tied together with string’; and ‘a cloud is a mass of water droplets or other particles in suspension’. By contrast, the ‘is’ in the following statements is the ‘is’ of definition: ‘a bachelor is an unmarried man’; and ‘a square is an equilateral rectangle’. Unlike this second type of identity, which is analytically true, the first type (employing the ‘is’ of composition) is discovered a posteriori. To recognize that a cloud is composed of a mass of water droplets (or that water is composed of oxygen and hydrogen), one must investigate, search, and engage with the real world. Through this empirical activity, one comes to discover a law bridging the macro and micro levels of experience. The same is true of the mind-body identity statement endorsed by Smart and Place. The reductive materialism or type identity theory that they advocate is committed to the following theses: first, mind-body identity is supported by laws linking mental and physical phenomena; and second, the mind is reducible to something physically constituted. 8. Crane and Mellor (1990) also raise this sort of issue with physicalism.

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9. In the face of this problem, Papineau (1993, 30) proposes to appeal to some ‘pre-theoretically given class of paradigmatic physical effects, such as stones falling, the matter in our arms moving, and so on’. If we take this class to be given pre-theoretically, on his account, then we can effectively characterize the rest of physics as all the categories that need to be brought in to explain these paradigmatic effects. Jackson’s ‘ostensive definition’ of physical things is similar to this proposal. Jackson (1998, 7) claims that physicalists can give a definition of ‘physical’ by pointing to ‘some exemplars of nonsentient objects such as tables, chairs, mountains, and the like’. That is, by ‘physical’ properties and relations, physicalists mean the kind of properties and relations needed to give a complete account of things like them. Stated in these terms, physicalism is clearly meant as a non-trivial claim. But this proposal, too, would still leave us with the body-problem, insofar as our conscious experience of such ordinary-sized objects would not reveal the true nature of materiality either. 10. In the chapter on the complex ideas of substances (II.xxiii), Locke spells out how one obtains the complex ideas of the spirit and body as nominal entities: ‘we are able to frame the complex Idea of an immaterial Spirit . . . by putting together the Ideas of Thinking and Willing, or the Power of moving or quieting corporeal Motion’; and ‘by putting together the Ideas of coherent solid parts, and a power of being moved . . . we have the Idea of Matter’ (II.xxiii.15). In the same chapter, Locke also provides a detailed description of the processes through which these two types of ideas—the ideas of the spirit and matter—are formed. When Locke says that ‘the complex Idea of an immaterial Spirit’ is formed through our internal observation, the term ‘an immaterial Spirit’ does not refer to a Cartesian type of soul, but rather to a nominal entity, as we shall see in Chapter 2 by examining more passages wherein the term appears. 11. Locke divides our knowledge into three categories: intuitive, demonstrative, and sensitive. In contrast to intuitive and demonstrative knowledge, sensitive knowledge is concerned with ‘the particular existence of finite Beings without us’ (IV.ii.14). Although this type of knowledge goes ‘beyond bare probability’ (IV.ii.14), Locke concedes that it does not reach ‘perfectly to either of the foregoing degrees of certainty’, i.e. intuition and demonstration (IV.ii.14). Yet Locke maintains that sensitive knowledge still deserves ‘the name of Knowledge’ (IV.ii.14). Unlike intuitive and demonstrative knowledge, sensitive knowledge is concerned with ‘actual real Existence agreeing to an Idea’ (IV.i.7). However, what guarantees that our simple ideas of sensation correspond with external objects in such a way as to enable sensory ideas to provide us with knowledge of the external world? On Locke’s account, simple ideas are ‘only constant Effects’ caused by external objects so as to stand ‘in that steady correspondence’ (II.xxx.2) with them. This regular correspondence between our ideas of sensation and their external causes is what provides the basis for sensitive knowledge: ‘whether they answer to those Constitutions, as to Causes, or Patterns, it matters not; it suffices, that they are constantly produced by them’ (II.xxx.2). One might still wonder whether this account successfully answers the question raised earlier as to what guarantees the correspondence between our simple ideas of sensation and external objects. An idealist might thus wonder how we can be sure that there is in fact any such correlation between them at all, noting that Locke concedes that sensitive knowledge cannot go ‘beyond bare probability’ (IV.ii.14). In the preceding quotations Locke seems to provide some externalist justification for sensitive knowledge. Bolton (2004) argues that Locke’s account on this

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12.

13.

14.

15.

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issue is ‘roughly reliabilist’. Recently, Allen (2013) and Weinberg (2016) have proposed that Locke’s conception of sensitive knowledge includes an internalist form of justification. On the basis of this observation, Locke goes on to provide a unified nominalist account of the three categories of body, space, and spirit: ‘[t]he same Reason will be as valid, I suppose, to prove that Space is not Body, because it includes not the Idea of Solidity in it; Space and Solidity being as distinct Ideas, as Thinking and Extension, and as wholly separable in the Mind one from another’ (II.xiii.11). We shall return to this issue in Chapter 3. Alternatively, one might think that Locke is here just speaking of laypeople’s notion of substance. As Newman (2000, 306) notes, however, ‘in ordinary usage, such ways of speaking need not imply that the said thing/subject is unobserved’. Leibniz further holds that Locke’s account of the superadded must ‘have recourse to miracles and to what the Scholastics used to call “obediential power”’ (NE, IV.iii.6: 379). As a result, Leibniz argues, Locke’s account of ‘the union of soul with body, or the joining of sensation with matter’ is incomprehensible (NE, IV.iii.6: 380). Leibniz thus levels two charges against Locke: first, that he is a materialist (as we saw in the Introduction); and second, that he renders the power of thought inexplicable. Leibniz hence attributes a special kind of materialism to Locke, which might be described as a kind of ‘non-reductive materialism’. When Locke states in the preceding cited passage that we do not know ‘wherein [the mind’s] Essence consists’, this should not be understood as a blindly agnostic stance that suspends any sort of metaphysical decision on the nature of mind. As we shall explore in Chapter 3, Locke’s epistemic humility is directed towards the intrinsic properties of the ‘greatest Instruments of Nature’, i.e. the basic physical particles. Our inability to resolve the mindbody problem, on his account, can be explained by reference to the fact that the secrets of the basic physical particles remain inaccessible to us so long as we are subject to the dualistic conception of nature generated by our ideas of mind and body, neither of which accurately represents the ‘true Nature of things’ (II.xxiii.32).

2

Mind-Body Nominalism

This chapter further examines Locke’s mind-body nominalism, which the preceding chapter discussed rather briefly in comparison to the major doctrines of materialism, substance dualism, and property dualism. We shall begin by considering the historical background of Locke’s theory of nominal essence and analyzing the textual details of his mind-body nominalism, as well as his use of the term ‘immaterial spirit’. This chapter also considers some parallels between Locke’s mind-body nominalism and Davidson’s anomalous monism. Davidson’s brand of non-reductivism can be viewed as a modern form of the nominal symmetry advocated in Locke’s Essay, in which mentality and physicality are both conceived as descriptive categories. As a modern mind-body nominalist, Davidson also understands these categories in terms of our descriptions of ‘events’ (i.e. unrepeatable particulars, each of which occurs at a specific time) such that each event acquires its status as mental or physical by virtue of being described in a certain manner. In contrast to Locke, however, Davidson’s more linguistically oriented approach refrains from addressing the deeper issue of what the intrinsic nature of a particular is beyond the descriptions that are applied to it. Our discussion of Davidson in relation to Locke’s mind-body nominalism will hence further illuminate the novelty of Locke’s approach as well as its relevance to recent debates in the philosophy of mind.

1.

Nominal Essence

In Book III of the Essay, ‘Of Words’, Locke draws his famous distinction between nominal and real essence. At the outset of Chapter iii, ‘Of General Terms’, he puts forward as an ontological axiom that ‘[a]ll Things that exist [are] Particulars’ (III.iii.1). While ‘particularism’ or ‘individualism’ might seem like the most natural label for this position, the view expressed in this quote is instead typically referred to as ‘nominalism’ (a term which derives from the Latin ‘nomen’, meaning ‘name’). The following statement provides the justification for this nomenclature: ‘General and Universal, belong not to the real existence of Things; but

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are the Inventions and Creatures of the Understanding, made by it for its own use, and concern only Signs, whether Words, or Ideas’ (III.iii.11). Here Locke presents a critical alternative to medieval realistic theories of universals, whether Platonic or Aristotelian. According to the realists, a group of particulars belong to the same kind in virtue of their sharing a universal entity (whether transcendent or immanent), which is eternal, immutable, and the cause of the set of qualities that each substance of the kind displays. For the scholastic Aristotelians, an individual substance was thought to consist in the union of a substantial form with materia prima. Locke expresses his opposition to this scholastic doctrine as follows: ‘[w]hen I am told, that something besides the Figure, Size, and Posture of the solid Parts of that Body, is its Essence, something called substantial form, of that, I confess, I have no Idea at all, but only of the sound Form; which is far enough from an Idea of its real Essence, or Constitution’ (II.xxxi.6). For Locke, kinds or sorts ‘concern only Signs, whether Words, or Ideas’ (III.iii.11). Words (i.e. linguistic signs) are ‘general when used, for Signs of general Ideas’; and ideas (i.e. mental signs) are ‘general, when they are set up, as the Representatives of many particular Things’. Whether conventional or natural, signs can be universal only in ‘their signification’; they themselves are particulars ‘in their Existence’ (III.iii.11). Certainly Locke does not think that universals are only names; they are also taken as ideas or concepts, as noted in the quote just cited. It is on these grounds that Woolhouse (1971, 102) describes Locke as a ‘conceptualist’ about universals. Yet Locke would not regard universals as only concepts either. So the term ‘conceptualism’ is not an apt label for Locke’s position. Alternatively, one might call Locke a ‘conventionalist’ about universals, noting that signs are conventional. Yet only linguistic signs (words) are entirely conventional; mental signs (ideas or concepts), in contrast, are ‘natural’ in that the complex abstract ideas that serve as internal signs for various kinds are formed though our naturally given faculties. Thus neither term fully captures Locke’s position with regard to universals. Justification for calling Locke a ‘nominalist’ can, however, be derived from the following quote from John Milton (1981, 129–30): The school usually described by historians as nominalist, that of William of Ockham and his successors, most certainly did not regard universals as mere names. It seems to me better to use the name ‘nominalism’ simply as a label for the historically more important position [that everything that exists is an individual], and thus bring [Locke’s] usage into line with the historian’s. It is not by any means an ideal name; ‘particularism’ or ‘individualism’ would be much better, but it is probably too late to introduce either. At any rate, in what follows the term ‘nominalism’ will be used for the view that everything that exists is an individual.

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Against nominalists such as Locke, the scholastics maintained that each individual substance has as its major component a substantial form that is (1) general, (2) immutable, and (3) the cause of the bundle of qualities that the substance it belongs to regularly displays. By contrast, Locke does not allow that anything has these three features simultaneously, and instead distributes them into two sorts of essence: nominal and real. (1) and (2) are ascribed to the nominal essence of a substance, while (3) is attributed to its real essence. The ascription of traits (1) and (2) to nominal essences can be explained as follows. Once agreed upon by members of society, the meaning of a name (which constitutes the nominal essence of the name’s referent) acquires universality or generality in terms of its semantic function of denoting a certain plurality of particulars. Nominal essences can also be said to be ‘immutable’ (III.vi.6) or ‘remain steadily the same whatever mutations the particular Substances are liable to’ (III.iii.19), in that, e.g., ‘whatever becomes of Alexander and Bucephalus, the Ideas to which Man and Horse are annexed, are supposed nevertheless to remain the same . . . as long as the same Name [to which the same abstract Idea is attached] can have the same signification’ (III.iii.19). It is thus to nominal essences alone that Locke applies the ‘Doctrine of the Immutability of Essences’ (III.iii.19). Here Locke differs from the scholastics in taking not only universality but also immutability as semantic features, rather than as metaphysical ones. By contrast, what Locke calls ‘real essence’ suffers constant physical change over time: Thus that, which was Grass to Day, is to Morrow the Flesh of a Sheep; and within few days after, becomes part of a Man: In all which, and the like Changes, ’tis evident, their real Essence, i.e. that Constitution, whereon the Properties of these several things depended, is destroy’d, and perishes with them. (III.iii.19) Here Locke takes real essences to be the grounds for those qualities displayed in the various sorts of individual substances that occupy the natural world created by God. Nominal essences, on the other hand, are the ‘Inventions and Creatures of the [human] Understanding’ (III.iii.11). As Kenneth Winkler (2016, 214) expresses it, ‘[e]ach of the individuals created by God in the first six days has what Locke calls a real essence’, namely ‘a private possession, as unique and unrepeatable as the individual possessing it’. The nominal essences of these individuals are then created by human beings such as ourselves in order ‘to communicate our Thoughts to one another, as well as record them for our own use’ (IV.xxi.4). Given Locke’s account of what constitutes the essence of any individual, the scholastic type of substance does not even qualify as an ‘individual’ substance in the Lockean sense. The scholastic Aristotelians regard substances as being composed of non-individual principles such as

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substantial forms. But how can such a universal entity be instantiated in each individual substance of a given kind? This question does not arise for nominalists like Locke. As Milton (1981, 129) notes, ‘[t]he test of a true nominalist is that he rejects this problem of how individuals are made individuals as a pseudo-problem’. Milton (1981, 129) defines the modern doctrine of nominalism that he attributes to Locke as follows: ‘[b]y “nominalism”, I mean the thesis that everything which exists is an individual; moreover that everything is in itself individual, and has not needed to be made individual in any way whatsoever. This last proviso may appear to be a mere example of inelegant variation, but it is in fact essential’. In Locke’s nominalism, the principle of individuation thus becomes ‘Existence it self, which determines a Being of any sort to a particular time and place incommunicable to two Beings of the same kind’ (II.xxvii.3). Ultimately, he takes atoms (the ‘greatest Instruments of Nature’) to be the most fundamental type of individuals; these constitute the variety of ordinary-sized substances that we interact with on a daily basis.1 As will be discussed in Chapter 3, Locke’s epistemic humility is directed primarily at this most basic class of individuals. Given that only individuals (in the sense explained earlier) exist in the created world, the classification of individuals into kinds must now be made ‘in respect of us’ (III.vi.21) by reference to linguistic or mental signs (i.e. words or abstract ideas). According to Locke, the individuals that belong to a given kind do not share in some type of universal entity, but are instead simply similar in respect of their typical features: ‘the sorting of them under Names, is the Workmanship of the Understanding, taking occasion from the similitude it observes amongst them, to make abstract general Ideas, and set them in the mind, with Names annexed to them’ (III. iii.13). In that regard, each nominal essence can be considered a ‘sorting device’, in Margaret Atherton’s term (2007, 260), by which ‘we delineate the boundaries of sorts or species’—the result being that ‘essential, and not essential, relates only to our abstract Ideas, and the names annexed to them’ (III.vi.4). With regard to such mental signs, what is ‘contained in the abstract Idea [of a kind]’ (III.vi.4) is a set of characteristic descriptions of the kind that a substance must satisfy in order to be classified as a member of that kind. The process of observing and classifying the various kinds of individual substances is heavily dependent upon nominal essences. Locke thus holds that ‘[i]f we suppose [the ranking of Things into Species] to be done by their real internal Constitution, and that Things existing are distinguished by Nature into Species, by real Essence, . . . we shall be liable to great Mistakes’ (III.vi.13). Locke even suggests that our classifications of things do not correspond with any objective distinctions in the real world: e.g., ‘in all the visible corporeal World, we see no Chasms, or Gaps. All quite down from us, the descent is by easy steps, and a continued series of Things, that in each move, differ very little one from the other’ (III. vi.12).2 Although there is room for disagreement about the precise nature

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of kinds within Locke’s theory of nominal essence, there is no doubt that Locke’s nominalism is a systematic criticism of scholastic essentialism. Locke’s nominalism of corporeal natural kinds has been much discussed in this light, but his mind-body nominalism has rarely been given due consideration. Even recent articles specifically focused on his theory of nominal essence seldom mention his application of the distinction between nominal and real essence to the higher categories of mentality and materiality. A rare exception to this general lack of attention to Locke’s mind-body nominalism can be found in Atherton’s (2007) reference to a passage where Locke applies his theory of nominal essence to ‘our Ideas of Spirits’: That our ranking, and distinguishing natural Substances into Species consists in the Nominal essences, the Mind makes, and not in the real Essences to be found in the Things themselves, is further evident from our Ideas of Spirits. For the Mind getting, only by reflecting on its own Operations, those simple Ideas which it attributes to Spirits, it hath, or can have no other Notion of Spirit, but by attributing all those Operations, it finds in it self, to a sort of Beings, without Consideration of Matter. (III.vi.11) Here Locke seems to take the human mind to constitute one of many mental species. He believes in bestial minds as well: ‘[t]here are some Brutes, that seem to have as much Knowledge and Reason, as some that are called Men’ (III.vi.12). In addition to kinds that are lower relative to us, Locke’s list of mental natural kinds also includes higher kinds such as angels. If the minds of brutes, humans, and angels all constitute their own distinctive mental species, these species would seem to have one feature in common—i.e. mentality. What, then, is this universal feature of mentality like? That is, what is the common feature that animal, human, and angelic minds share? Locke maintains that: It is not impossible to conceive, nor repugnant to reason, that there may be many Species of Spirits, as much separated and diversified one from another, by distinct Properties, whereof we have no Ideas, as the Species of sensible Things are distinguished one from another, by Qualities, which we know, and observe in them. (III.vi.12) Here Locke contrasts mental kinds with corporeal kinds such that while corporeal kinds are distinguished from one another by their publicly observable qualities ‘which we know and observe in them’, mental kinds are distinguished from one another ‘by [their own] distinct Properties, whereof we have no Ideas’. Here, the ‘distinct Properties, whereof we have no Ideas’ would include any conscious properties that are unique to the experience of other (non-human) mental kinds. Given this, Locke’s

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reference to properties ‘whereof we have no Ideas’ must be understood as applying to properties of the conscious experience of other mental kinds that are not instantiated in the conscious experience of our own mental species. My knowledge of your mind and the minds of other humans is still only inductively justified, though, on the basis of our similarity as members of the same species. Although ‘[i]t is not [logically] impossible to conceive, nor repugnant to reason’ to distinguish mental species in terms of their distinctive types of conscious experience, we have no access to the subjective experience of other sentient species; nor, a fortiori, to the angelic or divine mind. In reference to angels, Locke thus raises something like the problem of other minds: ‘there are different Species of Angels; yet we know not how to frame distinct specifick Ideas of them’ (III.vi.11). Locke remarks that our idea of God also depends on our simple ideas of reflection: ‘even the most advanced Notion we have of God, is but attributing the same simple Ideas which we have got from Reflection on what we find in our selves, and which we conceive to have more Perfection in them, than would be in their absence, attributing, I say, those simple Ideas to him in an unlimited degree’ (III.vi.11). It may seem at first that Locke’s purpose in raising the issue of mental species is merely to point out that the human mind is only one in a large multitude of possible mental kinds. However, his main point is rather that in constructing ideas of other mental kinds, we project our idea of spirit to the other mental species that we form ideas of. That is, as Atherton (2007, 271) also points out, the mentality or spirituality that we attribute to other mental kinds is actually based on our own complex idea of spirit, which is ‘abstracted from the [simple] ideas [of reflection] we receive from ourselves, and not based on real essences’. The same seems to be true of the category of physicality as well. As the body-problem examined in Chapter 1 indicates, our classification of the vast variety of specific physical kinds (e.g. neutrinos, photons, and dark matter) into a single kind (i.e. physicality), despite the absence of any known common real feature that runs across them, implies that our category of physicality is likewise an abstract idea made out of our simple ideas of sensation. Thus, ‘the intellectual and sensible World, are in this perfectly alike’ (IV.iii.23). In the following section, we shall explore Locke’s mind-body nominalism in more detail.

2.

Nominal Dualism

In a recent article by Rom Harré (2005, 11), the Lockean nominal essence is described as follows: ‘[t]he nominal essence of a type, kind or sort is the cluster of properties selected as necessary and sufficient at some historical epoch for a being to be assigned to a certain type or kind and so to be called by a certain kind name. A statement of a nominal essence serves as a definition which fixes the meaning of a word’. Here particular attention

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should be given to the statement that the nominal essence of a kind is the cluster of properties ‘selected as’ necessary and sufficient for membership in that kind. These properties are selected by the mind through a process of ‘abstraction’, which Locke describes as follows: [T]he Mind makes the particular Ideas, received from particular Objects, to become general; which is done by considering them as they are in the Mind such Appearances, separate from all other Existences, and the circumstances of real Existence, as Time, Place, or any other concomitant Ideas. This is called ABSTRACTION, whereby Ideas taken from particular Beings, become general Representatives of all of the same kind; and their Names general Names, applicable to whatever exists conformable to such abstract Ideas. (II.xi.9) For Locke, only abstract ideas can be given general names, and abstract ideas are ‘expressed by the words’ that such names consist of (II.i.1). In the phrase ‘idea of x’, x is replaced by a general (kind) name, and ‘the idea of x’ refers to an abstract idea of the x-kind, which contains the set of typical and characteristic features exhibited by instances of that kind. In the phrase ‘idea of gold’, e.g., ‘gold’ is a general name, and ‘the idea of gold’ refers to an abstract idea, which contains a set of typical and characteristic features of the gold-kind. We attribute a set of characteristics to a kind based on what we have learned about that kind through scientific investigation and ‘from Experience’ in general. Abstract ideas, in their descriptive content, become more accurate and rigorous as our understanding of the world continues to develop ‘for the easier and readier improvement, and communication of [our] Knowledge’ (III.iii.20). In Locke’s consistent nominalism, the same is true of the ideas of mind and body. As briefly examined in the preceding chapter, the categories of materiality and mentality correspond, respectively, to our ‘primary Ideas’ of body and spirit. They are higher-level abstract ideas that we form ‘by putting together’ the variety of more specific abstract ideas, e.g., ‘the Ideas of coherent solid parts, and a power of being moved’ in the case of body and ‘the Ideas of Thinking, Perceiving, Liberty, and Power of moving themselves and other things’ in the case of mind (II.xxiii.15). While neither type of idea can be explicated in terms of the other, their ‘contradistinction’ is nevertheless merely conceptual or functional. Although Locke did not develop his account of abstract ideas into a systematic theory of descriptions, following Woolhouse (1994, 156), one can take Locke’s brand of nominalism as entailing that an abstract idea is associated with ‘a description or set of characteristics’ that something must have for us to count it as being of a certain kind. Given, then, that abstract ideas have descriptive content, the nominal essence of body (or that of mind) can be identified with a system of descriptions in virtue of which particulars are classified into the body-kind (or mind-kind). In short, Locke identifies

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mentality and physicality as two ways of describing the world, rather than as two ways in which things are distinctively constituted. This is exactly what Davidson (1980, 211) contends in his ‘Mental Events’: an event is mental ‘if and only if it has a mental description’, while physical events are ‘those picked out by descriptions or open sentences that contain only the physical vocabulary essentially’. When Davidson, himself a mind-body nominalist, says that an event is mental or physical, he does not mean that the event is mentally or physically constituted, but only that it is mentally or physically described. Davidson’s claim that a particular event is mental or physical if and only if it is described in an appropriate manner thus has some parallels with Locke’s mind-body nominalism.3 For these nominalists, a thing’s intrinsic or constitutional nature is given less importance in determining how it is to be classified in relation to the mind-body distinction. Davidson hence does not treat an event as being constituted by the instantiation of a property. When referring to an event, he instead refers to a particular without in any way referring to its properties, where ‘properties’ are here understood in the Cartesian sense as constituting the entire essence of the things that possess them. In contrast to Descartes’ dualistic essentialism, Davidson’s mind-body nominalism holds that one picks out an event by describing it, and the way it is described is crucial for its classification as mental or physical. In the next section, I shall draw some more detailed parallels between Locke’s mind-body nominalism and Davidson’s. In the remainder of this section, however, I will argue that metaphysically dualistic interpretations of Locke’s theory of mind (such as that suggested by Aaron) confuse the nominal distinction between mind and body with a real distinction. In challenging this reading of Locke, I will show how the interpretation of Locke as a substance dualist is symptomatic of a more general neglect of the significance of his mind-body nominalism. During his own time, Locke was rarely regarded as a substance dualist. In the twentieth century, however, he has often been misinterpreted as such. In fact, Aaron’s (1971, 143) claim that Locke was committed to the ‘traditional’ mind-body dualism ‘accepted by the Church and upheld by Cartesianism’ would have seemed as radical to Locke’s contemporaries as the Essay itself struck them as being. Aaron cites the following passage in support of his reading: The one is as clear and distinct an Idea, as the other: the Idea of Thinking, and moving a Body, being as clear and distinct Ideas, as the Ideas of Extension, Solidity, and being moved. For our Idea of Substance, is equally obscure, or none at all in both; it is but a supposed, I know not what, to support those Ideas, we call accidents. It is for want of reflection, that we are apt to think, that our Senses shew us nothing but material things. Every act of sensation, when duly considered, gives us an equal view of both parts of nature, the

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Here Locke draws a clear distinction between mind and body, but the context in which the expression ‘both parts of nature, the Corporeal and Spiritual’ occurs indicates that the distinction is being drawn solely between the ideas of mind and body and the perceptual origins of these two types of ideas. The distinction between these ideas derives from the fact that sensation supplies the materials for our idea of corporeality, whereas reflection supplies the materials for our idea of mentality: ‘our Observation employ’d either about external, sensible Objects; or about the internal Operations of our Minds, perceived and reflected on by ourselves, is that, which supplies our Understanding with all the materials of thinking’ (II.i.2). Locke further holds that ‘[i]t is for want of reflection, that we are apt to think, that our Senses shew us nothing but material things’ (II.xxiii.15). If we were deprived of the faculty of reflection, then by this account, we would not be able to have the concept of mentality (but only that of corporeality). The converse is true of our faculty of sensation, without which we could not have the concept of corporeality (but only that of mentality). The striking implication of this claim is that the mental/physical distinction is contingent upon the ways in which we are able to view the world. If we were endowed with different perceptual equipment, we might have a different categorization of the world than that which follows from the duality of mentality and materiality. If, e.g., we were endowed with a third form of perception in addition to sensation and reflection, then we might have a third category besides the current dual categories of mind and body. In this vein, Locke maintains that the type of conscious experience that one enjoys is a function of the type of sensory faculties that one possesses: I think, it is not possible, for any one to imagine any other Qualities in Bodies, howsoever constituted, whereby they can be taken notice of, besides Sounds, Tastes, Smells, visible and tangible Qualities. And had Mankind been made with but four Senses, the Qualities then, which are the Object of the Fifth Sense, had been as far from our Notice, Imagination, and Conceptions, as now any belonging to a Sixth, Seventh, or Eighth Sense, can possibly be. (II.ii.3) This passage implies that if we were deprived of one of our faculties from birth, we would be unable to conceive of what those qualities that can

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only be apprehended through that faculty are like. Likewise, if we were to acquire a new faculty, then we would have some entirely new type of conscious experience. For all we know, an immaterial soul might exist in us, but Locke’s term ‘spirit’ acquires its meaning only through the introspective mode of experience. It could be argued that some of Locke’s phrases in the passage from II.xxiii.15 cited earlier suggest a form of substance dualism, particularly when he talks about ‘some Spiritual Being within me’ and ‘an immaterial thinking Being’. Aaron makes particular reference to these phrases in his interpretation of the passage, but I think the conclusion he draws from them is mistaken. First, Locke’s term ‘spirit’ (or ‘spiritual substance’) simply refers to a thinking thing with no ontological commitment to a Cartesian type of soul. He regards the power of thinking as what we experience by ‘experiment[ing] in our selves’ (First Letter, 33). The perception (through reflection) of the action or mode of thinking within ourselves is the ‘proof of a thinking substance in us, which in my sense is a spirit’ (First Letter, 33). As Jolley (1999, 83) comments, ‘[Locke’s] concept of a spiritual substance is weaker than one might imagine’. For Locke, to say that x is a ‘spirit’ is simply to say that x is a thing that has the power of thinking, which does not entail any commitment to its being an immaterial soul. Second, as used in the cited passage earlier from II.xxiii.15, the phrase ‘an immaterial thinking Being’ can be taken as referring to a non-human entity. When Locke says that mental activities ‘cannot be the action of bare insensible matter’, in my reading, the ‘bare insensible matter’ refers to systems of corpuscles that are not fitly disposed. On Locke’s view, only systems of matter that are ‘fitly disposed’ can have the power of thought (IV.iii.6). As we shall explore in Chapter 4, when Locke accounts for the possibility of thinking matter, he appeals to the possibility that God grants the power of thought to a suitable organization of corpuscles. The phrase ‘immaterial thinking Being’ might thus be taken as referring to a divine agency that sets up a rule regarding what kinds of corpuscular systems will be capable of giving rise to mentality. It could be argued that Locke is a substance dualist with respect to God and creation, but there is no clear evidence that he advocates a duality of substances within the created world. Against the interpretation just offered, one might still want to read the ‘immaterial thinking substance’ in the passage from II.xxiii.15 as referring to a thinking being in us. Even granting this reading, however, it can be shown that Locke’s use of the term ‘immaterial’ with reference to the human mind hardly implies that mind and body are metaphysically distinct. I shall examine additional examples of Locke’s use of the term ‘immaterial’ in the remainder of this section in order to demonstrate that Locke often uses this term not to refer to a real substance, but rather as an adjective that stands in mere nominal contrast to ‘material’. Like Aaron,

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Alexander (1991b, 208–9) also argues that Locke is a substance dualist. Alexander cites the following passage in support of this reading: The same happens concerning the Operations of the Mind, viz. Thinking, Reasoning, Fearing, etc., which we concluding not to subsist of themselves, nor apprehending how they can belong to Body, or be produced by it, we are apt to think these the Actions of some other Substance, which we call Spirit; whereby yet it is evident, that having no other Idea or Notion, of Matter, but something wherein those many sensible Qualities, which affect our Senses, do subsist; by supposing a Substance, wherein Thinking, Knowing, Doubting, and a power of Moving, etc. do subsist, We have as clear a Notion of the Substance of Spirit, as we have of Body; the one being supposed to be (without knowing what it is) the Substratum to those simple Ideas we have from without [i.e. by sensation]; and the other supposed (with a like ignorance of what it is) to be the Substratum to those Operations which we experiment in ourselves within [i.e. by reflection]. (II.xxiii.5) One of Locke’s main aims in this passage is to point out our tendency to mistakenly think that metaphysically disparate substrata underlie the two apparently distinct phenomena: mental and corporeal. While one may be tempted to accept the orthodoxy of substance dualism, Locke insists that the distinction between spirit and body is a merely nominal one. The contrast here is between those observable qualities that we call ‘mental’ and those that we call ‘corporeal’. As we saw in the preceding chapter, nominal dualism originates with the fact that we are endowed with two modes of experience. Through reflection, we observe the operation of our own mind. This inward-directed mode of experience is functionally distinguishable from the outward-directed one, through which our mind is directed towards the external world. According to Locke, the intrinsic nature of the created natural world is inaccessible to human understanding in either way: ‘[o]ur Thoughts can go no farther than our own, so impossible it is for us to enlarge our very Guesses, beyond the Ideas received from our own Sensation and Reflection’ (II.xxiii.13). Locke regards sensation and reflection as not only the original sources of all human knowledge but also as the two principal viewpoints that we have on the world. Although neither mode of experience is adequate to enable us to apprehend the ‘true Nature of things’ (II.xxiii.32), these dual modes give rise to the disparate types of primary ideas. In being ‘discovered to us only by the Senses from without, or by the Mind, reflecting on what it experiments in it self within’ (II.xxiii.32), these ideas are presented to us a posteriori in such a way that each word, ‘mind’ or ‘body’, carries a different meaning irreducible to the other. Locke explains how one ‘frame[s] the complex Idea of an immaterial Spirit’ as follows:

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[B]y putting together the Ideas of Thinking, Perceiving, Liberty, and Power of moving themselves and other things, we have as clear a perception, and notion of immaterial Substances, as we have of material. For putting together the Ideas of Thinking and Willing, or the Power of moving or quieting corporeal Motion, joined to Substance, of which we have no distinct Idea, we have the Idea of an immaterial Spirit; and by putting together the Ideas of coherent solid parts, and a power of being moved, joined with Substance, of which likewise we have no positive Idea, we have the Idea of Matter. (II.xxiii.15) Here, the term ‘immaterial’ is used to mean ‘mental’ (as a functional feature) rather than ‘nonphysical’. Hence, the meaning of the term—as used in that sense—has a natural basis, insofar as the fact that we are endowed with the aforementioned dual ways of viewing the world is itself part of the natural world. In the Essay, when Locke uses the term ‘immaterial Spirit’ in Sections 15, 21, 22, 31, and 32 of II.xxiii, he thus does not mean the term ‘immaterial’ to imply that spirit and body are substantially or metaphysically distinct. Rather, as used in these sections, the term ‘immaterial Spirit’ appears only in the context of Locke’s attempt to clarify the difference between our ideas of body and spirit. The nominal distinction between the idea of spirit and the idea of body is predominant throughout II.xxiii. Section 22, e.g., begins with the following statement: ‘Let us compare then our complex Idea of an immaterial Spirit, with our complex Idea of Body, and see whether there be any more obscurity in one, than in the other, and in which most’. When Locke uses the term ‘immaterial Spirit’, he contrasts body and spirit at the level of the ideas that we have of them. In Section 15 of II.xxiii, Locke distinguishes the way in which we form the complex idea of matter from the way we form the idea of spirit. We acquire the idea of matter ‘by putting together the Ideas of coherent solid parts, and a power of being moved’, whereas the idea of ‘immaterial Spirit’ is formed ‘by putting together the Ideas of Thinking, Perceiving, Liberty, and Power of moving themselves and other things’. Here, the term ‘immaterial’ is simply an adjective used in contrast to ‘material’. The idea of immateriality is a complex idea constructed by our mental processes. In this passage, there is again no sign that the thing that has the power of thinking (which we call ‘mind’) and the thing that has the power of solidity or of being moved (which we call ‘body’) are metaphysically distinct. The difference between the Lockean ideas of mind and body does not imply a difference in reality. When Locke uses the term ‘immaterial’ in the Essay and in his correspondence with Stillingfleet, he tends to use it in one of three ways. Most commonly, he uses it to refer to the human mind, in the context of contrasting the categories of mentality and materiality (but with no commitment to substance dualism). This usage of the term ‘immaterial’

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is most frequent in II.xxiii. At other times, Locke uses the term to refer to God, angels, or other super-human spirits. Occasionally, however, he uses it to refer to the Cartesian immaterial mind, for the purpose of making a point against it. Examples of this last kind of use are concentrated in the chapter on personal identity (II.xxvii), where Locke uses the term ‘immaterial substance’ several times in referring to ‘Cartesians’ who ‘place thinking in an immaterial Substance only’ (II.xxvii.12). In contending that personal identity lies in the continuity of consciousness, Locke offers a number of hypothetical cases, such as one in which ‘the same immaterial Being, being conscious of the Actions of its past Duration, may be wholly stripp’d of all the consciousness of its past Existence, and lose it beyond the power of ever retrieving again’ (II.xxvii.14). Here, Locke refers to immaterial beings in order to make the point that the identity of a person does not lie in substancehood, but rather in the continuity of consciousness. The foregoing arguments notwithstanding, there is still one passage that some commentators take as strong evidence that Locke is committed to substance dualism: ‘I agree the more probable Opinion is, that this consciousness is annexed to, and the Affection of one individual immaterial Substance’ (II.xxvii.25). I do not take this passage to imply that Locke is a substance dualist. On my reading, by ‘the more probable Opinion’, Locke just means the more widely held, widespread or popular opinion of his time; i.e., he is referring to the opinion that the majority of people (himself excluded) see as more readily acceptable or credible, and not the one that is more likely to be true. Locke takes it as given that the immateriality of the soul is the more popular view among his contemporaries. But Locke also claims in his correspondence with Stillingfleet that the immateriality of the soul cannot be proved or demonstrated ‘from natural reason’ (Second Reply, 474), and that ‘if your lordship means by a spiritual an immaterial substance, I grant I have not proved, nor upon my principles can it be proved, (your lordship meaning, as I think you do, demonstratively proved) that there is an immaterial substance in us that thinks’ (First Letter, 33). Accordingly, what Locke assents to is simply the historical fact that the immateriality of the soul is the more popular opinion of his time. At no point does he concede, however, that this opinion is therefore most likely to be true. As Jolley (1999, 81) correctly notes, ‘nowhere does Locke proclaim it as certain that the mind is a substance of a nature distinct from body’. I support Jolley’s contention that we should resist the temptation to read Locke as a substance dualist.

3.

Locke and Davidson

Wilson’s (1979) accusation that Locke is an ‘inconsistent mechanist’ stems from her view that Locke is committed to some form of property dualism or epiphenomenalism of the mental. In her article ‘Superadded Properties:

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Limits of Mechanism in Locke’, Wilson (1979, 144) contends that mental properties qua ‘superadded’ are of a type that ‘cannot be conceived as a “natural” consequence of Boylean primary qualities’. The Boylean mechanism that Wilson refers to is the view that all the properties of bodies, including mental properties, flow from the primary qualities of the insensible corpuscles of which such bodies are composed. Wilson (1979, 144) regards the Boylean hypothesis as Locke’s ‘initial’ and ‘official’ position, and contrasts it with ‘another set of views Locke espouses in the Essay, the Correspondence with Stillingfleet, and elsewhere’. This other set of views includes his account of the ‘superadded’ power of thought, which we shall investigate in Chapter 4. Wilson’s verdict is that Locke was an inconsistent mechanist.4 In this context, Wilson (1979, 146) states: Now Locke’s claim that thought cannot be produced by material corpuscles does lead to certain problems. It yields the somewhat anomalous result that a property as traditionally ‘essential’ to us humans as rational thought may lack natural connection with our Lockean real essences. It raises the question of what can be meant by saying a property belongs to, or inheres in an object, when that property does not derive from the object’s real essence. This criticism of Locke is reminiscent of Jaegwon Kim’s argument against Davidson’s anomalous monism in his article ‘The Myth of Non-Reductive Materialism’. In it, Kim (1993, 284) accuses Davidson of espousing a special form of materialism that is ‘not a stable position’. Kim (1993, 266– 7) further argues that Davidson has achieved his non-reductive theory by coupling ‘property dualism’ with ‘ontological physicalism’. The issue Kim raises regarding Davidson’s theory of mind is thus ‘whether or not a robust physicalist can, consistently and plausibly, swear off reductionism—that is, whether or not a substantial form of physicalism can be combined with the rejection of psychological reduction’. Kim regards Davidson’s anomalous monism as ‘a middle-of-the-road position’, arguing that a physicalist instead has ‘only two genuine options, eliminativism and reductionism’. According to Kim, an event is causally efficacious only by virtue of its physical properties. When a mental event (e.g. my decision to raise my arm) brings about a physical event (e.g. my arm going up), on Kim’s account, what actually does this causal work is a physical property of the mentally described event. Kim (1993, 270) thus claims that Davidson’s anomalous monism ‘allows mentality to exist’, but gives ‘no useful work’ to it. Accordingly, ‘its occurrence is left wholly mysterious and causally inexplicable. This doesn’t strike me as a form of existence worth having’ (Kim 1993, 270). This criticism rests on the metaphysical assumption that it is ‘in terms of properties and their interrelations’ that ‘we make sense of’ such crucial metaphysical topics as ‘laws, causality, explanation, and dependence’ (Kim 1993, 270).

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In contrast to Kim, however, both Locke and Davidson abstain from applying the mental-physical classification beyond the level of ideas or descriptions. Physical concepts (or the idea of body) are one way of describing and explaining events, and mental concepts (or the idea of mind) allow us to describe and explain events in another way. When referring to an event, Davidson refers to a particular without in any way referring to its constitutional properties. Like Locke, Davidson avoids using the term ‘property’ in the sense of a Cartesian principal property. For Davidson, an event is mental or physical only as it is described. If a description contains ‘at least one mental verb essentially’, such as ‘believe’, ‘wish’, ‘think’ or ‘fear’, then it is a mental description; and if an event is described by using at least one of these mental verbs, then it is a mental event. An event is physical, by contrast, ‘if and only if it is picked out by descriptions that contain only the physical vocabulary essentially’ (Davidson 1980, 211). We thus pick out an event by describing it. To describe an event requires the describer to stand in a certain epistemic relation to it. When we give an event a physical description, we treat it as a potential object of inquiry for the physical sciences. When we give it a mental description, we treat it as an object of one of our propositional attitudes, or as potential object of inquiry for psychology or cognitive science. These descriptions, whether physical or mental, are our descriptions—this is indeed the fundamental idea underpinning Locke’s theory of nominal essence with regard to mind and body. From the fact that physical laws are stricter than psychological laws, one might draw the conclusion that the physical is ontologically more basic than the mental. But for Davidson (1980, 217), these are separate issues: ‘lawlikeness is a matter of degree’. Events instantiate laws when properly described. When physically described they instantiate strict laws, but when mentally described they do not. Few would deny the strictness of the laws of physics, but it is a separate issue whether a description subsumable under strict laws reveals the nature of reality. This is arguably another parallel between Davidson’s anomalous monism and Locke’s distinction between nominality and reality. The mind-body theories of Locke and Davidson were at the center of philosophical debate in their respective eras, each inviting a great deal of criticism from their contemporaries. Whereas Locke’s theories drew fierce criticism from ardent defenders of the immateriality of the soul (e.g. Stillingfleet 1697), Davidson’s critics were largely admirers of physics (e.g. Kim 1993). Their respective versions of mind-body nominalism seem, however, to have been distorted by their opponents. Neither Locke nor Davidson set out to establish the primacy of either realm (mental or physical) over the other, or undermine the credibility of either category. Both Locke’s and Davidson’s nominalist mind-body theories instead assert the legitimacy of both realms. Although Locke was accused by his critics of undermining the authority of mentality by rejecting the immateriality of the soul, his mind-body nominalism does not give ontological precedence

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to the physical either. This aspect of Locke’s position derives from his commitment to the following thesis: (1) The fact that a phenomenon is physically described (or describable) does not entail that it is physically constituted. One might argue that Locke’s epistemic humility makes it logically possible that the role of physicality could be played by even mental beings, but his nominalism applies equally to the category of mentality. He is thus equally committed to the thesis that: (2) The fact that a phenomenon is mentally described (or describable) does not entail that it is mentally constituted. As mentioned in the Introduction, Reid suspected that Locke’s Essay bore the seeds of Berkeley’s idealism. The idealist interpretation at least correctly identifies Locke’s distinction between descriptions of reality and the actual nature of reality. Berkeleyan idealists would not deny the validity of the physical descriptions of the world provided by the physical sciences, but while they distinguish the type of description from the nature of reality, they apply this distinction only to physical descriptions. For the idealists, that is, while being physically describable does not entail being physically constituted (i.e. being constituted by some physical property, e.g. extension or solidity), being mentally describable does entail being mentally constituted (i.e. being constituted by some mental property). This explains Berkeley’s (1975, 251) remark that ‘that there is no matter in the world is still shocking to me’ and yet ‘if by matter is meant some sensible thing, whose existence consists in being perceived, then there is matter’. The term ‘matter’ means something very different for Berkeley than it does for materialists. For Berkeley, its essence lies in ‘being perceived’, not in being extended or solid. Thus, for idealists like Berkeley, while being mentally describable entails being mentally constituted, being physically describable does not entail being physically constituted. For materialists, on the other hand, to be physically describable does entail being physically constituted, but being mentally describable does not entail being mentally constituted. Both doctrines thus distinguish the descriptive character of a substance from its constitutional nature, while holding that the two come apart only in the case of descriptions that involve reference to properties outside the realm of those that their view deems as basic. For materialists, mental descriptions are only functional characterizations of a physically constituted substance, whereas for idealists, physical descriptions are only functional characterizations of a mentally constituted substance. Accordingly, materialism and idealism are both asymmetrical metaphysical positions in that each identifies either matter or mind as constituting the unique basis of reality, while treating the other as some sort of modification of that basis.

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Unlike these two asymmetrical doctrines, Locke’s more moderate ontology applies the distinction between the functional character of a substance and its constitutional nature equally to both categories: physicality and mentality. Locke’s nominal dualism thus implies that things are only describable physically or mentally (or both) in terms of their functional roles. According to his strict nominalism, any human classification or characterization of experienced reality is based on nominal essences. The only way one could have a perfect and adequate idea of the true nature of reality would be to become a different intellectual species endowed with super-human intelligence. The conjunction of Locke’s mindbody nominalism with his epistemic humility can be expressed as follows: (3) We have two kinds of concepts (mental and physical), but the true nature of the world is inaccessible to us. The strict distinction between what really is (real essence) and how it is conceptualized or described (nominal essence) underlies Locke’s mindbody nominalism. This distinction gives rise to a symmetrical view such that neither type of concept (mental or physical) is more privileged than the other in describing the true nature of reality. We need both types of concepts or descriptions, and we cannot do without either, as they are two equally legitimate perspectives that originate from our dual way of looking at the world. To adopt Davidson’s language (1999, 106), the mental and the physical are ‘conceptually’ dualistic in that ‘the mental and the physical vocabularies are neither definitionally nor nomologically reducible in either direction’. That is, the two types of descriptions are ‘two ways of conceiving—and hence of classifying—the same particular’. In his article on ‘Spinoza’s Causal Theory of the Affects’, Davidson (1999, 106) acknowledges the kinship of his view with that of this seventeenth-century philosopher: I do not feel abashed to admit that the reading I find plausible of Spinoza’s ontological monism coupled with dualistic explanation apparatus is close to my own view of the relation between the mental and the physical. I call this position anomalous monism, and I have from the start recognized its kinship with Spinoza’s view. Davidson stresses that the viewpoint in this later article is not a departure from his earlier position as expressed in ‘Mental Events’, but rather a clarification thereof. Further evidence for this continuity of his later thought with his earlier views can be drawn from his remark in ‘Mental Events’ that ‘we can afford Spinozistic extravagance with the mental’ and that such Spinozistic extravagance ‘can only strengthen the hypothesis that all mental events are identical with physical events’ (Davidson 1980, 212). As mentioned earlier in the Introduction, Locke was also read by his early

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eighteenth-century interpreter Carroll as having some significant points of agreement with Spinoza. The Spinozistic elements in Locke and Davidson have, however, rarely been considered as a tool for understanding their mind-body theories. Although Locke’s discussion of these matters is not as subtle as Davidson’s, he too believed in the irreducibility of mental types to physical types. This aspect of his position is conveyed in the following remark on the difference between our ‘contradistinguished’ ideas of mind and body: ‘Spirit is different from Body, because Thinking includes not the Idea of Extension in it’ (II.xiii.11). The distinction that Locke draws between the ‘primary Ideas’ of mind and body is his way of claiming that each nominal category represents a distinctive, irreducible perspective from which to view the world. Together, these two perspectives afford us ‘an equal view of both parts of nature, the Corporeal and Spiritual’ (II. xxiii.15). Davidson likewise treats the mental and the physical as two irreducible domains, each subject to different overarching constraints. The same token event can thus, on his view, be described in two different ways. When, e.g., a certain bit of behavior that I exhibit is described as a rational action, it is my mental events, such as my beliefs and desires, that should be referred to. In offering such a description, it is the logical relations among the contents of my propositional attitudes that are cited as relevant for assessing the rationality of my action. The central place that Davidson treats propositional attitude ascriptions as having in mentalistic descriptions of behavior stems from his belief that intentionality is the most crucial feature of mentality. Davidson’s and Locke’s favored brands of dualism both differ in this regard from the Jacksonian type of property dualism in which conscious or phenomenal states are considered as the primary and essential characteristic of mentality. Propositional attitudes are governed by various normative considerations about what people ought to do in certain conditions. The event of my going to a cafeteria, e.g., can be described by reference to certain mental events occurring in me. The rationality of my action is evaluated in reference to the contents of my beliefs and desires. When I have an appropriate desire to go there (e.g. to quench my thirst) and an appropriate belief (e.g. that the cafeteria is the best place to quench my thirst considering its location, prices, the sort of drink I prefer, etc.), my action of going there is rationally justified. However, the event of my going to the cafeteria can also be described in purely physical terms by reference to my physical attributes and the behavior that I exhibit, such as the movement of my legs, the speed with which my body moves, the direction in which it is heading, and so on. When the same event is described in physical terms without any reference to my mental attitudes, the rational justification for my action is left out. This is because the physical domain is governed by a radically different principle than that of rationality—namely, the principle of two-place predicates (Davidson 1980, 220). The physical predicates

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employed in physical descriptions are relational and transitive: e.g., in the case of ‘length’, if x is longer than y and y is longer than z, then x is longer than z. The same is true of other physical predicates, such as width, depth, speed, and weight. The distinction that Locke draws between the ‘primary Ideas’ of spirit and body can be viewed as an anticipation of these more modern views. The ideas ‘peculiar to Spirit’ include those of ‘Thinking, and Will, . . . [and] Liberty’ (II.xxiii.18); these represent what we now call the agent’s beliefs, intention, and choices, all of which are crucial elements in considering the rationality of their actions. In contrast, the ideas ‘peculiar to Body’ (II.xxiii.17) include ‘the Ideas of coherent solid parts, and a power of being moved’ (II.xxiii.20) as well as the power of ‘communicating motion by impulse’ (II.xxiii.17). These two types of ideas represent the two distinct viewpoints from which we conceive and classify the variety of things in the world. As we have seen in his account of two sources of experience (sensation and reflection), Locke’s analysis of human nature is grounded in two perspectives: first-person and third-person. My first-person awareness of my own actions constitutes my personal identity and thereby my moral responsibility as well. As Locke argues in the chapter ‘Of Identity and Diversity’, the reflective observation of one’s own mind is the source of one’s sense of ‘self’ considered as a ‘conscious thinking thing . . . which is sensible, or conscious of Pleasure and Pain, capable of Happiness or Misery, and so is concern’d for it self’ (II.xxvii.17). But we are not in fact fully aware of all our mental activities. Nor can we remember every detail of our past actions. It is thus the psychological continuity of our conscious memories that gives rise to the sense of our personal identity. In that regard, Locke distinguishes ‘person’ from ‘man’ and associates each of these terms with a different identity condition. What determines the sameness of my ‘man’-hood over time is my biological continuity, whereas the sameness of my ‘person’ lies in my psychological continuity. While the term ‘man’ refers to a biological being whose identity consists in ‘a participation of the same continued Life by constantly fleeting Particles of Matter’ (II.xxvii.6), a ‘person’ is the subject of rational action. What appears in my continuous stream of consciousness is me as a person. When I am viewed as a person by a third-person observer who ascribes rationality to me, the observer describes me by reference to my mental attitudes, which the observer infers from their observation of my behavior. When I am viewed as a purely physical/biological being, the observer’s description of my behavior takes a radically different form in which only my physical/biological attributes and movements are described in accordance with certain laws of the physical sciences. To put it in Lockean terms, I can be described under both the ‘primary Ideas’ of mind and the ‘primary Ideas’ of body. When described under the latter type of idea, I am treated as a physical object obeying the laws of physics. By contrast, when described under the former type, I am treated

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as a special kind of being who follows the rule of rationality. Locke takes ‘person’ as ‘a Forensick Term appropriating Actions and their Merit’ (II. xxvii.26). To provide rational justification for my actions, I must refer to my propositional attitudes under a certain mental description. The terms ‘man’ and ‘person’ stand for ‘one and the same thing’ (II.xxvii.15), but each represents a different aspect of human nature. Mentality is instantiated in mental descriptions of rational actions, yet the same person can also be physically described in terms of its manhood as a certain kind of biological organism—namely, a ‘system of matter fitly disposed’ (IV. iii.6). The further details of this account will be considered in Chapter 4, where we examine how a man’s physical/biological attributes give rise to conscious states.

4.

Nominal Symmetry

Just as the Lockean perspective can be adopted to better understand Davidson’s anomalous monism, the Davidsonian perspective enables us to appreciate the significance of Locke’s philosophy in a more recent context. Davidson’s anomalous monism can also, however, be critically examined from the Lockean point of view. Davidson conceives of all events as physical on the grounds that there is no event that cannot be physically described. There is also a sense in which every event is mental, insofar as he believes that any event can be mentally described as well. In ‘Actions, Reasons, and Causes’, Davidson (1980, 12) offers the following example: ‘there is a mental event; at some moment the driver noticed (or thought he noticed) his turn coming up, and that is the moment he signalled’. This is a case where the same event is picked out by both a mental and a physical description: his noticing his turn coming up, and his signaling.5 There is another example in ‘Mental Events’: Take some event one would intuitively accept as physical, let’s say the collision of two stars in distance space. There must be a purely physical predicate ‘Px’ true of this collision, and of others, but true of only this one at the time it occurred. The particular time, though, may be pinpointed as the same time that Jones notices that a pencil starts to roll across his desk. The distant stellar collision is thus the event x such that Px and x is simultaneous with Jones’ noticing that a pencil starts to roll across his desk. The collision has now been picked out by a mental description and must be counted as a mental event. (Davidson 1980, 211) An event x is picked out by a physical description ‘Px at t’ that is true of the collision of two stars in distant space, and the particular time t is picked out by a mental description: ‘Jones’ noticing that a pencil starts to roll across his desk’. Here Davidson maintains that ‘the collision has

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now been picked out by a mental description and must be counted as a mental event. This strategy will probably work to show every event to be mental’. Hence, ‘we can afford Spinozistic extravagance with the mental’ (Davidson 1980, 212).6 When no description can be given to an event, however, is that event neither mental nor physical? This is a Lockean question that might be asked of Davidson’s nominalism. While this sort of question appears in the Essay in the context of Locke’s discussions of his epistemic humility, Davidson has no interest in what the deeper nature of an event is, or what a given event might be beyond its mental or physical descriptions. Although Davidson would most likely find this kind of question unintelligible, there may nevertheless be a sense in which events as conceived by Davidson can be interpreted as being neither mental nor physical.7 Given that identity is a relation that all things bear to themselves ‘no matter how [they are] described’, and that an event is physical only insofar as it is physically described, one might conclude that an individual event without a description is neither physical nor mental.8 Nonetheless, Davidson’s apparent lack of interest in the deeper (description-independent) nature of events clearly contrasts with Locke’s approach. Locke’s epistemic humility renders the nominal symmetry implicit in his theory of mind and body more symmetrical than it is in Davidson’s system. This in turn enables Locke’s variety of nominal dualism to provide the basis for a stronger critique of materialism. Like the misguided suggestion that Locke was a substance dualist, the claim that Locke was a covert materialist also confuses the issue of what really is with the issue of how reality is conceptualized or described. These issues are clearly distinguished from one another in Locke’s mind-body nominalism. Against materialists, Locke would thus likely argue that ontological materialism conflates an intellectual abstraction (nominal essence) with what really exists (real essence). Locke does not commit himself to the view that everything is physically constituted, nor to any constitutional theory underpinned by the Cartesian doctrine of principal attribute. Any charge of materialism on this ground ends up distorting Locke’s nominal symmetry. While Locke might indeed support a purely ‘descriptive’ form of materialism that holds merely that everything can be physically described or explained, it is wrong to think that he would therefore also lend his support to ‘ontological materialism’. Rather, Locke’s mind-body nominalism should be viewed as a critical reflection on the ontological doctrines of both materialism and idealism. Given Locke’s philosophical commitments, it would in fact be nonsense for him to claim that things are physically constituted, for as the preceding discussion has shown, his term ‘physical’ has to do with the functional roles that things occupy and not with their intrinsic nature. For Locke, the physical, too, is a nominal category, its main features being only functionally identifiable in terms of physical vocabularies. The nominal

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character of the physical comes to the fore more in Locke’s mind-body nominalism than in Davidson’s, due to his epistemic humility about the intrinsic nature of things, as we shall explore in the next chapter.

Notes 1. Even recent articles specifically focused on Locke’s theory of nominal essence (e.g. Guyer 1994; Atherton 2007; Winkler 2016) rarely offer any account of the historical background of Locke’s specific form of ‘nominalism’ in which his theory of ‘nominal essence’ is grounded. Milton’s earlier works (1981, 1982) provide a noteworthy contrast to this neglect. In these works, Milton explores the influence of medieval nominalists like William of Ockham on Locke’s nominalism. The following is a lengthy but illuminating quote from Milton (1981, 128) on Locke’s position in the midst of the seventeenth-century debate between nominalists and realists: ‘[t]he great literary dispute between Ancients and Moderns at the end of the seventeenth century was not one in which Locke played any direct part. He was a man who markedly preferred fact to fiction. Nevertheless one can without any impropriety include him among the Moderns. He was an innovator, not a restorer, and his style was plain and unadorned. He hardly ever buttressed his arguments by appeal to authorities, and when he did so it was for his opponent’s sake and not for his own. For this reason it is easy and natural to confine a study of Locke’s intellectual background to his contemporaries and immediate predecessors: to Boyle, Descartes, Gassendi and the Cambridge Platonists. In accordance with this, the scholastic elements in Locke’s thought, when noticed, are treated as mere survivals, as evidence of how difficult it is to be entirely modern. This neglect of Locke’s scholastic sources would not, I suspect, have been regretted by Locke himself, whose references to “schoolmen” in general and his Oxford teachers in particular are invariably hostile. It does however involve a systematic misperception of his achievement. Locke was working, perhaps unconsciously, in a tradition usually known as nominalism which began in the later Middle Ages; and he was working within this tradition, and not against it’. 2. Jolley (1984, 146) takes Locke to be an anti-essentialist about natural kinds: ‘Locke’s primary concern may seem to be to argue that there are no natural kinds independently of our classification’. Many modern commentators are aligned with this anti-realist reading in one way or another (see, e.g., Ayers (1991), Guyer (1994), Stuart (1999), Atherton (2007), and Winkler (2016)). 3. The statement ‘x is F’ exhibits the logical form of our typical way of describing the various kinds of substances. In this form, x refers to an individual substance, and F refers to a property that x possesses. What makes it the case that x is F? There are two types of answers that can be given to this question: (1) F-ness constitutes x’s real essence; or (2) x is F solely by virtue of x’s satisfying the description ‘F’. The second is the nominalist’s answer. By virtue of what does x satisfy the description ‘F’? According to the nominalist, the fact that x satisfies ‘F’ is ultimately inexplicable, or can be explained by the fact that x bears a certain similarity relation to other things that can be legitimately described as ‘F’, or by the fact that x belongs to a certain similarity-class that has been conventionally determined as the extension of ‘F’. The statement ‘x is physical’ would thus mean that x’s satisfaction of a certain set of descriptions is necessary and sufficient for it to be of the physical kind. The same is true of the statement ‘x is mental’. 4. Milton (1985, 235–6) aligns himself with Wilson in maintaining that for Locke, God really does give to certain systems of bodies ‘additional powers,

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7.

8.

Mind-Body Nominalism which enable those bodies to think’, and that Locke’s frequent appeal to God’s omnipotence is consequently ‘very much more than a mere rhetorical device’. Recently, Stuart (2013) and Pyle (2013) have aligned themselves with the Wilsonian reading as well. We shall investigate Locke’s views on ‘superaddition’ in Chapter 4. One might point out, though, that predicate ‘signal’ involves some assumptions about x’s intentions (e.g. to communicate some bit of information) and is thus at least partly mental predicate. One might ask the question of what sort of mental description we could give of, say, the various events currently taking place on the surface of Jupiter, or events that took place before the emergence of sentient life? In arguing for mind-body symmetry in his paper on Spinoza, Davidson (1999, 109) appeals to the notion of God’s omniscience: ‘if God is omniscient, then his knowledge of the world as extended may reasonably be considered to consist of ideas “ordered and connected” as are the modes of extension’. This passage implies that a perfect symmetry can exist in a much wider context than can be accessed from the human perspective. Davidson offers no account, however, of what ‘a perfected science of psychology’ might be like, or how to achieve it. Davidson (1999, 108–9) simply acknowledges that ‘there remains a puzzle about how a scientific psychology can hope to parallel physics in precision and comprehensiveness’. Papineau (1990, 66) has identified Davidson’s events with bare particulars: ‘[t]here are various possible ways of instituting the required relationship between mental and physical causes. If we think of events as bare particulars, we can say that each particular mental cause is the same event as the relevant physical cause (cf. Davidson’s “Mental Events”)’. Davidson’s distinction between ‘causation’ and ‘causal explanation’ runs parallel to the distinction between events and descriptions. For Davidson, ‘causation’ happens regardless of how events are described and explained. The first principle of Davidson’s anomalous monism is that some mental events interact causally with physical events, and the third principle is the anomalousness of the mental. Whereas Davidson’s first and third principles relate to the mental-physical dichotomy, the second does not. This is the principle that events related as cause and effect fall under strict deterministic laws. Davidson (1980, 215) stresses in ‘Mental Events’ that this second principle of his anomalous monism is ‘blind to the mental-physical dichotomy’. That is, while ‘causation’ is simply something that happens in the world independently of how it is described, ‘causal relations’ obtain between events that are nomologically explained or predicted by virtue of being described in appropriate vocabularies. As Davidson (1980, 215) puts it: ‘[c]ausality [or causation] and identity are relations between individual events no matter how described. Laws, however, are linguistic; and so events can instantiate laws and hence be explained or predicted in the light of laws, only as those events are described in one or another way’.

3

Epistemic Humility

This chapter explores Locke’s epistemic humility both in historical and contemporary contexts. What is it for us to be incurably ignorant about the intrinsic nature of things in themselves? For Locke, even the most advanced human science cannot reveal to us the true nature of things. This chapter examines the justification that he provides for this claim by comparing it with the two most prominent modern brands of epistemic humility, one of which derives from the work of Frank Ramsey (Lewis 2009), while the other is ascribed to Kant (Langton 1998). These two modern brands of epistemic humility are based on a view called ‘quidditism’, which holds that the intrinsic nature of a property (its ‘quiddity’) is independent of the laws of nature. Their respective ways of arguing for their shared conclusion (epistemic humility) are, however, different. The basis of Langton’s Kantian epistemic humility lies in the supposed irreducibility of causal powers to their bearers, together with the thesis that we are only affected by the relational properties of things (namely, their causal powers), not their (causally impotent) intrinsic properties. The latter are thus hidden from us. This type of epistemic humility relies on a fundamental distinction between intrinsic and relational properties. By contrast, pivotal to the Ramseyan type of epistemic humility is the multiple realizability of causal roles. On this view, the status of being a power is equated with the occupancy of a certain causal role, where each such role is realizable by a multitude of different quiddities. What lies beyond our ken is which quiddity, among the many possible ones, actually performs the given role. Langton attributes to Locke the Kantian type of epistemic humility. However, this chapter shows that Locke’s view has more significant parallels with the Ramseyan position defended by Lewis. Locke’s nominalistic approach is better understood in terms of the notion of ‘realization’, which underlines the Ramseyan brand of epistemic humility, rather than as resting on the aforementioned Kantian dualism between intrinsic and relational properties. In Locke’s view, the ‘roles’ that the Ramseyan refers to are taken to be descriptive or theoretical entities whose functions are realized by certain extra-descriptive actual objects that possess their own real essences. The relation of ‘realization’ holds

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between the general, conceptual, and descriptive (on the one hand) and the concrete, real, and qualitative (on the other). The relation between roles and role-occupants corresponds with that between nominal and real essences. It is only in a trivial sense that a nominal essence can be described as irreducible to a real one, insofar as the one is a descriptive entity while the other is an extra-descriptive one. Locke does not advocate either the irreducibility of causal powers or the impotence of intrinsic properties, both of which are crucial theses of Langton’s Kantian epistemic humility.1 In Locke’s Ramseyan worldview, things-in-themselves are taken to be active role-occupants that perform the roles they occupy by virtue of their own distinctive intrinsic nature. According to Langton’s Kant, by contrast, things-in-themselves are only bearers of certain causal powers; they themselves are causally impotent. After further defending the Ramseyan construal of Locke’s epistemic humility, this chapter also critically examines Pierre Coste’s suggestion that Locke follows Newton in regarding physical bodies as modified portions of space.

1.

The Intrinsic Nature of the Created World

Locke never attempts to demonstrate the existence of the external world by any speculative argument. Nor does he doubt its existence: ‘[n]obody can, in earnest, be so sceptical as to be uncertain of the Existence of those Things which he sees and feels’ (IV.xi.3). He does offer some inductive grounds for belief in an external world in the Essay. It is, e.g., ‘only to be prized’, he claims, to believe in ‘the natural and regular productions of Things without us, really operating upon us’ (IV.xi.4). Locke likewise regards simple ideas as ‘constant Effects’ of the external world upon us, through which we can stand ‘in that steady correspondence’ with it (II. xxx.2). His philosophical concern, however, is not with the existence of the external world, but rather its intrinsic nature. In the Essay, Locke often appeals to a super-human species capable of penetrating into the ‘inmost Constitutions of Things’ (IV.iii.23). He also argues, however, that we cannot possibly conceive what it would be like to be a member of such a species, or to have such a ‘clear distinct [idea] of Substance it self’ (IV.iii.23). That is, we do not know ‘[w]hat Faculties . . . other Species of Creature have to penetrate into the Nature, and inmost Constitutions of Things, [or] what Ideas they may receive of them’ (IV.iii.23). Here Locke emphasizes our lack of a proper faculty by which to grasp the true nature of things: ‘the Ideas, we can attain to by our Faculties, are very disproportionate to Things themselves’ (IV.iii.23). We thus have no ‘positive clear distinct [idea] of Substance it self’ (IV.iii.23). Hence, ‘as to the real Essences of Substances, we only suppose their Being, without precisely knowing what they are’ (III.vi.6). There are several definitions of ‘real essence’ in the Essay. Among them, the following is fairly similar to what we now call ‘intrinsic nature’: a

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thing’s real essence is ‘[its] particular constitution, which every Thing has within itself, without any relation to any thing without it’ (III.vi.6). Locke describes ‘real essence’ elsewhere as ‘the very being of any thing, whereby it is, what it is’ (III.iii.15) and by virtue of which each individual thing can be what it is—in Winkler’s words (2016, 215), something like ‘a generative core, of which the thing’s qualities are expressions’. At times, Locke describes a thing’s real essence by reference to its causal role, by suggesting that it is that ‘on which [not only] these Qualities, [but also] their Union, depend’ (III.vi.6). This type of characterization, too, however, hardly reveals a thing’s intrinsic nature, for the status of being the union of certain causal powers only tells us what a thing does as its causal work, and not what it is intrinsically. The essence of water, e.g., is described in our science as a tiny bent molecule with the molecular formula H2O consisting of two light hydrogen atoms attached to a sixteen-fold heavier oxygen atom. This structural description, however, is underpinned by some more basic condition by virtue of which this particular type of molecular structure (rather than another) obtains—viz. ‘the very Essentia, or Being, of the thing it self, that Foundation from which all its Properties flow’ (III.iii.18). This is what Locke refers to as ‘internal essence’ in his correspondence with Stillingfleet: ‘if those powers and properties discover no more of those internal essences, but that there are internal essences, we shall know only that there are internal essences, but shall have no idea or conception at all of what they are’ (First Letter, 26). Locke maintains that a certain ‘reality’ is possessed by any real essence whereas nominal essences are merely descriptive or linguistic entities: ‘[the real essences of things] are the very real constitution of things, and therefore I easily grant there is reality in them; and it was from that reality that I called them real essences’ (First Letter, 83). While a thing’s nominal essence is given a general name for its kind, its real essence is identified with its individual constitution ‘without giving [it] any Name’ (III.iii.15).2 Even when an object’s molecular structure is discovered by the physical sciences, we remain ignorant of its real essence. We can only observe the manner in which its constituent particles cohere or interact without knowing why they behave as they do. It is only when we attain knowledge of the object’s real essence that we can answer the why-question. Given this conception of ‘real essence’, the following are examples of derivative types of epistemic humility that would be resolved if the real essences of things were revealed to us: (1) the humility expressed by the acknowledgment that ‘there is no discoverable connection between any secondary Quality, and those primary Qualities that it depends on’ (IV. iii.12); (2) the humility expressed by the acknowledgment that ‘there is yet another and more incurable part of Ignorance, which sets us more remote from a certain Knowledge of the Co-existence, or Inco-existence (if I may say so) of different Ideas in the same Subject’ (IV.iii.12); and (3) the humility expressed by the acknowledgment that ‘though Causes work

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steadily, and Effects constantly flow from them, yet their Connexions and Dependences being not discoverable in our Ideas, we can have but an experimental Knowledge of them’ (IV.iii.29). Locke’s term ‘Science’ or ‘scientific’ knowledge concerns the internal essences of things, which he insists are unknowable in principle. His term ‘Science’ is thus not synonymous with our term ‘natural science’. He refers to what we call ‘natural science’ as ‘experimental Philosophy’. In his view, the latter discipline is concerned only with nominally definable objects—those that are identified, characterized, and individuated by reference to their causal roles. In the following passage, Locke calls such objects ‘physical Things’: I am apt to doubt that, how far soever human Industry may advance useful and experimental Philosophy in physical Things, scientifical will still be out of our reach: because we want perfect and adequate Ideas of those very Bodies, which are nearest to us, and most under our Command . . . we are not capable of scientific Knowledge. (IV. iii.26) By contrast to knowledge acquired through ‘experimental Philosophy’ (i.e. ‘science’ in our modern sense of the term), what Locke refers to as ‘scientific Knowledge’ could only be obtained by a super-human species. He thus states that ‘we are not capable of scientific Knowledge’ (IV.iii.26), and that ‘[a]s to a perfect Science of natural Bodies, (not to mention spiritual Beings,) we are, I think, so far from being capable of any such thing, that I conclude it lost labour to seek after it’ (IV.iii.29). In Locke’s view, we are consequently in ‘perfect Ignorance’ (II.x.8), and in ‘an huge Abyss of Ignorance’ (IV.iii.24) about the intrinsic nature of this created world—for we are incapable of acquiring any positive knowledge of the real essences of the ‘greatest Instruments of Nature’ by which the world is constituted.

2.

Lockean Humility

Interestingly, Jaegwon Kim (2011, 134) notes some kinship between the Lockean view of nominal essence and Ramseyan functionalism in his recent introductory book on the philosophy of mind. As he puts it: ‘a functional kind has only a “nominal essence”, given by its defining causal role, but no “real essence”, a “deep” common property shared by all actual and possible instances of it’. According to functionalist approaches in the philosophy of mind, the nature of a mental state such as pain is determined by its causal role, and as that role is typically viewed as multiply realizable, the real essence of ‘pain’ consequently cannot be fixed. Functionalists seek to avoid both physicalistic and subjective ways of characterizing mental states by suggesting that what individuates the state

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of a pain is not any specific physical state, or its phenomenal quality, but only its causal role. Generalizing beyond the sphere of mental states, it becomes readily apparent that there are many cases in which we identify individual things by reference to their function. When I call a company, e.g., an operator connects me to a person with whom I would like to talk. I identify this operator by the following job description: if x is an operator for a company, then whenever y calls the number 000–000–0000, x answers y’s call and connects y to z, the person with whom x wants to talk; if z is not in the office, x receives y’s message and forwards it to z when z returns. The caller identifies the operator by the causal role that the operator performs and a set of sensory inputs, including the operator’s voice. But the caller is ignorant of the individual character of the operator, including his or her particular physical constitution, biological features, and personal traits. These types of specific properties of a role-player are parallel to what Locke refers to as a substance’s real or internal essence, which ‘every Thing has within it self, without any relation to any thing without it’ (III.vi.6). An automaton may replace the real person without the caller’s noticing, and perform the same causal role the real person fulfilled, including the production of the same voice, according to predetermined coded instructions. The caller may thus not know the real essence of the occupant of the operator-role. This is related to the fact that the role of being an operator is multiply realizable in that it can be realized in a system of molecules or in a system of electrical impulses or in any number of other types of physical systems. Locke’s nominal dualism applies this same functionalist analysis to physical entities as well. The same approach is also taken by Lewis in his Ramseyan account of epistemic humility. On this approach, names denoting physical properties (e.g. ‘mass’) are replaced by variables and then defined in terms of various functional predicates by constructing a so-called Ramsey sentence containing all the relational features that individuate those properties. In the case of the mental state of pain, e.g., the Ramsey sentence will provide a more rigorous definition of what is asserted when one says ‘I feel a pain’. On this analysis, anything that satisfies a certain set of functional descriptions can thereby be called ‘pain’. When no more mental vocabulary appears in the functional analysis of ‘pain’, the Ramsey sentence for pain is complete. The same is also true, mutatis mutandis, of physical kinds, such as electrons, protons, neutrons, and so on. One identifies each particle via its causal role, without knowing what it is intrinsically. Consequently, all one can say about each particle is that it is something that possesses certain relational features such as causal powers—without having any clear idea about its intrinsic nature. In the following definition of an electron, the term ‘electron’ is thus defined in terms of various causal or nomic relations among the elementary particles without any mention being made of the real essences of the relata of

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those relations: ‘(x is an electron) = (x is an elementary particle, classed as a lepton, with a rest mass of 9.1093897(54)×10–31 kg and a negative charge of 1.60217733(49)×10–19 coulombs, which is present in all atoms in groupings called “shells” around the nucleus; when they are detached from the atom, they are called “free electrons”)’. In this Ramseyan definition of an electron, an electron is defined in terms of its causal functions in relation to nuclei, protons, and neutrons. This functional definition provides us with no knowledge of the electron’s real essence: we are unable to ‘penetrate into the true Nature and inmost Constitution of Things’ (IV.iii.23). For Locke, our ideas of substances are thus obscure. They spell out how the substances of which they are ideas behave, but not what they are intrinsically. As Stillingfleet observes, Locke’s account of substance thus ‘not only tell[s] us That we can have no Idea of it by Sensation or Reflection; but that nothing is signified by it, only an uncertain Supposition of we know not what’ (Discourse, 234–5). Against Locke’s epistemic humility on this point, Stillingfleet argues that we have a ‘Rational Idea of Substance’ (Discourse, 236) that enables us to conceive of its essence clearly and distinctly—an idea, as Stillingfleet puts it, ‘whereof the mind hath a full and evident Perception’ and ‘whereby the mind perceives the difference of it from all others’ (Discourse, 276). From this Cartesian viewpoint, Stillingfleet accuses Locke of having ‘discarded Substance out of the reasonable part of the World’ (Discourse, 234). Against this, Locke responds to Stillingfleet as follows: Your lordship’s conclusion from your foregoing words is, ‘and so we may be certain of some things which we have not by those ideas [from sensation or reflection]:’ which is a proposition, whose precise meaning your lordship will forgive me if I profess, as it stands there, I do not understand. For it is uncertain to me, whether your lordship means, we may certainly know the existence of something which we have not by those ideas [from sensation and reflection]; or certainly know the distinct properties of something which we have not by those ideas; or certainly know the truth of some proposition which we have not by those ideas: for to be certain of something, may signify either of these. But in which soever of these it be meant, I do not see how I am concerned in it. (First Letter, 22) Here Locke is asking Stillingfleet what he means by the ‘Rational Idea of Substance’. According to Locke, when we say that we know about substance, we can be taken to be making at least one of the following three claims: we know about (1) its ‘existence’, (2) its ‘distinct properties’, or (3) ‘the truth of some proposition’ of it. Here Locke is analyzing the nature of our knowledge of substance into three dimensions: ontological, quidditist, and semantical.

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The Cartesian account of the ‘Rational Idea of Substance’ holds that knowledge of (2) guarantees knowledge of (1) and (3), as Descartes maintained that ‘if we perceive the presence of some attribute, we can infer that there must also be present an existing thing or substance to which it may be attributed’ (CSM I, 210). According to Stillingfleet, by contrast, Locke reasons that since we do not know about (2), we consequently have no knowledge of (1) or (3) either. But this claim of total ignorance of (1), (2), and (3) is not attributable to Locke. He is not as blindly agnostic as Stillingfleet presumes. His epistemic humility is directed solely at (2). Locke does not see our ignorance of (2) as implying that we are therefore also ignorant of (1) and (3). He applies this threefold distinction between kinds of knowledge of substance in his own account of epistemic humility, which can be analyzed as consisting of the following claims: (1) Wherever a role is observed, ‘something’ must exist that occupies that role. (Ontological claim) (2) That ‘something’ has ‘[its own] distinct propert[y]’. (Quidditist claim) (3) That distinct property is inaccessible to us. (Epistemic claim) (4) We certainly know the truth of ‘some proposition[s]’ (e.g. ‘material objects are solid’) by knowing the causal roles performed by the entities they refer to, notwithstanding our ignorance of the distinct properties of those entities. (Semantic claim) (1) is about the existence of ‘something’ that occupies a given role. (2) is about the quiddity of the role-occupant, such that the ‘something’— the role-occupant—has ‘[its own] distinct propert[y]’ by virtue of which it performs the given role. Each role-occupant plays its given role by virtue of ‘[its own] distinct propert[y]’. (3) is a statement of epistemic humility regarding our knowledge of the ‘distinct properties’ that occupy such roles. Locke distinguishes this epistemic claim from the semantic claim expressed in (4). Although the quiddities of the role-occupants are unknown, some meaningful statements can be made about them—in terms of the observable roles that they perform. We thus ‘certainly know the truth of some proposition[s]’, notwithstanding our incurable ignorance of their quiddities. Statements about the functional or relational features of material bodies, such as ‘they are solid’, are thus actually taken to be universally true, despite the fact that their truth is only grounded in the observable roles that such bodies occupy. The distinction Locke draws between the semantic and epistemic claims expressed in (3) and (4) can be found in the Essay’s chapter on solidity (II.iv). ‘[Solidity] carries something more of positive in it, than Impenetrability, which is negative, and is, perhaps, more a consequence of Solidity, than Solidity itself’ (II.iv.1). The impenetrability of physical objects is taken as ‘a consequence of Solidity’, rather than ‘Solidity itself’. Here ‘impenetrable’ is treated as a functional predicate, which describes

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how a substance would react when acted upon. It refers to the functional role of resisting the approach of other bodies into the space one occupies. By ‘Solidity itself’, in contrast, Locke means the intrinsic property of the role-occupant by virtue of which it plays that role—which, in his view, is ‘something [in solid substances] that we do not understand’ (Second Reply, 465). On the other hand, he also explains solidity in terms of an idea—e.g. ‘the Idea most intimately connected with, and essential to Body’ (II.iv.1). Here Locke refers to the ‘something’ unknown in terms of its nominal essence. ‘[T]he Idea [that] belongs to Body’ (II.iv.1) is the idea that contains a description of the characteristic role of bodies. The meaning of ‘solidity’ or ‘solid’ is thus likewise determined by the solidityrole, not the quiddity of the role-occupant. Hence, even if a substance that plays the distinctive role of solidity were replaced by a substance with a different intrinsic nature, the new substance that now occupies that role would still be considered a solid substance in that it plays the same role. It is at this nominal level that our term ‘solidity’ gains its universal meaning. The idea of solidity is applicable to every material body, though the intrinsic nature of its role-occupant is inaccessible to us. Locke thus distinguishes the semantic claim from the epistemic claim. This distinction also implies that Locke’s epistemic humility is not blindly agnostic but is instead targeted at a specific feature of substances: their intrinsic nature.

3.

Locke and Ramseyan Humility

The term ‘quiddity’ is widely used in recent metaphysics to refer to the intrinsic nature of a property (its ‘this-ness’ or ‘such-ness’). For any observed causal role, there must be some property that occupies and plays that role by virtue of its own nature, namely its quiddity. The question arises, however, whether it does so necessarily or contingently. There are two major theories about the relationship between roles and roleoccupants, which differ in the answers they give to this question. The view called ‘causal essentialism’ (or ‘necessitarianism’) holds that a property occupies its causal role essentially, by virtue of its own quiddity, which implies that there is no possible world wherein it occupies a different role than the one it does in this world. On this view, the laws of nature are metaphysically necessary. The quiddity of a property thus determines not merely its identity (what it is) but also its causal role (what it does).3 By contrast, the view called ‘quidditism’ holds that properties only occupy roles contingently. That is, the laws of nature are not metaphysically necessitated by the properties of individual things but are ‘thrust upon’ them, ‘irrespective, as it were, of what those properties are’, as Alexander Bird (2007, 2) puts it.4 The quiddity of a property thus only determines its identity, and not its causal role, which implies that the same quiddity can occupy a multitude of different roles. Consequently, in Lewis’ words (2009, 204), ‘[t]o be the ground of a disposition is to occupy a role, but

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it is one thing to know that a role is occupied, another thing to know what occupies it’. On this view, the quiddities and their roles thus come apart. The same quiddity can occupy multiple types of roles, so that ‘[b]eing the ground of a certain disposition is only one case among many of role-occupancy’ (Lewis 2009, 204). Conversely, the same role can be realized by multiple types of quiddities. The mass-role of resisting acceleration, e.g., is occupied in other possible worlds by a different type of quiddity than the one that actually occupies it in our world. All that can be observed in any world, however, is the role that a quiddity plays. We consequently identify the property of being massive only in terms of its role, not by reference to the unique quiddity of the property that plays that role. A negatively charged particle is repelled by other negatively charged ones. According to quidditism, the property that occupies the role of being negatively charged can play a different role than the one it actually plays in this world. And the role of being negatively charged can likewise be played by a different property than the one that actually plays it in this world. The same is true of all other fundamental properties discovered by our physical sciences. This doctrine of quidditism underpins what Lewis calls ‘Ramseyan Humility’, according to which what quiddities actually occupy the roles we observe is beyond our ken: ‘no amount of knowledge about what roles are occupied will tell us which properties occupy which roles’ (Lewis 2009, 204). Given that our empirical knowledge is only capable of discovering the variety of causal roles, a true and complete ‘final theory’ would thus only provide a full inventory of the causal roles, not the quiddities of their occupants. Even in a final theory, ‘[n]o possible observation can tell us which (possible actualization) is actual, because whichever one is actual, the Ramsey sentence [describing the functional features of all the fundamental constituents of the world] will be true’ (Lewis 2009, 207). The argument for this Ramseyan form of epistemic humility can be summarized as follows: (1) To be an object of some kind is to play its characteristic role. (2) The same role can be realized by a multitude of quiddities. (3) Empirical knowledge can provide us only with an inventory of observable roles; it cannot tell us what occupies each role. (4) It is beyond the scope of our knowledge to see what actually plays any given role that we observe. Some parallels can be found between this recent brand of epistemic humility and Locke’s. To be of a certain kind, on Locke’s account, is to satisfy an abstract idea of that kind in which the characteristic role occupied by members of that kind is spelled out. This role constitutes the nominal essence of that kind. Locke thus states that ‘[i]n my sense of [the phrase “true sun”], any thing will be a true sun, to which the name sun

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may be truly and properly applied’ (First Letter, 84). The status of being a member of kind x (e.g. a sun) is established by a thing’s occupancy of the x-role (the sun-role). Inaccessible to us is the occupant’s ‘real, internal, individual constitution, i.e. [its] real essence, that makes it to be what it is’ (First Letter, 85). As noted earlier, the multiple realizability of roles is crucial to the Ramseyan brand of epistemic humility. References to such multiple realizations can also be found in the Essay. In Book III, Locke suggests that the sun-role may be multiply realizable: ‘though there be but one Sun existing in the World, yet the Idea of it being abstracted, so that more Substances (if there were several) might each agree in it; it is as much a Sort, as if there were many Suns, as there are Stars’ (III. vi.1). In this world, the sun has a unique realization. Locke, however, allows that the sun-role can be realized by ‘more Substances [than one] (if there were several)’ (III.vi.1). The different realizers occupy the same role by ‘agree[ing]’ upon the ‘one common Conception’ that makes up the nominal essence of ‘sun’ (III.vi.1). Here, Locke relies solely on the abstract nature of nominal essence. He further holds that: The common Names of Substances, as well as other general Terms, stand for Sorts: which is nothing else but the being made signs of such complex Ideas, wherein several particular Substances do, or might agree, by virtue of which, they are capable to be comprehended in one common Conception, and be signified by one Name. (III.vi.1) In his answer to Locke’s first letter, Stillingfleet objects to Locke’s proposal that there could be multiple realizations of the sun-role as follows: To clear this, I put the Instance of the Sun, where an Essence was said by you to be in one Individual; and yet more Suns might agree in it. In this one Sun there is a Real Essence, and not a meer Nominal and Abstracted Essence: upon which I asked, If there were more Suns, would not each of them, have the Real Essence of the Sun? For what is it makes the second Sun, to be a true Sun, but having the same Real Essence with the first? If it were but a Nominal Essence, then the Second would have nothing but the Name. (First Answer, 117) Here Stillingfleet finds an apparent absurdity in the Lockean nominalist account. For Locke, while substances that belong to the same kind are similar in certain respects, each nonetheless has its own unsharable individual essence. As his nominalism implies, there is no universal property in the physical world that can be shared by different substances. Substances are classified as of the same kind due merely to the fact that they happen to be similar in certain respects. Those respects in which they are taken to be similar constitute their nominal essence. Stillingfleet contends that if a second sun were to exist, it must have

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‘the same Real Essence with the first’. On Locke’s account, however, all one can observe about things of the same kind is the fact that they occupy the same role.5 We can find a more elaborated metaphysical discussion of the multiple realizability of each nominal essence in other passages from Locke’s correspondence with Stillingfleet. In his first letter to Stillingfleet, Locke draws a noteworthy distinction between the ‘ideas of men’ and ‘the will of the Creator’: [I]t is true, the real constitutions or essences of particular things existing, do not depend on the ideas of men, but on the will of the Creator; but their being ranked into sorts, under such and such names does depend and wholly depend on the ideas of men. (First Letter, 91) This passage may at first glance appear to reiterate the point that human classification of things into kinds reflects the observers’ perspectives and interests. However, while the ‘ideas of men’ signifies our observation of the variety of causal roles by means of empirical inquiry, Locke’s remarks about the ‘will of the Creator’ can be considered as expressing a commitment to quidditism. This passage can be taken to suggest that: (1) By his will, God can create individual substances out of whatever stuff or constitution he desires. (2) This implies that the quiddity that actually occupies a given role in our world is not the only possible type that can do so. (3) Consequently, roles and role-occupants can come apart. There are a few ways in which (3) might hold true: (a) Strong quidditism: roles and role-occupants can come apart even under the same laws of nature. On this view, God can change the roles occupied by quiddities or replace the quiddities that actually perform certain roles by another possible set without changing the laws of nature, and thus even without us noticing this radical change. However, the quidditist might instead opt for the following position: (b) Weak quidditism: quiddities and their roles can come apart only under different laws of nature. God cannot make the aforementioned kinds of changes without thereby establishing new laws of nature. Alternatively, one might attempt to read the cited passage from Locke’s first letter to Stillingfleet as compatible with a weak form of causal essentialism, such that if God wants to have certain roles performed in

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the world, he must include certain specific quiddities as the occupants of those roles; namely, those quiddities whose essences contain the potencies or powers associated with those roles. That is, (c) Weak causal essentialism: the causal roles occupied by the quiddities that God choses are part of the essence of those quiddities. Once God chooses a set of quiddities to use in constructing the world, the laws of nature and causal roles occupied in the world would thus necessarily follow. This weak form allows for possible worlds in which God makes use of different sets of quiddities in constructing the world, thereby resulting in different laws. By contrast, a stronger form of causal essentialism does not allow for such possibilities. This view can be stated as follows: (d) Strong causal essentialism: the laws in the actual world are metaphysically necessary. It is impossible for the laws of nature to be different than they actually are. Locke’s account of the divine will in the cited passage does not endorse (d). My contention is that Locke is also not committed to (c) or (b), but instead holds a view closer to (a). Locke himself mentions a particularly extreme case of such role-change. While discussing God’s omnipotent power in his correspondence with Locke, Stillingfleet refers to a case that bears some similarity to a case involving what we would call a possible world: ‘God can alter the Laws of Motion in another System’ (Second Answer, 149). Stillingfleet takes it that ‘[God] may if he please, change a Body into an Immaterial Substance’ (First Answer, 78). In his response, Locke expresses his agreement with Stillingfleet by affirming that, despite such a radical alteration in the role it occupies, ‘[t]he same substance remains’ (Second Reply, 470). As Locke emphasizes, he is speaking here about a ‘change’ (of a material body into an immaterial substance), not a ‘creation’ (of an immaterial substance ‘de novo’): [I]f the same substance remains not, body is not changed into an immaterial substance, but the solid substance, and all belonging to it, is annihilated, and an immaterial substance created; which is not a change of one thing into another, but the destroying of one, and making another ‘de novo’. (Second Reply, 470) This passage suggests that the selfsame quiddity can even play both the materiality-role and the immateriality-role. For both Locke and Stillingfleet, however, the resultant ‘immaterial substance’ in this example would not be identified as a mental substance.

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As a mind-body substance dualist, Stillingfleet would deny that God could change a material being into a mental being. By contrast, Locke would acknowledge that God could do so. Unlike orthodox Cartesian dualists, however, Locke would not regard an immaterial substance as inherently mental, allowing instead for the possible existence of non-mental immaterial substances. As we shall explore in Chapter 4, he nevertheless deems it reasonable to suppose that God gives the power of thought to some systems of matter fitly disposed. Locke goes on to ask Stillingfleet, Now I crave leave to ask your lordship, why God, having given to this [immaterial] substance the faculty of thinking after solidity was taken away from it, cannot restore to it solidity again, without taking away the faculty of thinking? (Second Reply, 471) Here Locke conceives of a series of divine acts (which seem to take place in the same world under the same laws of nature) such that: (1) God makes a material substance into an immaterial one by ‘tak[ing] solidity away from it’; (2) God then gives the resulting immaterial substance the faculty of thinking; and (3) God makes the resulting immaterial mental substance into a material (mental) substance by ‘restor[ing] to it solidity again’. This series of divine acts implies that the faculty of thinking can be given to any type of substance, material or immaterial. Locke sees no contradiction in any type of substance being made capable of thought. In his view, it is thus epistemologically possible for the human mind to be immaterial, although (as we shall explore in Chapter 4) he does not think it is reasonable to assume that this is so. At any rate, in the preceding cited passage describing the hypothetical transformation of a material substance into an immaterial one, Locke’s main focus does not seem to be on the mind-body problem, but rather on the role-change of a quiddity. Here Locke’s central point seems to be that even under the same laws of nature, the selfsame quiddity can occupy one role or another—even the materiality-role and the immateriality-role. The entire nature of such a multi-tasking quiddity cannot be identified or individuated by any specific role (among the multitude of possible ones) that it performs. Its flexible nature does not by itself determine which specific role it must occupy when God switches the roles of quiddities. It is thus one thing to observe that a certain role is occupied, another to know what occupies it. While this quidditist position of the stronger form underlies Locke’s epistemic humility, Langton’s Kant takes it that roles are assigned or altered only under certain laws of nature: ‘God could have created a world where the laws of gravity were different, or where there was no gravity [e.g.] at all, yet where substances had the same intrinsic properties they do in our world’ (Langton 1998, 118). From this weak type of quidditism, Langton’s Kant derives the controversial thesis that each quiddity—though distinctively natured—is causally idle in and

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of itself. Such a non-causal, qualitative nature is hidden from us. Langton ascribes this type of Kantian humility to Locke, too. The next section investigates Langton’s account of Kant and its relevance to Locke.

4.

Locke and Langton’s Kant

In her 1998 book on Kant, Langton develops a position that she calls ‘Kantian Humility’ and explains how it differs from the Ramseyan type advocated by Lewis. Langton (2004, 133) acknowledges that ‘similar though they are’, these two modern brands of epistemic humility proceed from different premises in arguing for their shared conclusion that we are incurably ignorant of the intrinsic properties of things in themselves. Langton sees Locke as holding a form of epistemic humility similar to that which she attributes to Kant. This similarity, she claims, derives primarily from their shared commitment to the irreducibility of causal powers: Locke does not hold a Leibnizian view according to which relations and relational properties are unreal, but rather, like Kant, he believes that they are irreducible to intrinsic properties. Applying this to the case of the [causal] powers, Locke believes that powers do not supervene on the primary qualities of a thing, but rather have their source in a superadding creative act of God. (Langton 1998, 154–5) Lewis and Langton’s Kant share the quidditist view that the causal powers of things are not metaphysically necessitated by their intrinsic properties. From this general quidditist position, Langton’s Kant argues for a further thesis: that intrinsic properties are causally impotent. According to Locke’s Ramseyan worldview, by contrast, things-inthemselves are viewed as multi-tasking role-occupants, each performing any given role in virtue of ‘[its own] distinct propert[y]’, as examined in the foregoing sections. Let us consider Langton’s own comparison of her Kantian form of epistemic humility with Lewis’ Ramseyan view: [T]he Kantian answer to the epistemological question depends not on the multiple realizability of [roles], but on a kind of receptivity of knowledge, and a kind of irreducibility of causal power. The latter thesis makes things as they are in themselves ‘idlers’, in Lewis’s terminology. The intrinsic properties of which we have no knowledge deserve the name ‘idlers’ because they are actually instantiated, but they play no active part in nature. All the more reason, then, for drawing a distinction between Kantian and Ramseyan Humility, similar though they are. Things in themselves, Kantian version, are not quite things in themselves, Ramseyan version. Idler properties can’t be realizer properties—or at least they can’t while they’re actually idling! (Langton 2004, 133)

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On Langton’s reading, Kant proceeds from the quidditist notion that intrinsic properties are independent of laws,6 and from this derives the further thesis that intrinsic properties bear causal powers, but are themselves causally idle: ‘[i]ntrinsic properties are required, not to provide the basis for forces or powers—for they cannot, in Kant’s opinion, do that—but only for the very general reason that substances require some intrinsic properties or other’ (Langton 1998, 120). Langton thus sees Kant as subscribing to a form of property dualism according to which we are only affected by the causal powers (as relational properties) of things-inthemselves, not their intrinsic properties. The form of property dualism that Langton attributes to Kant reflects her own challenge to readings of Kant that take him as holding that there are two sorts of objects (rather than properties), phenomenal and noumenal, the one being the cause of the other. Langton argues that her alternative reading of Kant resolves what she calls the ‘old problem’,7 which is a charge of inconsistency in Kant’s argument for his epistemic humility. Langton reconstructs the traditional readings of Kant’s epistemic humility as follows: (1) Things-in-themselves exist. (2) Things-in-themselves are causes of phenomenal appearances. (3) Therefore, we can have no knowledge of things-in-themselves. Here the conclusion implies total ignorance—even about the existence of things-in-themselves. Given the conclusion, we could not know whether premises (1) and (2) were true—i.e. whether the things-in-themselves exist at all, or whether they are the causes of phenomenal appearances. Langton’s proposal is an attempt to save Kant from this type of objection. According to Langton, Kant’s epistemic humility is thus directed at the intrinsic properties of things-in-themselves, not whether the things-inthemselves exist or not. Langton (1998, 12–3) regards Kant as endorsing a ‘one-world view’ combined with the aforementioned form of property dualism: ‘[t]here is one world, one set of things, but two kinds of properties: intrinsic properties, and properties that are “in opposition” to the intrinsic, namely relational properties’. Kant’s terms ‘phenomena’ and ‘noumena’ thus refer to ‘different classes of properties of the same set of entities’ (Langton 1998, 13). Here is Langton’s (1998, 15–28) summary of her Kantian epistemic humility as stated in terms of the major theses that constitute the view: (1) Receptivity: human knowledge depends on sensibility, and sensibility is receptive; we can have knowledge of an object only insofar as it affects us. (2) Distinction: things in themselves are substances that have intrinsic properties; phenomena are relational properties of substances.

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(3) Irreducibility: relational properties are irreducible to intrinsic properties; only relational properties of substances can affect us. (4) Humility: we therefore have no knowledge of the intrinsic properties of substances. As (1) indicates, our being affected by the external world is an empirically acceptable indication of its existence. Locke would of course accept this first premise, but not the second or third. The conjunction of (2) and (3) saves Kant from what Langton calls the ‘old problem’. By ‘relational properties’, Langton means causal powers. In order to be acquainted with external objects, one must be affected by them, yet we are only affected by their relational properties, not their intrinsic properties. Thus the causally impotent intrinsic properties are inaccessible to us. Langton (1998, 120) admits that the view she attributes to Kant is not so popular at present, especially regarding the thesis that intrinsic properties are causally inert: ‘[b]y contrast, many metaphysicians of our own time take powers, constructed as dispositions, to be causally impotent, and believe that the real causal work is always done by intrinsic properties— notwithstanding the fact that powers are not reducible to intrinsic properties’. Here Langton refers to a different form of property dualism, according to which intrinsic properties are causally active while powers are impotent. This position, too, agrees with quidditism in holding that intrinsic properties are the contingent ground for powers or dispositions.8 But Locke would not readily accept this form of property dualism either. He would not advocate any type of ontological irreducibility between powers and their bearers. For him, powers are understood as a kind of nominal entities, each of which is multiply realizable. They constitute the ideas of substances, rather than the substances themselves: ‘[p]owers . . . make a great part of our complex Ideas of Substances’ (II.xxiii.10).9 The complex ideas of substances contain a set of functional descriptions of their causal roles. The ‘realization’ relation holds between the descriptive entities and extra-descriptive entities. It is thus only in a trivial sense that one is irreducible to the other. As we have seen, crucial to Locke’s account of epistemic humility is the multiple realizability of roles by various actual or possible objects. According to this functionalist view, the idea of a power, active or passive, is obscure in that it only tells us what something does: ‘when by impulse [a Ball] sets another Ball in motion, that lay in its way, [it] gives us but a very obscure Idea of an active Power of moving in Body’ (II.xxi.4). By observing the role alone, one thus cannot infer what the roleoccupant is. The occupant of an active role can even be switched with one that plays a passive role. The role’s character does not determine the nature of the role-occupant. This Lockean epistemic humility, however, does not imply that each role-occupant is causally idle. In fact, the reasoning that underpins Langton’s Kantian humility and proceeds from the contingency of laws to the impotence of intrinsic properties is fallacious. To use James

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Van Cleve’s example (2002, 226), ‘[i]t is contingent that a hot ember applied to my skin will burn it, but that does not imply that the burn is not caused by intrinsic properties of the ember’. Van Cleve further argues that in the passages Langton cites in support of the impotence of intrinsic properties, Kant does not make any specific claim about the causal impotence of intrinsic properties, but instead merely highlights the general quidditist view—through his own thought experiments—that God can change the causal powers of things while leaving their intrinsic nature the same. We shall not, however, examine whether Kant really subscribed to the causal impotence of intrinsic properties. For the purpose of this chapter, it will suffice to have established that Locke would not accept the type of epistemic humility that Langton attributes to Kant.

5.

Locke and the Newtonian Conception of Matter

This final section considers Locke’s epistemic humility in relation to the Newtonian conception of matter. For Newton, a physical body is nothing more than a modified region of space that performs the role of a physical object, e.g., by emitting sound, reflecting light, preventing other physical bodies from entering its own occupied region, and so on. In order to create a mountain, e.g., all God needs to do is to render a certain mountain-shaped and -sized portion of space to play the mountain-role, i.e. the functional role that the things we call ‘mountains’ play. As Bennett (1984, 89) observes, ‘[i]f the job were done right, Newton says, we would have every reason to suppose that a mountain had been added to the furniture of the world; and he takes this to support his suggestion that actual physical things are just regions of space which have been suitably thickened, so to speak’. For Newton (1962, 27), a physical body thus ‘does not exist by necessity but by divine will’. This account of matter has some affinities with occasionalism wherein God is take to be the immediate cause of both physical events and human sensation.10 It can also be viewed, however, as a functionalist account of matter, in that it treats the creation of a material body as equivalent to the bestowal of the body-role on a region of space by appropriately modifying it—regardless of what the occupant of that role happens to be.11 In order to produce a physical body in a spatial world, God only needed to transform a portion of empty space into a solid region by imposing on it the conditions of materiality such as impenetrability, mobility, and the power to produce sensations in human minds.12 By taking those conditions away from it, God can turn a material (or solid) region into an immaterial (or unsolid) one as well. As we have seen, Locke also often mentions such role-changes and acknowledges their possibility in his correspondence with Stillingfleet. In the interest of further investigating Locke’s views on these matters, this final section examines the Newtonian conception of matter and considers whether Leibniz’s and Pierre Coste’s ascriptions of it to Locke are correct.

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In the New Essays, Leibniz takes Locke to follow Newton in regarding space as a substance and physical bodies as accidents or qualities of it, which are ‘fleeting and transitory in the way accidents are’ (NE, IV.x.18: 442). What Leibniz found upsetting in this position was the suggestion that matter is an accident or quality of space. He takes this to lead to a materialistic account of the human mind. For Leibniz too, matter is an accident of something, yet not of space but of mental atoms (i.e. monads). In his letter to Lady Masham (1704), Leibniz writes that ‘I noticed in Mr. Locke’s Essay, Book IV. Chapter x, a thought which appears important, which he seems to have been unwilling to reveal to the uninitiated but which ought not to be allowed to slip through our fingers since this remarkable man is still with us’ (Bennett and Remnant 1978, 3; their translation). The puzzling passage that Leibniz mentions here is the following, wherein Locke mentions a ‘vulgar’ conception of matter which he seeks to abandon in favor of a rather new account of matter—in his words, some ‘dim’ conception of ‘how Matter might at first be made’: If we would emancipate our selves from vulgar Notions, and raise our Thoughts, as far as they would reach, to a closer contemplation of things, we might be able to aim at some dim and seeming conception of how Matter might at first be made, and begin to exist by the power of that eternal first being. (IV.x.18) Although Locke does not explain here exactly what the ‘vulgar’ view of matter is, it is not too difficult to infer what he had in mind. Locke must have been referring to the then widely held Boylean view of solidity, according to which each corpuscle or atom is perfectly solid by virtue of being physically fully packed with no interstitial space within itself. On this view, solidity is thus explained by a kind of physical fullness, rather than by the dynamic or dispositional nature of solid things.13 Against the ‘vulgar’ conception of matter, Locke holds above that ‘we might be able to aim at some dim and seeming conception of how Matter might at first be made’. Leibniz also writes in reference to this same passage in the Essay: ‘I assure you, sir, that I believe there is something fine and important hidden under this rather enigmatic passage’ (NE, IV.x.18: 442). The passage that Leibniz here describes as ‘enigmatic’ was also noted by Coste, the French translator of Locke’s Essay. In his note to IV.x.18, Coste offered a testimony of what he heard from Newton regarding Locke’s views on the nature of matter: Here Mr. Locke arouses our curiosity but is unwilling to satisfy it. Within a short time after my translation appeared, many people asked me to divulge it to them; but I had to confess to them that Mr. Locke had kept it a secret even from me. Eventually, long after [Mr. Locke’s death], the whole mystery was unveiled for me by Sir Isaac

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Newton, to whom I happened to mention this part of Mr. Locke’s book. Smiling, he told me first that it was he himself who had devised this way of explaining the creation of matter, the thought of it having come to him one day when he happened to touch on this question in company with Mr. Locke and an English lord. . . . Here is how he expounded this thought to them. One could (he said) in some fashion form an idea of the creation of matter by supposing that God could through his power prevent everything from entering a certain portion of pure space, space being by its nature penetrable, eternal, necessary, infinite; for thereafter that portion of space would possesses impenetrability; which is one of the essential qualities of matter. (Bennett and Remnant 1978, 5; their translation) According to Coste, Locke had in mind a Newtonian view. The Boylean God creates the perfect solidity of body ex nihilo. By contrast, the Newtonian God only needs to modify a region of space by imposing a set of appropriate powers or dispositions on it. Physical bodies are thus made out of something that already exists, i.e. a portion of space, not ex nihilo. The Newtonian conception of matter that Coste attributes to Locke can be summarized as the conjunction of the following theses: (1) Matter is not created ex nihilo but is an altered region of space; and (2) Space is ontologically prior to matter. For a material body to have the power of resistance that occasions the quality of solidity is thus nothing more than for God to give it the power to prevent other bodies from entering into its region. Given that no region of empty space has the power of resistance inherently, it follows that: (3) The power of solidity imposed on a region of space is irreducible to the bearer. There is a sense in which Locke would accept (1) to some extent—in particular, with respect to its agreement with his view that materiality is not created (by God) ex nihilo but is instead a nominal essence (created by us). However, Locke would not endorse (2) or (3). My contention is that Locke would reject (2) and (3) because he conceives not only physical bodies but space, too, in terms of its functional role. His epistemic humility thus runs deeper than Coste and some of our modern commentators suppose. It should be noted that in the Essay, Locke contrasts empty space and matter in terms of our ideas of them: ‘[solidity] is the Idea belongs to Body, whereby we conceive it to fill space’ (II.iv.2), and ‘our Idea of Solidity is distinguished . . . from [the idea of] pure space, which is capable neither of Resistance nor Motion’ (II.iv.3). The following statement

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also clearly shows that the distinction between body and space is strictly nominal: ‘Space is not Body, because it includes not the Idea of Solidity in it’ (II.xiii.11). Locke further observes that: ‘[i]f it be demanded (as usually it is) whether this Space void of Body, be Substance or Accident, I shall readily answer, I know not: nor shall be ashamed to own my Ignorance, till they that ask, shew me a clear distinct Idea of Substance’ (II.xiii.17). This passage indicates that our idea of space is also obscure in that it only encompasses what space does. More often, its function is characterized in terms of what it doesn’t do; e.g. it does not resist the approach of physical bodies into its own region. Though this description of space is negative, it is nevertheless a kind of functional account: space does occupy these negatively characterizable roles. Given these roles, there must be something that occupies them, but what occupies them is beyond our ken. Coste seems to think that if we adopt the Newtonian account, all the secrets of physical bodies would finally be uncovered. Some modern commentators, such as Bennett (1984) and Christopher Conn (2008), seem to think the same. In support of Bennett, Conn (2008, 438) maintains that ‘Newton’s account of how bodies were made provides us with an account of what bodies are’. Yet, if one can understand even space only in terms of its role, the Newtonian account of matter—as a product of God’s alteration of space—would never reveal its true nature. Given the passage cited in the foregoing section where Locke observes that the same quiddity can play both the materiality-role and immateriality-role, Locke may likewise have thought it possible that some more fundamental being occupies both the body-role and the space-role. He seems to think that the solidity of body is only nominally irreducible to the emptiness of space. In the following passage, Locke provides a unified account of mind, body, and space in terms of our ideas of them: [I]f it be a Reason to prove, that Spirit is different from Body, because Thinking includes not the Idea of Extension in it; the same Reason will be as valid, I suppose, to prove, that Space is not Body, because it includes not the Idea of Solidity in it; Space and Solidity being as distinct Ideas, as Thinking and Extension, and as wholly separable in the Mind one from another. Body then and Extension, ’tis evident, are two distinct Ideas. (II.xiii.11) Certain observations of McGinn’s are helpful in advancing this Lockean point of view. On McGinn’s account, just as the term ‘physical’ has two meanings, narrow and wide,14 so, too, does the term ‘space’. McGinn (2004, 18) observes that ‘physicalists don’t want to identify the mind with empty space; they want to identify it with what occupies space— but then we need to know what kinds of things are being considered as potential occupants’. In some ultimate theory, our current conception of space might be radically revised to the extent that we might not even

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use the word ‘space’. McGinn’s idea is that the mind will presumably be related to this entity that we now call ‘space’—‘no matter what its nature turns out to be’ (McGinn 2004, 16). What indeed is the intrinsic nature of those things that occupy certain portions of space (the things we now call ‘physical bodies’)? This is exactly the type of question Locke also raises. Our current understanding of space, as McGinn, too, notes, might be radically revised by future science, and thus we might someday have a completely different account of what we now call ‘space’, and therefore of ‘mind’. Locke’s epistemic humility is thus deeper and more symmetrical with regard to the nature of space and physical bodies than our modern commentators would suppose. The next chapter examines how Locke explains the presence of minds in this world whose intrinsic nature lies beyond our ken.

Notes 1. According to Van Cleve (2002, 226), Kant did not in fact argue for the causal impotence of intrinsic properties from the contingency of causal powers. In his review of Langton’s book on Kant, Van Cleve observes that the claim ‘that intrinsic properties have their effects only contingently does not imply that they do not have them at all’, nor that ‘we are not affected by intrinsic properties’. This chapter does not discuss whether Langton’s interpretation of Kant captures what Kant really had in mind. Our concern is rather with the question of whether the view that Langton ascribes to Kant is also attributable to Locke, as Langton claims it is. 2. There is nonetheless a passage in the Essay where Locke says that ‘[real] Essence, even in this sense, relates to a Sort, and supposes a Species’ (III.vi.6). In reference to this passage, Guyer (1994, 133) has suggested distinguishing ‘real essence’ from ‘real constitution’, such that the former (real essence) should be taken as the ground of the qualities of a sorted substance while the latter (real constitution) is that of an unsorted substance ‘in no way depending upon our own mental activity (of classifying nominal kinds)’. For a similar observation, see Owen (1991). 3. According to causal essentialism, each quiddity is considered to be essentially dispositional; its essential nature consists in its nomic relations with its causal partners. Their causal relations obtain by virtue of the facts about their dispositional nature. An early form of causal essentialism was suggested by Shoemaker (1980) and has been elaborated and defended by Swoyer (1982), Ellis (2001), and Bird (2007). 4. Prominent proponents of quidditism include Lewis (1986, 2009), Armstrong (1999), and Shaffer (2005). Their respective ways of elaborating the general idea of quidditism are, however, different. According to Lewis, all there is in the world is the individual things with distinctive properties, and the laws are nothing more than regular patterns of their behaviors. This Humean position contrasts with the more robust view of Armstrong, according to which the laws are independent facts imposed on the properties of individual things. While Lewis’ view is fully Humean, Armstrong’s is semi-Humean, as Bird (2007, 2) puts it, ‘because on the one hand, it invokes nomic necessitation in nature, and so cannot be a vanilla kind of Humeanism, while on the other hand nomic necessitation is entirely contingent’. By contrast, causal essentialism denies both types of quidditism, and is thus anti-Humean.

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5. One might think that the fact that a number of objects share the exact same observable qualities gives us reason for suspecting that they share the same real essence. Yet Locke is a particularist with regard to real essences, as examined in Chapter 2. For him, each individual substance possesses its own unsharable essence; that is what Locke calls its ‘real essence’. Only nominal essences (or roles) are sharable. The real essences of members of the same kind (or those of role-realizers) are only similar to one another in certain respects. 6. Langton’s (1998, 119) definition of an intrinsic property is as follows: ‘[a]n intrinsic property is a property something has no matter what else exists, no matter what the laws are. . . . In short, a property is intrinsic just in case it is compatible with loneness and lawlessness’. 7. For a more detailed discussion of what Langton calls the ‘old problem’ as well as her own project, see Langton (1998, 7–14). Van Cleve (2002, 219) describes Langton’s approach as follows: ‘Kant is sometimes interpreted as holding that there are two classes of objects in the world (phenomena and noumena), that some kind of idealism holds for the phenomena, and that the noumenal are utterly unknowable. The resulting philosophy is what Langton calls “the worst of all veil of appearance philosophies: Berkeley plus unknowable things in themselves” (Langton 1998, 15). She wants to avoid the entire package—not just the complete unknowability of things in themselves, as already noted, but also the two-worlds picture and the Berkeleyan idealism. She treats the noumenal-phenomenal distinction as a distinction between two kinds of properties rather than two kinds of things’. 8. As described by Langton (1998, 120), this alternative form of property dualism holds that ‘intrinsic properties are required for two reasons: First, there is the general requirement with which Kant would agree, that substance must have some intrinsic properties or other. Second, there is a particular requirement with which Kant would disagree, that substances which have dispositions must have intrinsic properties which form the (contingent) ground of the dispositions’. 9. Shoemaker (1980, 112) refers to this passage in arguing for causal essentialism and against quidditism. As I read him, Shoemaker misses Locke’s nominalist point that powers are conceived as theoretical entities to be realized by the unknown real essences of substances. 10. Gorham (2011) advocates such an occasionalist reading of Newton’s views on this issue. By contrast, Dempsey (2014, 102) proposes a more naturalized reading of Newton, wherein physical bodies themselves are taken to be the immediate causes of both physical events and human sensations: ‘it would be incorrect to suggest that, for Newton, when we direct our gaze toward an object, God specifically wills that we have certain sensations. We should rather say that God has endowed that region of space with certain powers to affect our sense organs in a certain way’. The powers described here are exerted directly by the altered regions of space. A more elaborate description of this naturalized type of Newtonianism can be found in the following observation by Stein (1970, 276–7): ‘[i]t is not metaphor, but a literal truth, that Newton’s metaphysics of body reduces the notion of matter to the notion of a field. A body, Newton tells us, is a region of space endowed with certain properties . . . they are dispositional characteristics of the spatial region, like the field qualities of gravity or electro-magnetism’. 11. Reid (1895, vol. 2, 286) reads the passage from IV.x.18 discussed later in a more idealistic manner, taking it to suggest the Berkeleyan notion that God could create physical objects more directly than even Newtonian proposes by

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causing perceptions in human minds, rather than by modifying portions of space. For a discussion of Reid’s comments on IV.x.18, see Woolhouse (1982, 87), who remarks that ‘the crux of what Reid wants to attribute to Locke is the idea of matter as God’s intention to produce certain ideas directly in finite spirits; whereas for Coste’s Newtonian Locke such ideas are produced not immediately by God but via the mediation of altered portions of space (i.e., by matter) and so only mediated by God’. 12. For recent discussions on this issue, see Gorham (2009, 2011) and Dempsey (2014). 13. We shall return to Boyle on this issue in Chapter 7. 14. Narrow physicalism holds that consciousness is reducible to, in McGinn’s (2004, 16) words, ‘the properties now described in books of neurophysiology and physics’; and wide physicalism, by contrast, is the doctrine that the mental is reducible to ‘what would feature in an ideal theory of the world’. The trouble with narrow physicalism is that it leaves no room for the fact that physical sciences expand with the discovery of new properties and laws. As a result, narrow physicalism will turn out to be empirically false. The trouble with wide physicalism, by contrast, is that it is totally vacuous. The ideal future theory to which it refers might invoke entities or properties that are very different from those we understand today. If one were to insist on calling such an ideal future theory ‘physical’, this would be for no more than ‘boring institutional reasons’ (McGinn 2004, 17). The conclusion McGinn draws is that we do not know what we mean by ‘physical’ in either sense. A similar point was made earlier in Hempel’s dilemma (1969). We shall explore McGinn’s account of ‘cognitive closure’ in Chapter 5, as an example of a contemporary Lockean approach to the mind-body problem.

4

1.

The Superadded Power of Thought

Emergentism: A Reasonable Possibility

Since the publication of the Essay, commentators have engaged in a series of debates as to what Locke meant by contending that ‘God can, if he pleases, superadd to [a system of] Matter [fitly disposed] a Faculty of Thinking’ (IV.iii.6). His contemporary critics read this remark as suggesting a materialistic view. In IV.iii.6, however, Locke affirms that, given our ‘Notions’ of ‘Matter’ and ‘Thinking’, it is epistemically possible for any type of substance, whether material or immaterial, to be granted the power of thought (IV.iii.6). Reflection provides ‘another set of Ideas’ (II.1.4) that are distinct from those we acquire through sensation. The ideas of mind and body that we derive from these two sources are both ‘primary’ ideas in that each is considered to be conceptually basic, neither being explainable in terms of the other. They are ‘distinct Ideas’ (II.i.4), but not contradictory in their content. Consequently, materialism and substance dualism are both conceivable ‘in respect of our Notions’: ‘[i]t [is], in respect of our Notions, not much more remote from our Comprehension to conceive, that GOD can, if he pleases, superadd to [a system of] Matter [fitly disposed] a Faculty of Thinking, than that he should superadd to it another [immaterial] Substance with a Faculty of Thinking’ (IV.iii.6). Locke’s contemporary critics failed to pay adequate attention to his equal treatment of materialism and substance dualism. Some may have viewed his acknowledgment of both doctrines as a potential threat to the immateriality of the mind. Our modern commentators, by contrast, take notice of Locke’s equal treatment of both doctrines, but many of them regard him as agnostic about which doctrine is correct, thereby ascribing to him no particular theory of mind. While both doctrines are, on Locke’s account, epistemically possible, not all epistemic possibilities are such that it is reasonable to believe that they are also metaphysically possible. For Locke, the immateriality of the human mind provides an example of this point. As we saw in Chapter 3, Locke does not view immaterial substances as inherently mental. If God wants to create an immaterial

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mental substance, he must thus endow some immaterial substance with the power of thought. He may then, if he wishes, go on to combine the resulting immaterial mental substance with a material substance. But no reasonable account is available to us of how such a union or interaction between the immaterial and the material is possible. This constitutes the mind-body problem in its traditional sense as raised by Princess Elisabeth.1 Locke was likewise critical of many of the metaphysical assumptions underlying Cartesian dualism. As we saw in Chapter 1 and will see again in this chapter, Locke makes no such assumptions about the metaphysical disparity between mind and body. Although he regards Descartes’ dualism as epistemically possible, Locke holds that ‘no body, before Des Cartes, . . . ever pretended to show that there was any contradiction in [the suggestion that God should, if he pleased, give to some systems of senseless matter a faculty of thinking]’, and that ‘[even] the father of the Christian church never pretended to demonstrate that matter was incapable of receiving a power of sensation, perception, and thinking, from the hand of the omnipotent Creator’ (Second Reply, 469). Locke even accuses substance dualism of limiting God’s omnipotency ‘to a narrow compass [of our ideas]’ and ‘bring[ing] down God’s infinite power to the size of our capacities’ (Second Reply, 461). This accusation stems from the fact that, from the perspective of Locke’s nominal dualism, Descartes’ distinction between mind and body mistakenly treats what is only nominally distinct as being really distinct. When Locke speaks of the human mind, he typically refers to ‘a system of matter fitly disposed’ as its reasonable ontological ground. In IV.iii.6, he remarks that ‘I see no contradiction in it, that the first eternal thinking Being should, if he pleased, give to certain Systems of created senseless matter, put together as he thinks fit, some degree of sense, perception, and thought’. Many commentators think that Locke treats the notion of a system of matter endowed with thought as merely an epistemic possibility or a hypothesis. I suggest, however, that Locke is committed to treating this as something that it is reasonable for us to view as more than merely epistemically possible. In this regard, we should note the distinction that Locke draws between ‘two sorts of Beings in the World’ in the chapter ‘Of our Knowledge of the Existence of a GOD’ (IV.x). According to Locke, ‘there are but two sorts of Beings in the World, that Man knows or conceives’ (IV.x.9): First, Such as are purely material, without Sense, Perception, or Thought, as the clippings of our Beards, and paring of our Nails. Secondly, Sensible, thinking, perceiving Beings, such as we find our selves to be, which if you please, we will hereafter call cogitative and incogitative Beings; which to our present purpose, if for nothing else, are, perhaps, better Terms, than material and immaterial.

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Locke here does not speak of the metaphysical disparity between natural and supernatural (or ‘immaterial’) entities, but only of that between cogitative and incogitative beings. By ‘sensible, thinking, perceiving Beings’, he does not refer to supernatural entities, but some systems of atoms fitly disposed, ‘such as we find ourselves to be’. The ‘incogitative’/‘cogitative’ distinction he draws here is thus confined to natural beings that are made of basic physical particles. In other words, the incogitative/cogitative dichotomy corresponds to that between ‘bare matter’ and ‘fitly disposed matter’. What Locke refers to as a (finite) ‘cogitative’ being should thus be taken as a mental being grounded in a system of basic particles fitly arranged. The purely material (incogitative) beings and cogitative beings that Locke distinguishes are both made of basic particles, and are the only two sorts of beings in this created world that ‘Man knows or conceives’— in my reading, they are only two sorts of things that we can reasonably know or conceive. Given that the two sorts of things are both made of basic particles, what makes one cogitative, and the other incogitative? According to Locke, only a system of matter ‘fitly disposed’ is capable of thought (IV.iii.6). What makes it such a fit organization for the power of thought? This chapter addresses these questions. My claim is that Locke takes a system of matter fitly disposed to be the immediate cause of its own mental features. Its power of thought may appear to be entirely distinct from the parts of the system but in fact depends on them. I shall refer to this view that I ascribe to Locke as ‘emergentism’. As Locke did not use this term himself, I will adopt the following as a working definition of the view in this chapter’s discussion: [T]o claim that some entities are emergent is to make a claim about the world’s structure. The emergentist is saying that not everything about the world’s structure can be explained in terms of smaller parts building into larger, more complex wholes. Sometimes the collective activity of the smaller parts produces not just a complex thing made up of those smaller things, but also something fully distinct from (‘emergent’ from) those parts, their sum, and anything they compose. And that is a claim about how the world is structured. (Barnes 2012, 874) In my reading of Locke, the power of thought is conceived as being produced by some ‘collective activity of the smaller parts’ of a given system of matter to which that power belongs.2 I shall argue that what Locke refers to as ‘superadded’ can be viewed as ‘emergent’ in this sense.3 This proposed reading contrasts with the widely held view that Locke is a property dualist. As we saw in Chapter 3, Langton (1998, 154–5) ascribes a Kantian form of property dualism to Locke, according to which causal powers are irreducible to their bearers: ‘Locke believes that powers do not supervene on the primary qualities of a thing, but rather have their source

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in a superadding creative act of God’. In this passage, Langton reads Locke’s term ‘superadding’ as supporting her proposed Kantian account of his position. Despite the various problems with this interpretation raised in the previous chapter, the reading of Locke as a property dualist is still popular. Pyle (2013, 110) holds that: The ordinary powers of compound bodies will be reducible to the arrangements of their parts, as Boyle and the corpuscularians have taught us. But the mind, Locke is telling us, is entirely different, and we can know it to be irreducible simply from the inspection of our ideas. In the same vein, Stuart (2013, 250) asserts that: Locke argues for what is often called property dualism, and uses that to argue for the existence of God and [thus] for substance dualism [of an immaterial substance (God) and his created world]. The reading of Locke as a property dualist has generated many criticisms of his position. Wilson (1979) accuses Locke of being an inconsistent mechanist, and both Pyle and Stuart argue that his proof of the existence of God, allegedly based on property dualism, is fallacious. This chapter argues that Locke is not a property dualist but only a nominal dualist, and that he is therefore immune to the foregoing criticisms. This chapter also argues that Locke would find emergentism (as defined previously) to be a reasonable possibility. Against the line of interpretation described earlier, this chapter will show that Locke’s nominal dualism, combined with his emergentism, explains why the power of thought may appear to be entirely distinct from and over and above the parts of a material system it belongs to; viz., because that system can be viewed from the nominally dualistic perspective of our ‘Notions’ of ‘Matter’ and ‘Thinking’ (IV.iii.6).

2.

Nominal Dualism Versus Property Dualism

Modern readers of the Essay tend to become careless about the term ‘idea’ due to Locke’s excessive use of it throughout the book. Locke himself worried about his own ‘frequent use of the Word Idea’ when he stated in the introductory section of the Essay that: ‘before I proceed on to what I have thought on this Subject [human Understanding], I must here in the Entrance beg pardon of my Reader, for the frequent use of the Word Idea, which he will find in the following Treatise’ (I.i.8). The superaddition paragraph in IV.iii.6, too, begins with a description of the mind-body dichotomy in terms of ‘the Idea of Matter, and Thinking’: We have the Idea of Matter, and Thinking, but possibly shall never be able to know, whether any mere material Being thinks, or no; it being

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The Superadded Power of Thought impossible for us, by the contemplation of our own Ideas, without revelation to discover whether Omnipotency has not given to some Systems of Matter fitly disposed, a power to perceive and think, or else joined and fixed to Matter so disposed, a thinking immaterial Substance. (IV.iii.6)

The limited nature of human knowledge is the main point Locke seeks to make here. This passage refers to two methods of conceiving the mindbody relationship. The first is a human method: ‘by the contemplation of our own Ideas’ (of the mind and body). The second is a more divine method: by ‘revelation’. The second one would reveal to us the truth about the mind-body relationship but is not naturally available to us, while the first one is naturally available to us but does not enable us to know the truth. Locke mentions the two rival doctrines of dualism and materialism in this context. Cartesian dualism and materialism are both epistemically possible in terms of our ‘Notions’ of ‘Matter’ and ‘Thinking’. Neither the idea of extension nor that of thought includes or precludes the other. They are ‘distinct Ideas’ (II.1.4)—acquired through different types of perceptual routes (sensation and reflection)—but are never contradictory to each other; thus there is nothing to prevent us from conceiving of an immaterial mind or material one. One cannot, however, determine whether the mind is in fact identical with a material body by considering ‘the ideas of Matter and Thinking’ alone, just as one can never find a circle equal in area to a given square by considering ‘[our] Ideas of a Square, a Circle, and Equality’ alone. The paragraph to which the preceding cited passages belong begins by comparing the ‘Ideas of Matter and Thinking’ with the ‘Ideas of a Square, a Circle, and Equality’: We have the Ideas of a Square, a Circle, and Equality; and yet, perhaps, shall never be able to find a Circle equal to a Square, and certainly know that it is so. We have the Ideas of Matter and Thinking, but possibly shall never be able to know, whether any mere material Being thinks, or no. (IV.iii.6) To find a square equal in area to a given circle was the famous problem of ‘squaring the circle’, inherited from Greek mathematics. In the late nineteenth century, an argument was given, now universally accepted by mathematicians, that the problem of squaring the circle has no solution, because no polynomial having only integer coefficients has pi as its root. But in Locke’s day, this consensus about pi had not yet been achieved— hence, Locke said that ‘perhaps’ we shall never find a circle equal to a square.4 We are likewise unable to see—using only our ideas—whether matter and mind are identical or substantially distinct (or whatever the relationship between them might be). Each type of idea (material and mental) only gives us ‘an equal view of both parts of nature, the Corporeal

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and Spiritual’ (II.xxiii.15). All that we can find in those ideas is hence a conceptual dualism of ‘Corporeal and Spiritual’. Despite his restriction of any dualism between mind and body to the nominal or conceptual level, the ascription of property dualism to Locke is still popular. Pyle (2013, 110) contends that for Locke, the irreducible nature of the mind can be known ‘simply from the inspection of our ideas’. Here he seems to treat the Lockean idea of mind as a clear and distinct idea of the Cartesian type. For Locke, however, the ideas of mind and body are both obscure ideas, each only specifying a set of functional roles, as discussed in the foregoing chapters. When one observes one billiard ball colliding with another and the second ball moving off in a certain direction, one does not directly observe the first ball actually producing motion in the second: ‘we observe it only to transfer, but not produce any motion’ (II.xxi.4). In the following quotation, Locke describes the activity of the first ball in terms of its functional role of transferring motion to the second one: A Body at rest affords us no Idea of any active Power to move; and when it is set in motion it self, that Motion is rather a Passion, than an Action in it. For when the Ball obeys the stroke of a Billiardstick, it is not any action of the Ball, but bare passion: Also when by impulse it sets another Ball in motion, that lay in its way, it only communicates the motion it had received from another, and loses in it self so much, as the other received; which gives us but a very obscure Idea of an active Power of moving in Body, whilst we observe it only to transfer, but not produce any motion. For it is but a very obscure Idea of Power, which reaches not the Production of the Action, but the Continuation of the Passion. (II.xxi.4) In this passage, the functional nature of the ball’s ‘activity’ is determined by reference to neighboring objects and the surrounding environment in a wide causal context. This functionalist perspective can also be found in the following quotation concerning the mental active power: The Idea of the beginning of motion, we have only from reflection on what passes in our selves, where we find by Experience, that barely by willing it, barely by a thought of the Mind, we can move the parts of our Bodies, which were before at rest. So that it seems to me, we have from the observation of the operation of Bodies by our Senses, but a very imperfect obscure Idea of active Power, since they afford us not any Idea in themselves of the Power to begin any Action, either motion or thought. (II.xxi.4) Locke views the activity of an active power, whether physical or mental, as identifiable only by its functional role, so that one has ‘a very imperfect obscure Idea of active Power’. In each case, one thus has only ‘superficial

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Ideas’ of ‘the true Nature of things’ (II.xxiii.32). No viable form of property dualism can be established on the basis of these two types of ideas, both being obscure and imperfect. Such Lockean ideas can at best support nominal dualism. Pyle refers to the following passage to defend his ascription of property dualism to Locke: There was a time then, when there was no knowing Being, and when Knowledge began to be; or else there has been a knowing Being from Eternity. If it be said, there was a time when no Being had any Knowledge, when that eternal Being was devoid of Understanding. I reply, that then it was impossible there should ever have been any Knowledge. It being as impossible, that Things wholly void of Knowledge, and operating blindly, and without any Perception, should produce a knowing Being, as it is impossible, that a Triangle should make it self three Angles bigger than two right ones. For it is as repugnant to the Idea of senseless Matter, that it should put into it self Sense, Perception, and Knowledge, as it is repugnant to the Idea of a Triangle that it should put into it self greater Angles than two right ones. (IV.x.5) Here Locke holds that it is ‘impossible’ that ‘Things wholly void of Knowledge, and operating blindly, and without any Perception, should produce a knowing Being’. But, it should be noted, the impossibility here relies on the idea of matter: ‘[f]or it is as repugnant to the Idea of senseless Matter, that it should put into it self Sense, Perception, and Knowledge’. Locke takes the features of sense, perception, and knowledge to be ‘repugnant’ to ‘the Idea of senseless Matter’ rather than to its real essence. Truths concerning nominal essences are in fact time-sensitive, as such essences are the product of empirical investigations conducted by individuals whose understanding is confined to the science and common sense of their own time. Nominal essences thus ‘advance but slowly’, as Locke points out (III.iii.20). As I see it, the ‘repugnancy’ Locke describes (between sense, perception, and knowledge and the idea of matter) rests on the then generally accepted belief or theory according to which matter is conceived as entirely passive and inert. Although Locke acknowledges that the power of thought is incompatible with such an idea of matter (which was the view most widely held at that time), we mustn’t forget that he also allows for the metaphysical possibility of a system of matter capable of thought. In my reading, the ‘repugnancy’ he refers to relies on the conventional duality between matter and thought, based on the then dominant view of matter, which he describes in IV.x.18 as dependent on certain ‘vulgar Notions’ (as seen in the foregoing chapter’s discussion of the more refined, Newtonian conception of matter that Locke seemed to favor).5 Pyle (2013, 108–14), in contrast, takes Locke’s discussion of the ‘repugnancy’ between sense, perception, and knowledge and the idea of

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matter as evidence of his commitment to property dualism. On the basis of this presumed commitment, Pyle reconstructs Locke’s proof of God’s existence in IV.x as follows: (1) Some minds (e.g. my mind) exist. (2) No mind can arise from mindless entities (e.g. atoms). (3) There must be an eternal mind that causes this particular mind to exist. Here the truth of (2) relies on the supposed irreducibility of the mental. Stuart (2013, 250) also contends that Locke’s attempt to prove God’s existence relies on a form of property dualism about human mental features and their physical bearers. As they both point out, such reasoning from property dualism to God’s existence is fallacious. A single supreme mind cannot be proven to exist by the existence of a particular finite mind since some non-eternal entity could cause the latter. The existence of a particular mind does not rule out the possibility of a plurality of eternal entities either. Stuart (2013, 251) thus contends that ‘Locke’s glaring mistake is to draw the much stronger conclusion that there must be something eternal that caused [a finite mind] to exist’. However, this accusation rests on the controversial assumption that Locke is indeed a property dualist.

3.

The Superadded as ‘Emergent’

According to the form of property dualism commonly attributed to Locke, only the power of thought is irreducible; all other (non-mental) features are presumed to flow from the real essences of material bodies. This view postulates a deep gap between human mental features and the physical world, the former being regarded as uniquely special for this reason. In the emergentist picture, however, all qualities, mental and physical, lower- and higher-level, are regarded as equal members of the world. These equal members are nevertheless hierarchically ordered with respect to their structural complexity. Locke’s account of the superadded is likewise not confined to the power of thought, but instead applies to all natural qualities (except for solidity), including self-motion, life, and rational thought. Consider, e.g., the following passage: The idea of matter is an extended solid substance; wherever there is such a substance, there is matter, and the essence of matter, whatever other qualities, not contained in that essence, it shall please God to superadd to it. For example, God creates an extended solid substance, without the superadding any thing else to it, and so we may consider it at rest: to some parts of it he superadds motion, but it has still the essence of matter: other parts of it he frames into plants, with all the

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The Superadded Power of Thought excellencies of vegetation, life, and beauty, which are to be found in a rose or a peach-tree, &c. above the essence of matter in general, but it is still but matter: to other parts he adds sense and spontaneous motion, and those other properties that are to be found in an elephant. Hitherto it is not doubted but the power of God may go, and that the properties of a rose, a peach, or an elephant, superadded to matter, change not the properties of matter; but matter is in these things matter still. But if one ventures to go on one step further, and say, God may give to matter thought, reason, and volition, as well as sense and spontaneous motion, there are men ready presently to limit the power of the omnipotent Creator, and tell us he cannot do it; because it destroys the essence, ‘changes the essential properties of matter’. To make good which assertion, they have no more to say, but that thought and reason are not included in the essence of matter. I grant it; but whatever excellency, not contained in its essence, be superadded to matter, it does not destroy the essence of matter, if it leaves it an extended solid substance; wherever that is, there is the essence of matter: and if every thing of greater perfection, superadded to such a substance, destroys the essence of matter, what will become of the essence of matter in a plant, or an animal, whose properties far exceed those of a mere extended solid substance? (Second Reply, 460–1)

Here Locke uses the verb ‘frame’ as an alternative for ‘superadd’. God adds a higher-level power to a material body by ‘framing’ the particles into an appropriate form of organization. All the higher-level qualities are thus given to material bodies by the same method. Locke conceives the act of superaddition as arranging the parts of a whole into an organic system of some type wherein a nomological order is established between the lower level and the higher: (1) ‘[God] superadds [to some parts of matter] motion, but [an extended solid substance] has still the essence of matter’. (2) ‘[H]e frames [other parts of matter] into plants, with all the excellencies of vegetation, life, and beauty, which are to be found in a rose or a peach tree . . . but it is still but matter’. (3) ‘[H]e adds [to other parts of matter] sense and spontaneous motion, and those other properties that are to be found in an elephant’. (4) ‘[T]o go one step further, . . . God may give to matter rational thought, reason, and volition, as well as sense and spontaneous motion’. It should also be noted that the preceding cited passage begins by placing an emphasis on the idea of matter: ‘[t]he idea of matter is an extended solid substance; wherever there is such a substance, there is matter, and

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the essence of matter, whatever other qualities, not contained in that essence, it shall please God to superadd to it’. Here ‘the essence of matter’ refers to its nominal essence. On Locke’s account, all higher-level qualities ‘not contained in that [nominal] essence [of matter]’ are considered to be ‘superadded’ to it. Any material body, to which certain higher-level qualities have been superadded, ‘has still the [nominal] essence of matter’, but the idea of matter per se does not contain those higher-level qualities (e.g. the ‘vegetation, life, and beauty’ of a rose, the ‘sense and spontaneous motion’ of an elephant, or the ‘rational thought, reason, and volition’ of a human), but only the (nominally) basic feature of solidity. Higherlevel entities may thus appear to be entirely distinct from and over and above the solid particles of which they are composed, but are nevertheless described as ‘superadded’ only in the sense that they are not contained in the idea of matter. The basic particles of the world (each of which is, in Locke’s view, ‘an extended solid substance, without the superadding any thing else to it’) are unique among created things in that they alone depend on nothing other than themselves once created. In order to create this world as it is now, God must therefore first create the basic particles. But even God does not get the higher-level features ‘for free’, as Barnes (2012, 885) puts it, simply by creating the basic particles. While the original act of creation consists in the creation of those basic particles, the further act of ‘superaddition’ introduces higher-level entities into the world by arranging the bare particles into appropriate forms. Those features introduced through God’s act of superaddition acquire the status of being a higher-level feature of some kind in relation to the structure of the systems of matter they belong to. A rose, e.g., is part of the created world, having its own distinctive ontological makeup grounded in the fundamental material constituents of the world, whereby the set of biological features that constitutes its rose-ness depends on the arrangement of the particles that compose it. The same is true of humans and the power of thought. There are, however, some passages in IV.x that might appear to support the property dualist reading against the emergentist reading here proposed. The following passage, e.g., says that physical particles, ‘however put together’, cannot give rise to the power of thought: ‘[u]nthinking Particles of Matter, however put together, can have nothing thereby added to them, but a new relation of Position, which ’tis impossible should give thought and knowledge to them’ (IV.x.16). Here the phrase ‘however put together’ may appear to mean that physical particles cannot by any means produce the power of thought. In my reading, however, the main point Locke is trying to make here is that the activity of thought cannot be explained by reference to the ‘juxta-position of parts’ (IV.x.16), i.e. the static or positional relations among physical particles. Thought is instead produced by certain activities of a ‘corporeal System’ (IV.x.17), just as temperature is generated by the dynamic activity of the particles

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that make up a certain object or system, rather than by the static and positional properties of those particles. A supreme mind may then take on the role of deciding the level and kind of such activities at which a given higher-level feature emerges, and which are necessary and sufficient for its emergence. With these points in mind, Locke’s proof of God’s existence can be summarized as follows: (1) Some minds (e.g. my mind) exist. (2) A material body cannot by itself determine the level and kind of activities that its constituent particles must perform in order for a certain type of higher-level power of thought to emerge. (3) There must be an eternal mind that determines the level and kind of activities that are necessary and sufficient for such emergence. In this argument, the act of superaddition is taken to furnish the world of atoms with a set of higher-level features by determining the level and kind of atomic activity at which each type of higher-level feature emerges. The basic particles do not by themselves determine these laws of emergence. God creates each particle and assembles them into such organic forms as he thinks suitable to assign specific higher-level features to. In determining the laws of emergence for a particular type of higher-level quality, God adopts a holistic perspective: ‘God has no doubt made us so, as is best for us in our present Condition. He hath fitted us for the Neighbourhood of the Bodies, that surround us, and we have to do with’ (II.xxiii.13). Since the basic particles have no awareness of what is the best role for each of them to play in such a holistic context, God, as a coordinating intelligence, must exist to assign appropriate roles to things of such different levels. On this view, God distributes such a great variety of roles to such a great number of things by arranging their particles into appropriate forms. Furthermore, by assigning lower-level roles to the various parts of a larger system, God also bestows higher-level roles such as the mind-role upon the system as a whole. Whereas the argument for God’s existence, based on the property dualist reading of Locke, was fallacious, the same needn’t be true of the argument as reconstructed from an emergentist perspective. The complexity of the task of role-assignment can only be accomplished by a single supremely intelligent being—‘an eternal, most powerful, and most knowing Being’ (IV.x.6), not any lower-level being. The difficulty with emergentism, however, is to understand what it means to say that particular types of higher-level features emerge in a physical system. Locke holds that ‘to give beginning and being to a Spirit, would be found a more inconceivable effect of omnipotent Power’ (IV.x.18). This passage comes right after the following (which we already encountered in Chapter 3): ‘we might be able to aim at some dim and seeming conception of how Matter might at first be made, and begin to exist by the power of that eternal first being’ (IV.x.18). In what sense is the

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creation of a spirit ‘more inconceivable’ than that of a single particle? In my reading, Locke is here suggesting that it is more difficult to apprehend how (and what it means to say that) God determines the laws of emergence for each type of higher-level feature (i.e. the level and kind of atomic activity that is necessary and sufficient for that feature). Locke maintains that ‘Matter . . . by its own Strength, cannot produce in it self so much as Motion’ (IV.x.10). Consequently, the higher-level features ‘must . . . be produced, and added to Matter by some other Being more powerful than Matter’ (IV.x.10). Here ‘Matter’ refers to the unorganized particles— those that have yet to be fitly disposed, and are thus ‘operating blindly’ as they just ‘knock, impel, and resist one another’ (IV.x.10). The point Locke makes here is merely that unorganized material particles cannot produce the higher-level features ‘by [their] own Strength’. Once fitly organized, however, they give rise to the higher-level features collectively ‘by [their] own Strength’. It is thus only a suitably organized system to which Locke ascribes the higher-level features, including the power of thought. In a suitably arranged system, thought is produced by a collective activity of its parts. This collective activity is more than the sum of the respective shapes and locations of the individual parts and is thus not fully describable in terms of their static and positional features. In support, however, of the alternative, Pyle-Stuart line,6 Jolley (2015, 92) has recently argued as follows: It seems, then, that Locke inconsistently claims that the organization of matter both does and does not make a difference to its capacity for receiving a faculty of thinking. IV.x.16 dogmatically rules out thought being an emergent property of matter: however the particles are organized, they cannot produce thought. IV.iii.6, by contrast, seems more favourable to emergentism, for some organizations of material particles are more suitable than others for having the capacity to think. Jolley takes the phrase ‘however put together’ in IV.x.16 as suggesting property dualism. I agree with Jolley that this doesn’t lead to any genuine inconsistency on Locke’s part, but the ways in which Jolley and I view Locke’s consistency on this issue are rather different. In keeping with his reading of IV.x.16, Jolley likewise reads the phrase ‘a system of matter fitly disposed’ from IV.iii.3 as suggesting property dualism, and thereby takes both passages to support the property dualist interpretation of Locke. By contrast, I read both IV.x.16 and IV.iii.3 as supporting the emergentist interpretation of Locke. Jolley acknowledges that for Locke, only systems of matter fitly disposed are capable of thought. Simpler forms of matter, such as shoes and turnips, are not. On Jolley’s reading, however, even when the particles are fitly disposed, God must add an additional power qua power to them. Jolley (2015, 92) observes, ‘[t]he

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problem of consistency, in its more sophisticated form, can be solved by supposing that God’s action is necessary to give causal powers to matter for thinking, even when the particles are fitly disposed’. This reading may render Locke’s view consistent, but only at the cost of ascribing inconsistency to God. On Jolley’s account, the fitness of organization is one thing, and a power qua power is another. This account would make it logically possible that even when a system of matter is suitably organized as he thinks fit, God may refrain from giving it an appropriate power. There would then be a contradiction on his end between his thought and action, such that he ends up denying the power of thought to systems that he thinks fit to possess that power, while granting it to systems that he deems unfit to possess it. On Jolley’s account, there may be a nomological relation between God’s adding a power qua power and the fitness of an organization, such that God grants a certain type of power to a system of matter only when it is fitly disposed. But the main idea of property dualism is that the power of thought can be added to a material body independently of the real essences of its parts. According to the property dualist reading, furthermore, only the power of thought is taken to be irreducible to any form of material body. Locke, in contrast, takes all higher-level qualities to be ‘superadded’. Here, then, are the options that we have discussed: (1) Emergentism: all the higher-level features (e.g. self-motion, volition, the power of thought) are emergent features. (2) Property Dualism: only the power of thought is irreducible; other higher-level properties are natural consequences of the primary qualities of insensible particles. Property dualism can be further distinguished into two different forms: (a) Weak Property Dualism: the power of thought can be added only to some forms of material bodies; namely, those systems of matter that are fitly disposed. (b) Strong Property Dualism: the power of thought can be added to any form of material body. We might also define the following, more radical position: (3) Pan Property Dualism: all the higher-level features are irreducible to their bearers. The weak form of property dualism (a), suggested by Jolley, may not be a viable position. Even if God could give the power of thought qua power only to a system of matter fitly disposed, the power of thought would on this view still be metaphysically incompatible with the real essence of

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matter. The fitness of a system would consequently turn out to be causally redundant insofar as it would not by itself make the system capable of thinking. It would serve as a precondition or occasion for God to grant the power of thought, but what makes it a fit organization in the first place is God himself. According to emergentism, by contrast, the fitness of an organization is itself the immediate cause of its capacity to think. Once a system is so arranged, the power of thought emerges in it due to its structural fitness for the higher-level power. Locke would not find the other options (b) and (3) to be reasonable possibilities either. In my view, Locke would consistently apply his reasons for resisting substance dualism to any form of property dualism as well (or any other type of metaphysical dualism for that matter). His naturalistic account seems to give priority to explanatory strength. Priestley (1777) read Locke in this way, and for this reason took Locke to be committed to the principle of ontological parsimony in his account of mind. In the first section of the Disquisitions, titled ‘Of the Nature of essential Properties of Matter’, Priestley reminds the reader about the ‘rules of philosophizing’ laid down by Newton, such that ‘we are to admit no more causes of things than are sufficient to explain appearances’; and that ‘to the same effect we must, as far as possible, assign the same causes’ (Disquisitions, 2). Particularly noteworthy is his frequent reference to Locke’s application of the Newtonian rules to the ontology of the mind. Priestley regards Locke as a forerunner of his dynamic theory of the ‘conjunction of [mental and material] powers in the same thing, or substance’ (Free Discussion, 23). Priestley asserts that: ‘Mr. Locke did not apprehend that there was any real inconsistency between the known properties of body, and those that have generally been referred to mind’ (Disquisitions, 32). I take this statement to suggest that Locke does not believe in any real inconsistency between matter and mind, whether in the form affirmed by substance dualists or that affirmed by property dualists. Only nominal dualism can be derived from Locke’s distinction between the two. We shall return to Priestley’s thoughts on this issue in Chapter 7.

4.

The Classic Debate Revisited

Contemporary discussion of Locke’s account of ‘superaddition’ began with an interpretive debate between Wilson (1979, 1982) and Ayers (1981, 1991). Against Wilson, Ayers argues that Locke is a ‘consistent’ and ‘pure’ mechanist in holding that the essence of matter completely determines the laws of physics to the extent that all the properties that a material body possesses can be explained by the laws of physics. Ayers combines this mechanical reading with his epistemological reading of Locke’s use of the term ‘superaddition’. According to Ayers, Locke invokes the divine act of superaddition in order to highlight the limits of human knowledge of how mental states arise from bodily states. That is, Locke’s use of the term

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‘superaddition’ is intended to make the point that one is ignorant about the psychophysical link between mind and body. In that regard, Locke’s use of the term ‘superaddition’ is merely a rhetorical matter (Ayers 1991, vol. 2, 150). In his response to Wilson, Ayers (1981, 228) observes that ‘[i]n the ordinary seventeenth-century usage the phrase “superadded properties” (the title of Wilson’s article) would be a contradiction or solecism’ inasmuch as the term ‘property’ in Locke’s time meant an attribute inseparable from a given substance. Ayers’ claim is that if ‘superadded’ were taken to imply irreducibility as Wilson argues, the phrase ‘superadded property’ would be self-contradictory. In her reply to Ayers, Wilson (1982, 251) acknowledges that her phrase ‘superadded property’ could be self-contradictory as Ayes points out, but imputes this nonsense to Locke himself: ‘I would like to point out, though, that the expression “superadded properties” can in fact be given a perfectly good Lockean interpretation’. Wilson (1982, 252) also makes the following observation in reference to the passage from Locke’s Second Reply (460–1) to Stillingfleet that we examined earlier: Here one may agree, in partial acknowledgement of Ayers’ point, that ‘sense and spontaneous motion’ are considered properties with respect to elephants (i.e., to follow from their essence), but superadded with respect to matter (do not follow from its essence, as ‘matter in general’). It still seems perfectly correct to say that some properties of (the different sorts of) material things are superadded to that essence which they possess merely as material things. Similarly, I take it, Locke would say that thought, a property of spirits (thinking things) is in every case superadded to any created entity that in fact thinks, insofar as the entity is considered just as material or immaterial thing. So it can indeed rightly be styled a ‘superadded property’—though admittedly with a more subtle and convoluted significance than I originally had in mind. According to this passage, the higher-level features are considered as being ‘superadded’ to material objects with respect to their materialness or solidity, yet as being ‘properties’ with respect to their specific kind. For example, the sense and self-motion that we find in an elephant are considered as being ‘superadded’ with respect to its being a solid material being, but as being ‘properties’ with respect to its elephant-ness. An elephant thus has two levels of features: one relating to its materialness in general, and another to its elephant-ness. The latter are taken as ‘superadded’ to the former. The same is true of the power of thought. It is considered as being ‘superadded’ to the basic material features that make up a human body, but ‘essential’ to its human-ness. Here Wilson relativizes the meaning of superaddition such that every higher-level feature is considered as being ‘superadded’ to an object with respect to

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its essence as a member of the material kind, but ‘essential’ to it with respect to its specific kind. While her initial paper (1979) focused more on the irreducibility of the superadded, this relativistic point of Wilson’s (1982) rather resembles the central idea of emergentism.7 Jolley’s (2015) distinction between two conceptions of superaddition— strong and weak—will be helpful in further clarifying my view. The stronger conception holds that the power of thought is added to a substance in the way suggested by Pyle and Stuart. By contrast, the weak conception holds that ‘a property is superadded to a substance just in case it is neither contained in or deducible from the nominal essence of the substance, nor a determinate of a nominally essential property—i.e. one contained in or deducible from the nominal essence’ (Jolley 2015, 77). On the latter view, the power of thought is thus irreducible only to what we know about matter. My position is closer to the weak conception, while Jolley commits himself to the strong one. According to my reading, Locke’s weak form of superaddition is underpinned by his emergentism.8 Ayers’ mechanical reading can be considered as falling within this same emergentist vein of interpretation.9 In further support of this reading, Downing (2007, 374) also observes that ‘there must be something internal to the thinking thing that would, in principle, explain its ability to think’ and which ‘we do not know’. As Downing notes, Locke’s epistemic humility implies that the intrinsic nature of such a common support (more precisely, the intrinsic nature of each particle composing the system fitly disposed) cannot be conceptualized by our human understanding. What Downing here refers to as ‘something internal to the thinking thing’ is nothing other than the ‘substratum’ of a complex form of material body, a system of matter fitly disposed.10 We shall examine this further in Chapter 6. In the next chapter, we shall see how the combination of Locke’s emergentism and nominal dualism can shed light on three authors: Burthogge (1678, 1694), Carroll (1706), and McGinn (1989, 2004).

Notes 1. Against Descartes, Princess Elisabeth argues that even if the mind and body, as two distinct substances, were to actually interact, their interaction would be unintelligible. In his response to Princess Elisabeth (May 21, 1643), Descartes maintains that the notion of a mind-body union is more primitive or fundamental than that of their interaction: ‘for the soul and the body together, we have only the notion of union, on which depends the notion of the force that the soul has to move the body and the body to act on the soul, causing its sensations and its passions’ (Descartes 2000, 214). Modern critics have pointed out, however, that the notion of mind-body union cannot be more primitive than that of their interaction since their union actually depends on the notion of their interaction. I can say that this body, e.g., to which my mind is united, is my body, since I can only interact with this body and not another (Kim 2003). The point of this criticism is that the mind-body union is ultimately unintelligible since their interaction is so.

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2. On Barnes’ account, there are four types of entities: (1) fundamental and independent; (2) fundamental and dependent; (3) derivative and independent; (4) derivative and dependent. The first type includes all and only those entities that God needs to create in order to make the world how it is. The basic particles belong to the first type, for they depend on nothing other than themselves once created. Barnes classifies ‘emergent’ features as of the second type: they are ‘dependent’ on the basic particles, but still ‘fundamental’ in that they are part of the world and have their own distinctive causal powers, which render them capable of making a difference to any world that contains them. Although emergent features are dependent entities, they may nevertheless appear to be entirely distinct from and over and above the basic particles on which they depend, due to the fact that their presence or emergence in a given system of matter is not explainable in terms of the static and positional features of its parts. Barnes cites numbers as an example of the third category. For Platonists, numbers would belong to the category of being ‘fundamental’, whereas for nominalists, they do not constitute any given created component of the actual world but exist only in human minds. On Barnes’ classification, numbers are ‘derivative’ in this nominalist sense (rather than ‘fundamental’), but nevertheless ‘independent’ (though nominally). They differ in this respect from things like sides and angles, which depend on certain figures and thus belong to the fourth category of ‘derivative’ and ‘dependent’. 3. ‘Supervenience’ is a relation often used by physicalists such as Kim (1993) who wish to argue that mental properties not only co-vary with but also depend on physical properties, yet without being ontologically reducible to them. Emergentism and mind-body supervenience thus provide similar accounts of the mind-body relation, but their points are rather different. Supervenience concerns the dependence of mental properties on physical ones (that is, the physical determination of mental properties). However, some argue that supervenience cannot establish such ‘dependence’ or ‘determination’, but only a ‘co-variation’ between mental and physical properties, insofar as it cannot explain why and how they co-vary. It is partly for this reason that Horgan (1993) and Wilson (1999), e.g., think that mindbody supervenience is insufficient for physicalism. At any rate, given Locke’s epistemic humility and the long-standing association of supervenience with physicalism, Locke’s position may align more closely with emergentism than mind-body supervenience. According to Locke, the physical cannot be said to determine the mental, for both are nominal categories. It was in this regard that we discussed Locke’s epistemic humility as a critique of physicalism in the foregoing chapters. On his view, the physical, too, is merely a certain functional feature of entities whose intrinsic nature is unknowable to us. Emergentism does not require that the physical be more ontologically basic than the mental, as the focus of the position is not on the physical character of the ground level, but rather on the point that the properties of a whole are more than those of its parts—whatever the nature of those parts happens to be. I shall use the term ‘emergentism’ as implying this non-physicalist aspect of the position. 4. I owe this point to David Clemenson through personal correspondence. 5. In the passage cited from IV.x.5, however, Locke refers to triangles as another instance of ‘repugnancy’. One might take this as suggesting a kind of logical or geometrical incompatibility rather than a merely conventional one. But what Locke takes to be repugnant to ‘the Idea of a Triangle’ is its ‘mak[ing] it self three Angles bigger than two right ones’—e.g. the capacity of turning itself into a rectangle. What is repugnant to the idea of matter is likewise the capacity of turning itself into a mental being—viz. that of ‘put[ting] into it self

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Sense, Perception, and Knowledge’. The point Locke makes by this analogy is that, like the idea of triangle, the idea of matter, too, only contains its static and positional features. Jolley (1999) is among those who take Locke to be a materialist for reasons outlined in the Introduction. However, the version of materialism that Jolley (2015) attributes to Locke is fairly weak, in that he sees Locke as allowing for the irreducibility of the mental despite the fact that the fundamental reality is taken to be physical. In an attempt to resolve the Wilson-Ayer debate, McCann (1985) has associated ‘superaddition’ with the contingency of laws of nature. The primary qualities of matter are not sufficient to give rise to the power of thought, so God must enact a general law of nature that governs all the qualities of objects including the power of thought. What gets added is thus a set of natural laws. The term ‘superaddition’ would consequently have to do God’s will or choice at the initial stage of creation. McCann sees Locke as endorsing a weaker form of causal essentialism, according to which once a set of laws is chosen, all the qualities including the power of thought are then necessitated by the essences of things. The question then arises why Locke used the term ‘superaddition’ only in relation to certain sorts of qualities or powers. In my reading, Locke’s focus, when he uses the term ‘superaddition’, is on a particular power (rather than on the laws of nature) superadded to a particular sort of material body (rather than the world as a whole). The chief point Locke is trying to make with his use of the term ‘superaddition’ is not that the laws could have been otherwise, as McCann’s view implies, but rather that the higher-level properties of a system are those that appear to be new entities: distinct from and over and above its parts. The strong conception of superaddition would also require us to have access to the real essence of matter. To claim that a certain power is irreducible to the essence of a substance implies that it is not contained in the real essence of a substance. Its ontologically irreducibility would thus be established only when its real essence is known to us—just as Descartes’ property dualism (which underlies his substance dualism) was established on the claim that we have a clear and distinct idea of the essence of substance. For Locke, however, we are only omniscient with respect to our idea of matter, not its real essence. The difference between Ayers’ reading and mine is that while his epistemological reading is focused on the psychophysical link, mine is concerned with the true nature of reality. My epistemological reading thus runs deeper than Ayers’. As seen in Chapter 3, the epistemic humility that I ascribe to Locke entails the epistemological reading advanced by Ayer. Even the notion of a ‘psychophysical link’ must be understood in terms of Locke’s nominal dualism; the ‘link’ between the mental and the physical thus cannot be taken to indicate a metaphysical relation hidden from us. Our ideas of matter and mind are only nominally different. While property dualist readings of Locke are still popular, there is another line of interpretation that was current in Locke’s time but has since received relatively little attention from modern critics. Contrary to Leibniz, a group of orthodox Cartesians associated Locke’s account of superaddition with an essence-determined phenomenon. In place of Leibniz’s criticisms, they instead accused Locke of ascribing both thought and extension to the same substance as its principle attributes. In L’Immaterialité de L’Ame, Demonstrée contre M. Locke, Gerdil (1747) also charged Locke with allowing for a third kind of substance in which the two attributes intermingle to the extent that each is no longer of the kind it used to be. The resulting substance would no longer be wholly or solely extended, nor would it be wholly or solely mental, but

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The Superadded Power of Thought rather a mixture thereof. This criticism presumes the principle of Cartesian dualism according to which ‘[t]o each substance there belongs one [and only one] principal attribute; in the case of mind, this is thought, and in the case of body it is extension’ (CSM I, 210). In his criticism of Locke, Benjamin Hampton (1711), another Cartesian commentator, emphasizes that God would not give ‘the Faculty of one Being [e.g. the power of thought], to any other Being [e.g. a system of matter] to whom that Faculty does not naturally belong’ (quoted from Yolton 1984, 24). For more discussion of these Cartesian critics, see Yolton (1984, 24–5). What these Cartesian critics found objectionable in Locke’s account of the human mind is what we have referred to as his emergentism in this chapter.

5

Burthogge, Carroll, and McGinn

This chapter further examines how Locke’s naturalistic view of the human mind is related to other aspects of his position, such as his mind-body nominalism and epistemic humility. In doing so, this chapter examines three thinkers who responded to Locke’s Essay in their major works. Two of them, Richard Burthogge (fl. 1654–1702) and William Carroll (fl. 1705–11), are relatively lesser-known contemporaries of Locke’s, and the third is the contemporary philosopher Colin McGinn. All three have connections to Oxford. Burthogge entered All Souls College in 1654 and received his BA in 1658 and an MD at the University of Leiden in 1662. Locke was six years Burthogge’s senior, but graduated with a BA in 1656 and an MA in 1658. Carroll was an associate of Jonathan Edwards, Vice-Chancellor of Oxford from 1689 to 1691. McGinn also worked at Oxford for his BPhil under the supervision of Ayers. All three of the aforementioned figures are also original and controversial thinkers in their own right. Ayers (2005, 179) regards Burthogge as ‘the first modern European idealist’. Carroll wrote six polemical books against Locke and other Whig philosophers (1705, 1706a, 1706b, 1707, 1709, 1711) (and has consequently been described as ‘more of a polemicist than a rigorous philosopher’ (Yolton, Price, and Stephens 1999, 180)). And McGinn is well known for his account of ‘cognitive closure’, which purports to provide a solution to the mind-body problem. Most relevant for our purposes is the fact that all three are insightful readers of Locke’s Essay who pay due attention to his epistemic humility and his consistently nominalist theory of mind and body. By considering their responses to Locke, this chapter aims to offer a comprehensive account of his philosophical outlook in the context of both his own time and more recent discussions.

1.

Locke’s ‘Doctrine of Signs’ and Burthogge’s ‘Modi Concipiendi’

In the final chapter of the Essay (IV.xxi), titled ‘Of the Division of the Sciences’‚ Locke classifies all sciences into three sorts: ‘natural Philosophy’, ‘Ethicks’, and the ‘Doctrine of Signs’.

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Burthogge, Carroll, and McGinn All that can fall within the compass of Humane Understanding, being either, First, The Nature of Things, as they are in themselves, their Relations, and their manner of Operation [‘natural Philosophy’]: Or, Secondly, That which Man himself ought to do, as a rational and voluntary Agent, for the Attainment of any End, especially Happiness [‘Ethicks’]: Or, Thirdly, The Ways and means, whereby the Knowledge of both the one and the other of these, are attained and communicated [‘Doctrine of Signs’]; I think, Science may be divided properly into Three sorts. (IV.xxi.1)

The ‘Sciences’ that Locke divides into three sorts here are said to ‘fall within the compass of Humane Understanding’, and are as such different from the ‘Science’ that he elsewhere claims is ‘out of our reach’ (IV.iii.26). While the latter refers to the knowledge of an omniscient being (as noted in Chapter 3), the former mentioned in the preceding passage encompass all human intellectual activities that are based on the empirical principles put forth in the Essay. The first sort is ‘natural Philosophy’, which Locke sometimes refers to as ‘experimental Philosophy’ (IV.iii.26) in contrast to the strict sense of ‘Science’ or ‘scientific Knowledge’ (which concerns the quiddities of things). Locke further explains the first sort as follows: First, The Knowledge of Things, as they are in their own proper Beings, their Constitutions, Properties, and Operations, whereby I mean not only Matter, and Body, but Spirits also, which have their proper Natures, Constitutions, and Operations as well as Bodies. This in a little more enlarged Sense of the Word, I call Φυσική, or natural Philosophy. (IV.xxi.2) In this passage, Locke includes ‘spirits’ among the objects of ‘natural Philosophy’. As explored in the foregoing chapters, the Lockean human mind is bereft of the kind of privileged status that the Cartesian mind enjoys, as it is grounded in the very same atoms that constitute the various kinds of physical objects. The Lockean mind is thus part of the natural world, while its kind—as a mind—is conceived as a nominal entity. The same is true of the body. We are only able to obtain a ‘primary Idea’ of the body—a ‘sign’ of it. These nominal categories of mentality and materiality originate with the contingent fact that we view the world from two distinct perspectives. The final chapter of the Essay also emphasizes this point, particularly in the definition of the third sort of science—the ‘Doctrine of Signs’. Another name for this branch of science is ‘Logick’. As used by Locke, this term does not merely mean what we now call ‘formal logic’ but carries a much broader meaning: it is a philosophical study of ‘ideas’—as ‘signs’—including their origin, classification, and representational nature. Consider the full passage wherein Locke defines this discipline:

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Thirdly, The Third Branch may be called σημειωτική or the Doctrine of Signs, the most usual whereof being Words, it is aptly enough termed also λογική, Logick; the business whereof, is to consider the Nature of Signs, the Mind makes use of for the understanding of Things, or conveying its Knowledge to others. For since the Things, the Mind contemplates, are none of them, besides it self, present to the Understanding, ’tis necessary that something else, as a Sign or Representation of the thing it considers, should be present to it: And these are Ideas. And because the Scene of Ideas that makes one Man’s Thoughts, cannot be laid open to the immediate view of another, nor laid up any where but in the Memory, a no very sure Repository: Therefore to communicate our Thoughts to one another, as well as record them for our own use, Signs of our Ideas are also necessary. Those which Men have found most convenient, and therefore generally make use of, are articulate Sounds. The Consideration then of Ideas and Words, as the great Instruments of Knowledge, makes no despicable part of their Contemplation, who would take a view of humane Knowledge in the whole Extent of it. And, perhaps, if they are distinctively weighted, and duly considered, they would afford us another sort of Logick and Critik, than what we have been hitherto acquainted with. (IV.xxi.4) As this passage explains, one cannot grasp the true nature of the world directly, but only through those signs of it that are ‘the greatest Instruments of Knowledge’. The aim of the ‘Doctrine of Signs’ is ‘to communicate our Thoughts [about the world] to one another as well as record them for our own use’. Such signs—ideas or words—belong to the nominal world, whereas atoms, ‘the greatest Instruments of Nature’ (IV.iii.25), constitute the actual world. Locke’s mind-body nominalism treats the ideas of mind and body, too, as mere signs. We have these ideas ‘to communicate our Thoughts’ of mentality and materiality, each being ‘an equal view of both parts of nature, the Corporeal and Spiritual’ (II.xxiii.15). We conceive these parts of nature in a dualistic manner in accordance with our ideas of mind and body, which derive from the ways that our perceptual capacities happen to be. Some readers viewed such nominalization of the two categories of mind and body as favoring some form of idealism. Reid (1895, vol. 2, 286) thus held that Locke had ‘a glimpse of that system which Berkeley afterwards advanced’. Reid’s suspicion that Locke was a proto-idealist must have been motivated by his awareness of the emphasis that Locke places on the idea of body. But Locke is a realist; he allows for mind-independent entities that serve as intermediaries between the creator and human minds, referring to these entities as ‘external Object[s]’. As Locke maintains, ‘[t]he Truth of . . . Perceptions in our Minds [consists] . . . only in their being answerable to the Powers in the external Objects to produce by our

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Senses such Appearances in us’ (II.xxxii.16); and ‘such Appearances . . . must be suitable to those Powers [God] has placed in external Objects’ (II. xxxii.14). For example, ‘God hath given Sight’ to ‘a Creature’; that is, ‘a Power to receive [the Ideas of Colours] by the Eyes from external Objects’ (I.ii.1) ‘by established Laws and Ways’ (II.xxxii.14). With these quotations in mind, Burthogge’s idealism can be seen to be far more relevant to Locke’s mind-body nominalism than Berkeley’s. Like Locke, Burthogge also endorses a ‘real Thing’ that exists ‘without the thinking of any one upon it, whether it be minded or no’ (ERS, 78). For Burthogge, the term ‘idealism’ can only be understood as meaning that our minds substantially determine the ways we perceive and understand the external world. Ayers (2005, 182) thus suggests the term ‘conceptualism’ or ‘conceptualist’ for Burthogge’s position, as for him, ‘every object of thought is shaped by the faculty of thought and by its medium, language’. As Ayers (2005, 179) further observes, ‘[Burthogge’s] theory is quite unlike Berkeley’s, although, as some of those few who have discussed him point out, there are some remarkable affinities with Kant. Yet, in some ways he may be more like Locke than like Kant, and in one or two deep ways he may be more like Quine than like any of them’. Locke began to correspond with Burthogge in 1694, when Burthogge published his Essay Upon Reason, and The Nature of Spirits, dedicated to Locke. In its two-page preface, Burthogge wrote to Locke: ‘Sir, I take the Liberty of making a present of the following Essay into you, as to a Person who being acknowledged by all the Learned World for one of the Greatest Masters of Reason, are therewithal allowed a most Proper and Competent Judge of any Discourse concerning it’. In a letter to Locke, dated May 15, 1694, Burthogge repeats his description of Locke as ‘one of the Greatest Masters of Reason’: If nothing that I have said in my Essay is more obnoxious to confutation than what you find in its Epistle in reference to your selfe I shall have little cause of Apprehension concerning it. What I there affirm with the greatest justice in the name of all the learned world I must now repeat in mine own. For by your very obliging letter of the 8’th instant I am afresh convinced that Mr Lock[e] is one of the greatest Masters of Reason. (DeBeer 1979, vol. 5, 51) In his Essay, Burthogge develops his idealist view that our minds make a substantial contribution to the appearances of the external world and the ways that we view and understand it. The distinction Burthogge draws between the appearance of the world and its true reality presumes a ‘real Thing’ whose existence differs from our understanding of it. Burthogge contends that: [A]ll the Sentiments of Sense, those of the Mind, and even meer Objective Notions, are Things, not things of Mundane and External

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Existence, but of Cogitation and Notion; Intentional, not Real things. For such are Colours, Sounds, Sapors, Time, Place, Substance, Accident, Cause, Effect; &c. they are intentional things, things that, as such, have only an esse Objectivum, an esse Cognitum, as the Schoolmen phrase it. (ERS, 79) The preceding passage anticipates Hume’s sentimentalism about the ground of causation and Kant’s account of space and time as a priori intuitions. Burthogge further contends that there are no substances or accidents in the world, but that they are instead all intentional entities: There [is] no such thing in the World as a Substance, or an Accident, any more than such a thing as a Subject, or an Adjunct; and yet we apprehend not any thing but as one of these, to wit, as a Substance, or as an Accident; so that we apprehend not any at all, just as they are, in their own realities, but only under the Top-knots and Dresses of Notions, which our minds do put on them. (ERS, 64) A core thesis of Burthogge’s form of idealism—which might likewise be labeled a form of ‘error theory’ (using his own word)—was already put forth in an earlier work of his titled Organum Vetus et Novum, or A Discourse on Reason and Truth: ‘[i]t is an Error (and a most dangerous one too) to assert, that seeming or intellectual sense (for clear and distinct Perception signifies no more) is the measure of Truth: There are so many ways wherein a thing may be seen clearly and distinctly, that is, may seem true, and yet not be so’ (OVN, 51). For Burthogge, what appears to us as true is thus merely a subjective feature of our ideas. It is, however, an error to project such subjective features onto the world as if they were objective. Another error is to think that human minds are the only measure of truth. Against this error, Burthogge observes that there are ‘so many ways wherein a thing may be seen clearly and distinctly’. As Locke likewise notes, the human mind is only one of ‘many Species of Spirits’ (III.vi.12).1 The same world is thus multiply realized in the various manners in which it appears to different intellectual species, just as the same nominal essence is multiply realizable in different possible worlds, as noted in Chapter 3. Burthogge also holds that: Faculties and Powers, Good, Evil, Virtue, Vice, Verity, Falsity, Relations, Order, Similitude, Whole, Part, Cause, Effect, &c. are Notions; as Whiteness, Blackness, Bitterness, Sweetness, &c. are Sentiment: and the former own no other kind of Existence than the latter, namely an Objective (one).2 (OVN, 15) Here Burthogge uses the term ‘objective’ in the scholastic sense as equivalent to ‘representational’. On his view, entities such as powers, moral virtues, and causality are not real qualities in the external world: they are mental

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constructs in our mind. Burthogge goes on to say, ‘[w]e generally conceive Faculties, Good, Evil, and other Notions (under which the Minde apprehends things) to be Realities, and to have an Existence of their own without Minde to think of them, when indeed they are but Noemata, Conceptions, and all the formal being any of them have, is onely in it’ (OVN, 15). Burthogge applies this idealist point of view to the mind-body distinction as well: ‘such a thing [i.e. reality] is [called] matter . . . and such a thing also is [called] Mind’ (ERS, 78). The constitutional account that reality can be both mental and physical in the sense that it is both mentally and physically constituted would conflict with Burthogge’s error theory. But if read in light of the Lockean descriptivist insight that things can be classified as belonging to both the mind-kind and the body-kind with reference to human ideas of them, then the preceding passage is consistent with Burthogge’s position. This idealist point of view implies that reality is neither mental nor physical without us; in other words, it can be described as either or both within our conceptual schemes. Locke also uses the term ‘notions’ with regard to mind and body in the following passage, which we encountered previously in Chapter 2: ‘[w]e have as clear a Notion of the Substance of Spirit, as we have of Body’ (II.xxiii.5). Here Locke’s term ‘notions’ means complex ideas constructed out of simple ideas. In Burthogge’s words, Lockean complex ideas are ‘things as they are in the mind’ after having ‘undergo[ne] an Abstraction and sublimation’ (ERS, 61). Burthogge further describes a ‘notion’ as ‘any conception formed by the Mind in reference to Objects’ (ERS, 52), viz. ‘Modus Concipiendi, a certain particular manner of conceiving; a manner of conceiving things that corresponds not to them but only as they are Objects, not as they are Things’ (ERS, 56). As Burthogge notes, ‘Attention of Mind, is [thus] the Application of [Conceptions] unto Objects, and therefore in Men, is called Minding’ (ERS, 8). According to Burthogge, what laypeople generally conceive as ‘things’—even including minds and bodies—are nothing more than ‘notions’, ‘Modi Concipiendi’, or ‘Entities of Reason’ (ERS, 64). They are ‘Intentional, not Real things’ (ERS, 79)—in Locke’s terms, they are ‘nominal’ entities. The ‘unknown’ referred to in Locke’s Essay will remain so as long as we as observers remain the same intellectual species as we are now. His use of the negative phrase ‘unknown to us’ can thus be taken to imply that the mind-body classification, too, only obtains ‘with the ideas of men’ (First Letter, 91). Given his mind-body nominalism, there is a sense in which what he describes as ‘Things without us’ are neither physical nor mental but can only be classified as such within our conceptual schemes. The phrase ‘without us’ hence does not only make the ontological claim that certain things exist independently of us but also the semantic point that it is meaningless to speak of them without referring to our conceptual schemes. This aspect of Locke’s mind-body nominalism is more fully elaborated in Carroll’s Dissertation upon the Tenth Chapter of the Fourth Book of Mr. Locke’s Essay, concerning Humane Understanding (1706).

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Lockean Spinozism: Carroll on Mind-Body Nominal Symmetry

Carroll’s treatise on Locke was published a year after Burthogge’s death. In it, Carroll claims that for Locke, mind and body are ‘two Nominal, and not two Real substances’ (Dissertation, 38). The interest of the comparison that Carroll subsequently draws between Locke and Spinoza lies not in its rarity, but rather in the fact that Carroll saw the two— one of whom was credited as the founder of British empiricism while the other was conceived as the most rationalist of the Rationalists— as so closely related; Carroll even accused Locke of ‘copying’ Spinoza (Dissertation, iii).3 In modern times, Locke has more often been compared with Leibniz, the author of the New Essays, the most prodigious and systematic critique of Locke’s Essay. In their own time, however, Locke and Spinoza were often associated with one another as the epitome of atheistic materialism.4 The Spinozism that I ascribe to Locke, however, concerns his mind-body nominal symmetry and should thus be distinguished from materialism. In his Epistle to the Reader, Carroll writes: The main Error, wherewith that Gentleman is charg’d in his Dissertation upon the 10th Chap. of the 4th Book of his Essay of Human Understanding, is this, viz. That he teaches Spinoza’s Doctrine throughout that Book, and finally and compleatly establishes his Hypothesis, in the fore-mentioned Chapter, viz. The Eternal Existence of one only Cogitative and Extended Material Substance, differently modified in the whole World, that is, the External Existence of the whole World it self; to which those two Authors give the Holy Name GOD, and ascribe some of his Divine Attributes. (Dissertation, ii) Carroll gained a reputation through the six highly polemical works he wrote, but as noted in Yolton, Price, and Stephens (1999, 182), ‘[t]hat may be why, after publishing six books in as much years, Carroll disappeared from the world of letters’. Though repetitive and tedious, Carroll’s treatise on Locke makes the interesting contention that he ‘copied’ Spinoza (Dissertation, iii), or at least had ‘Spinoza’s Pattern before him’ (Dissertation, iv). As its main title—A Dissertation upon the Tenth Chapter of the Fourth Book of Mr. Locke’s Essay, concerning Humane Understanding—indicates, the work is an analysis of IV.x, which we ourselves examined in Chapter 4. As its subtitle—WHEREIN That Author’s Endeavors to Establish Spinoza’s Atheistic Hypothesis, more especially in that Tenth Chapter, are Discover’d and Confuted—shows, Carroll views IV.x as containing a secret defense of atheistic materialism. Carroll thus writes that ‘[w]hat [Locke] calls in this place, this Thinking System, is what he calls a Corporeal System in the beginning of this Section’ (Dissertation, 222) and he elsewhere attributes to Locke the view

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that ‘[i]t is a certain Motion of [this Corporeal System’s] Parts wherein its Thinking consists’ (Dissertation, 214). Carroll’s criticism of Locke stems from the challenges that Locke’s philosophical outlook raised to the established orthodoxies of his century, e.g. substance dualism, the doctrine of innate ideas, and epistemic certainty regarding the essences of substances. Locke’s challenge to substance dualism, however, does not involve any commitment to materialism. His mind-body nominal symmetry gives no ontological priority to either mentality or materiality, but views both as nominal categories. Even Carroll failed to fully appreciate the significance of this point. He sometimes interprets this aspect of Locke’s position as a rhetorical device that Locke uses to hide his atheistic materialism: ‘[The Essay] is indeed a Master-Piece in its kind, in the Equivocal and Sophistical Art’ (Dissertation, 4). At certain points, however, Carroll does demonstrate an awareness of the novel nature of Locke’s view: ‘[Locke] makes [not only] the Word Spirit [but also the Word Body] a Sign’ (Dissertation, 33), with the result that mind and body are construed as ‘two Nominal . . . substances’ (Dissertation, 38). Underlying the alleged ambiguity in Locke’s use of the term ‘idea’ is, in my view, a powerful critique of both Cartesian dualism and materialism. It is this aspect of his position that I refer to as ‘Lockean Spinozism’. For Locke, the Cartesian principal attributes of thought and extension are better understood as ‘primary Ideas’ (II.xxiii.17). The mind-body distinction depends on how individual things are conceived or described within our conceptual framework. In fact, Spinoza, too, uses epistemic language in his definition of ‘attribute’, which states that an attribute is ‘what the intellect perceives of a substance, as constituting its essence’ (Spinoza 1996, 1; Part I, Definition 4). Here Spinoza defines a key metaphysical concept in terms of the intellect’s perception: an attribute is what the intellect perceives of a substance as constituting its essence. Various interpretations have been given of this puzzling definition. Among them, Harry Wolfson’s nominalist reading is noteworthy for its similarity to the Lockean form of Spinozism described earlier. Wolfson (1929, vol. 1, 145) defines the term ‘attribute’ as ‘a description of the manner in which substance, unknowable in itself, manifests itself to the human mind’.5 While this conception of attributes helps illuminate the connection between Locke and Spinoza, Bennett’s reading of Spinoza proves more useful than Wolfson’s in illustrating how this bears on Locke’s epistemic humility, as we shall see later. In his Epistle to the Reader in the Dissertation, Carroll writes that in order to reveal Locke’s kinship with Spinoza, it is necessary to give his readers ‘a short Parallel of those two Authors’ (Dissertation, ii). To do so, Carroll draws our attention to the following passages from Spinoza’s Ethics and a passage from Locke’s letter to Stillingfleet. The passage from the Ethics is the following often-quoted one regarding Spinoza’s

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mind-body identity thesis: ‘[t]he Thinking and the Extended Substance, is One and the same Substance, which is sometimes conceived under the One, and something under the Other Attribute’ (Part II. Proposition 7. Scholium; Carroll’s translation in his Dissertation, 7).6 Carroll notices a parallel between this and the following passage from Locke’s letter to Stillingfleet, where Locke characterizes the mind and body in terms of two ‘modifications’, while asserting that ‘the general idea of substance’ is ‘the same every where’: The general idea of substance being the same every where, the modification of thinking, or the power of thinking joined to it, makes it a spirit, without considering what other modification it has, as whether it has the modification of solidity or no. As on the other hand, substance, that has the modification of solidity, is matter, whether it has the modification of thinking or no. (First Letter, 33) In reference to the preceding passage, Carroll writes that ‘[Locke] imagines and teaches that his common Support, Subject of Inhesion, or Substance, is One and the same every where’ (Dissertation, 31).7 In this passage, Locke holds that what enables a substance to be of the spiritual kind is only its having the power of thought (‘without considering what other modification it has’), and that what enables it to be of the material kind is only its having the power of solidity (‘without considering what other modification it has’), while ‘the general idea of substance’ is ‘the same everywhere’. Carroll calls attention to the fact that Locke uses the term ‘substance’ in two different senses. When he uses it in the plural, it refers to the mind and the body as ‘two nominal Substances’, or ‘bare different Modifications of One and the same single Substance’; whereas when he uses it in the singular, it refers to the ‘One and the same single Substance’ (Dissertation, 21). As Carroll himself puts it: When [Locke] takes that Word [‘substance’] in the former Sense . . . in the Singular number . . . he makes it to stand for his One Single Substance, common Support, Substratum or Subject of Inhesion to Modes, Qualities, or Accidents. . . . When he uses that Word in the plural number, as when he says, Spiritual and Material Substances, several sorts of Substances, different particular Substances, and the like; then he always takes the Word Substance in the latter Sense, that is, for distinct Combinations of Modifications only. (Dissertation, 25–6) For Spinoza, each Aristotelian individual substance (such as a rose, a horse, or a human) is in truth a ‘mode’ of the single substance which Spinoza refers to as ‘God’—the ‘one only [Cogitative and Extended Material] Substance, differently modified’, as Carroll (Dissertation, ii)

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describes it. Each mode of this one substance can nevertheless be called a ‘thing’ in its more ordinary meaning. It is this ordinary sense of ‘thing’ that Carroll seems have in mind in referring to each mode as a ‘Nominal substance’. There is, however, another meaning that Carroll associates with this term. Insofar as a given attribute of each mode (whether thought or extension) is understood as a distinctive way in which the same single substance is conceived or described, each mode can also be described as a ‘Nominal substance’ in the sense that its given attribute is a nominal feature of the one substance.8 Bennett’s account of a ‘trans-attribute’ essence is an excellent illustration of the Lockean unknown support for the two types of qualities (mental and physical). In his study of Spinoza (1984), Bennett characterizes the trans-attribute substratum in terms of its functional role. Consider, e.g., the following account of the trans-attribute essence: ‘[a]lthough the truth about my body has the form Reality is [Extension and F] for a value of F such that the truth about my mind has the form Reality is [Thinking and F], it is absolutely impossible for any mind, however powerful, to have the thought of F in abstraction from both thought and extension’ (Bennett 1984, 144). Here F-ness, the unknown ‘trans-attribute’ essence, ‘spreads across’ (Bennett 1994a, 23) both the realms of thought and extension. The F-ness can thus only be characterized by referring to its dual attributes while its own intrinsic nature is ‘unabstractable’ by human intellectual power (Bennett 1984, 144). There are two kinds of concepts available to us (mental and physical), but the intrinsic nature of the F-ness has no corresponding concept. It can only be characterized in terms of its functional role of instantiating the dual attributes. To characterize the F-ness, it is therefore necessary to refer to both attributes, though neither reveals to us the intrinsic nature of the F-ness. Despite its affinity with Locke’s view, Bennett does not attribute his notion of a ‘trans-attribute’ essence to Locke, but instead that of a bare or naked substratum (as we saw briefly in Chapter 1 and will explore again in Chapter 6). It is rather Carroll who attributes a Bennett-style Spinozism to Locke. One important characteristic of Bennett’s doctrine of trans-attribute essence is that it is an anti-materialist position, inasmuch as it implies that the material is not the most basic feature, but rather one of two aspects of a more fundamental reality. The following observation from Bennett is worth noting in this regard: If you start with the various specific features of an extended thing, and ask what they all have in common—what they are all specifications of—the answer will inevitably be extension. In fact, each of them consists of something of the form ‘F and extended’, where F could also be combined with other attributes; but that fact is not accessible to any intellect, and so extension will be perceived by any intellect as a Cartesian essence or nature of the substance that has it. It isn’t

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really a Cartesian essence or nature, however; it is not the most basic thing that is predicated of the substance. On the contrary, the transattribute modes are in a clear sense more basic, in that they can spread across all the attributes. (Bennett 1994a, 23) Given the existence of a trans-attribute essence, no direct relation would hold between its dual attributes, for each would depend on the underlying common essence and not one another. Thus one cannot say that the material determines the mental. The trans-attribute reality is ‘not accessible to any intellect’ but ‘will be perceived by any intellect as a Cartesian essence or nature of the substance that has it [whether mental or physical]’.9 Such ‘perceived’ attributes would be ‘nominal Substances’ in Carroll’s terms, or ‘Modi Concipiendi’ (or ‘intentional entities’) in Burthogge’s. On Locke’s account, as discussed in Chapter 4, a system of particles, fitly disposed, gives rise to the power of thought, but the real essence of each particle is unknown, and consequently ‘we know not wherein Thinking consists’ (IV.iii.6). Hence, something-I-know-not-what underlies both thought and matter, these being strictly nominal entities grounded in the contingent structure of our perceptual capacities. A more modern form of this Lockean Spinozism can be found in McGinn’s approach to the mind-body problem. Following Locke, McGinn regards physicality and mentality as a posteriori concepts acquired through our dual modes of experience. This concept-empiricism about the two categories provides the basis for McGinn’s solution to the mindbody problem in terms of his account of cognitive closure. McGinn (1989, 351, footnote 4) notes the parallels between his view and that of Locke: ‘[c]ombining Nagel’s realism with Chomsky-Fodor cognitive closure gives a position looking very much like Locke’s in the Essay Concerning Human Understanding: the idea that our God-given faculties do not equip us to fathom the deep truth about reality’. On McGinn’s account, God’s idea of the true nature of the world would be radically different from ours at least partly because it would not involve our ideas of mind, body, and the mind-body problem. The dual attributes of thought and extension only appear in the world as viewed through human ideas. As in Burthogge’s idealism and Carroll’s reading of Locke, for McGinn (2004, 24), too, the dual concepts of physical and mental are ‘just human constructs’.

3.

McGinn’s ‘Cognitive Closure’: A Modern Lockean Account

In his paper ‘Can We Solve the Mind-Body Problem?’, McGinn (1989, 352) argues as follows: (1) some natural property (or properties) P accounts for consciousness; (2) we are cognitively closed off from P; therefore (3) there is no philosophical mind-body problem. According to McGinn, there is nothing metaphysically mysterious about the mind-body

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relation. The mind-body problem arises from our lack of epistemic access to P. That is, it is an inevitable consequence of our cognitive predicament. As McGinn notes, there have been two main attempts to solve the mindbody problem. The first approach is to invoke supernatural entities such as immaterial substances or some irreducible type of properties. The second is physicalism, which McGinn (1989, 350) defines as an attempt ‘to specify some natural property of the brain (or body)’ and then explain mental phenomena in terms of it. McGinn describes this second approach as ‘constructive’ in that it takes the relevant ‘physical’ property as nothing more than a theoretically or functionally constructed feature. This constructive approach fails to solve the mind-body problem, for it can at best characterize the nature of P as whatever property explains consciousness—that is, in terms of its functional role. In order to solve the mind-body problem, however, we must have an adequate account of the P-ness that underlies both the nominal categories of mentality and physicality—and this would require us to take up a completely different view of the world, one in which no dualistic description or language would appear. It is impossible for us to achieve such a viewpoint, though, for it would require us to become a different intellectual species. On this account, the mind-body problem is consequently a human-made problem. In arriving at this diagnosis of the problem, McGinn (1989, 352) has acknowledged his intellectual debt to Locke, describing the kinship of his position with Locke’s as follows: We would expect that a moderately intelligent enquiring Human mind will feel permanently perplexed and mystified by the physical world, since the correct science is forever beyond its cognitive reach. Indeed, something like this was precisely the view of Locke. He thought that our ideas of matter are quite sharply constrained by our perceptions and so concluded that the true science of matter is eternally beyond us—that we would never remove our perplexities about (say) what solidity ultimately is. But it does not follow for Locke that nature is itself inherently mysterious; the felt mystery comes from our own cognitive limitations, not from any objective eeriness in the world. Here McGinn explains the exact nature and scope of Locke’s epistemic humility. As McGinn affirms, our incurable ignorance of the intrinsic nature of the world does not entail that we are therefore ignorant about whether some supernatural entities reside in the world or not: our cognitive closure does not mean that our world is ‘inherently mysterious’. McGinn (1989, 353) rejects ‘the magic touch of God’s finger’. Nor does his account lead to irrealism. It only suggests that realism does not require that everything real be open to the human concept-forming faculty. According to McGinn, our conscious experience is produced by ‘some natural property’ of the brain. We are, however, ‘cognitively closed’ with

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regard to that property. McGinn’s notion of ‘cognitive closure’ includes not only perceptual closure but also our inability to form any concept of P. McGinn (1989, 350) defines ‘cognitive closure’ as follows: ‘[a] type of mind M is cognitively closed with respect to a property P (or theory T) if and only if the concept-forming procedures at M’s disposal cannot extend to a grasp of P (or an understanding of T)’. Here the P-ness that McGinn describes resembles Bennett’s F-ness in his reading of Spinoza. To clarify his position, McGinn adopts the Lockean strategy of referring to the knowledge of some higher species. Given that there are numerous properties for which monkeys, e.g., have no concept whatsoever but we do, it would be absurd to assume that what we do not know does not exist. Any metaphysics that does not tolerate the possibility of such unknown properties is hence a flawed metaphysics.10 On Locke’s account, sensation and reflection are ‘narrow Inlets’ that are ‘disproportionate to the vast whole extent of all Beings’ (IV.iii.23). Our ideas of mind and body are thus ‘superficial Ideas of things’ (II.xxiii.32). In McGinn’s terms, we are cognitively closed with respect to the hidden nature of reality in two distinct ways. What McGinn refers to as ‘perception’ and ‘introspection’ correspond to what Locke calls ‘sensation’ and ‘reflection’. The Lockean claim that we are cognitively closed with regard to P in these two ways suggests that these two faculties are the only two possible routes given to us for viewing the world. We view the world through these two epistemic channels, but they both also block us from grasping the intrinsic nature of P. McGinn (1989, 359–60) elaborates on this Lockean aspect of his position in the following passage: Our acquaintance with the brain and our acquaintance with consciousness are necessarily mediated by distinctive cognitive faculties, namely perception and introspection. Thus the faculty through which we apprehend one term of the relation is necessarily distinct from the faculty through which we apprehend the other. In consequence, it is not possible for us to use one of these faculties to apprehend the nature of the psychophysical nexus. No single faculty will enable us ever to apprehend the fact that consciousness depends upon the brain in virtue of property P. Neither perception alone nor introspection alone will ever enable us to witness the dependence. The scientific study of the brain—as a physical object ‘fitly disposed’— aims at understanding the property P from the outward-directed point of view. Introspection is another way in which we may try to gain cognitive access to P, but we are cognitively closed to P through this more direct form of awareness as well. The faculty of ‘perception’ involves not merely sensory perception but also related reasoning in its broader sense. It is an epistemic route by which we may try to approach the property P from

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a non-phenomenological point of view. Thus P is not a supernatural property but part of the created natural world. Given the two distinct types of perception that we are endowed with, we are only constituted to perceive the world as being dualistic. Locke’s account of the origins of the ‘primary Ideas’ of mind and body would thus complement McGinn’s view. Like Bennett, McGinn also considers the hidden property P as a link between the two types of concepts, physical and mental. The latter concept is ‘subjective, acquaintance-dependent, and introspectively ascribed’, while the former is ‘objective, acquaintance-independent, and perceptually ascribed’ (McGinn 2004, 20). On this view, P is a deep linking property (or a ‘transattributal’ one in Bennett’s terms), which can again only be characterized by its functional role of ‘mediat[ing] between . . . surface properties’ (McGinn 1991, 100). To resolve the mind-body problem, we thus need to acquire ‘a type of concept that belongs to neither category, yet links the two’ (McGinn 2004, 21). This implies that we need more than a change of paradigms. Human science has experienced paradigm shifts that have overthrown earlier ways of conceiving the world, from Aristotelian physics to Newtonian, and from Newtonian physics to our current worldview. To solve the mind-body problem, though, we would need something more than this type of revolution—namely, a perspective shift. For McGinn, a solution to the mind-body problem would ultimately lie in an account of P, which cannot be grasped by means of either mental or physical concepts. A higher intellectual species could obtain an adequate account of P which would enable them to see a priori how the phenomena we call ‘mental’ and ‘physical’ are related to each other. The mind-body problem is thus conceived as a human-created problem that arises due to the contingent structure of our perceptual capacities. McGinn (2004, 24) maintains that ‘[w]e need to remember that our concepts are just human constructs, constructed by biology, the contingent tools of finite beings’. The faculties that give rise to our ideas of mind and body both create the mind-body problem and at the same time preclude us from solving it. It is impossible in principle for us to produce the kind of shift or third type of concept necessary to resolve the problem, for it would require us to be equipped with a type of cognitive faculty that we are not endowed with— that is, it would require us to be a different species than we presently are. This needn’t worry us, however, since the problem, being an artifact of our own cognitive limitations, isn’t a problem that we actually need to solve. A higher intellectual being such as God, e.g., ‘obviously does not apprehend the world by directing his senses towards it—seeing it, hearing it, smelling it, etc. . . . There is no process of divine theory construction, confirmation, induction, inference to the best explanation, and so on . . . perhaps God understands the mind-brain relation in somewhat the way we understand geometry. . . . For God, there is [thus] no mind-body problem’ (McGinn 2004, 23). If we were to obtain such an account of the

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P-ness, our nominal categories of mind and body would no longer figure in it. The only way of solving the mind-body problem would thus be to become a different species for whom it would no longer be a problem. The species for whom it would no longer be a problem, however, would no longer be us. It would thus be contradictory for us to solve the mind-body problem by becoming a different species; i.e. beings that are not us. We are the creators of the problem but cannot solve it. The mind-body problem is part of our nature; our identity is reflected in it. We saw this Lockean diagnosis of the mind-body problem in both Burthogge’s idealism and Carroll’s Spinozistic reading of Locke. From these Lockean perspectives, the mind-body problem is not a genuine problem that we are intellectually obliged to resolve, but one created by us, and oftentimes misidentified as a problem that we can and should solve.

Notes 1. As seen in Chapter 2, Locke refers to non-human kinds of intelligence in accounting for real essences of things in III.vi. Each mental kind is endowed with its own epistemic perspective, producing thereby a distinctive type of nominal essence of the same world. Locke even considers the existence of bestial minds. He considers non-human animals as having such a perspective: ‘[t]here are some Brutes, that seem to have as much Knowledge and Reason, as some that are called Men’ (III.vi.12). Locke’s inventory of mental natural kinds includes both these lower kinds and higher kinds such as angels: ‘[t]here are different Species of Angels; yet we know not how to frame distinct specifick Ideas of them’ (III.vi.11). Some higher species are capable of accessing the ‘secret Composition’ of things (III.vi.22), but humans are not. 2. As Ayers (2005, 182) explains, Burthogge tends to bracket superfluous words as part of his own unique style of writing. 3. Locke and Spinoza were exact contemporaries, being born in the same year (1632). Locke had copies of Spinoza’s work in his library, including his Opera Posthuma (1677), published posthumously in the year of Spinoza’s death with the Ethics included. For more about this, see Harrison and Laslett (1971, 238). 4. The following is a description of Carroll in The Dictionary of the EighteenthCentury British Philosophers: ‘Carroll was the author of six polemical books against Locke and other leading Whig philosophers. In these works he was preoccupied with Spinoza and concerned that secret Spinozism (which he diagnosed in Locke, Toland, Collins, Tindal and Le Clerc) was threatening to undermine both the Church and the State. The importance of Spinoza for Carroll and some of the other High Church champions of orthodoxy is that Spinozism was regarded as an amalgam of the worst tendencies of the philosophy of the times, in which materialism and “atheism” had anti-clerical and republican corollaries’ (Yolton, Price, and Stephens 1999, 180–1). We can also find a comparison between Spinoza and Locke in Stillingfleet’s letter to Locke, where Stillingfleet accuses Locke of treating the human mind as ‘a Mode of Matter, as Spinoza hath made it’ (First Answer, 79). Stillingfleet maintains that ‘after all, you [Locke] tell me, That God being Omnipotent, may give to a System of very subtil matter, Sense and Motion. Your words before were, a Power to perceive or think; and about that, all our debate runs; and here again you say, That the Power of Thinking joined to Matter, makes

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6. 7.

8.

Burthogge, Carroll, and McGinn it a Spiritual Substance. But as to your Argument from God’s Omnipotency, I answer, That this comes to the same Debate we had with the Papist’s about the Possibility of Transubstantiation’ (First Answer, 78). For further historical discussion of Carroll’s Spinozistic interpretation of Locke and the meaning of ‘Spinozism’ in Locke’s time, see Brown (1996). In his reading of Spinoza, Wolfson (1929, vol. 1, 143) draws attention to two facets of the medieval term ‘attribute’. On the one hand, attributes were associated with essential properties of God. On the other hand, it was widely agreed that no attribute expresses the real essence of God since his essence must remain beyond comprehension and forever unknowable. Wolfson mentions medieval thinkers such as Maimonides, Averroes, and Moses ha-Lavi as spokesmen of the nominalist approach who reject realist conceptions of attributes. According to the nominalists, there is no real plurality in any essence. Plurality exists only in the human mind, not in things themselves. On Wolfson’s view, Spinoza’s philosophy was influenced by this medieval subjectivism about attributes and agnosticism about real essences. Wolfson (1929, vol. 1, 142) thus observes that ‘[t]he God or substance of Spinoza, like the God of mediaeval rationalists, is unknowable in His essence’. In Spinoza (1996, 35), Curley translates this passage as follows: ‘the thinking substance and extended substance are one and the same substance, which is now comprehended under this attribute, now under that’. The full passage from which this quote is taken runs as follows: ‘[t]hat [Locke] imagines and teaches that his common Support, Subject of Inhesion, or Substance, is One and the same every where, and in all Things, is evident beyond any Exception, by what he says in the Quotation before us, in the following words. The idea of Substance, (i.e. of his one only common Support or Subject of Inhesion,) is the same every where, that is, his one only common Support, or Substance it self, is the same every where; which he proves thus. For ’tis the Modification of thinking joined to it, (i.e. to one and the same single substance,) makes it, (i.e. one and the same single Substance,) a Spirit, without considering what other Modifications it, (i.e. one and the same single Substance,) has; as whether it, (i.e. one and the same single Substance,) has the Modification of Solidity, or no. As on the other side, Substance (i.e. one and the same single Substance,) that has the Modification of Solidity, is matter, whether it, (i.e. one and the same single Substance,) has the Modification of Thinking, or no’ (Dissertation, 31). Here Carroll stresses Locke’s use of the term ‘substance’ as referring to the unique reality by tediously inserting the phrase ‘one and the same single Substance’ after every reference to it. An appropriate parallel to the Lockean mind-body union is Spinoza’s ‘form’ or ‘ratio of motion or rest’. In the Ethics, Spinoza accounts for a body’s individuality in terms of the preservation of a certain ratio of motion and rest among its component parts. Despite the constant changes among the simpler bodies involved in it, a complex body keeps its identity or unity by preserving a certain pattern among the bodies that compose it: ‘[i]f, of a body, or of an individual, which is composed of a number of bodies, some are removed, and at the same time as many others of the same nature take their place, the [NS: body, or the] individual will retain its nature, as before, without any change of its form’ (Spinoza 1996, 42; Part II. Lemma 4). The ratio of motion to rest functions as a common support for bodily and conscious features. To put it in Lockean terms, a system fitly disposed gives rise to the power of thought. A system is thus considered as a physical body, ‘under this attribute [extension]’, and as a mind ‘under that [thought]’, as Spinoza describes it (Spinoza 1996, 75; Part II. Proposition 7).

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9. Here Bennett (1994, 23) seems to refer to a non-divine or human type of intellect, whereas the intellect relevant to his interpretation (1984, 62) of Spinoza’s definition of attribute in the Ethics (Part I. Proposition 4) is a divine one. 10. In support of this point, McGinn (1989, 351, footnote 4) acknowledges a kinship between his position and Nagel’s in The View from Nowhere, where Nagel argues for a form of realism that affirms ‘the possibility of properties we can never grasp’. The epistemic humility advocated by both philosophers challenges our conventional notion of ‘objectivity’ by suggesting that human objectivity may not correspond to reality: as Nagel (1986, 91) puts it, ‘the world may be inconceivable to our minds’. The distinction Nagel draws between ‘what there is’ and ‘what we, in virtue of our nature, can think about’ echoes Locke’s distinction between nominal and real essence.

6

A Functionalist Account of Substrata

Our world is populated by many different kinds of things, such as water, gold, diamond, oaks, swans, horses, elephants, and men. Locke refers to such things as ‘particular sorts of Substances’ (II.xxiii). In his view, such individual things depend on the atoms that compose them for their existence, where these atoms are individual things in their own right. Composite individuals are nonetheless considered by Locke to be basic members of the world as well, each having a distinctive atomic constitution from which a set of characteristic qualities and powers flow. Lockean individual substances are thus ‘substances’ in a loose sense, in contrast to the strict sense of substances that Locke mentions in the chapter ‘Of Identity and Diversity’ (II.xxvii), where he lists the ‘three sorts of Substances’: ‘God’, ‘Finite Intelligence[s]’ (or ‘Finite Spirits’), and ‘Bodies’ (II.xxvii.2). The third sort—‘Bodies’—refers to the ‘Particle[s] of Matter’. Each atom, once created, depends on nothing other than itself. As Locke puts it, ‘[a]ll other things [besides atoms]’ are ‘but Modes or Relations ultimately terminated in [atoms]’ (II.xxvii.2). What Locke refers to as ‘particular sorts of Substances’ are thus modes of the atoms, in that each depends on those smaller, more basic individuals for its existence.1 Locke posits his much-contested ‘substratum’ only in relation to ‘particular sorts of Substance’, not in relation to any of the ‘three sorts’ mentioned in II.xxvii. In this chapter, we shall examine Locke’s controversial definition of substratum as ‘a supposed but unknown support of the Qualities’ (II.xxiii.2) and consider its relevance to the mindbody issue. In Locke’s list of the ‘three sorts of substances’, the second— ‘Finite Spirits’—seems to refer to spirits qua spirits, rather than embodied or material minds. In the Essay, it should be noted, Locke’s term ‘spirit’ refers not only to human minds but also to non-human immaterial spirits: ‘[i]t is not impossible to conceive, nor repugnant to reason, that there may be many Species of [finite] Spirits, as much separated and diversified one from another by distinct Properties, whereof we have no Ideas’ (III. vi.12). As Locke holds, the three sorts of substances ‘do not exclude one another out of the same place’, though ‘they must necessarily each of them exclude any of the same kind out of the same place’ (II.xxvii.2).

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Accordingly, atoms cannot occupy the same place at the same time, but an atom and a ‘Finite Spirit’ can. Their co-existence, however, does not lead to a union of mind and body; here Locke merely says that a finite spirit does not spatially exclude physical particles, implying that the former is thus immaterial. Noteworthy is Locke’s inclusion of ‘men’ in the list of the ‘particular sorts of Substances’. In addition to a common support for the whole range of qualities displayed in each human, Locke assigns a specific substratum to each type of qualities, mental and physical. But this reference to dual substrata does not entail metaphysical dualism. As noted in Chapter 5, Carroll’s reading of Locke and McGinn’s Locke-inspired solution to the mind-body problem both shed some light on the Lockean notion of a common support. In this chapter, we shall explore Locke’s own account of substratum by examining the two chapters from the Essay that bear most directly on this issue, II.xxiii and II.xxvii.

1.

Substratum: A Support for the Qualities in a Particular Sort of Substance

Locke’s discussion of the ‘three sorts of Substances’ appears in the second section of the chapter on identity. From the third section onwards, he begins to discuss the main topic of the chapter: what makes an ordinary object (which he refers to as a ‘particular sort of Substance’) identical over time? Before Locke, this question was not seriously discussed among scholastic Aristotelians, who explained the identity of an individual substance by appealing to the ‘substantial form’ allegedly instantiated in it. Lockean individual substances have no such immutable and unchangeable elements, but instead suffer constant changes at the microscopic level, as some of atoms that constitute them are ‘taken away’ and new ones ‘added’ (II.xxvii.3), and at the macroscopic level as well, as when, e.g., ‘[a]n Oak grow[s] from a Plant to a great Tree’, or ‘a Colt grow[s] up to a Horse, sometimes fat, sometimes lean’ (II.xxvii.3). Nonetheless, when one says that the ‘same’ oak tree has existed in a certain place over the years, what justifies the use of the term ‘same’? This question of the identity of ordinary objects over time is the main question Locke raises in II.xxvii. Unlike the ‘particular sorts’ of substances, none of the ‘three sorts’ suffers changes over time. First, God is ‘without beginning, eternal, unalterable’, so ‘concerning his Identity, there can be no doubt’ (II.xxvii.2). The second sort, ‘Finite Spirits’, are also immutable, once created. As Locke states, each spirit has ‘its determinate time and place of beginning to exist, [and] the relation to that time and place will always determine to each of them its Identity as long as it exists’ (II.xxvii.2). Once created at a particular time and place, each finite spirit suffers no substantial change in its immaterial nature over time, but only undergoes changes in what Descartes would call its ‘modes’ (e.g. by having different thoughts at different times). Its identity is consequently determined solely by its

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spatiotemporal origin. The same is true of the third sort of substance: ‘[t]he same will hold of every particle of Matter, to which no Addition or Subtraction of Matter being made, it is the same’ (II.xxvii.2). Each particle suffers no substantial changes in its simple nature as long as it exists, but only undergoes changes in its extrinsic properties such as its location or its speed and direction of motion. The identity of each particle is thus likewise a sole consequence of its own nature: ‘[an Atom] is, in that instant, the same with it self. For being, at that instant, what it is, and nothing else, it is the same, and so must continue, as long as its Existence is continued: for so long it will be the same, and no other’ (II. xxvii.3). Locke must have felt the need to clarify the exact nature of the new philosophical problem of the identity of ordinary objects over time that he addresses in this chapter, by contrasting ordinary objects with substances in the strict sense. This may explain why Locke refers to the ‘three sorts’ of substances at the beginning of II.xxvii, despite the fact that the chapter’s main topic is the identity of ordinary objects.2 In contrast to the ‘three sorts’ of substances, the identity of a ‘particular sort’ of substance depends not on the numerical identity of its parts but rather on the series of continual changes it suffers over time—e.g., in the case of organisms, the changes involved in the communication of ‘the same continued Life . . . to different Particles of Matter’ (II.xxvii.8). Locke thus uses a different criterion for the identity of ordinary objects than he does for individual atoms: ‘truly they [an Oak or Horse] are not either of them the same Masses of Matter [over time], though they be truly one of them the same Oak, and the other the same Horse. The reason whereof is, that in these two cases of a Mass of Matter, and a living Body, Identity is not applied to the same thing’ (II.xxvii.3). In the Lockean physical world, the various natural kinds are composed of atoms fitly disposed. A swan, e.g., regularly displays the following qualities: ‘white Colour, long Neck, red Beak, black Legs, and whole Feet, and all these of a certain size, with a power of swimming in the Water, and making a certain kind of Noise, and so on’ (II.xxiii.14). Some qualities are directly observable (e.g. size and shape) while others are manifested only when appropriate conditions are met (e.g. the power of swimming or of making certain noises). Both types of qualities are at any rate ‘all united in one common subject’ (II.xxiii.14)—namely, a substratum. Locke states that ‘we accustom our selves, to suppose some Substratum, wherein [the bundle of qualities] do subsist, and from which they do result, which therefore we call Substance’ (II.xxiii.1). Locke is no bundle theorist. According to him, it is inconceivable that a quality or a set of qualities can exist on its own without some underlying support: ‘because we cannot conceive, how [a bundle of qualities] should subsist alone, nor one in another, we suppose them exiting in, and supported by some common subject’ (II.xxiii.4). The role of a substratum is to ‘unite’ a given set of qualities: they are ‘all united

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together in an unknown Substratum’ (II.xxiii.37). The demand for such a support may appear rationalistic, yet Locke characterizes the postulated substratum solely in terms of its functional role, with no reference to its intrinsic nature or a Cartesian-style principal attribute. The following two principles regarding substrata can thus be found in II.xxiii: Support Principle (SP): Whenever a set of qualities is regularly exhibited by a given sort of substance, there must be a support (substratum) for those qualities in that substance. Functionalist Principle (FP): A substratum can only be identified by its functional role of uniting a given set of qualities. Locke applies these two principles to each particular sort of substance without exception. SP demands a ground for any given set of co-instantiated qualities. According to SP, a single quality or a set of qualities cannot exist on its own, but needs some ground for its existence. There were no major objections to SP among Locke’s contemporary critics. What upset them was FP. Stillingfleet must have picked up on FP when he accused Locke of ‘discard[ing] Substances out of the reasonable part of the World’ (Discourse, 234). As Locke himself confesses, the idea of a substratum is ‘obscure’ and ‘relative’ (II.xxiii.3) in that we can never spell out what the support is, but only what it does. Given FP, combined with SP, a substratum is identified only in terms of its unifying role, which is also its sole role: ‘if any one will examine himself concerning his Notion of pure Substance in general, he will find he has no other Idea of it at all, but only a Supposition of he knows not what support of such Qualities’ (II.xxiii.2). A substratum may thus appear to be an ‘abstract’ entity, and indeed Locke himself describes it as such (II.xxiii.6). By ‘abstract’ here, however, Locke is invoking a more modern notion of abstractness—viz. that of a functional entity, which is defined in terms of its role alone, with no reference to the specific nature of whatever happens to occupy that role. Although substrata are abstract in this more modern, functionalist sense, each substratum is nevertheless to be regarded as a particular. An individual substance has its own substratum as the support for the particular set of qualities it displays. There is no ‘common substratum’ shared by all the members of a given kind. Ayers (1975) identifies substrata with real essences,3 but while real essences are entirely created by God, substrata are not. In the opening section of II.xxiii, Locke justifies the supposition of a substratum by reference to human mental activities, whereby the idea of a support is made through a process of abstraction out of the various simple ideas perceived through sensation and reflection. In his account of real essences, by contrast, Locke never refers to such mental activities. A real essence is what makes a given substance what it is—‘the very being . . . whereby it

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is, what it is’ (III.iii.15)—regardless of how it is viewed by us as observers. Consider the following passage from the beginning of II.xxiii: The Mind being, as I have declared, furnished with a great number of the simple Ideas, conveyed in by the Senses, as they are found in exteriour things, or by Reflection on its own Operations, takes notice also, that a certain number of these simple Ideas go constantly together; which being presumed to belong to one thing, and Words being suited to common apprehensions, and made use of for quick dispatch, are called so united in one subject, by one name; which by inadvertency we are apt afterward to talk of and consider as one simple Idea, which indeed is a complication of many Ideas together; Because, as I have said, not imagining how these simple Ideas can subsist by themselves, we accustom our selves, to suppose some Substratum, wherein they do subsist, and from which they do result, which therefore we call Substance. (II.xxiii.1) Here Locke explains the supposition of a substratum in terms of the unity of a complex object. The role of the substratum is to unite the various qualities into ‘one thing’, or ‘one subject’, called ‘by one name’. However, it should be noted that Locke also explains the unity of a given object by appealing to the idea of that object: ‘a certain number of these simple Ideas go constantly together; which being presumed to belong to one thing . . . [and] not imagining how these simple Ideas can subsist by themselves, we accustom our selves, to suppose some Substratum’ (II.xxiii.1). And as Locke states in the chapter on complex ideas, ‘the Mind has a power to consider several [simple ideas] united together, as one Idea’ (II.xii.1), such as ‘Beauty, Gratitude, a Man, an Army, the Universe’ (II.xii.1). Although complex in its composition, a complex idea is nevertheless considered as ‘one Idea’, or ‘one entire thing’, which is ‘signified by one name’. Locke invokes this representational or semantic account of the unity of complex objects in his justification for positing a substratum. The unity of qualities in a one individual, on Locke’s view, represents the perspective of observers such as ourselves; we find the various qualities to be thus united. This is another indication of the Burthogge-style idealism that can be found in Locke’s Essay. As explored in the foregoing chapter, Burthogge endorses ‘real things’ that exist independently of our minds (ERS, 78) and argues that our minds substantially determine the ways we understand the things. Burthogge applies this idealistic viewpoint to the mind-body distinction as well. On his view, their distinction is made in terms of our ‘Notions’—viz. our particular ways of conceiving the mind-independent ‘real things’. When they are conceived under a certain ‘Notion’, they are no longer considered as things in themselves, but ‘objects’. As Burthogge emphasizes, the ‘Notions’ are particular ways of conceiving the things ‘as they are Objects, not as they are Things’

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(ERS, 56). The distinction between ‘objects’ and ‘things’ is helpful in understanding Locke’s view of substratum. While the real essence of a given substance is identified as what makes it what it is as a thing in itself, its substratum is its unifying component (a support for its qualities) as an object. Burthogge also held that even ‘Whole’ and ‘Part’ are ‘Noemata’ or ‘Conceptions’ (OVN, 15). A particular sort of substance, conceived as a complex system, is thus considered an object. Accordingly, a substratum should be viewed as a notional component of an object (rather than an actual component of a thing in itself). Its ontological status as a substance in the loose sense is thus relative to a specific (nominal) kind. For example, a ‘rose’ is regarded as a particular sort of substance under the abstract idea of rose. It is also viewed as one thing (as a ‘rose’) when conceived under that particular kind (or some other kind such as a ‘flower’ or a ‘physical’ object), being individuated from other members of the same kind, as well as from things belonging to other kinds. The postulation of a substratum for the one-ness (i.e. the unity or individuality) of a particular sort of substance is thus grounded in Locke’s account of nominal essence. However, Locke does not think that substrata are merely notional. He states that if ‘questioned, what such a thing [i.e. a substratum] is, which they know not’, perhaps the most satisfactory answer a person could give would thus be to say that: ‘[i]t is something’ (II.xxiii.2). On this account, some property actually exists in any given particular sort of substance, which occupies the unifying role, but that is all we can say about it. We cannot single out the role-player. The reason for this can be explained by appealing to the discrepancy between the notional and the actual world. The entities of the notional world (e.g. substrata) do not directly correspond to the entities of the actual world (e.g. bunches of atoms) in a one-to-one fashion. We cannot single out a specific aggregate of atoms as occupying the unifying role. For Locke and Burthoggean idealists, we can only assume that there is something that plays the role in any particular sort of substance; the assumption of an isomorphic correspondence between the notional and actual worlds can never be justified. Locke’s epistemic humility about substrata thus has a different basis than his epistemic humility with respect to real essences. While the latter is mainly due to our epistemic limitations concerning the intrinsic properties of real things, the former is due to the discrepancy between notional and actual entities. As discussed in Chapter 3, Locke’s epistemic humility regarding real essences is directed ultimately at the solid particles and thus concerns the intrinsic nature of the world itself. The role of solidity can be realized by different natures than the one that occupies it in the actual world. Consequently, the real essence of a complex object remains unknown, as it consists of an arrangement of solid particles. Our ignorance of substrata, by contrast, is more specific: it concerns what actually occupies the unifying role in a particular sort of substance. As noted earlier, it is only as a member of a certain kind that a complex

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object is considered to be ‘one thing’, called by a single name. A rose is a collection of petals, a stem, thorns, leaves, basal stipules, and so on, all considered as ‘one thing’—as a ‘rose’. This particular sort of substance, i.e. a system of atoms wherein a support for the rose’s qualities is posited, is thus considered as one thing, despite its complex structure. This indicates that substrata are conceived as notional components of objects, while real essences are features of the things in themselves.4 Lowe (2005, 70) identifies the substratum of a given object with ‘that very object’. That is, he views a whole system of atoms to be involved in playing the role of uniting the qualities that the system displays. However, this reading would end up overlooking Locke’s claim (expressed in SP) that an individual substance is more than an aggregate of qualities. Locke regards a substratum as a component of an individual substance, rather than as the substance itself. What Locke regards as unknown is the substratum qua occupant of the unifying role, not the whole substance.5 This reading of Locke’s notion of substrata can be usefully compared with C.B. Martin’s, who views the substratum of an object as ‘something about the object’ (Martin 1980, 6), namely, an aspect of it, or a way it is, so that ‘[t]he relation between substrata and [the] properties [that they support] . . . stands between things about or ingredients of objects and not between objects themselves’ (Martin 1980, 7).6 Lowe (2005, 72–3) interestingly uses the term ‘role’ in his characterization of Martin’s reading, which he says ‘in some ways resembles’ his own: ‘Martin’s suggestion is that a Lockean substratum is neither an object nor a property, but, rather, is what it is about an object that plays the role of bearing (or supporting) the object’s properties’. In Martin’s discussion, however, the functionalist viewpoint that I suggest is not fully developed.7 Lowe’s description of Martin’s interpretation thus more accurately characterizes my own reading than Martin’s.

2.

The ‘Bare Being’

The so-called bare substratum reading is a long-standing interpretation of Locke’s view on substratum, advocated by A.S. Pringle-Pattison (1924), Gerd Buchdahl (1969), and Bennett (1971, 1987), among others. Even some modern metaphysicians take it to be a standard reading of Locke. For example, Armstrong (1989, 61) remarks that Locke’s substratum is ‘unsatisfactory’, and that ‘[t]he great hostility to substance that you find in the British tradition has been hostility to [Locke’s] substratum’. Armstrong further observes that ‘[t]he British Empiricists were really reacting against Locke’s unknown substratum. This in turn created a climate of opinion favourable to the Bundle Theory, which gets rid of substratum by identifying a thing with the bundle of its properties’. In short, Locke’s naked substratum precipitated the rise of bundle theory. It has been customary to view Locke’s substratum in this way, and the

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connotations of the expression ‘Lockean substratum’ have consequently been largely negative. On the bare substratum reading, an object’s qualities are supported by a naked bearer—‘a subject in which a set of properties is instantiated while itself being property-less or bare or unqualified in some problematic way’, in Bennett’s words (1987, 199). The naked substratum stands in opposition to the trans-attribute substratum, discussed in Chapter 5. Bennett characterizes the latter as spreading across the realms of thought and extension by virtue of occupying the active role of realizing both attributes. This role, which mediates the dual attributes, is occupied by some positively natured property, though its intrinsic nature is unknown. We have no way of describing it except in terms of its functional role. Bennett ascribes this type of an unknown yet natured substratum to Spinoza, but not to Locke. Pringle-Pattison associates the bare substratum reading with Locke’s account of superaddition, seeing him as suggesting a naked support ‘to which any kind of qualities may be arbitrarily annexed’.8 Such descriptions of the Lockean substratum have become entrenched as a widely held criticism of Locke. Some scholars, e.g. Ayers (1975, 1991), Martin (1980), Alexander (1991), Lowe (2005), Millikan (2015), and Kim (2015), have, however, repudiated the bare substratum interpretation.9 Although they disagree with one another on many specific points, they agree in thinking that Locke’s substratum is far more substantive than Bennett’s ascription of bareness implies. Though a naked substratum may be logically conceivable, it cannot actually exist in the Lockean world, wherein to be is to be natured; for anything ‘granted to have a being’ is ‘in nature, of which we have no ideas’ (First Letter, 18). As discussed in Chapter 3, any role-realizing activity must be performed by a positively natured property. This applies also to any potential realizer of the unifying role. The role of uniting an object’s qualities into a single thing must be occupied by some natured property. Hypothetical naked entities are thus not eligible candidates for the unifying role in terms of which Locke’s substratum is defined. It is logically impossible for a substratum to be part of the bundle of qualities it supports, but this does not entail that substrata are naked. Locke’s view is rather that the set of qualities that distinguishes an object must be borne by a positively natured property, which is functionally differentiated from them. As seen in Chapter 3, Langton likewise does not regard Locke’s substratum as naked, but instead views it as possessing some non-causal intrinsic nature. Langton reads both Kant and Locke as holding that while the underlying substratum is natured, it only bears certain qualities or powers; it is itself causally inert. Lack of causal powers, however, does not entail nakedness. As we have seen, Kant’s epistemic humility stems from the idea that one has no access to an object’s underlying

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substratum, since one is only affected by the powers it bears, not the bearer itself. This type of epistemic humility is based on the claim that the bearer of any given set of powers is itself causally inert. However, this Kantian form of property dualism, which distinguishes causally operative features from their non-causal bearers, is not attributable to Locke. As discussed in Chapter 3, from Locke’s perspective, in assessing the relationship between an object’s real and nominal essence, it is not reducibility but rather realization that matters. The relation of realization holds between the conceptual (or descriptive) entities and actual (or qualitative) entities. The relation between roles and role-realizers thus corresponds with that between nominal and real essences. It is thus only in a trivial sense that conceptual, nominal entities are irreducible to actual entities. One should instead view the former as realized by the latter. Human physical theories only spell out the roles performed by the fundamental entities that constitute the world; they don’t give us knowledge of their intrinsic nature. As noted in Chapter 3, this Lockean variety of epistemic humility should be differentiated from Kant’s, as it rejects the dualism of causally operative features and non-causal bearers on which the latter is founded. It was characteristic of Locke’s account of the intrinsic nature of things in themselves to refer to a higher intelligent being: ‘what Idea [other Species of Creatures] may receive of [the inmost Constitutions of Things], far different from ours, we know not’ (IV.iii.23). This reference to higher intelligent beings is meant to imply that, though unknown to us, the intrinsic constitutions of things are positively natured, never bare. SP and FP are thus combined with the view that any given role is occupied by a positively natured property. Accordingly, the role of uniting a set of qualities must likewise be occupied by some actual property of the object whose qualities are thus united. The combination of these two aspects of Lockean substrata—the unifying role and the role-realizer—has often been overlooked. With respect to the former, a substratum may seem to be an abstract entity. If only this aspect is taken into consideration, a substratum might appear to be naked or lack actual features. In its role-realizing aspect, however, the unifying activity that defines a given substratum must be performed by some actual property. Both of these aspects of substratum must be taken into account in order to grasp its nature properly. Advocates of the naked substratum reading have sometimes seized on the fact that Locke himself does use the term ‘bare’ in a passage from his correspondence with Stillingfleet: God has likewise created and made to exist, de novo, an immaterial substance, which will not lose its being of a substance, though God should bestow on it nothing more than this bare being, without giving it any activity at all. (Second Reply, 464)

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In this passage, however, Locke’s use of the term ‘bare’ does not imply a Bennett-style bareness but rather a state in which no higher-level features are yet instantiated, such as the power of thought, self-motion, or spontaneity. Here the phrase ‘bare being’ refers to some inactive being, which should be distinguished from the Bennett-style notion of nakedness. As Locke clarifies, ‘[God] . . . may leave [a substance] in a state of inactivity, and it will be nevertheless a substance; for action is not necessary to the being of any substance, that God does create’ (Second Reply, 464). Here ‘inactivity’ means that the hypothetical substance displays no actual action. On Locke’s account, it is not necessary for a substance to display such activity, for substances can be positively characterized in terms of their dispositions, and the ascription of a disposition does not entail that that disposition is or will be manifested. One can thus ascribe fragility to a glass even when it is not actually breaking, and indeed, even if it never actually breaks. The satisfaction of a condition that would be sufficient for the glass’ fragility to manifest itself (e.g. its being struck with a certain amount of force) is a contingent matter. Even when a substance does not actually manifest its powers, those powers can consequently still be ascribed to it. This explains how God may leave a substance ‘in a state of inactivity’ while it is ‘nevertheless [still] a substance’. In discussing the dispositional nature of substance, Locke suggests a metaphysically possible case, in which two entirely distinct substances are each ‘in a state of inactivity’ (Second Reply, 464). He asks us to imagine two substances of radically different types: one material and the other immaterial. Both substances exhibit no observable behavior, but are nevertheless distinguishable in terms of their intrinsic nature: ‘here are now two distinct substances, the one material, the other immaterial, both in a state of perfect inactivity’ (Second Reply, 464). Both are likewise created substances. Here, God and the two created substances, material and immaterial, represent the ‘three sorts of Substances’ that Locke lists in II.xxvii.2. Despite their inactivity, both created substances ‘may each of them have their distinct beings, without any activity superadded to them’ (Second Reply, 465). The term ‘superadd’ is significant here, as its use in this passage suggests that a ‘bare’ substance (whether material or immaterial) is one wherein no higher-level features are realized. Each bare particle (or an aggregate of particles not yet suitably organized) is by itself incapable of realizing spontaneity, self-motion, or the power of thought. An individual particle is merely solid, although its being so never implies a Bennett-style nakedness. Similarly, a bare immaterial substance is an inactive being that is nevertheless endowed with all the unactualized dispositions characteristic of immateriality, and no other dispositions besides these. Though Locke does not explain how God might do this, if God were to make a bare immaterial substance into a mental being, he would have to add the power of thought to it. The superaddition of the power of thought to such a bare immaterial substance would nevertheless

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be radically different from the superaddition of that same power to a material system. Alexander (1991b, 208–9) takes the immaterial substance that Locke refers to in the preceding passage to be an inherently passive substance, to which the active power of thought must therefore be superadded. Alexander (1991b, 216) hence attributes to Locke a derivative form of substance dualism wherein (in contrast to traditional, Cartesian dualism) the human mind is taken to be essentially passive: ‘[t]here are signs in the Correspondence that [Locke] is moving towards replacing [thinking] by sensation which, since the mind is passive with respect to it, at least, might be for him a better candidate than thinking’. Alexander does not accept the naked substance reading, but instead interprets what Locke refers to as a ‘bare’ substance (whether material or immaterial) as one that is inherently passive or sentient; that is, Alexander reads a bare material substance as a bare particle, and a bare immaterial substance as the human mind. While Alexander’s reading of the bare material substance is correct, his interpretation of a bare immaterial substance is not. On his reading, the human mind is taken as inherently sentient and only sentient. The divine act of superaddition would thus be understood as adding the power of thought to such a sentient being. The Lockean human mind does have passive capacities (e.g. sensation), but it also has active powers (e.g. thought and will). This is what Locke means by saying that ‘Understanding and Will are two Faculties of the mind’ (II. xxi.6). Locke denies that the human mind is endowed with innate ideas, but acknowledges that the intellectual faculties or powers are innate: ‘no Body, I think, ever denied, that the Mind was capable of knowing several Truths. The Capacity, they say, is innate, the Knowledge acquired’ (I.ii.5). Given that the intellectual faculties are innate, the essential nature of the human mind consists of more than mere sentience. Furthermore, the notion of a sentient immaterial substance would make little sense, given that a sentient being of any type would need a material body (since ‘sentience’ means a capacity to be aware of the world through the senses). If some immaterial senses were to exist, then a sentient immaterial being might also exist. But even so, Locke would not identify the human mind with any variety of immaterial substance. In his view, the human mind is an emergent feature that arises in some suitably organized system of material particles, as explored in Chapter 4.

3.

The Substratum of Human

This section examines the relevance of Locke’s account of substrata to the mind-body issue. As seen earlier, he applies SP equally to each species, including ‘Man, Horse, Gold, Water, etc.’ (II.xxiii.3). As this list indicates, SP applies to the human species as well. Each of us thus has a substratum that unities the whole range of qualities that we exhibit,

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mental and physical. There is also, however, an additional application of SP that applies only to the human species. As the following passage from II.xxiii.5 indicates, Locke allows a further substratum for each set of qualities that we exhibit, mental and physical: [B]y supposing a Substance, wherein Thinking, Knowing, Doubting, and a power of Moving, etc. do subsist, We have as clear a Notion of the Substance of Spirit, as we have of Body; the one being supposed to be (without knowing what it is) the Substratum to those simple Ideas we have from without [i.e. by sensation]; and the other supposed (with a like ignorance of what it is) to be the Substratum to those Operations which we experiment in ourselves within [i.e. by reflection]. This passage appears to treat the human species differently than other particular sorts of substances by allowing a support for each specific set of qualities, mental and physical, in human beings while positing only one single substratum for all of the qualities in the case of other species. In the case of the human species, it is ‘by supposing a Substance, wherein Thinking, Knowing, Doubting, and a power of Moving, etc. do subsist, [that] We have . . . a Notion of the Substance of Spirit’. As stated in this passage, the mental features require a substratum for themselves, separate from the substratum for our physical features. In conjunction with SP, Locke likewise applies FP separately to our mental and physical qualities: ‘the one being supposed to be (without knowing what it is) the Substratum to those simple Ideas we have from without; and the other supposed (with a like ignorance of what it is) to be the Substratum to those Operations, which we experiment in our selves within’. For Locke, however, these specific applications of SP and FP do not lead to metaphysical dualism. Rather his general application of these principles implies a monistic view. Locke never used the term ‘monism’ himself, but would instead likely say that there is no metaphysical repugnancy among the qualities, physical or mental, displayed in an individual. In Locke’s sense, to say that something is ‘one’ thing is to say that there is no such repugnancy among the various qualities that a given substratum is posited as a support for. His account of the unity of individual substances is at times ideational, yet his inclusion of men in the list of particular sorts of substances implies a rejection of metaphysical dualism. Alexander (1991b) paid particular attention to the passage from II.xxiii.5. His reading of Locke as a metaphysical dualist can be seen as a consequence of neglecting the general application of SP. As explored in Chapter 2, Locke often refers to human psychological tendencies as the ground for dualistic beliefs, such that ‘we are apt to think’ that our own mental activities are ‘[a]ctions of some other Substance, which we call Spirit’ (II.xxiii.5). This sort of appeal to human psychological tendencies appears in his account of

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substrata as well: ‘we accustom our selves, to suppose some Substratum’ (II.xxiii.1). Likewise, as stated in the passage quoted earlier, ‘[w]e have . . . a Notion of the Substance of Spirit’, by supposing a support for the mental operations or activities ‘which we experiment in our selves within’, while our ‘[Notion] of Body’ is obtained from supposing a support for the ‘simple Ideas we have from [the physical qualities of external objects]’ (II. xxiii.5). These dual substrata are both posited by reference to the mental activities that one introspects in oneself, and the simple ideas caused by external objects. On Locke’s account, our complex abstract ideas of minds and bodies are formed from these two types of materials, perceived through reflection and sensation, respectively. The dual substrata are posited through two separate processes of abstraction, carried out on these two different types of ideas. For Locke, each human is conceived as a system of matter suitably organized, from which a set of higher-level properties emerge. God’s knowledge of the real essence of men would thus be based on ‘a quite other Idea of’ our real essence than ‘what now is contained in our definition of’ men (III.vi.3). Our idea of ourselves is dualistic, but only nominally so. As discussed in the foregoing chapter, our distinct ideas of mind and body are, as McGinn (2004, 24) puts it, just ‘human constructs’. This point of view helps us to make sense of Locke’s account of the separate identity conditions for masses of matter, men, and persons: ‘[i]t [is] one thing to be the same Substance [i.e. Particles of Matter], another the same Man, and a third the same Person’ (II.xxvii.7). These three types of entities can be seen as the three major dimensions of human nature: physical, biological, and psychological, respectively. The identity of the first, i.e. of each individual particle, consists in the numerical identity of each one over time. The identity of an aggregate of particles is likewise so determined that an aggregate remains the same over time if and only if ‘every one of [its constituent] Atoms [is] the same, by the foregoing Rule’ (II.xxvii.3). This strict sense of identity, however, is not applicable in the actual world, in which ‘[a]ll Things, that exist, besides their Author, are all liable to Change’ (III.iii.19). No physical object is actually numerically identical over time. Locke thus invokes a different identity condition for higher-level entities such as plants and animals, whose identity ‘depends not on a Mass of the same Particles; but on something else’ (II.xxvii.3). By ‘something else’ here, Locke refers to the biological continuity sustained in each organic being, despite ‘a manifest change of [its] parts’ (II.xxvii.3). As Locke writes, ‘the variation of great parcels of Matter alters not [their] Identity’; for example, ‘[a]n Oak, growing form a Plant to a great Tree, and then lopp’d, is still the same Oak: And a Colt grown up to a Horse, sometimes fat, sometimes lean, is all the while the same Horse’ (II.xxvii.3). Each one, being a system of atoms suitably organized, can be seen as the ‘same’ through time by virtue of its parts’ participation in ‘one Common Life’ (II.xxvii.4). In

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this respect, each organic system can be said to ‘continue to be the same’ through time, by virtue of their parts being ‘vitally united’ into a ‘one coherent Body’ (II.xxvii.4). This second criterion of identity thus depends on the continuous existence of ‘such an Organization of [a system’s] parts’ (II.xxvii.4). Locke applies the same criterion of identity to ‘Man’ that he does to plants and animals. The identity of a human thus consists ‘like that of other Animals in one fitly organized Body’ (II.xxvii.6). As Locke further states, ‘the Identity of the same Man consists . . . in nothing but a participation of the same continued Life, by constantly fleeting Particles of Matter, in succession vitally united to the same organized Body’ (II.xxvii.6). Human nature can thus be described in relation to our biological life, as well as in relation to our existence as physical beings. In light of our discussion in Chapter 4, biological features can be said to be ‘emergent’ entities in a physical system suitably organized. That is, an organism’s biological features may appear to be entirely distinct from those of the physical particles that constitute it, while nevertheless ontologically depending on those particles. The idea of emergentism is thus that not every feature of a physical system can be explained entirely in terms of its parts. The psychological features exhibited by certain organisms (e.g. ourselves) are also higher-level emergent entities. They may appear to be entirely new entities over and above the physical particles, but in fact cannot exist without them. What Locke refers to as a ‘person’ represents the psychological dimension of human nature—as ‘a thinking intelligent Being, that has reason and reflection, and can consider itself as it self, the same thinking thing in different times and places; which it does only by that consciousness, which is inseparable from thinking, and as it seems to me essential to it’ (II.xxvii.9). This definition of a person requires no biological identity. It even allows for multiple realizations of the same personality: ‘if the same consciousness (which, as has been shewn, is quite a different thing from the same numerical Figure or Motion in Body) can be transferr’d from one thinking Substance to another, it will be possible, that two thinking Substances may make but one Person’ (II.xxvii.13). This account, however, does not imply that a person is constituted by a metaphysically distinct entity over and above the system of the atoms that makes up a human body. Locke’s supposition of a substratum for the mental and another for the physical might appear to suggest substance dualism, but he posits a further substratum in which such dual qualities inhere. These three entities—atoms, man, and person—are not thus ontologically distinct, but ‘three Names standing for three different Ideas’ (II.xxvii.7). Each represents a different dimension of human nature. As seen earlier, Locke’s account of ‘Men’ in II.xxvii is focused on the biological dimension of human nature. But in the list of the

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‘particular sorts of Substances’ in II.xxiii, ‘men’ refers to individual humans endowed with both physical and mental features, and suggests that a single substratum must be posited for both types of qualities. In the functionalist reading of substratum advocated previously, a substratum is that component of a system (whatever it is) that plays the role of unifying its various qualities. It is, however, oftentimes hard to single out the occupant of the unifying role, due to the structural complexity of the system being considered. There may even be multiple layers of functionally distinguishable substrata in each human. A set of qualities found in any lower level may also be given a substratum, all the way down. This possibility is broached in Locke’s discussion of the ‘insensible Parts’ or ‘minute Parts of corporeal things’ in II.xxiii (in particular, sections 12, 13, and 23–27). As Locke holds, ‘[t]he little Bodies that compose that Fluid, we call Water, are so extremely small, that I have never heard of any one, who by a Microscope, (and yet I have heard of some, that have magnified to 10000; nay, to much above 100,000 times,) pretended to perceive their distinct Bulk, Figure, or Motion: And the Particles of Water are also so perfectly loose one from another, that the least force sensibly separates them’ (II.xxiii.26). As we approach the level of ‘little Atoms’, further substrata are thus posited at lower layers. At any given level, each substratum ‘tie[s] [the] heaps of loose little Bodies together’ (II.xxiii.26). In other words, it serves as a ‘Bond’ or ‘Cement’ that makes the particles ‘stick . . . fast one to another’ (II.xxiii.26). Locke thus posits a specific substratum for each layer-specific bundle of physical qualities, as well as one for the whole of the physical qualities (that is, all the physical qualities taken together), and yet another higher-order substratum in each human that serves as the common support for our mental and physical qualities.

4.

Substratum, Mind-Body Nominalism, and Dynamic Realism

As we have seen, a bundle of qualities and their unifier are the principal components of a particular sort of substance. Locke applies this general account not only to specific sorts of substances but also to more general kinds, e.g. minds and bodies. He likewise posits a substratum for each bundle of qualities, mental and physical, but does not commit himself to metaphysical dualism. For Locke, the mind-body distinction is a nominal, based on the difference between the two forms of experience, sensation and reflection. This distinction is not only crucial to his account of experience in general, but underpins his mind-body nominalism as well. The duality of mind and body is explained by the dual ways in which we conceive the world. Thus, as Carroll observes, minds and bodies are for Locke ‘two Nominal, and not two Real substances’, which ‘Co-exist in One and the same Substance’ (Dissertation, 38). The two nominal

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entities are differentiated only by reference to their functional roles in our psychological and physical theories. As discussed in Chapter 4, this nominal division is made within a naturalistic framework. The Lockean mind-body distinction thus rests on how we humans conceive or describe ourselves in the natural world. In conceiving or describing ourselves, we employ certain perspectives or conceptual frameworks. Accordingly, the Lockean ideas of mind and body comprise two distinct perspectives from which we view the world. The dual features, physical and mental, result from our being endowed with two different sorts of faculties through which we approach the world. As examined in the foregoing chapters, Locke’s mind-body nominalism is grounded in a naturalistic view, in which a system of matter fitly disposed realizes the spirit-role, although the intrinsic nature of each particle that constitutes the system is inaccessible to us. One can thus only know that the current system of particles that constitutes our body is fitly disposed to think, but not why this type of system is so while others are not. The fact that such a system is suitable to think is discoverable a posteriori, but why it is so is beyond our ken. Locke’s epistemic humility is thus ultimately directed towards the fundamental building blocks of the world. As we have seen in Chapter 3, Locke applies his functionalist account to each particle as well. The next chapter explores how Locke’s account of primary qualities becomes more descriptive in regard to microscopic objects. As Locke states, while ordinary-sized objects are ‘enough to be perceived’ by our ‘senses’, our ‘Mind’ understands them rather differently (II.iv.1). As applied to ordinary-sized objects, our idea of solidity typically refers to the simple idea of touch: ‘[t]he Idea of Solidity we receive by our Touch’ (II.iv.1). By contrast, Locke’s account of the solidity of insensible particles is much more descriptive and functional, as we shall see in Chapter 7. As noted in this chapter, Locke refers to a substratum as a supposed support for the co-instantiated qualities of a particular sort of substance, not as the real essence of that substance. If we were able to know a substance’s real essence by accessing all the facts about its constituent particles, from which all its qualities flow, we might be able to know why one set of qualities is united in a given substance rather than another. The unifying role may appear to be an abstract stipulation, in that it does not refer to any specific property as the realizer of that role. Nevertheless, Locke was a realist about role-occupants. There must hence be something that occupies the unifying role, and this role-player need not be bare in the sense of being perfectly property-less. Rather, his view is that the unifying role is an active role realizable in some positively natured property. Some eighteenth-century dynamic realists contended that Locke’s account of substratum anticipated their own dynamic conception of matter. In the next chapter, I explore the idea of dynamic realism and its relevance to his functional approach to substrata.

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Notes 1. Lowe (2005, 61) also notes that the three sorts of substances are ‘the only genuine substances’ whereas the particular sorts of substance are substances in ‘the looser way of talking’. 2. Locke’s account of the three sorts of substances has some affinities with Descartes’ definition of substance, wherein only God is a substance in the primary sense (since only God depends on nothing other than himself for his existence), while human minds and bodies are substances in a derivative sense (since the two sorts of finite substances each depends on God): ‘[b]y substance, we can understand nothing other than a thing which exists in such a way as to depend on no other thing for its existence. And there is only one substance that can be understood to depend on no other thing whatsoever, namely God. In the case of all other substances [i.e. corporeal substances and human minds], we perceive that they can exist only with the help of God’s concurrence’ (CSM I, 210). For Descartes, each finite mental substance is identified with a human mind, but Locke’s ‘Finite Spirit’ is a spirit qua spirit, not necessarily a human mind. 3. In fact, Locke ascribes the unifying role to real essences as well, describing them as ‘an unknown Support and Cause of [the] Union’ of various qualities (III. vi.21). Given this, substrata may appear to be redundant entities or reducible to real essences. 4. Locke’s account of real essences is thus not necessarily confined to particular sorts of substances, but also applies to atoms—the ‘greatest Instruments of the Nature’. Although some scholars, e.g. Owen (1991) and Guyer (1994), contend that Locke’s account of real essences is grounded in his account of nominal essences, it is rather the postulation of substrata that follows from Locke’s account of nominal essences. 5. Lowe’s view is also inconsistent with Locke’s claim that a substratum is an unknown support, as Lowe (2005, 70–1) himself acknowledges: ‘[o]n this account, [however] . . . substrata . . . are not, in general, “something we know not what”—for we know at least something of them in knowing some of their properties. Hence, I say, this view of substratum almost certainly cannot be attributed to Locke himself’. Lowe (2005, 71) thus ends up proposing a theory of substrata that he thinks is more defensible than Locke’s, rather than a reading of what Locke himself thought about them: ‘what we may be able to say is that it was open to Locke to adopt this view, consistently with many— even if not all—other important aspects of his philosophy’. 6. On Martin’s account, a substratum is not a physical part of the given object. The monitor of a laptop, e.g., is a part of it, but can also be an object by itself when detached from the laptop’s other parts. In contrast, a substratum cannot exist on its own by any means. It is nothing like the detachable monitor. According to Martin, a substratum is not a ‘property’ either, for every property must be borne by a substance, and a substratum is not borne by anything other than itself. It depends on the object of which it is a substratum only in the sense that it is an aspect of it. 7. Martin would have to say that the bundle of qualities is another aspect of the given object, and that one aspect (the bundle of qualities) depends on another aspect (the substratum). But it would make little sense for one aspect to depend on another, given that an aspect is a selective and partial consideration of the whole. It may be more correct to say that both aspects depend on the same object with no direct relation of ontological dependence between themselves. Locke’s clam that a substratum is the support for an object’s qualities seems, however, to designate the former as ontologically more basic than the latter.

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8. Pringle-Pattison offered this criticism in a footnote to his edited Essay (1924) III.iii.15. 9. Ayers (1975, 2) holds that the description of Locke’s substratum as ‘naked’ or ‘bare’ distorts the views of a philosopher ‘who is an anti-Aristotelian corpuscularian’. Agreeing with Ayers, Alexander (1991a, 183) maintains that Locke was ‘less imperceptive and inconsistent than is usually supposed’. Lowe (2005, 68) likewise observes that ‘[a] “bare particular” would, it seems, be something with an identity but no properties or nature of its own . . . Locke says, to be sure, that a substratum is something “we know not what” and that it is indeed not just unknown but unknowable to us. But at times he also intimates that a substratum may have a “nature”, which might in principle be knowable to other intelligences than ours—perhaps to angels and presumably to God’.

7

1.

Locke and Dynamic Realism

Priestley on Locke as a Proto-Dynamic Realist

For Locke, a system of particles, suitably arranged, can give rise to a set of higher-level features, including the power of thought. These ‘emergent’ features—none of which can be found in any of the system’s lowerlevel parts—nonetheless depend on that system. The underlying idea of emergentism is that there is no metaphysical inconsistency or repugnancy between mental and physical features.1 In Locke’s time, however, many people still found this idea objectionable. The objection that was most common at the time can be summarized as follows: (1) If a system of matter can think, each atom constituting it can also think. (2) However, no atom can think (since atoms are inherently inert and non-cognitive). (3) Thus, no system of atoms can think. Both premises of this argument are, however, based on false or controversial ideas. The first premise commits the so-called fallacy of division by ascribing the properties of a whole to its parts. According to emergentism, the power of thought is a feature of a whole (i.e. a system of matter fitly disposed) that is not found in its parts. The second premise is based on the controversial assumption that matter is passive. As an exponent of the dynamic conception of matter, Priestley (1777) challenges the second premise in particular, accusing the long-standing belief in the passivity of matter of a ‘[v]ery great misconception’ about ‘what have been called material and thinking substances’; a misconception that, in his view, had ‘very generally prevailed’ amongst his contemporaries (Disquisitions, 2). Priestley regards this misleading conception of matter as forming the basis of metaphysical dualism: ‘[m]ost of the objections that have been made to the possibility of the powers of sensation and thought belonging to matter, are entirely founded on a mistaken notion of matter, as being necessarily inert and impenetrable’ (Disquisitions, 81).

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In Priestley’s dynamic realism, power is ‘absolutely essential to [the] very nature and being [of matter]’ (Disquisitions, 5). ‘Take away the power . . . and the solidity of the atom entirely disappears . . . it is then no longer matter’ (Disquisitions, 6). Accordingly, the traditional dichotomy between the activity of mind and the passivity of matter disappears in Priestley’s dynamic theory of matter. All material entities are said to share a ‘common property’ such that ‘the most exalted and refined part of matter [such as the power of thought] cannot be deemed to differ essentially from the grossest matter’ (Disquisitions, 71). In a phrase that is evocative of emergentism, Priestley thus describes the distinction between mind and matter as a distinction made only in terms of ‘the scale of being’ (Disquisitions, 71). As James Dybikowski (2008, 87) remarks, ‘[o]ne of the first philosophical works Priestley read as a young man was Locke’s Essay concerning Human Understanding. It repeatedly surfaced in his philosophical writings as a marker against which he defines his positions’. Priestley read Locke as a forerunner of his own dynamic conception of matter, as indicated in the following passage: Though Mr. Locke considered solidity as constituting the essence of matter (See Essay, & c. vol. ii. p. 141, where he says, ‘that substance that has the modification of solidity is matter’,) yet it is plain he had an idea of something else, being in fact necessary to its cohesion. (Disquisitions, 8) The ‘idea of something else’ that Priestley refers to here is his own dynamic notion of matter. In the following passage, he mentions Locke once more, as a precursor of the naturalistic view of the human mind that is derived from the dynamic conception of matter: Mr. Locke did not apprehend that there was any real inconsistency between the known properties of body, and those that have generally referred to mind . . . he ought, as became a philosopher, to have concluded that the whole substance of man, that which supports all his powers and properties, was one uniform substance, and by no means that he consisted of two substances. (Disquisitions, 32) Locke and Priestley share the view that there is no metaphysical inconsistency or repugnancy between mental and physical features. In Priestley’s own words, ‘[a]ll that I contend for is such a conjunction of powers in the same thing, or substance, by whatever term it be denominated, as we find by experience always go together, so as not to multiply substances without necessity’ (Free Discussion, 23). In this chapter, we shall examine whether Locke was indeed committed to the new, dynamic conception of matter that Priestley advances, and how

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Locke’s naturalism relates to this view of matter. In particular, we shall analyze the phrase ‘active parts of Matter’ from the following passage where Locke refers to the ‘insensible Corpuscles’ as being ‘active’: These insensible Corpuscles, being the active parts of Matter, and the greatest Instruments of Nature, on which depend not only all their secondary Qualities, but also most of their natural Operations, our want of precise distinct Ideas of their primary Qualities, keeps us in an incurable Ignorance of what we desire to know about them. (IV. iii.25) The phrase ‘parts of Matter’ refers to the insensible particles, the ‘greatest Instruments of Nature’. Hence, Locke’s phrase ‘active parts of Matter’ implies that the particles are ‘active’. Locke, however, offers us no further account of what it means to say that these particles are active. Priestley views Locke’s account of matter as a predecessor to his own full-blooded dynamic essentialism, wherein ‘no substance can retain any form without [power]’ (Disquisitions, 5). I shall use the term ‘dynamic realism’ to refer to Priestley’s contention that powers, as real potencies, are the only type of properties in the actual world.2 This chapter explores the relevance of Priestley’s dynamic realism to Locke’s functionalist position as examined in Chapter 6, illuminating its historical significance.

2.

Priestley’s Dynamic Realism

In the seventeenth century, the world was conceived as a huge machine. The working of machinery such as one cogwheel engaging with another was taken as the paradigmatic picture of the world. In a machine, an action is transmitted from one part to another by contact. When one thing appears to act on another at a distance, a continuous chain of connections is supposed to exist between them. This is the worldview developed by the so-called mechanical philosophers or mechanists of the seventeenth century. In the scholastic period, matter was understood as a potentiality in and of itself. Its actualization was obtained through an ontological union with its metaphysical correlate, substantial forms. For the seventeenthcentury mechanists who rejected the scholastic model, the significance of the clock example lay in the suggestion that the outward behavior of any given complex object can be explained in terms of the arrangement and movement of its internal parts. Boyle postulated atoms or corpuscles as the basic elements that figured in his mechanical explanation of the world, wherein any given ordinary-sized object’s features are explained in terms of the tiny particles of which it is composed. Boyle’s doctrine of ‘primary qualities’ can be considered as an answer to the question of what the basic particles are like. Boyle (1965b , 211) states that ‘[a]t the first production of mixt bodies, the universal

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matter whereof they among other parts of the universe consisted was actually divided into little particles, of several sizes and shapes, variously moved’. Each Boylean atom is actually shaped and sized in a specific mode. Their primary qualities thus serve as a principle that not only distinguishes the material particles from immaterial entities but also individuates one particle from another. On Boyle’s account, however, the tiny particles resemble ordinary-sized objects. Ernan McMullin (1978, 15) points out a logical problem with the Boylean notion of perfect solidity. According to Boyle, the intrinsic features of insensible particles (which explain the perceptible properties of ordinary bodies) are characterized by reference to what they causally explain (the perceptible properties of ordinary bodies). That is to say, X causally explains Y; yet the features of X are characterized in terms of the features of Y. This is a kind of induction from the observable to the unobservable. McMullin characterizes Boyle’s reasoning about the nature of insensible particles as an inference ‘from particular instances to other instances of the same kind’, where the particles and the complex objects they constitute are both conceived as ‘characterizable by the same predicates and covered by the same laws’. 3 McMullin claims that Locke was suspicious of the validity of this kind of reasoning: ‘[t]here were those, like Locke, who worried about the validity of such a move, but most scientists incorporated the new “corpuscles” into their physics without the addition of any new concepts’. As seen previously, in the late eighteenth century, Priestley was more than worried about the validity of Boyle’s inference. Boyle (1965b, 213) further holds that ‘[t]hough [each material particle] be mentally, and by divine Omnipotence divisible, yet by reason of its smallness and solidity, nature doth scarce ever actually divide it; and these may in this sense be called minima or prima naturali’. Here Boyle makes the point that although each particle is ‘mentally’ (i.e. conceptually) divisible, it is physically impossible for humans to divide a single particle into smaller ones; only a divine power can do so. The conceptual divisibility of the physically indivisible particles implies a physical fullness with no interstitial space in it, which Priestley describes as being ‘perfectly solid’ (Disquisitions, 5). This notion of perfect solidity is combined, in Boyle’s conception of physical particles, with the presumed inertness of matter. Priestley himself described Boyle’s view of matter as follows: It is asserted, and generally taken for granted, that matter is necessarily a solid, or impenetrable substance, and naturally, or of itself, destitute of all powers whatever, as those of attraction or repulsion, &c. or, as it is commonly expressed, that matter is possessed of a certain vis inertiae, and is wholly indifferent to a state of rest or motion, but as it is acted upon by a foreign power. (Disquisitions, 2–3)

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Rejecting Boyle’s notion of perfect solidity, Priestley sees the power of resistance as essential to materiality: [R]esistance, on which alone our opinion concerning the solidity or impenetrability of matter is found, is never occasioned by solid matter, but by something of a very different nature, viz. a power of repulsion always acting at a real and in general an assignable distance from what we call the body itself. (Disquisitions, 4) Downing (2011, 131) remarks that Boyle’s ‘conceptual point’ about primary qualities—i.e. that one cannot conceive them as reducible to any other (more basic) types of properties—is challengeable, since it seems possible to conceive of size and shape as reducible to location plus repulsive force. Priestley’s dynamic realism can thus be viewed as challenging Boyle’s conceptual point by claiming that ‘no such figured thing can exist, unless the parts of which it consists have a mutual attraction’ (Disquisitions, 5). That is, a given object’s figure and size are a consequence of the repulsive and attractive powers of its parts. Matter appears to be inactive, but its underlying nature is very different. Material bodies appear inactive because there is a balance between the operations of attractive and repulsive powers. Beneath this appearance, such powers are operating incessantly. Priestley applies the primacy of powers to the basic particles all the way down: ‘[t]his argument equally affects the smallest atoms, as the largest bodies that are composed of them’ (Disquisitions, 5). A year after the publication of Priestley’s Disquisitions, Richard Price (1778) asked Priestley what underlies a power. If all power is a power of something, what is the thing that attracts and repels, and what is this thing like? This question concerns the ‘categorical’ basis of power. In Price’s view, to say that matter has no essential properties besides powers of attraction and repulsion is no more than to say that ‘void space attracts and repels’ (Free Discussion, 12). A Priestleyan body consequently appears to be a ‘non-entity’ or ‘nothing’, for it is identified with a bundle of power with no non-dispositional basis (Free Discussion, 14). In Price’s words: ‘Is it a power of attraction and repulsion only that perceives, thinks, reasons, &c? Is it only powers that circulate in our veins, vibrate in the nerves, revolve round the sun, &c?’ (Free Discussion, 15). According to Priestley, the Boylean primary qualities that are entailed by perfect solidity (e.g. shape, size, and impenetrability) are just ‘superficial appearances’ of matter, which ‘the real appearance will not authorize’ (Disquisitions, 4). Priestley criticizes the Boylean distinction between primary and secondary qualities on the grounds that, so distinguished, these qualities are conceived as lacking a common property. This same criticism is leveled against the common distinction between mind and matter, which in Priestley’s view is based on the presumed difference between the passivity of matter and the activity of mind. This dichotomy causes people to

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view the interaction between mind and body as ‘a difficulty’—even as ‘a mystery that we cannot comprehend’ (Disquisitions, 60).4 Priestley’s dynamic realism, by contrast, is established upon the principle of ‘the uniform composition of the whole man’ (Disquisitions, 74). He again mentions Locke in relation to this principle: Mr. Locke, who maintains the immateriality of the soul, and yet maintains that, for any thing we know to the contrary, matter may have the property of thought superadded to it, ought to have concluded that this is really the case; since, according to the rules of philosophizing, we ought not to multiply causes without necessity, which in this case he does not pretend to. (Disquisitions, 73) As Priestley notes, Locke’s reference to the immateriality of soul in the Essay and his correspondence with Stillingfleet does not refer to the human mind but to a spirit qua spirit or some non-human species, as we examined in the foregoing chapters. Priestley, however, sees the ‘superadded’ power of thought as grounded in a ‘uniform composition of the whole man’ (Disquisitions, 74). This reading of Locke stands in opposition to the property dualist readings advocated by Wilson, Pyle, Stuart, and Langton, which we examined in Chapter 4. Which of these readings is more plausible? To answer this question we must determine whether Priestley was right in viewing Locke as a proto-dynamic realist.

3.

‘Active Parts of Matter’: Was Locke a Proto-Dynamic Realist?

Locke’s treatment of primary and secondary qualities stands in stark contrast to Descartes’ a priori account wherein primary qualities are deduced from the principal attribute of extension. As will be shown in this section, Locke’s approach to this distinction is based on his empiricism, and is even more empiricist than Boyle’s. Boyle’s notion of absolute solidity, from which the other primary qualities are derived, is clearly non-empiricist and causes a logical problem with Boyle’s method of projecting the features of ordinary objects onto the insensible particles. As will be shown in the next section, Locke’s epistemic humility regarding the primary qualities of insensible particles can be seen as a departure from the Boylean doctrine. Let us begin this section by examining major passages from the Essay on the distinction between primary, secondary, and tertiary qualities. In most discussions of Locke’s conception of secondary qualities, one tends to hear them referred to in terms of their causal products. Lockean secondary qualities are thus often defined in relation to certain kinds of simple ideas, such as smells, colors, tastes, sounds, and tactile sensations, caused in sentient beings by external objects. This popular way of

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speaking about secondary qualities, however, may not accurately represent Locke’s view of them. In the Essay, Locke himself sometimes explains the secondary qualities in terms of their causal products, but strictly speaking, he regards them as powers that objects have ‘to produce various Sensation in us by their primary Qualities, i.e. by Bulk, Figure, Texture, and Motion of their insensible parts, as Colour, Sounds, Tastes, etc.’ (II.viii.10). In more modern parlance, powers are dispositional features that manifest themselves whenever certain conditions are met. Although a glass, e.g., is not currently manifesting its fragility by shattering, one can still ascribe fragility to it. Hence, the condition of possessing a dispositional property should be distinguished from the state in which the disposition is manifested. The possession of a disposition has to do with an object’s atomic structure. We can therefore meaningfully say that the glass is fragile at times when it is not actually breaking. In addition to primary and secondary qualities, Locke also speaks about a third kind of quality, often referred to by commentators as ‘tertiary’. The tertiary qualities are also powers, but these powers cause changes in other physical bodies: ‘the Sun has a Power to make Wax white, and Fire to make Lead fluid. These are usually called Powers’ (II.viii.23). By contrast, secondary qualities are powers to produce sensations in the mind of sentient beings. For example, the sun’s power to melt gold and destroy the consistency of the metal’s insensible parts and thus its hardness is called ‘tertiary’, whereas its power to cause sensations of heat in us is called ‘secondary’, though both types of power are grounded in the same atomic structure of the sun. The tertiary qualities are no less significant than secondary qualities in the discussion of dispositions in general. There is a strong tendency to view Locke as simply adopting the Boylean doctrine of primary qualities. In contrast to the dispositional qualities (secondary and tertiary), Locke’s ‘primary’ qualities are thus often described as ‘categorical’, meaning non-dispositional or spatially extended. In Locke’s own words, the primary qualities are ‘inseparable’ from bodies (II.viii.9) and are the ‘original’ (II.viii.9) and ‘real’ (II.viii.17) qualities of them. Yet, being ‘inseparable’, ‘original’, or ‘real’ does not imply that they are non-dispositional. Priestley’s dynamic realism provides an example of a view in which dispositional features are intrinsic in that power—as a real potency—is ‘absolutely essential to [the] very nature and being [of matter]’ (Disquisitions, 5). Locke’s ‘primary’ qualities have sometimes been taken as ‘intrinsic’, and sometimes as ‘categorical’, without any appropriate distinction being made between these two notions, despite the fact they are logically independent (though closely related).5 Locke himself does not hold that the primary qualities are intrinsically non-dispositional. It has often been overlooked that in several passages in the Essay, Locke refers to primary qualities in terms of their dispositional or causal capacities. For example: ‘a Snow-ball having the power to

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produce in us the Idea of White, Cold, and Round, the Powers to produce those Ideas in us’ (II.viii.8). Here, the ‘Idea’ of ‘Round’ means our visual or tactile experience caused by the sphericity of the snowball. In this passage, Locke explains the snowball’s sphericity in terms of its causal power of producing a visual or tactile experience of its spherical shape in the human mind. This secondary quality-ish account of the primary qualities can be found in the following passage as well, in which Locke speaks of a piece of manna’s primary qualities by reference to its power of causing the ‘Idea of a round or square Figure’. Locke states that ‘[a] piece of Manna of a sensible Bulk, is able to produce in us the Idea of a round or square Figure; and, by being removed from one place to another, the Idea of Motion’ (II.viii.18). Here Locke describes the cubic shape of the piece of manna by reference to its causal power of causing the conscious experience of that shape. Even in his official definition of qualities, he defines qualities in general, whether primary or secondary, in terms of their dispositional nature: ‘[t]he Power to produce any Idea in our mind, I call Quality of the Subject wherein that power is’ (II.viii.8). Hence, ‘when truly considered, [the qualities] are only Powers’ (II.xxiii.37). However, these passages shouldn’t be read as suggesting that primary qualities are solely or essentially dispositional either as Priestley claims. For Priestley, if a substance is ‘divested of [its] power’, then it would become nothing. For Locke, by contrast, it is still something, albeit unknown. I attribute to Locke a view that I call ‘contextual dualism’, according to which a given quality can be referred to both categorically and dispositionally, although neither way allows us access to its true nature. Before discussing this view further, let us summarize the possible ways of construing the primary/secondary qualities distinction, based on our discussion so far. First, Priestley’s view can be characterized thus: (1) Dispositional Monism: only dispositional features (powers) exist; categorical features are theoretical constructions. Priestley views the inertness of matter as an abstract idea and offers the following explanation for why ‘solid extent’ has been mistakenly accepted as a ‘complete definition of matter’: ‘[i]t was imagined that we could separate from our idea of [solid extent] every thing else belonging to it, and leave these two properties [solidity and extension] independent of the rest, and subsisting by themselves’ (Disquisitions, 6). Rejecting this idea, Priestley instead holds that the primary qualities entailed by the Boylean notion of perfect solidity are merely ‘superficial appearances’ of matter, which ‘the real appearance will not authorize’ (Disquisitions, 4). There are, however, two possible objections to Priestley’s dispositional monism. The first one is: (2) Property Dualism: there exist two types of real properties, categorical and dispositional, each one being irreducible to the other.

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The view Langton ascribes to Locke (as seen in Chapter 3) would fall into this category, according to which powers are irreducible to their bearers, which are themselves non-dispositional but not naked. The second line of objection to Priestley’s dispositional monism can be characterized as follows: (3) Categorical Monism: only categorical features exist; dispositional features are theoretical constructions. Hume (1975, 61–2) may be considered an exponent of this third position in stating that ‘[t]here are no ideas which occur in metaphysics more obscure and uncertain that those of power, force, energy, or necessary connection’. On his view, ‘categorical’ features are spatiotemporally characterizable features. Notions such as power, force, and causality depend on and are reducible to the categorical features of things plus the spatiotemporal relationships (such as constant conjunction or regularity) that they bear to one another. In my reading, Locke’s position belongs to none of the preceding three categories. The view that I attribute to him can be described as: (4) Contextual Dualism: the distinction between an object’s categorical and dispositional features depends on how the object is considered. When narrowly considered, an object may appear to possess ‘categorical’ (or ‘primary’) qualities, but when widely considered, that same object may exhibit certain ‘dispositional’ (or ‘secondary’) qualities as well. On this view, whether a given quality is categorical or dispositional is a context-sensitive matter. This contrasts with the property dualist position that a quality is inherently either categorical or dispositional, with each of these types of qualities being ontologically irreducible to the other. There is a significant similarity between this interpretation of Locke’s distinction between primary and secondary qualities and John Heil’s (2003, 112), who writes that ‘[a] property’s dispositionality and its qualitativity are, as Locke might have put it, the selfsame property differently considered’. In Heil’s view, categorical and dispositional features are two different aspects of the selfsame property. Although Locke himself does not use the term ‘aspects’ in this sense, his term ‘nominal essence’ clearly refers to our abstract consideration of an object, which is a perspective-dependent consideration of it. Heil’s account of the primary/secondary qualities distinction may also seem analogous to Martin’s (1980, 6) interpretation of substratum as ‘something about the object’ (examined in Chapter 5). In my reading, what Heil and Martin refer to as an ‘aspect’ of an object would be better described as a ‘nominal’ feature that describes a certain

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role the object plays in an appropriate context. The ascription of this view to Locke is supported by the following passage: [T]he greatest part of the Ideas, that make our complex Idea of Gold, are Yellowness, great Weight, Ductility, Fusibility, and Solubility, in Aqua Regia, etc. all united together in an unknown Substratum; all which Ideas, are nothing else but so many relations to other Substances; and are not really in Gold, considered barely in it self, though they depend on those real, and primary Qualities of its internal constitution, whereby it has a fitness, differently to operate, and be operated on by several other Substances. (II.xxiii.37) The qualities listed here include primary, secondary, and tertiary qualities: weight is a primary quality; yellow is a secondary quality; and ductility, fusibility, and solubility are tertiary qualities. Locke refers to these qualities in the context of discussing a substratum that unites them into an individual thing (as explored in Chapter 6). In the preceding passage, the following two statements may at first appear contradictory: (1) dispositional features are not in the object, but (2) they depend on the object’s internal constitution. In my reading, these two statements are not contradictory, but each makes a different point with respect to dispositional qualities: (1) is about their ascription conditions, while (2) concerns their ontological ground. With this distinction, we can read the preceding passage as suggesting that while an object’s dispositional features typically require a wide context for their ascription (in Locke’s words, by considering ‘[the object’s] relations to other Substances’), they are still ontologically grounded in the object’s atomic structure. When the object is narrowly considered (‘when considered barely in it self’), we have no basis for ascribing any dispositional features to it. Such features might consequently appear not to be inherent in the object, but this does not imply that they are ontologically irreducible to it. Despite the fact that categorical qualities, by contrast, typically require a narrow context for their ascription, Locke nonetheless refers to them in terms of their causal capacity in the passages that we examined. That is, although wide considerations are not typically required for their ascription, Locke still refers to categorical qualities in terms of their causal capacities. This dispositional account of categorical qualities can be taken to suggest that the categorical/dispositional distinction is context-sensitive. There is another case that can be taken to support the point that whether a given quality is categorical or dispositional is a context-sensitive matter. Although dispositional features typically require a wider context, Locke’s geometry-physics analogy seems to imply that they can also be ascribed narrowly. If we were to know the real essences of objects, we could know

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a priori—in Locke’s words, ‘without Trial’ (IV.iii.25)—how they interact with each other. In this hypothetical case, one would be aware of an object’s dispositional features narrowly, by knowing their real essences. Consider the following passage where Locke conceives of this narrow ascription of dispositional qualities: I doubt not but if we could discover the Figure, Size, Texture, and Motion of the minute Constituent Parts of any two Bodies, we should know without Trial several of the Operations one upon another, as we do now the Properties of a Square, or a Triangle. Did we know the Mechanical affections of the Particles, of Rhubarb, Hemlock, Opium, and a Man, as a Watchmaker does those of a Watch, whereby it performs its Operations, and of a File which by rubbing on them will alter the Figure of any of the Wheels, we should be able to tell before Hand that Rhubarb will purge, Hemlock kill, and Opium make a Man sleep; . . . The dissolving of Silver in aqua fortis, and Gold in aqua regia, and not vice versa, would be then, perhaps, no more difficult to know, than it is to a Smith to understand, why the turning of one Key will open a Lock, and not the turning of another. (IV.iii.25) If the real essences of objects were all revealed to us, all the observable properties of objects could be deduced from them, just as the properties of a triangle are deduced from its definition. Given Locke’s epistemic humility, however, it is impossible for us to know the dispositional features of things from a narrow perspective in this way. As seen in Chapter 3, Locke is skeptical about our ability to attain such ‘a perfect Science of natural bodies’ (IV.iii.29). Such ‘a perfect Science’ is attainable by omniscient beings, but not by us. At any rate, since the physics-geometry analogy implies that dispositional features, too, can be viewed both widely and narrowly (though the latter mode of consideration is not available to humans), the previously cited passage lends further support to the point that whether a given quality is categorical or dispositional is a contextsensitive matter. According to contextual dualism, neither way of description gives us access to the true nature of the object to which both features are ascribed. Dispositional features of objects are not observable to us in a narrow context. What is actually observed, even in a wide context, is the causal role of each quality. For example, the malleability of gold depends on the hardness of a hammer; its solubility depends on the chemical properties of its solvent, the aqua regia; its yellowness depends on the perceiver’s visual system plus various environmental factors. Each quality is only identified by reference to its typical or characteristic causal role. Hence, powers only constitute ‘our complex Ideas’ of substances (II.xxiii.8). That is, the complex idea of a substance spells out the bundle of dispositional features consisting of its various causal roles, each of which is described in

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reference to its relation to other substances: ‘all which Ideas, are nothing else, but so many relations to other Substances’ (II.xxiii.37). The ‘active’/‘passive’ distinction is also context-dependent. When one perceives that fire melts a piece of wax, a different causal value is assigned to the wax and the fire: the fire is viewed as active, whereas the wax is passive. Locke thus distinguishes powers into two sorts, active and passive: ‘[p]ower thus considered is twofold, viz. as able to make, or able to receive any change: The one may be called Active, and the other Passive’ (II.xxi.2). The causal role of each object changes, however, when they are placed in a different causal context. For example, fire is considered active in relation to wax, but passive in relation to water that is able to extinguish it. This relativity of causal value also implies that activity and passivity are both dispositional. An object is considered active or passive only when observed in an appropriately wide causal context. In a narrow context, the object is merely considered in terms of its categorical features. Dispositionality, whether passive or active, is thus a causal concept, which is why both activity and passivity require an appropriately wide causal context for their ascription. Locke understands the activity of the ‘active parts of Matter’ (IV.iii.25) merely by reference to their role. We consequently have ‘a very imperfect obscure Idea of active Power’ (II.xxi.4), for ‘[w]e cannot by any means come to discover’ the ‘Subject’ or ‘Essence’ which ‘[the powers] are in’, or ‘the ways of operating’ of the ‘Active and Passive Powers of Bodies’ (IV. iii.16). When we observe a billiard ball colliding with another, in Locke’s example, we cannot directly observe the active power of the first ball or its actual production of motion: ‘we observe it only to transfer, but not produce any motion’ (II.xxi.4). The activity of the first ball lies in its role of transferring motion to the neighboring ball. For Locke, a power, active or passive, is understood as a role that an object plays in an appropriately wide causal context. By contrast, Priestley understands powers as real potencies that constitute the real essence of objects and make them what they are. Locke would view the activity that Priestley attributes to matter as one of the roles that matter occupies when considered by reference to what it does in an appropriately wide causal context. For Locke, ascribing such a role to a substance does not reveal the true nature of the thing that occupies that role; to think otherwise is to confuse the substance’s nominal essence with its real one. As discussed in Chapter 3, Locke can consistently endorse a Newtonian account of matter while still maintaining that we are incurably ignorant as to the nature of matter. The Newtonian conception of matter likewise provides a functional account of matter, based on the role that it plays in a certain condition. Priestley may appear to be endorsing a more realistic view of matter, but he also ends up relying on what material objects do, not what they are, in his account of the activity of power. Interestingly, Priestley likewise confesses some degree of epistemic humility as to what the true nature of

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matter is: ‘[i]t is impossible to know more of matter than can be inferred from the phenomena in which it is concerned’ (Free Discussion, 20). This statement of epistemic humility seems to stand in conflict with his official dispositional essentialist position.6 Given his use of the phrase ‘active parts of Matter’ (IV.iii.25), Locke might appear to anticipate the dynamic conception of matter, but we cannot confidently conclude that he would fully endorse that view.

4.

Dynamic Realism, Epistemic Humility, and Mind-Body Nominalism

It should be noted that Locke has two different accounts of the primary qualities in the Essay. In II.viii, he lists those features that one can find in ordinary-sized objects, such as solidity, extension, figure, and mobility as the characteristic examples of primary qualities. In IV.iii, however, he offers an alternative account of primary qualities in which his epistemic humility is deeply involved. It has often gone unnoticed that Locke’s account of primary qualities in IV.iii is particularly focused on insensible particles, and that he contends that we have no precise ideas of the primary qualities of such particles: [O]ur want of precise distinct Ideas of [the insensible Corpuscles’] primary Qualities, keeps us in an incurable Ignorance of what we desire to know about them. (IV.iii.25) [W]hilst we are destitute of Senses acute enough, to discover the minute Particles of Bodies, and to give us Ideas of their mechanical Affections, we must be content to be ignorant of their properties and ways of Operation. (IV.iii.25) In these passages, Locke abstains from listing those features that one can find in ordinary-sized objects. Solidity is consequently the only clear example that he can give us in IV.iii.25. Locke attributes solidity to all material bodies; however, on the basis of the nominal essence of matter: it is only ‘the Idea [of solidity]’ that is ‘most intimately connected with, and essential to Body’ (II.iv.1). The ascription of solidity to all material objects is thus based solely on the universal applicability of the idea of solidity to them.7 It is thus not merely the sensation of solidity that Locke speaks about in IV.iii; he is also discussing the complex abstract idea of it. His account of solidity and other primary qualities in II.viii, by contrast, may appear to simply follow the Boylean doctrine without any invocation of the previously mentioned epistemic humility about the nature of tiny particles. In II.viii, Locke lists the qualities that one finds in ordinarysized object as his examples of primary qualities, and even holds that

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the ideas of primary qualities ‘resemble’ them in the sense that how one perceives them corresponds with how they exist in the actual world: ‘the Ideas of primary Qualities of Bodies, are Resemblances of them, and their Pattern do really exist in the Bodies themselves’ (II.viii.15). In the case of ordinary-sized objects, it is rather intuitive that the ideas of primary qualities resemble them in more or less the way that a portrait of Locke resembles him. In such cases, what you see as being cubic really exists outside of your mind as cubic. In the case of tiny particles, however, Locke contends that we lack ‘precise distinct Ideas of [the insensible Corpuscles’] primary Qualities’, as seen earlier (IV.iii.25). Locke can be considered as a common sense realist with regard to ordinary-sized objects. How one perceives objects represents how they really are. Locke, however, does not apply this principle of common sense to the insensible particles, but instead stresses our lack of ‘precise distinct Ideas of [the insensible Corpuscles’] primary Qualities’, which ‘keeps us in an incurable Ignorance of what we desire to know about them’ (IV.iii.25). Locke accordingly mentions two different sorts of faculties—‘Sense’ and ‘Mind’—in his account of the primary qualities. While ‘Sense’ furnishes us with ideas that have a portrait-style resemblance to objects that ‘[have] bulk enough to be perceived’ (II.viii.9), ‘Mind’ is concerned with theoretical reasoning and inference regarding insensible particles. Locke mentions the two faculties in his account of solidity as well. In accounting for solidity of minute particles, he refers to ‘Mind’ as the subject of observation: ‘the Mind, having once got this Idea [of solidity] from such grosser sensible Bodies, traces it farther; and considers it, as well as Figure, in the minute Particles of Matter, that can exist; and finds it inseparably inherent in Body, where-ever, or however modified’ (II. iv.1). Here Locke speaks of solidity at two levels of observation: macro and micro. With regard to the basic particles at the micro level, one can identify their qualities through more complex observational procedures including more rigorous theoretical observation of their causal roles. My suggestion is that the ‘resemblance’ that ‘Mind’ finds between the primary qualities of such particles and our ideas of them should be read in terms of descriptive accuracy, such that the more our ideas of particles resemble them, the more accurately we can describe them. There is a certain type of description that provides us with an accurate theoretical representation of the world, whereas terms such as ‘red’, ‘hot’, ‘sweet’, and ‘bitter’ do not properly describe the structure or constitution of things but only specify their effects on our sense organs.8 The following description of an electron, used in Chapter 3, can be seen as an example of the accurate and objective type of description: ‘an elementary particle, classed as a lepton, with a rest mass of 9.1093897(54)×10–31 kg and a negative charge of 1.60217733(49)×10–19 coulombs, which is present in all atoms in groupings called “shells” around the nucleus’. This definition of an electron, however, only describes the electron-role. Although this

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description may be taken as a characterization of an electron’s ‘primary’ or ‘categorical’ qualities, it doesn’t give us access to its true nature.9 As the historical shift in the meaning of ‘matter’ indicates, this term is inherently vague. What Priestley means by ‘matter’ is different from what Boyle or Descartes meant by it. For Priestley, the essence of matter lies in its repulsive and attractive powers, while Boyle and Descartes regard it as inherently passive and inert. As Priestley confesses in the beginning of his Disquisitions, the dynamic conception of matter, ‘though not absolutely new, will appear paradoxical to most persons’ (Disquisitions, 5). Berkeley’s term of ‘matter’ has yet another meaning—‘some sensible thing, whose existence consists in being perceived’ (Berkeley 1975, 251)—which is radically different from the realistic meanings (active or passive) assigned to the term by Priestley, Boyle, and Descartes. Locke’s nominalism does not fall into Berkeleyan idealism.10 It has certain Burthoggean conceptualistic elements, but these are mostly confined to his treatment of substratum (as seen in Chapters 5 and 6). Locke’s mind-body nominalism should be seen as warning us against confusing what is nominal with what is real in any way. Locke’s mind-body nominalism and his contextual dualism with respect to primary and secondary qualities are not entirely separate doctrines. Indeed there are significant parallels between the two. According to contextual dualism, neither primary nor secondary qualities reveal the true nature of reality. Particularly with respect to the insensible particles, each category represents a different aspect of objects. ‘Primary’ qualities are those that are ascribed to objects when narrowly considered, while ‘secondary’ qualities are ascribed to them when widely considered. While both primary and secondary qualities are ascribed to material objects, there is yet another type of qualities ascribed to the mind, namely mental qualities. The ascription of mental qualities to the mind requires yet another way of considering the entities to which such qualities are ascribed: viz. one’s introspective observation of one’s internal states, such as one’s beliefs and desires as well as one’s interactions. This mode of consideration is radically different from those we adopt in relation to material bodies when ascribing primary and secondary qualities to them. Reference to mental states from the perspective of this third mode of consideration is contained in any mental descriptions governed by the principle of rationality. It is through this sort of description that one can form the conception of rational agency as realized in a physical/biological system. In this regard, Locke would have no objection to Priestley’s observation that ‘Mr. Locke did not apprehend that there was any real [ontological] inconsistency between the known properties of body, and those that have generally referred to mind’ (Disquisitions, 73). The idea of emergentism presumes that there is no metaphysical inconsistency or repugnance between them. As noted earlier, however, there is a difference between

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Locke and Priestley. While Priestley justifies the compatibility of mind and matter by appealing to the activity/dynamic nature of matter, Locke doesn’t. In Locke’s view, Priestley’s dispositional essentialism commits the common mistake of attempting to explain what the world really is by reference to one of its nominal features. Locke gives us a different reason for believing in the compatibility of the mind and matter. Priestley himself stated what this reason is: ‘Mr. Locke . . . ought to have concluded that this is really the case [i.e. that matter has the property of thought superadded to it]; since, according to the rules of philosophizing, we ought not to multiply causes without necessity, which in this case he does not pretend to’ (Disquisitions, 73). By ‘superadded’ here, Priestley means ‘emergent’. In Priestley’s view, Locke’s account of the compatibility of mental and material features is based on ‘the [Newtonian] rules of philosophizing [that] we ought not to multiply causes without necessity’ (Disquisitions, 73).11 Furthermore Priestley regards Locke as a forerunner of the dynamic conception of matter. Locke would agree with Priestley on the ‘rules of philosophizing’ underlying their shared commitment to naturalism, but not with his dispositional essentialism. Locke would instead say that his naturalism is justified by the rules alone, while treating even the Priestleyan activity of matter as one of its nominal features.

Notes 1. In light of this point, Yolton (1984, 30) refers to Anthony Collins as an exponent of emergentism, regarding Collins’ emergentism as one of the ‘three discernable strands in the development of materialism in Britain’, together with Locke’s account of the superadded power of thought and Priestley’s dynamic conception of matter: ‘Locke’s suggestion provided a strong impetus toward materialism, but it was not the only one. There are at least three discernable strands in the development of materialism in Britain: Locke’s suggestion of thinking matter; Collins’s insistence that organized masses of matter can have properties that none of the individual parts has; and the change in the scientific concept of matter, from passive corpuscles to active forces’. 2. In discussing the tension between the two conceptions of matter, passive and active, in the eighteenth century, Schofield (1970, 125) has used the term ‘dynamic corpuscularians’ to refer to those such as Priestley who regard power or force as being inherent to matter, while restricting the term ‘materialists’ to Cartesian dualists who hold that matter is entirely passive, dead, and inert. Schofield includes Locke and Spinoza among the ‘dynamic corpuscularians’. Priestley’s dynamic realism might be better labeled as a form of ‘dispositional essentialism’. As Blackburn (1990, 38) expresses it, dispositional essentialism is the view that there exist only dispositional properties ‘all the way down’. Basic particles are thus regarded as existing only in the form of dispositions and powers: they are identified and characterized in terms of their dispositions to interact with other particles. The term ‘dynamic corpuscularism’ is thus closer to what we now call ‘physicalism’, in that both presume that the physical world is causally closed and self-sufficient, whereas the dualists’ ‘material’ world isn’t. Dualists invoke nonphysical agents such as God and

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3. 4.

5.

6.

Locke and Dynamic Realism human minds in explaining the causes of physical motion. For them, powers are external to matter. For the dynamic realists, by contrast, powers are inherent in it. The dynamic realists of the eighteenth century include Baxter (1733), Knight (1748), Boscovich (1763), Priestley (1777), Nicholson (1782), Young (1788), and Hutton (1792, 1794). Heimann and McGuire (1971, 281) contend that ‘[w]ith James Hutton, the Lockean doctrine of power was developed in a somewhat similar way—from the philosophical point of view—as in Priestley’s Disquisitions’. Schofield (1970), McMullin (1978), and Yolton (1984) also explore the significance of the dynamic realists in relation to Locke. Yolton (1984, 65) remarks that ‘Locke’s suggestion [regarding the superadded power of thought] was rendered more plausible with a force concept of matter, than with a corpuscular concept’. McMullin (1978, 15) uses McGuire’s term ‘transduction’, which McGuire (1970, 3) employs to distinguish this kind of reasoning from induction. In relation to this point, Priestley refers to Malebranche as a proponent of the passivity of matter: ‘Malebranche refined upon this hypothesis [occasionalism], supposing that we perceive the ideas of things not only by the divine agency, but in the divine mind itself; all ideas being first in the divine mind, and there perceived by us’ (Disquisitions, 63). Priestley regards Berkeley’s idealism as a variety of occasionalism in which even occasional causes are eliminated for the reason that they are causally inefficacious and idle: ‘the divine Being himself presented the ideas of all things to our minds, and nothing material exists’ (Disquisitions, 65). Against the occasionalist account of causation in general, Priestley raises the question of how God, an immaterial being, can move material things by his willing alone: ‘how can the mere volition, which is the mere act of a spirit, affect it?’ (Disquisitions, 65). Berkeleyan idealism is actually free from this difficulty, since, on Berkeley’s view, God directly causes sensations in human minds without acting upon physical bodies. To Priestley’s eye, however, this is not a genuine solution to the problem. Priestley’s dynamic realism takes a different approach by identifying the causal powers of physical bodies with their essential features. For discussions of Priestley’s views on science and religion, see Hiebert (1980), McEvoy (1987), and Dybikowski (2008). Lowe (2005, 48) points out these two interpretations of the Lockean primary qualities as follows: ‘[a] closely related notion is that the primary qualities of a body are its intrinsic properties—those which it could in principle possess even in the absence of any other body. Another is that the primary qualities are those which a physical body possesses purely by virtue of being spatially extended [i.e. its categorical properties]’. An object’s intrinsic property can be dispositional, as is the case with Priestley. According to his dispositional essentialism, a real potency can exist even in the absence of other body—as being intrinsically dispositional. Other dynamic realists also professed some degree of epistemic humility. Young (1788) mentions Priestley’s influence in his acceptance of the dynamic view that solidity is the result of the power of resisting, and that ‘all which is real, positive, and peculiar to body, are certain active powers’ (1788, 20). What underlies the powers then? This becomes a key metaphysical question among the late eighteenth-century British dynamic realists. Regarding this issue, Nicholson (1782, vol. 1, 7) contends that ‘matter is known to us only by its properties . . . [so that] we are totally ignorant about of the substance in which those properties are united’. A more systematic account of the underlying substratum appears in Hutton (1794, 398), who claims that when power is exerted, there must be ‘a substance existing, in which that

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7.

8.

9.

10.

11.

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power should reside’. Hutton distinguishes between two levels of matter: matter in its physical aspect and matter in its metaphysical aspect. The first is matter as manifested by powers; the second is matter as the substance in which powers reside. Hutton calls the first ‘body’ and the second ‘matter’ (1794, 399), and takes this distinction as differentiating between the ‘physical and metaphysical ideas of matter’ (1794, 407)—namely, between matter as identified by its powers and matter as what underlies them. The dynamic realists thus maintained Locke’s epistemic humility along with his view that matter is (in a certain respect) active. Ayers (2011, 140) offers an explanation of why solidity is a ‘primary’ quality for Locke—perhaps the most primary among the primary qualities—even though our awareness of it depends on our sensation of it. The feeling of solidity is not merely a specific sensory effect that external objects have on our sense organs, but a sign of their presence: ‘feeling a body’s solidity is not like seeing its colour or feeling its warmth, since to feel its solidity (as, perhaps, also its shape) it is necessary to feel its resistance: that is, it is necessary to be sensorily aware of its bodily, mechanical interaction with ourselves’. Alexander’s (1977, 75) stance on this issue is similar to my reading: ‘[Locke] was interested in language and the relations between our descriptions of the world and what they describe. . . . Now primary qualities are such that the words we use in describing our ideas of them are also appropriate words for describing the qualities; secondary qualities are such that the words we use in describing our ideas of them will not do for describing the qualities’. Chapter 3 made the case that the nominal essence of electron is multiply realizable. According to Locke’s quidditism, many different quiddities could occupy the electron-role besides the one that actually occupies that role. Even if such radical changes at the level of the role-occupants were to occur, the two different types of quiddities would still both be considered as electrons inasmuch as they occupy the same role. According to Bolton (1976, 126), Locke’s account of primary and secondary qualities in the published versions of the Essay did not exist in its earlier drafts: ‘[m]any of the doctrines of the Essay can be found in the early drafts, but it is my contention that the doctrine of primary and secondary qualities is not among them. Its absence has not generally been noted’. Bolton’s claim is that Locke added this distinction to the final versions of the Essay to provide a solution to some philosophical difficulties that he faced in the early drafts of the Essay, where he treated a body as a bundle of powers without the doctrine of primary qualities. One undesirable consequence of this view of bodies is that since God is omnipotent and has the power to produce ideas of the sensible properties of gold, e.g., in the human mind, God would count as gold, and by parallel reasoning as any kind of material body whatsoever. Locke’s introduction of primary qualities is thus intended to ensure that a thing is a body if and only if it has the primary qualities of solidity, shape, and size, and movability. Bolton also draws attention to the fact that in the published versions of the Essay, secondary qualities are considered not just as powers, but powers to produce ideas by means of the primary qualities. Bolton’s view is thus that Locke developed the account of primary and secondary qualities to provide necessary and sufficient conditions for being a body, which would enable him to avoid committing himself to Berkeleyan idealism or atheism. In the first section of the Disquisitions, titled ‘Of the Nature of essential Properties of Matter’, Priestley reminds the reader of the ‘rules of philosophizing’ laid down by Newton: ‘I am sorry to have occasion to begin

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Locke and Dynamic Realism these disquisitions on the nature of matter and spirit, with desiring my reader to recur to the universally received rules of philosophising, such as are laid down by Sir Isaac Newton at the beginning of his third book of Principia’ (Disquisitions, 1). These rules are: first, ‘we are to admit no more causes of things than are sufficient to explain appearances’; and second, ‘to the same effect we must, as far as possible, assign the same causes’ (Disquisitions, 2).

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Index

Aaron, Richard 2, 3, 41, 43 Alexander, Peter 2, 3, 44, 123, 126–7, 133n9 anomalous monism 8, 9, 34, 47–8, 50, 53, 56n8; see also Davidson, Donald Armstrong, David 77n4, 122 Atherton, Margaret 37–9, 55n1 atoms 6, 11, 15, 31n5, 37, 62, 74, 87, 90, 100–101, 116–18, 121–2, 128–30, 132n4, 134–8, 140; fitly disposed (or suitably organized) 82, 118, 128; in Locke’s sense 12n8; see also corpuscles; particles Ayers, Michael 12n9, 26, 55n2, 93–5, 97n9, 99, 102, 113n2, 119, 123, 133n9, 151n7 Barnes, Elizabeth 82, 89, 96n2 Baxter, Andrew 11, 150n2 Bennett, Jonathan 2, 4, 11n2, 12n6, 26, 73, 76, 106, 108, 111–12, 115n9, 122–3, 125 Bermúdez, José Luis 2–4, 11n2, 26 Bird, Alexander 64, 77n3, 77n4 body-problem 20–1, 32n9, 39 Bolton, Martha 32n11, 151n10 Boscovich, Roger Joseph 11, 150n2 Boyle, Robert 15, 136–48 Boylean notion of matter 11, 137 Boylean notion of primary qualities 136–40 Boylean notion of solidity 74, 137–9, 141 Buchdahl, Gerd 122 Burthogge, Richard 10, 95–113, 120–1, 148; see also conceptualism; idealism

Carroll, William 7, 8, 10, 12n10, 51, 95, 99, 104–13, 113n4, 113n7, 117, 130 categorical basis of power 138 categorical/dispositional distinction 138, 140–5, 150n5 categorical feature 141–5, 148, 150n5; see also disposition categorical monism 142; see also dispositional monism causal essentialism 64, 67–8, 77n3, 77n4, 78n9, 97n7; see also quidditism Chalmers, David 29 Collins, Anthony 149n1 conceptualism 35, 102; Burthogge’s 10, 148, 182; see also idealism Conn, Christopher 76 contextual dualism 141–2, 144, 148; see also categorical monism; dispositional monism continuity: biological 52, 128; of consciousness 46; psychological 52 corpuscles 6, 11, 31n5, 43, 47, 136–7, 146–7; active 136; passive 149n1; suitable organization of 43; system of, fitly disposed 43; see also atoms; particles Coste, Pierre 58, 73–6, 79n11 Davidson, Donald 8, 9, 34, 41, 46–8, 50–1, 53–5, 56n6, 56n7, 56n8; see also anomalous monism Descartes, René 1, 3, 8, 14–17, 24–5, 30n1, 41, 63, 81, 95n1, 97n8, 117, 132n2, 139, 148 disposition (or dispositional features) 6, 12n7, 64–5, 72, 74–5, 78n8, 125, 140–4, 149n2

Index dispositional essentialism 149, 149n2, 150n5 dispositional monism 141–2; see also categorical monism Downing, Lisa 11n3, 12n9, 95, 138 dualism: Cartesian 5, 21, 81, 84, 98n10, 106, 126; metaphysical 3, 4, 93, 117, 127, 130, 134; substance 1–4, 9, 14, 22, 25, 27, 34, 43–6, 80–1, 83, 93, 97n8, 106, 126, 129; see also nominal dualism; property dualism Dybikowski, James 135 dynamic corpuscularians 149n2 dynamic realism 130–1, 134, 136, 138–40, 146, 149n2, 150n4 emergentism 12n9, 80, 82–3, 90–3, 95, 98n10, 129, 134–5, 148, 149n1; and property dualism 92; and supervenience 96n3 epistemic humility 4, 6, 9, 10, 11n4, 13n11, 22, 30n3, 33n15, 37, 49–50, 54–5, 57–79, 95, 96n3, 97n9, 99, 106, 110, 115, 121, 123–4, 131, 139, 144–6, 150n6, 151n6; Langton’s Kantian 57–8, 70–3, 123–4; Lewis’ Ramseyan 8, 9, 57–8, 61, 64–6, 70; Locke’s derivative types of 59; Locke’s main type of 22; McGinn’s 10, 109; Priestley’s 145–6, 150n6 essence: internal 59–61; real 5, 6, 17, 18, 29, 34–9, 47, 50, 54, 57–62, 66–7, 77n2, 78n5, 86–7, 92, 109, 113n1, 115n10, 119, 121–2, 124, 128, 132n3, 132n4, 143–5; transattribute 108–9; see also nominal essence extension 3, 15, 18, 19, 25–6, 49, 51, 76, 106, 108–9, 123, 139, 146; as the consequence of solidity 18; see also idea of extension function 6, 12n7, 14, 16, 27, 57, 61–2, 76 functional account of solidity 19 functional characterization of a physical system 16, 49 functional role 9, 22, 30n3, 50, 54, 64, 73, 75, 85, 108, 110, 112, 119, 123, 131; see also role

163

Garber, Daniel 15 Gassendi, Pierre 14–16, 19, 30n1, 55n1 God: in Berkeleyan idealism 78n11, 79n11; in emergentism 89–91, 96n2; idea of 39; and immaterial substance 68–9, 80–1, 124–6; in naturalism 6, 10; Newtonian 73, 75–6, 78n10; in occasionalism 73, 150n4; in property dualism 83, 87, 92; in quidditism 67–73; see also substance, ‘three sorts’ of; superaddition God’s idea of the true nature of the world 109 God’s knowledge of the real essence of man 18, 128 hard problem of consciousness, the 29 Harré, Rom 39 Heil, John 142 Heimann, P.M. and McGuire, J.E. 150n2 Hobbes, Thomas 1, 14, 16 Hume, David 103, 142 Hutton, James 11, 150n2, 150n6, 151n6 idea: abstract 5, 18, 23–4, 35–7, 39, 40, 65, 121, 141, 146; complex 5, 19, 23, 32n10, 39, 44–5, 72, 104, 120, 144; obscure, of active power 62, 85, 145; ‘primary’ 5, 22, 24, 27, 40, 44, 51–2, 80, 100, 106, 112; as a sign 35, 37, 99, 100–101, 106; simple 23–4, 28, 31n5, 32n11, 39, 58, 104, 119, 120, 127–8, 131, 139; see also reflection; sensation idealism 5, 49, 54, 78n7, 101–3, 109, 113, 120, 148, 150n4, 151n10; Berkeley’s 49, 78n7, 78n11, 102, 148, 150n4, 151n10; Burthogge’s 102–4, 109, 113; and materialism 49 idea of body 24, 45, 48, 52, 101 idea of extension 19, 24, 26, 51, 76, 84 idea of immaterial spirit 32n10, 44–5 idea of matter 11n3, 12n9, 32n10, 45, 83–4, 86–9, 96n5 idea of solidity 18, 25, 30n4, 31n5, 33n12, 64, 75–6, 131, 146 idea of space 30n4, 33n12, 76

164

Index

ideas of mind and body 5, 9, 22–4, 27, 29, 33n15, 40, 42, 44–5, 48, 51–2, 80, 85, 100–101, 106, 111–12, 128, 131 ideas of primary qualities 146–7 identity: of each particle 118; of ordinary objects 117; personal 46, 52; separate identity conditions for masses of matter, men, and persons 52, 128–30; see also continuity immateriality of soul 1, 2, 7, 15, 19, 46, 48, 139 immaterial substance 3, 16, 45–6, 68–9, 80–4, 110, 126; bare 125–6; non-mental 69; sentient 126; thinking (or mental) 43, 69, 81 intrinsic nature 6, 9, 14, 16, 18, 27, 34, 54, 57–61, 64, 73, 77, 95, 108, 110–11, 119, 121, 123–5, 131 Jackson, Frank 27, 28, 32n9, 51 Jolley, Nicolas 2, 3, 13n11, 43, 46, 55n2, 91–2, 95 Kim, Jaegwon 19, 47–8, 60, 96n2 Knight, Gowin 11, 150n3 Langton, Rae 57–8, 69–73, 82–3, 123, 142 Leibniz, Gottfried Wilhelm 2, 16, 28, 73–4, 105 Lennon, Thomas 12n10, 16 Lewis, David 8, 9, 57, 61, 64–5, 70 Lowe, E.J. 112, 123, 132n1 Malebranche, Nicholas 150n4 Martin, C.B. 122, 142 materialism: agnostic 21; and idealism 49; non-reductive 33n14, 47; ontological 54; and physicalism 19; as a precariously grounded doctrine 4; purely ‘descriptive’ form of 54; reductive 31n7; see also physicalism matter: active conception of matter 11, 136; bare 43, 82; Berkeley’s term 49, 148; dynamic conception of 131, 134–5, 146, 148–9, 149n1; functionalist account of 73; mechanistic conception of 15; Newtonian conception of 73, 75, 86, 145; passive 134; system of, fitly disposed (or suitably organized) 9, 43, 53, 69, 80–2, 86,

91–2, 95, 128, 131, 134; thinking 43, 149n1; ‘vulgar’ notion of 4, 74, 86; see also atoms; corpuscles; extension; particles McCann, Edwin 97n7 McGinn, Colin 8, 10, 76–7, 79n14, 95, 99, 109–13, 115n10, 117, 128 McMullin, Ernan 137, 150n2 mechanical philosophy 14, 15 Milton, John 35, 37, 55n1 mind-body nominalism 4–6, 8–10, 11n3, 12n9, 24, 29, 30, 34, 38–9, 41, 48, 54–5, 99, 101–2, 104, 130–1, 148; see also nominalism mind-body nominal symmetry 11n3, 34, 53–4, 105–6 mind-body problem 1, 4, 8, 9, 10, 14, 15, 20, 29, 69, 79n14, 81, 99, 109–10, 112–13, 117 mode: in Descartes 25, 117; in Locke 116; in Spinoza 107–8 Montero, Barbara 20 multiple realizability (or realization) 57, 66–7, 72; see also role naturalism 6, 136, 149 Newton, Isaac 58, 73–6, 78n10, 78n11, 86, 93, 112, 145, 149, 151n11 Nicholson, William 11, 150n2, 150n6 nominal dualism 4, 5, 9, 12n9, 29, 44, 50, 54, 61, 81, 83, 86, 93, 95, 97n9 nominal essence 5–9, 11n3, 17–19, 26–7, 29, 30, 34, 36–40, 48, 50, 54, 55n1, 58–60, 64–7, 75, 78n5, 86, 89, 95, 103; see also essence nominalism 7, 34–8, 40; see also mind-body nominalism notion: in Burthogge 104, 120; in Locke 104, 119 Odegard, Douglas 2, 3 Papineau, David 20–1, 31n6, 32n9, 56n7 particles: active 136; bare 125–6; not yet suitably organized 125; system of, fitly disposed (or suitably arranged/organized) 6, 10, 109, 126, 128–9, 132, 134; unorganized 91; see also atoms; corpuscles; matter person 46, 52–3, 128–9

Index personal identity see identity physicalism 19, 20; causal argument for 21; and materialism 19; ontological doctrine of 19–22, 47; and property dualism 27–30; see also materialism power: and disposition 12n7; as a real potency 136, 140, 145; superadded 9, 10, 12n9, 28, 33n14, 47, 126, 139, 149n1; see also idea; superaddition Priestley, Joseph 11, 31n5, 93, 134– 49, 149n1, 149n2, 149n4, 149n5, 149n6, 149n11 principal attribute 24–5, 54, 98n10, 106, 119, 139 Pringle-Pattison, A.S. 122–3, 133n8 property: in the Cartesian sense 48; deep linking 112; intrinsic 30, 64, 78n6, 150n5; intrinsic/functional 6; ‘natural’ 10, 109–10; as roleoccupier 64; superadded 94 property dualism 2–5, 11n2, 14, 27, 29, 34, 46–7, 51, 71–2, 78n8, 82–3, 85–7, 91–3, 97, 124, 141; and emergentism 92 Pyle, Andrew 4, 29, 83, 85–7 qualities: primary 29, 31n5, 47, 59, 82, 92, 131, 136–43, 146–8, 150n5, 151n7, 151n8, 151n10; secondary 31n5, 59, 136, 138–43, 148, 151n8, 151n10; tertiary 139–40, 143 quidditism 57, 64–5, 67, 69, 72, 77n4, 78n9, 151n9; strong/weak 67, 69 quiddity 57, 63–5, 67–9, 76, 77n3; causally idle 69; multi-tasking 69 reflection 23–4, 41–4, 52, 62, 80, 84, 111, 119–30; simple ideas of 23–4, 39; see also sensation reflection and sensation: as two disparate modes of experience (or two principal viewpoints that we have on the world) 23, 42, 44, 52, 84, 111, 130 Reid, Thomas 4, 12n6, 49, 78–9n11, 101 repugnancy between thought and matter 17, 86, 96n5, 127, 134–5, 148

165

resemblance between primary qualities and ideas of them 31n5, 147 role: body- 73, 76; -change 68–9, 73; immateriality- 68–9, 76; materiality- 68–9, 76; mind- 90; of physicality 49; solidity- 19, 31n5, 64, 121; space- 76; spirit- 131; of substratum 118; unifying 119, 123, 131 Schofield, Robert 149n2, 150n2 scholastic Aristotelians 14, 35–6, 117 sensation 3, 17, 18, 23–5, 41–2, 44, 52, 62, 73, 80–1, 84, 111, 119, 126, 128, 130, 134, 139, 140, 146; simple ideas of 23–4, 28, 32n11, 39; see also reflection sensitive knowledge 32n11 Shoemaker, Sydney 77n3, 78n9 solidity: and extension 18; functionalist account of 19; perfect 75, 137–8, 141; in Priestley 135–6; and space 30n4, 33n12; see also Boylean notion of solidity; extension; idea of solidity; role space 15, 18, 30n4, 33n12, 58, 64, 73–7, 138 Spinoza, Benedictus de 1, 7, 14, 50–1, 56n6, 105–8, 111, 113n3, 113n4, 114n4, 114n5, 114n6, 114n8, 114n9, 123, 149n2 spirit: complex idea of an immaterial 32n10, 34, 39, 44–5; Locke’s term 43; non-human immaterial 116; ‘primary ideas’ of 52; qua spirit 132n2, 139; see also idea; substance, ‘three sorts’ of Stillingfleet, Edward 1–3, 7, 11, 16, 45–8, 59, 62–3, 66–9, 73, 94, 106–7, 113n4, 119, 124, 139 Strawson, Galen 21 Stuart, Matthew 2, 4, 11n2, 29, 55n2, 56n3, 83, 87, 91, 95, 139 substance: Descartes’ definition of 132n2; in the loose sense 116; ‘particular sorts’ of 116–19, 121–2, 127, 130–1, 132n1, 132n4; in the strict sense 116, 118; ‘three sorts’ of 116–18, 125, 132n1, 132n2 substantial form 14, 35–7, 47, 117, 136

166

Index

substratum 10, 11, 12n5, 18, 22, 44, 95, 116–31, 132n5, 132n6, 132n7, 132n9, 142–3, 148; bare (or naked) 26, 108, 122–6, 133n9; functionalist account of 4, 11, 116; higher-order 130; ‘obscure’ and ‘relative’ idea of 119; qua occupant of the unifying role 122; transattribute 108, 123; unknown yet natured 123 superaddition 10, 11n3, 12n9, 28, 83, 88–90, 93–5, 97n7, 97n8, 97n10, 123, 125–6; see also power, superadded

things in themselves 6, 9, 57–8, 70–1, 78, 120, 122, 124 Van Cleve, James 73, 77n1, 78n7 Wilson, Margaret 28–9, 46–7, 55n4, 56n4, 83, 93–5, 97n7, 139 Winkler, Kenneth 36, 55n1, 55n2, 59 Wolfson, Harry 106, 114n5 Woolhouse, Roger 12n6, 35, 40, 79n11 Yolton, John 2, 3, 149n1, 150n2 Young, Robert 11, 150n2, 150n6