Scientific Ontology: Integrating Naturalized Metaphysics and Voluntarist Epistemology [1 ed.] 9780190651466, 0190651466, 9780190651480, 0190651482, 0190651458, 9780190651459

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SCIENTIFIC ONTOLOGY

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OXFORD STUDIES IN PHILOSOPHY OF SCIENCE

General Editor: Paul Humphreys, University of Virginia Advisory Board Anouk Barberousse (European Editor) Robert W. Batterman Jeremy Butterfield Peter Galison Philip Kitcher Margaret Morrison James Woodward The Book of Evidence Peter Achinstein Science, Truth, and Democracy Philip Kitcher Inconsistency, Asymmetery, and Non-​Locality: A Philosophical Investigation of Classical Electrodynamics Mathias Frisch The Devil in the Details: Asymptotic Reasoning in Explanation, Reduction, and Emergence Robert W. Batterman Science and Partial Truth: A Unitary Approach to Models and Scientific Reasoning Newton C. A. da Costa and Steven French Inventing Temperature: Measurement and Scientific Progress Hasok Chang The Reign of Relativity: Philosophy in Physics 1915–​1925 Thomas Ryckman

Making Things Happen: A Theory of Causal Explanation James Woodward Mathematics and Scientific Representation Christopher Pincock Simulation and Similarity: Using Models to Understand the World Michael Weisberg Systemacity: The Nature of Science Paul Hoyningen-​Huene Causation and its Basis in Fundamental Phyiscs Douglas Kutach Reconstructing Reality: Models, Mathematics, and Simulations Margaret Morrison Understanding Scientific Understanding Henk de Regt Scientific Ontology Anjan Chakravartty

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SCIENTIFIC ONTOLOGY Integrating Naturalized Metaphysics and Voluntarist Epistemology

Anjan Chakravartty

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1 Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide. Oxford is a registered trade mark of Oxford University Press in the UK and certain other countries. Published in the United States of America by Oxford University Press 198 Madison Avenue, New York, NY 10016, United States of America. © Anjan Chakravartty 2017 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, by license, or under terms agreed with the appropriate reproduction rights organization. Inquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above. You must not circulate this work in any other form and you must impose this same condition on any acquirer. Library of Congress Cataloging-in-Publication Data Names: Chakravartty, Anjan, author. Title: Scientific ontology : integrating naturalized metaphysics and voluntarist epistemology / by Anjan Chakravartty. Description: Oxford, UK : New York, NY : Oxford University Press, [2017] Identifiers: LCCN 2017001545 | ISBN 9780190651459 (hardcover : alk. paper) Subjects: LCSH: Ontology. | Science—Philosophy. Classification: LCC Q175.32.O58 C43 2017 | DDC 501—dc23 LC record available at https://lccn.loc.gov/2017001545 1 3 5 7 9 8 6 4 2 Printed by Sheridan Books, Inc., United States of America

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The history of philosophy is to a great extent that of a certain clash of human temperaments. … Of whatever temperament a professional philosopher is, he tries when philosophizing to sink the fact of his temperament. Temperament is no conventionally recognized reason, so he urges impersonal reasons only for his conclusions. Yet his temperament really gives him a stronger bias than any of his more strictly objective premises. It loads the evidence for him one way or the other, making for a more sentimental or a more hard-​hearted view of the universe, just as this fact or that principle would. He trusts his temperament. Wanting a universe that suits it, he believes in any representation of the universe that does suit it. —​William James One may, of course, independently of one’s logic of discovery, believe that the external world exists, that there are natural laws and even that the scientific game produces propositions ever nearer to Truth; but there is nothing rational about these metaphysical beliefs; they are mere animal beliefs. —​Imre Lakatos (on Popper’s Logik der Forschung) A scholar’s heart is a dark well in which are buried many aborted emotions which rise to the surface as arguments. —​Natalie Clifford Barney The situation appears fairly desperate, but is it serious? —​Peter Lipton

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CONTENTS

Preface 

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PART I

NAT U R A L I Z ED META P H Y S IC S 1. Ontology: scientific and meta-​scientific  1.1 Scientific and philosophical conceptions of ontology  1.2 Deflationary ontology: historicism; sociology; pragmatics  1.3 Ontological limits: empiricism; scientific realism; metaphysics  1.4 Do case studies of science settle ontological disputes?  1.5 Examples of the robustness of ontology under cases 

3 3 8 14 20 24

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2. Science and metaphysics, then and now  2.1 Ontology and the nature of metaphysical inference  2.2 Is modern science inherently metaphysical?  2.3 Epistemic stances regarding scientific ontology  2.4 Metaphysical inferences: lowercase ‘m’ versus capital ‘M’ 2.5 The (possible) autonomy of (some) metaphysics from science 

33 33 38 45 51 59

3. Naturalism and the grounding metaphor  65 3.1 In hopes of a demarcation of scientific ontology  65 3.2 On conflating the a priori with that which is prior  71 3.3 How not to naturalize metaphysical inferences  76 3.4 Unpacking the metaphors: “grounding” and “distance”  83 3.5 On the distinction between theorizing and speculating  88 PART II

IL L USTR ATI ON S A N D  M O R A L S 4. Dispositions: science as a basis for scientific ontology  99 4.1 How dispositions manifest in the philosophy of science  99 4.2 Explanatory power I: unifying aspects of scientific realism  104 4.3 Explanatory power II: giving scientific explanations  112 viii

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4.4 Explanatory power III: consolidating scientific knowledge  4.5 Property identity and the actual power of explanatory power  5. Structures: science as a constraint on scientific ontology  5.1 Thinking about ontology in the domain of fundamental physics  5.2 Situating an ontological inquiry into subatomic “particles”  5.3 Structuralist interpretations of the metaphysics of particles  5.4 Reasoning about ontological bedrock: an unavoidable dilemma  5.5 Dissolving the dilemma: the variability of belief and suspension 

121 127 132 132 137 141 148 158

PART III

VOL U N TA R I S T EP I S TEMO L O G Y 6. Knowledge under ontological uncertainty  6.1 Inconsistent ontologies and incompatible beliefs  6.2 Belief and ontological pluralism: perspectival knowledge?  6.3 A trilemma for perspectivism: irrelevant; unstable; incoherent  6.4 Two kinds of context-​transcendent pluralism about ontology  6.5 Ontological explanation and contrastive what-​questions  ix

167 167 171 178 188 194

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7. The nature and provenance of epistemic stances  7.1 An indefeasible persistence of ontological disagreement  7.2 Stances revisited: deflationary; empiricist; metaphysical  7.3 A voluntarist primer on choosing stances and beliefs  7.4 Epistemic stances in conflict: rationality and robustness  7.5 In defense of permissive norms of rationality for stances  8. Coda: ontoloy with lessons from Pyrrho and Sextus  8.1 Getting to the bottom of it all, while awake  8.2 Skeptical arguments: some Modes of Agrippa  8.3 A Pyrrhonian analogy: isostheneia and aphasia  8.4 Extending the analogy a bit further: ataraxia  8.5 A transformative epistemology of scientific ontology  Bibliography  Index 

201 201 205 214 223 229 235 235 237 241 244 247 253 265

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PREFACE

Ontology is a branch of philosophy that is concerned with questions of existence. What things exist? What categories or types of things are there? What are the natures of these things and categories? To many, these questions will naturally sound like very philosophical questions. On reflection, though, it seems clear that fields other than philosophy, such as the sciences, are also concerned with questions of existence. Perhaps, one might think, these other fields are interested in such questions in different sorts of ways. After all, and for example, if ever there were forms of human inquiry into the nature of the world that occupy different ends of a spectrum, many would likely see science and philosophy as plausible candidates. Scientists wear lab coats and specialized field gear, perform observations and experiments using highly sophisticated pieces of technology, and model and analyze their data and phenomena of interest with incredibly powerful computational devices. Philosophers wear loose-​fitting garments (togas or the modern-​day equivalent), spend their time in dimly lit caves (libraries, offices), and think as hard as they can, the depth of their thoughts inevitably constrained by the size of their impressive yet nonetheless, it must be said, puny brains.

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The picture I  have just sketched of some distinctions between philosophy and science is, I believe, correct. It is also very misleading, for it suggests that philosophical and scientific explorations of questions of existence are entirely separate projects. It suggests that they have entirely separate methods and subject matters. It is fair to say that in relatively recent times, many philosophers and scientists have held (and continue to hold) the view that what we have here are two rather separate domains of ontology. This view, however, is deeply problematic in at least two ways, or so this book will contend. First, it is ill-​judged in one direction: philosophical investigations of ontology that are wholly disconnected from scientific investigations ignore arguably the best possible starting point for ontological theorizing, namely, a vast array of empirical explorations of the nature of the world. Second, the view is not merely ill-​judged but also straightforwardly incorrect in the other direction: the sciences have always incorporated philosophical thinking, both in terms of methodology and in terms of how their subject matters are conceived. In this book, I aim to consider the deeply interwoven nature of science and philosophy and, indeed, just how crucial these connections are if we are to have anything resembling a scientific ontology. As a primer, it may be helpful to see how issues surrounding the nature of ontology in science and philosophy arise almost immediately for anyone who is interested in the nature of scientific knowledge. Much of my own previous work has focused on questions regarding what kinds of knowledge scientific theories and models provide, as contested by scientific realists and antirealists (in one formulation, very roughly and respectively:  those who do and do not take our best theories and models to yield approximately true descriptions of the world). In defending their views, scientific realists often invoke pivotal concepts including specific notions of properties, causation, and structural relations in connection with things like laws of nature and scientific taxonomy. Scientific antirealists xii

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sometimes invoke rival conceptions of these things in articulating their own views. Different takes on precisely these sorts of things are the subjects of ongoing debates in metaphysics—​the subdiscipline of philosophy to which ontology belongs. Once one begins to probe these issues, however, questions inevitably arise about how much of this probing is required in order to give a clear picture of scientific knowledge, for one can almost always pose yet further questions about the concepts one invokes. I have not myself been able to resist the temptation to (attempt to) illuminate some of the metaphysical concepts underpinning different accounts of scientific knowledge, and in past work I have argued for particular views in certain metaphysical debates favoring specific conceptions of various bits of ontology. In the process I have come to see in greater detail and much more clearly, I think, that in order to understand debates about these underlying metaphysical concepts, we must have better insight into a number of epistemic commitments that lie deeper still. These commitments concern our assessments of how far empirical results can be plausibly extended so as to give us knowledge, not only of some of the first-​order content of science—​ the observable and unobservable objects, events, processes, and properties that are putative objects of detection, experimentation, and postulation for explanatory purposes by scientists—​but also regarding deeper ontological theorizing. The result is this book, in which understanding the nature of scientific ontology as an exercise in both science and metaphysics is simultaneously an understanding of the epistemic commitments that license scientific ontologies. At issue is the reasonable scope and limits of human knowledge based on the evidence of the sciences. In some of these prior pursuits I have had much company. Recent years have witnessed an explosion of work dedicated to metaphysical studies of the contents of science, now commonly and collectively labeled ‘the metaphysics of science.’ The ambition of much of this xiii

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work is to spell out what its practitioners regard as the ontological implications of our best science. The idea is to take scientific work as a starting point for metaphysical inquiry, resulting in accounts of things that are not the first-​order or explicit subject matters of scientific theories and models per se, but rather things that are mentioned en passant in our attempts to describe the knowledge that these outputs of science contain, such as causation, laws, and modality (necessity, contingency, and possibility). In the whirlwind of this surge of interest, however, I believe that a number of confusions have entered the mix. One of these confusions concerns what it could mean to say that ontological theorizing that reaches beyond what happens in the lab or in the field (for example, regarding the natures of things described in fundamental physics, or the causal status of certain parameters in evolutionary biology) is “grounded” in empirical science. Another involves conflations of what is entailed by scientific description and what is, in fact, merely compatible with such description. In what follows, I will have these issues squarely in my sights. Part I of the book, ‘Naturalized Metaphysics,’ examines the relationship between the modern sciences and metaphysics in order to clarify what it is to engage in the project of scientific ontology. In chapter 1, I introduce the most prominent conceptions of ontology to emerge in the history of the philosophy of science, including views that aim to “deflate” the ontological project and, conversely, those that take it at face value as an inquiry yielding knowledge, in some form or other, of a world that exists independently of the thoughts of human inquirers concerning it. Next I turn to the widespread view that while a number of philosophical concerns were part and parcel of the progenitors of the modern sciences, the latter have moved beyond such philosophical trappings. Chapter 2 considers the ways in which this picture is true and, perhaps surprisingly, the ways in which it is false, arguing that whatever one’s take on scientific ontology, at least some forms of what I will call ‘metaphysical inference’ xiv

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are inevitable, thus making philosophical presuppositions an inextricable part of the interpretation of the outputs of science. I go on to describe these inferences as admitting of greater and lesser degrees and, in chapter 3, aim to put some meat on the bones of this characterization by spelling out a number of metaphors concerning what it could mean to “naturalize” metaphysical inferences by “grounding” them in scientific knowledge. In Part II, ‘Illustrations and Morals,’ I delve into some details of two case studies in the metaphysics of science, with the goal of demonstrating how the conclusions of Part I are exemplified in practice. Chapter 4 considers one of the most active areas of recent research in this sphere: the appeal to a specific kind of property—​dispositional properties—​in interpretations of scientific theories, models, and practice. While this serves as a case study of the use of scientific knowledge and practice as a basis for ontological theorizing, a second and related use of scientific knowledge, as an intended constraint on ontological theorizing, is considered in chapter 5. Here I investigate a highly influential research program over the past two decades whose objective is to unpack the nature of ontology relating to fundamental physics in terms of various conceptions of the idea of ‘structure.’ With these cases, I hope to illustrate how explanatory considerations are brought to bear on assessments of the plausibility of ontological proposals. In the process, I contend that the acceptance of different assessments is very much in the eye of the beholder and irreducibly so. This suggests, I believe, a tempting fusion of realism and pragmatism regarding the nature of scientific ontology. One of the recurring, underlying themes of Parts I and II is that ontological commitment is something that varies across those holding different philosophical presuppositions regarding its defensible scope and limits. In fact, I suggest in a number of places that judgments concerning the precise determination of the limits of scientific ontology do not merely vary, but vary in ways that indicate that at xv

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least some such differences are irresolvable, for different assessments may be rationally permissible. In Part III of the book, ‘Voluntarist Epistemology,’ I bring these claims to the surface for a more thorough examination. The epistemic implications of ontological uncertainty in the sciences are considered in chapter 6, where I investigate some responses to this uncertainty including the notion of perspectivism and (what I will call) a contrastive theory of ontological explanation. Chapter 7 explores in greater depth a key analytical tool introduced earlier to explain how different epistemic agents come to different assessments of metaphysical inferences—​the idea of epistemic stances—​by scrutinizing the idea of voluntary choice in connection with stances and ontological belief, as well as a permissive conception of the rationality of stances. In chapter 8, the final chapter of the book, the resulting picture of how different agents believe and suspend belief with respect to ontological questions is presented as a transformative epistemology of scientific ontology. The contents just described represent my efforts to extrapolate and link a number of ideas that have been in the background of my thinking for some time. Some of these ideas have also been in the foreground of some recent work, and I would like to thank the following publishers for their permission to develop and extend some aspects of material originally appearing under their auspices: Brill for ‘Suspension of Belief and Epistemologies of Science’ in the International Journal for the Study of Skepticism 5: 168–192 (2015); Elsevier B. V. for ‘Perspectivism, Inconsistent Models, and Contrastive Explanation’ in Studies in History and Philosophy of Science 41: 405-​412 (2010); Oxford University Press for ‘Six Degrees of Speculation: Metaphysics in Empirical Contexts’ in B. Monton (ed.) Images of Empiricism (2007), and ‘On the Prospects of Naturalized Metaphysics’ in D. Ross, J. Ladyman, & H. Kincaid (eds.) Scientific Metaphysics (2013); Palgrave Macmillan for ‘Metaphysics Between the Sciences and Philosophies of Science’ in P. D. Magnus & J. Busch xvi

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(eds.) New Waves in Philosophy of Science (2010); Routledge for ‘Dispositions for Scientific Realism’ in R. Groff & J. Greco (eds.) Powers and Capacities in Philosophy (2013); and Springer Science & Business Media for ‘A Puzzle about Voluntarism about Rational Epistemic Stances’ in Synthese 178: 37–​48 (2011), and ‘Particles, Causation, and the Metaphysics of Structure’ in Synthese DOI 10.1007/​s11229-​015-​0913-​z (2015). Many people have greatly assisted me with comments in conversation or writing on different aspects of this material over the past few years. I would especially like to thank Robert Audi, Richard Bett, Paul Blaschko, Otávio Bueno, Philip Catton, David Chalmers, Paul Dicken, Michael Esfeld, Arthur Fine, Curtis Forbes, Axel Gelfert, Ron Giere, Michael Glanzberg, Richard Grandy, John Greco, Ruth Groff, Ian Kidd, Martin Kusch, Kerry McKenzie, Mary Morgan, John Norton, Huw Price, Matthew Ratcliffe, Gurpreet Rattan, Alan Richardson, Darrell Rowbottom, Alex Rueger, Matthew Slater, Mark Sprevak, Kyle Stanford, Paul Teller, and Johanna Wolff. Nevin Climenhaga, Xavi Lanao Camara, and Sebastián Murgueitio Ramirez were kind enough to read the manuscript cover to cover, resulting in many extremely helpful suggestions. For the sort of support and inspiration in various ways that one can only be implausibly lucky to receive, I am grateful to Steven French, Paul Humphreys, Margie Morrison, Stathis Psillos, and Bas van Fraassen. Finally, none of this would have been possible without Aleksandra, who has helped in ways too many to enumerate and it would be foolish of me to try. Let me say one last thing to those who are reading this and still wondering whether to take the plunge into the world of scientific ontology. Though my hope is that this book will be of interest to professional philosophers and graduate students, I have made a sincere attempt to write it in a way that will be accessible to undergraduate students with a little bit of exposure to some metaphysics and epistemology, say, from an introductory course in philosophy, or for that xvii

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matter to anyone with an interest in philosophy who is willing to look up the odd word in the dictionary. In our time, given the pivotal roles played by forms of scientific knowledge in our many cultures, there is a case to be made that understanding the nature of scientific knowledge is paramount, and perhaps it is not too much to hope that everyone should have at least some understanding of the nature of scientific ontology. Those who are already seasoned philosophers of science will recognize examples drawn from across the sciences (mostly the natural sciences, with some exceptions), as one would expect of a work in general philosophy of science. Let me invite these aficionados to consider the framework for thinking about scientific ontology presented here in relation to their own more specific work in the philosophy of particular scientific subdisciplines, theories, and models. Throughout this book I  have used single quotation marks to indicate quotations, or the mention of a term as opposed to its use. Double quotation marks indicate the figurative or metaphorical use of a term. The occasional use of hyperbole and irony is unmarked. Enjoy! A.C. Notre Dame August 2016

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NATURALIZED METAPHYSICS

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Ontology Scientific and meta-​s cientific

1.1 SCIENTIFIC AND PHILOSOPHICAL CONCEPTIONS OF ONTOLOGY As any good dictionary will confirm, ontology is the study of what there is: what things, and what kinds of things, exist, and what those things and kinds of things are like. This everyday definition of ‘ontology’ is accurate so far as it goes, but it does have an unfortunate tendency to conflate what most people would regard as numerous and rather distinct areas of ontological concern. After all, ontology is part of metaphysics, itself a branch of philosophy, but characterized simply in terms of an investigation into things and kinds of things and their natures, it hardly seems like a field of study that is rightly the private domain of philosophers. Grocery store shoppers are surely interested in what sorts of things there are in those grocery store aisles and, if they are concerned at all about their health, what those things are like. Florists, art critics, pest control workers, and collectors of antique furniture all have their own objects, events, and systems of classification. Most important for present purposes, the sciences are often viewed as our best hopes for determining the ontology of the natural world and at least some aspects of the social world in which

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we live. Thus one might well ask: what is it that philosophers interested in ontology are doing, if not simply more of the same? The answer commonly given to the question of what is distinctive about philosophical ontology, on the basis of which one might then refrain from conflating it with other ontological projects, is (it seems to me) a bit glib. Many of the most excellent dictionaries suggest that in philosophy, ontology concerns more general or fundamental questions of existence than those that preoccupy exterminators and cereal purchasers. That is to say, they are interested in ontological questions at a certain “level” of generality or fundamentality. Historians may be interested in particular events, such as the moon landing of 1969, but philosophers are interested in the more general or fundamental question of what an event is, precisely. A carpenter may be interested in the roughness of a piece of sandpaper, but philosophers are interested in the more general or fundamental question of what properties like roughness are, exactly. Similarly, scientists are concerned with specific properties of things, kinds of things, laws of nature, causes, and so on, but as a philosophical endeavor, philosophical ontology concerns more general or fundamental things than these subjects of scientific interest. One might then distinguish scientific ontology from philosophical ontology in terms of some conception of the relative generality or fundamentality of their respective subject matters. If only it were that simple! It is certainly an interesting question—​ and a highly contentious one, in contemporary philosophy—​ whether there can be anything like a viable, purely philosophical study of ontology that is neatly separable, by means of some notion of generality or fundamentality or otherwise, from scientific investigations into what things exist and what they are like.1 I will not take a strong stand on that debate here, but will be absorbed instead by 1.  For a recent defense of the independence of metaphysics generally, see Paul 2012. Some contrary views will crop up in the discussion to follow in chapters 2 and 3.

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the converse question: is there such a thing as a viable, purely scientific conception of ontology that is neatly separable from philosophy? One of the themes of this book is the idea that in order to talk about scientific ontology at all, one inevitably views the outputs of scientific work through a philosophical lens, whether self-​consciously or, as is often the case (especially among those who have never studied philosophy), inadvertently. This idea may strike some as disconcerting, but it will come as no surprise to students of the history of science, since what we call the sciences and their historical predecessors have always been interpreted by their practitioners and others in ways that reflect, implicitly, substantive philosophical commitments. Such commitments have a direct bearing on what every person, scientist or philosopher, understands scientific ontology to be and what it can achieve. Why might one think that the sciences cannot deliver the goods of scientific ontology all by themselves? After all, one might think it quite easy: simply read the ontology of science straightforwardly from our descriptions of scientific theories and models, taking these claims at face value, as it were, as descriptions of scientific ontology. Therein lies a rub, for as it happens, there is often no such thing as a straightforward reading of scientific claims. One cannot always simply read ontology off of descriptions of theories and models, because they do not always wear their ontological interpretations on their sleeves. There is often significant underdetermination of ontology by the sciences, which is to say that theories and models are often compatible with contrary readings of the ontologies one may describe with them, and they do not themselves indicate which of these readings, if any, is “correct.” For example, naively, one might interpret every substantive term used in describing a theory as referring to something—​that is, some part of the ontology of the world as described by science—​and likewise interpret every parameter of a model. But this will not do, for we know that not all such terms and parameters are intended to be 5

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understood in this way. Theories and models incorporate fictitious forces, idealizations which no one takes to have counterparts in reality, merely calculational devices, and so on. Fair enough, one might say, but if scientists were simply to agree about which bits of theories and models should be taken seriously from an ontological point of view, could we not overcome the underdetermination of ontology by science? Perhaps we could, but as it happens, scientists do not always agree with respect to ontology, even when they are engaged in the very same scientific practices, theorizing, and experimentation. This by itself should be sufficient to show that all by themselves, scientific practices, theorizing, and experimentation do not have the right sorts of resources to settle all questions of scientific ontology. Consider, for instance, the so-​called Standard Model of modern physics, which describes a taxonomy of particles composing matter at the subatomic level. Ex hypothesi, these are particles with properties that make them very unlike the everyday sorts of things that most people would describe as particles, but even thus understood, many physicists hold that a particle ontology is not really the right way to think about subatomic ontology, and that the nature of subatomic stuff should be interpreted in a rather different way. Historically, scientists have often differed regarding their ontological commitments, with some, for example, extending belief to putative objects, events, processes, and properties at the cutting edge of research, while others are more cautious, remaining noncommittal regarding ontological claims there and even with respect to more established scientific work. It is because the actual practice of science is so forgiving as to allow coordinated action among scientists despite their possible differences regarding ontological commitment that I  say that science itself underdetermines scientific ontology, and it is because of this that I would describe scientific ontology as inherently meta-​ scientific. That is, it involves criteria for ontological commitment 6

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that are not themselves constitutive, or essentially constitutive, of the relevant scientific practice, theorizing, or experimentation. Though such criteria are adopted by scientists and philosophers alike in giving accounts of scientific ontology, they are, in a sense, extra-​ scientific; they reflect philosophical commitments that may vary even among those engaged in one and the same program of scientific research. Throughout the course of this book I will contend that these differences in ontological commitment are a function of differences in the sorts of epistemic commitments that different scientists (and philosophers) are willing to make. If this contention is correct, it would seem to follow, pace some philosophers who would prefer to separate them, that scientific ontology is inextricably interwoven with epistemology, nolens volens. This refrain, on the role of epistemic considerations in the production of scientific ontologies, will be the soundtrack to everything that follows. As I  intimated earlier by noting that background philosophical commitments may be explicit or implicit, it is clear that at least some scientists on the explicit side of the ledger are sufficiently philosophically self-​aware and sophisticated as to know what philosophical commitments they bring to bear in their interpretations of scientific work and have articulated these commitments. This is the reason, of course, that so many of the greatest philosophers of science to populate the history of philosophy have been scientists, or practitioners of the various forms of investigation that predate and gave rise to what we now call the sciences. It is surely part of the job of philosophers of science who have an interest in scientific ontology to shed whatever light we can on the ways in which science and philosophy interact so as to produce scientific ontologies. That, ultimately, is the aim of this book. In elaborating the nature of scientific ontology, I will of necessity leave a number of topics that might reasonably fall under this heading untouched. For example, I  will not engage here with the fascinating 7

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question of whether ontologies at “higher levels” of description are in some sense reducible to those at “lower levels” (whether psychological ontologies are reducible to biological ones, which are themselves reducible to chemical and physical ones, etc.), or whether ontologies at different “levels” are in some sense or senses independent of one another. Rather than focus on very specific subtopics such as this, it is my intention instead to explore the nature of ontological commitment in the context of the sciences more generally, so that we may better understand the principles that govern it, and the integration of metaphysics and epistemology that it inevitably entails. In the rest of this chapter, I will sketch the most prominent of the traditional philosophical approaches in terms of which one might understand what the sciences are telling us about what exists and what those things are like, en route to an overview of the even more (I suspect) provocative theses regarding scientific ontology that I will champion in the chapters to come.

1.2 DEFLATIONARY ONTOLOGY: HISTORICISM; SOCIOLOGY; PRAGMATICS In the recent history of philosophy of science, conceptions of ontology have varied significantly in ways that reflect their formative influences in a number of prominent philosophical schools or traditions. In this section, I  will briefly review some influential approaches which, though differing greatly in their details, have one important thing in common: they are all, in senses to be specified, deflationary about the very idea of scientific ontology. Deflationism is, of course, a technical term in philosophy. It connotes, if not the outright dismissal of a philosophical concept or project, a specific understanding of it that recasts it in terms of something else. A deflationary theory of truth, for example, holds that truth is not a substantive feature of 8

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propositions or beliefs that explains why they are true; talk about truth does not add anything substantive to the everyday phenomena of certain propositions being asserted and certain things being believed. Similarly, a deflationary view of ontology is one that recasts the study of what things and kinds of things exist, and what they are like, in terms of something else. Most deflationists in this domain are willing to grant that there is nothing wrong with talk of scientific ontology per se, so long as this is understood in an appropriate way. Let us consider these views—​historicist, sociological, and pragmatic approaches to scientific ontology—​in turn. The 1960s were a time of significant upheaval in the philosophy of science, marked by what many now refer to as a “historical turn.” Fueled by work associated with authors including Norwood Russell Hanson, Thomas Kuhn, and Paul Feyerabend, the idea that attention to the details and history of scientific practice is crucial to any philosophical examination of it gained impressive currency. Thus was born the dream of history and philosophy of science as a unified discipline, which was then reified institutionally with the advent of a number of dedicated departments and programs at universities internationally. In particular, Kuhn’s The Structure of Scientific Revolutions played a telling role in crystallizing a form of historicism about scientific knowledge which has deflationary implications for scientific ontology. Though Kuhn was certainly not alone in championing this kind of view, let me single him out here as a prominent exemplar for the purpose of illustration. Kuhn described the history of the sciences in terms of a cyclical pattern of development: periods of so-​called normal science punctuated by scientific revolutions, the latter overturning the established order and thereby laying foundations for new periods of the former. Classical physics in the wake of Isaac Newton, for example, spanned an era of normal science that was ultimately supplanted by the normal science of our own era, dominated by the relativistic spacetime 9

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physics of Einstein and quantum theory concerning the smallest bits of matter and energy. Central for Kuhn was the idea that scientific concepts, including those pertaining to ontology, are learned in groups in specific historical contexts, typified by interconnected elements definitive of any given period of normal science—​the relevant “paradigm,” which also includes symbolic representations, metaphysical commitments, values, and problem-​solving techniques. This is a version of what is sometimes called meaning holism, or the contextual theory of meaning: the very meanings of scientific terms come with strictly defined boundaries determined by contexts of normal science. In Kuhn’s lingo, the paradigms of any two periods of normal science in a given domain are “incommensurable” with one another (from the Greek geometrical concept of having ‘no common measure’) and, indeed, engender a profound discontinuity which he referred to as “world change.”2 The upshot of this story is that scientific practice and knowledge generally, and whatever one may regard as scientific ontology more specifically, are largely a function of a historical context and the paradigm that infuses it. Talk of scientific ontology is, on this view, predominantly a function of and elliptical for certain connections between the elements of a specific paradigm. In describing scientific knowledge, Kuhn does not speak of the existence of particular objects, events, processes, or properties so much as the specific account of these things that appears to feature in a given context of science governed by a specified paradigmatic framework. When one period of normal science gives way to another, the meanings of whatever scientific terms survive are invariably altered. The term ‘mass’ as used

2.  Among the great number of studies of these topics, a useful handful includes Horwich 1993, Hoyningen-​Huene 1993, Sankey 1994, and Bird 2000. For a later statement and clarification of Kuhn’s thoughts on the failure of meaning-​preserving translations from the lexicon of one paradigm to another, see Kuhn 1983.

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in classical physics, for instance, means something importantly different than the term ‘mass’ as used in relativistic physics. Any talk of the ontology of mass must be unpacked in historical terms and has no sense otherwise. In this way, such talk simply dissolves into historical contexts of use, and it is for this reason that I refer to this kind of historicism as a deflationary view of ontology. It dissolves or recasts the notion of scientific ontology into sets of historically contingent relations between ideas about the world. One impact of the historical turn in the philosophy of science was a more widespread attention to the social environments within which the sciences are imbedded—​an issue that Kuhn gestured toward, for example, in discussing the nature of theory choice and the entrenchment of new paradigms after scientific revolutions. This gesture proved the thin edge of the wedge for a number of scholars interested in studying the sciences from a sociological perspective and exploring various, often allied theses according to which scientific knowledge is, in a non-​trivial sense or senses, socially constructed. Many in this area have suggested that once one appreciates the ways in which social factors (including economic, political, institutional, and other such factors) dramatically shape the inputs, the exercise, and the outputs of scientific practice, from the ways in which work is funded and conducted, to the training of researchers, to complex relations of collaboration and competition and risk and reward, one is inevitably driven to the view that such factors directly influence and in some ways determine what ends up counting as a scientific fact. The implication here is that different social factors could and may well have produced not merely different but contrary scientific facts.3 In emphasizing the power of social construction, much of this work suggests a deflationary attitude toward scientific ontology. That 3.  A  sampling of formative approaches to the sociology of science can be found in Knorr-​ Cetina 1981, Pickering 1984, Shapin & Schaffer 1985, Latour & Woolgar 1986, Collins & Pinch 1993, and Barnes, Bloor & Henry 1996.

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is to say, it recasts the project of scientific ontology in terms of social relations between scientists, institutions, and other people and things whose interactions generate what we recognize as the outputs of scientific work. It is not unusual here to find assertions to the effect that claims regarding scientific ontology, reflecting the nature of scientific knowledge more generally, are ‘social institutions’: claims whose meanings are principally constituted by and thus partially or wholly reducible to the social acceptance of their use. On this conception, the meanings of scientific terms and concepts are strictly relative to particular communities and have no community-​transcendent purchase. Echoing the Kuhnian idea that scientific concepts are learned in and defined by contexts of use, the idea here is to extend this thinking in such a way as to incorporate the full gamut of social factors including education, training, and more general acculturation within scientific and larger communities. This suggests that talk of scientific ontology is, in fact, an alternative way of describing the status of the relevant social processes. In this way, the former is dissolved into the latter, and scientific ontology is recast in terms of sets of social relations. The third and last account of deflationism that I will mention here comes as a recommendation to adopt a pragmatic attitude toward scientific ontology. It would be misleading to suggest that this kind of recommendation is the province of any one specific tradition or school of philosophy, for the idea that scientific ontology might be recast in pragmatic terms has a number of different sources that differ significantly in their philosophical commitments more broadly. To cite one famous example, Rudolph Carnap (1950) is often heralded as the chief proponent of a variant of logical empiricism (the dominant movement in twentieth-​century philosophy of science prior to the historical turn) according to which ontological questions as traditionally conceived are “external” questions—​external, that is, to the linguistic framework that one employs in scientific practice and in discussing the content of scientific knowledge. On this sort of view, to which one might be 12

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drawn quite independently of any commitment to logical empiricism, the notion of a scientific fact is itself meaningful only “internal” to the relevant linguistic framework of science. As a consequence, properly conceived, the idea of scientific ontology concerns merely the choice of language one employs so as to pose internal questions about scientific practice and knowledge. This choice of language can only be made on the basis of pragmatic considerations regarding (for example) how, most conveniently, to systematize scientific claims, as opposed to “factual” considerations of what exists. This form of deflationism resonates nicely with some who think of ontological disputes as ‘merely verbal’ disputes, namely, disagreements about what terms or languages to use, as opposed to disagreements about what things and kinds of things there are and what these things are like, as conceived in a non-​deflationary manner. For instance, some argue that the existential quantifier (the logical term for ‘there is,’ symbolized by ‘∃’) has different meanings in different contexts, depending on what one thinks about the domains of putative things to which it is applied (e.g., see Hirsch 2002). This ‘quantifier variance’ provides a handy explication of how one might happily discuss scientific ontology, but in a deflationary manner, for in this case one’s use of terms like ‘exist’ in the apparently ontological claim ‘DNA exists’ may simply be understood as a reflection of one’s pragmatic choice of a convenient language with which to talk about certain biological phenomena. Using the term ‘DNA’ might be especially simple and unificatory of a lot of things one wants to say in this domain, and thus one might consider it a good pragmatic choice. Someone else, however, may prefer a different use of the term or a different terminology altogether. This dissolution of questions of scientific ontology into questions regarding what forms of language optimize pragmatic benefits for the practice and discussion of science is a beautiful example of deflationism at work. 13

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Another exemplifier of pragmatic attitudes toward scientific ontology is, unsurprisingly, Pragmatism, which is a label for a number of closely connected views in nineteenth-​and twentieth-​century philosophy, incorporating a reaction to what its proponents see as unproductive approaches to metaphysics and epistemology. This reaction is reflected in classic pragmatist accounts of notions like meaning and truth. One influential criterion of meaning here, suggested by C. S. Peirce (1992, in ‘How to Make Our Ideas Clear,’ originally published in 1878), associates the content of a proposition with its ‘practical consequences,’ understood in terms of human experience: as having implications for actual or possible empirical observations, scientific predictions, and heuristic uses in problem solving, where claims are conceived as a basis for action. William James (1979/​1907) parlayed some of this into a theory of truth, according to which utility of the sort indicated by helpful practical consequences is a marker of truth (itself sometimes conceived as that which will be agreed in the ideal limit of scientific inquiry). Meaning and truth thus conceived are intended to exhaust one’s conception of reality; the very notion of scientific ontology is thus recast in terms of pragmatic concepts such as utility. Talk of what things exist, what kinds of things exist, and what they are like is simply elliptical for whatever descriptions optimize positive utility. In this way, scientific ontology, conceived as a project in and of itself, is dissolved.

1.3 ONTOLOGICAL LIMITS: EMPIRICISM; SCIENTIFIC REALISM; METAPHYSICS Of course, not everyone is deflationary about scientific ontology. It is possible to take the project of interpreting what the sciences are telling us about what exists at face value, literally as per the dictionary definition of ‘ontology,’ as opposed to viewing it as something 14

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that is ultimately elliptical for something else. Many philosophers do just this. Though aspects of deflationism, such as the notion of pragmatism, will come up again in what follows, from this point onward I will generally discuss the idea of scientific ontology in a face-​value sort of way. Given this intention it is worth noting here at the outset, for those who are skeptical of the earnest idiom I will adopt, that it is always possible to employ the sorts of paraphrases suggested by the deflationary views just considered to illuminate what one is “really” up to in scientific ontology, if one is that way inclined. Everything I say henceforth will be amenable to being read in such a way with a little determination and an appropriate translation into the relevant deflationary view. With this irenic thought in mind, let us now turn our attention to the main issues to be examined in the rest of this book. I will motivate and outline these issues now in the context of disputes between those who, for the most part, think of scientific ontology in a face-​value way. The central question that will frame everything to come is this:  what ontologies are described by our best scientific theories? There is a short answer to this question—​it depends on whom you ask—​but that all by itself would make for a very short book. I want to unpack this answer, first by noting that differences in the ways that people answer the question follow immediately from the sorts of beliefs they think our best scientific theories license. Those who are stingier when it comes to the range of beliefs (about things, kinds of things, and what they are like) they take to be warranted by the sciences will answer my central question above in parsimonious ways. Those who are more extravagant about belief in this context will answer in more bounteous ways. This is, in part, the reason I  suggested earlier that questions of scientific ontology are inextricably linked with questions of epistemology, namely, concerning warranted belief. The question of what scientific ontology amounts to thus admits of different answers, and this state of affairs follows 15

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immediately from my earlier suggestion that answers to such questions are a function of prior philosophical commitments that one brings to a consideration of the sciences. It is fair here to wonder whether ‘belief ’ is a univocal notion, and getting clearer on this is essential to understanding how epistemology bears on scientific ontology. Consider a spectrum of strengths of commitment that one might associate with a scientific proposition regarding the existence of an object, a property, or what have you in just the way that some epistemologists speak of “degrees of belief.” At one end of the spectrum there is cast-​iron belief, beliefs about which one is extremely confident. From here one can imagine attenuations in one’s confidence, and at a certain point one will find oneself entertaining claims for which one’s confidence is sufficiently low that one simply cannot assent. At this point, one would not expect a person to admit the relevant thing or things into her reading of scientific ontology; that is, we would not expect her to include such things among those in which she thinks it reasonable to believe given the evidence. At a certain point, one’s confidence or degrees of belief may be so low that one wonders whether the inquiry that produces such claims is worthwhile at all. This is one diagnosis of the view that in some domains, ontological claims are simply meaningless. This is a view that is sometimes held, for example, by philosophers who despair of analytic metaphysics as an academic discipline.4 The idea that one’s view of the epistemic reach of the sciences is intimately connected to one’s view of scientific ontology immediately suggests the idea of ontological limits. One’s view of what

4.  I will return to this issue in chapter 3. Some certainly appear to claim that the subject matter of metaphysics is literally meaningless (i.e., nonsense), but I do not see how this claim can be defended except as a hyperbolic assertion regarding matters not worth theorizing about, given an assessment of the potential epistemic gain. I suspect that finding metaphysics literally meaningless is likely indicative of a lack of effort given to understanding it. And of course, failing to understand a proposition does not, by itself, render it meaningless.

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knowledge the sciences are capable of producing surely and strongly influences one’s judgment of what limitations there may be on the ontologies that science can reveal. It is important to note here that talk of ‘knowledge’ in the philosophy of science typically admits of a caveat that is not often expressed in the field of epistemology as pursued elsewhere. In analytic epistemology it is commonly assumed that in order for something like a statement, a belief, or a proposition to qualify as knowledge, it must be true. In the context of scientific ontology, however, knowledge is typically a more forgiving concept, allowing for reasonably good approximations of truth to count. A scientific claim regarding the existence of something like a molecule of DNA may be true simpliciter, but a characterization of its properties may be incomplete and not entirely correct in every detail and yet be judged to be likely close enough to the truth to constitute knowledge. Granted, this notion of “approximate truth” is a difficult one to spell out (several have tried; see Niiniluoto 1998 for a summary), but I will proceed here with the arguably intuitive thought that some descriptions of scientific ontology may be close enough to the truth to count as knowledge even if not perfectly correct in every detail. The idea of different conceptions of the limits of scientific ontology is probably best illustrated with a quick look at some famous examples taken from the history of the philosophy of science. Consider, for instance, the family of views comprising forms of ‘instrumentalism,’ all of which have in common the thought that scientific theories and models should be understood merely as instruments, whose function is simply to facilitate predictions of observable phenomena and systematizations of observation reports, where ‘observable’ things are those that can be detected using one’s unaided senses (e.g., water, turtles, swamps), such as vision. Traditionally, instrumentalists hold that scientific descriptions of unobservable things (e.g., subatomic particles, endoplasmic reticula, dark energy) are meaningless, strictly speaking. They are tools, and in just the way 17

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that it would be peculiar to contemplate the meaning of a hammer that one uses to build a house, it would be rather missing the point to contemplate the meaning of descriptions of unobservables. Thus incorporating an epistemological point of view according to which the only knowledge expressible using scientific theories and models is that concerning observable things, instrumentalism goes hand in hand with a limited conception of scientific ontology: one according to which the ontological insight derivable from science is confined to the realm of the observable. Many instrumentalists are motivated, epistemologically, by an attachment to a particularly strong form of empiricism, which is itself traditionally characterized as the view that not only is experience (conceived, again, in terms of the operation of our unaided senses) the only source of our knowledge of the world, but that the resulting knowledge is knowledge of our experiences only, or perhaps, at best (according to some), the objects of such experience. In chapter 2 and more broadly in Part III, I will consider in some detail a non-​ traditional version of this strongly empiricist sentiment, but the moral for our purposes will remain the same: committing to an epistemological point of view on which knowledge is limited to facts about (experiences of) observable objects, events, processes, and properties thereby limits the remit of scientific ontology to those kinds of facts. One widely discussed form of empiricism in this context is what Bas van Fraassen calls ‘constructive empiricism,’ which advocates an epistemic conception of science in terms of “empirical adequacy”: ‘a theory is empirically adequate exactly if what it says about the observable things and events in the world, is true’ (1980, p. 12; a more technical definition appears on p. 64). While this is not a form of instrumentalism traditionally conceived, because constructive empiricists may regard scientific descriptions of unobservables as meaningful even while not believing them, it nonetheless shares a perspective with instrumentalism regarding the limits of scientific ontology. 18

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Unsurprisingly, the most expansive conceptions of scientific ontology are associated with the most liberal conceptions of what sorts of knowledge the sciences deliver. These most liberal conceptions are collectively known as forms of ‘scientific realism,’ almost all of which share the view that our best scientific theories yield knowledge of both observable and unobservable features of the world. There are many versions of scientific realism, and though we will encounter some of the most influential of them in the final sections of this chapter, it will not be my intention here to consider the broader notion comprehensively (for a detailed survey, see Chakravartty 2011). For present purposes, the point is simply to note that in extending its assessment of the epistemic potency of the sciences further, to unobservable objects, events, processes, and properties, scientific realists are open to conceptions of scientific ontology that go well beyond the conceptions of those who oppose realism in a number of ways, thereby subscribing to one of the many positions that fall under the blanket heading of ‘scientific antirealism.’ Realists in this domain entertain the tenability of, and accept, far more expansive ontologies than their antirealist interlocutors. Even within the scientific realist camp, however, there are dramatic differences regarding just how much ontology is defensible, and these differences concern one of the central themes of what is to follow: differing attitudes toward the fruitfulness of what I will call metaphysical inferences. I will consider the nature of metaphysics and its relationship to the sciences in chapters 2 and 3, but for now, let it suffice to recall that ontology is a branch of metaphysics. Thus, in theory, any inference concerning what exists, what kinds of things exist, and what they are like, is a metaphysical inference. In practice, however, it is not uncommon to find that the way in which the term ‘metaphysical’ is used varies significantly as a function of how far removed the subject matter is from what a given user readily accepts as commonplace realities. For example, some empiricists consider beliefs 19

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about scientific unobservables, like leptons or genes, to be metaphysical, but scientific realists generally do not, quite independently of whether they accept the inferences in question. Realists typically reserve the term ‘metaphysical’ for subjects that go beyond what they take to be the primary foci of scientific investigation, including topics that are mentioned in scientific discourse but only en passant, like the nature of scientific laws, or properties, or modality (necessity, contingency, and possibility). As we will see, there are many differences to be found among realists concerning precisely how much ontology is appropriate in interpreting the outputs of science.

1.4 DO CASE STUDIES OF SCIENCE SETTLE ONTOLOGICAL DISPUTES? As it happens, some philosophers think that at least some differences in opinion concerning the proper scope of scientific ontology can be resolved in something like an empirical manner. Taking inspiration from the historical turn in the philosophy of science, one of whose immediate consequences was a groundswell of enthusiasm for the idea that history and philosophy of science should be regarded as two sides of a unified project, a number of scientific realist and antirealist philosophers have turned to case studies of science, drawn from both the historical record and the present, as potential arbiters of the reasonable scope of scientific ontology. In the rest of this chapter I will examine the promise of this approach, ultimately concluding that, while case studies are useful, important, and in some ways indispensable, they cannot arbitrate regarding how best to think about the remit of scientific ontology in the way that many appear to think they do. This will open the door to a rather different approach to understanding the defensible scope of scientific ontology, which will occupy us for the rest of the book. 20

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The debate about case studies in this setting follows from a prior debate surrounding an influential argument against scientific realism, commonly known as the ‘pessimistic induction’ (or the pessimistic meta-​induction). Consider the history of the sciences, full of past theories that were once widely accepted but then eventually replaced as newer theories were developed and surpassed their predecessors. The track record of the history of science, so the argument goes, is one of discontinuity over time. As history reveals, updating theories has entailed repeated changes in our descriptions of all manner of things, but perhaps most impressively, repeated and often radical changes to our descriptions of the unobservable objects, events, processes, and properties that scientific realists are wont to endorse. From the perspective of any given moment, most past theories are regarded as mistaken, and thus by induction, surely it is likely that our best theories today will be regarded as mistaken at some future time. The general worry here can be expressed more precisely in a number of ways, one of which is in terms of recurrent discontinuity in accounts of scientific ontology over time.5 On this basis, some contend that case studies from the history of science make plain the silliness of thinking about scientific ontology as realists do. In the following, I will use the term ‘case study’ in a completely ahistorical way to refer to studies of both past and present science, for the latter are no less relevant to thinking about questions regarding the promise of scientific ontology. Indeed, since presumably any potential for success in the project of scientific ontology is closely tied to the quality of scientific theories, and since it seems uncontroversial to assume that our best theories are likely the ones that

5.  Laudan 1981 is the source of much of this literature, though a related challenge is clearly implicit in Kuhn 1970/​1962. Stanford 2006 adds an important twist to these sorts of historically motivated contentions.

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we have presently (as the present rumbles on into the future), the outputs of current science are always the obvious starting point. Nevertheless, as we have seen, the threat posed by the pessimistic induction to the wisdom of engaging in the project of scientific ontology at all turns on a consideration of what it makes sense to say about theory change over time, leading up to the present. It is for this reason that so much of the energy given to discussing this argument, expended by philosophers and historians of science alike, is historical in nature. Given that the challenge here stems from historical cases and, consequently, that responses must delve into cases from the past leading up to the present, is it not obvious that case studies are important to thinking about scientific ontology? Surely they are, not least because until some such work has been done, it is often extremely difficult to appreciate just what the relevant theory is supposed to be in the first place. Commonly, emanating from a complex whirl of scientific practice, conducted by different people in different places over significant periods of time, there is simply a mess of stuff: mathematical formalisms; partially overlapping models; journal articles; archived documents and preprints; conference presentations and proceedings; press conferences; textbooks; and many claims, not all of which may be entirely consistent with one another. It is part of the function of the case study to tell us what the theory is.6 In order to demarcate the relevant descriptions of the natural world that may then serve as a starting point for engaging with questions of scientific ontology, much work needs to be done. Clearly, this work is a necessary condition for considering scientific ontology, because it furnishes the very claims whose ontological interpretation one may then discuss. There can be no debate here without cases. They are essential. 6.  For a similar view citing articles, textbooks, and scientific practice in particular, see Burian 1977, p. 29: ‘ “Actual scientific theories” are not givens …’

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The question I want to explore here is not whether case studies are important or crucial, since they are, but rather whether they are also telling for debates about scientific ontology, in the sense that they can establish or rule out the plausibility of certain approaches, such as scientific antirealism or realism, on the basis of arguments like ones for or against the pessimistic induction. Can the study of cases shed some telling light on how these disputes should be resolved? Some philosophers appear to think so, but I believe that they are mistaken. As a first step toward understanding why, let us begin by noting that much has happened in the several decades since discussions of the pessimistic induction came to the fore initially. It is fair to say that, in large measure (if not entirely) in response to this argument, views such as scientific realism and antirealism have evolved. In particular, many of the most popular and compelling versions of scientific realism these days are selective. While the pessimistic induction was originally taken to condemn scientific theories in a coarse-​grained sort of way—​‘past theories are generally regarded as false’; ‘their central terms often do not refer to anything in the world’—​versions of selective realism contend that even false theories, many of which employ terms that do not refer to anything, may still incorporate finer-​grained truths and referring terms, which may then serve as the basis of continuities across theory change, thus sparing realist blushes. The notion that our best science offers correct descriptions of the world despite (no doubt) getting other things wrong, and the idea that one may identify those aspects of scientific theories and models that are correct, thereby plausibly expecting them to be preserved in subsequent theorizing and modeling as the sciences continue to develop, have fueled much of the evolution of versions of scientific realism in recent decades. It is the opposition to such maneuvering as a strategy for resisting the force of the pessimistic induction that has fueled a great deal of scientific antirealist work to the effect that selective realist approaches are unsuccessful. As one might expect, 23

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these debates are often premised on case studies of scientific theories and theory change, in which realist and antirealist morals are drawn, respectively. It is strongly suggested on both sides that a careful look at the precise details of representative cases can establish the tenability or untenability and perhaps even the correctness or incorrectness of positions like scientific realism. In the next and last section of this chapter, I will briefly consider three of the most influential versions of contemporary selective realism and contend that attempts to employ case studies to good effect notwithstanding, there is significant reason to be suspicious of the idea that this kind of evidence can be telling in the ways their proponents suggest.

1.5 EXAMPLES OF THE ROBUSTNESS OF ONTOLOGY UNDER CASES The first account of selective realism that I will examine, arguments about which are heavily invested in case studies, is what I  will call explanationism. As an exemplification of realist selectivity, explanationism attaches epistemic warrant to those parts of our best scientific theories that are, in a sense to be clarified by its advocates, indispensable or otherwise centrally important to explaining why these theories are empirically successful, to the extent that they are. The term ‘empirical success’ is commonly cashed out here in terms of successful predictions, or even better still, novel predictions (i.e., regarding phenomena that we have yet to investigate) that become successful as they are borne out in subsequent observation and experiment. The explanationist recommends realism about those aspects of theories, including unobservable aspects, that are essential to deriving these predictions. If it were possible both to identify such aspects and to demonstrate that they have been preserved across theory change, or are likely to be preserved in future, the explanationist would seem 24

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to have an answer to the pessimistic induction. It is in this spirit, for example, that Philip Kitcher (1993, pp. 140–​149) distinguishes between what he calls ‘presuppositional posits’ or ‘idle parts’ of theories on the one hand, and ‘working posits’ on the other, the latter being apt for realism. For purposes of illustration, let us consider a specific example of arguments for and against the explanationist strategy. In a detailed study, Stathis Psillos (1994) argues that a classic case of a successful scientific theory whose central theoretical term turned out not to refer to anything—​the late eighteenth-​, early nineteenth-​century theory of caloric—​can be viewed in a way that is compatible with scientific realism. Caloric was posited as a substance, a fluid of fine particles, to account for phenomena such as heating and cooling, changes of state, and the flow of heat toward equilibria; hotter bodies were postulated to contain more caloric than cooler ones, and changes in amounts of heat were explained in terms of its absorption and release. Ultimately, the caloric theory was supplanted by the kinetic theory of heat, which accounts for these phenomena in terms of the motions of the atoms and molecules composing things, not a separate substance of heat. Psillos aims to show that by doing some historical work, one can demonstrate various explanationist claims regarding the caloric theory, namely:  that the scientists involved in developing the theory ( Joseph Black, Pierre-​Simon Laplace, Antoine Lavoisier, etc.) were not themselves strongly committed to the existence of caloric; that derivations of the key empirical successes of the theory do not depend on such a commitment; and that the properties, mechanisms, and processes on which these derivations do depend are in fact preserved in the later theory of thermodynamics. As Psillos himself puts it (p. 162): ‘I  am … interested in the attitude that scientists had towards their theories and the commitments they were willing to undertake, as evidenced in what they explicitly stated in their writings, as well as in the principles and hypotheses they 25

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used in their demonstrations.’ Later he adds (p. 183) that ‘careful historical studies can reveal which theoretical assumptions and beliefs were used in the derivation of the laws and in theoretical generalizations’ that were empirically successfully. The case study itself comprises a historical narrative that weaves together information about what the relevant scientists did and said in their writings and in public pronouncements regarding the nature of heat, all of which points to the idea that they were, at a minimum, very cautious about committing to the existence of caloric and were perhaps even skeptical about it. Quite independently of what the historical actors themselves might have thought, there is a further suggestion to the effect that the relevant derivations are independent of any such commitment. Hooray then for scientific realism! But this, gentle reader, was not the last word. In later work examining the same case, Hasok Chang (2003) and Kyle Stanford (2003) are critical of Psillos’s handling of the evidence. As one would rightly guess, the technical and historical details are fascinating, but I  will forgo them here in hopes of expediting the moral I wish to draw. These later authors suggest, in effect, that the earlier case study warps the history of theorizing about caloric in such a way as to serve realist ends. They present counter-​narratives according to which it turns out that, much to the explanationist’s chagrin, most of the relevant scientists did, in fact, firmly believe in caloric as a distinct material substance, and that this belief was central to the relevant derivations and successful applications of the theory. Furthermore, they suggest that in at least some cases where scientists appeared to be circumspect about this commitment, it was for reasons that offer no encouragement to the realist, such as a tendency to give measured statements regarding scientific commitments in accord with the rhetorical norms of the day and particular contexts of exposition. Skepticism is suggested regarding even the possibility of divorcing a supposition of the existence of caloric from the relevant derivations in context. 26

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What is a neutral reader to make of this? Perhaps, on examining the details on both sides, one might lean in one direction or the other based on an assessment of the relative quality of the historical narratives. There are, after all, widely accepted historiographical standards that one might bring to bear in a comparative judgment: consulting an appropriate variety of sources; exercising good judgment about the quality and evidential force of those sources; optimizing narrative consistency with the evidence (sometimes in proportion to its quality); and so on. Herein lies the difficulty, however, for the mere existence of shared standards does not yield determinate answers regarding which side in the dispute about caloric is correct. Historiographical standards must be interpreted and applied, and their relative importance weighed when they sometimes pull in different directions, and it is here that even agreement on standards can easily dissolve into disagreement regarding which conclusions are best supported (cf. Kinzel 2016). Not all facts are created equal in the context of case studies. No doubt there are hypothetical facts for which the evidence is so clear-​cut and unequivocal that it would be silly to resist an obvious conclusion. Perhaps there is so much uncontroversial evidence for the fact that Lavoisier was born in Paris in 1743, for example, that only a conspiracy theorist would doubt it. But the case of caloric is not of that sort. What distinguishes the example of scientific realist and antirealist readings of theorizing about caloric on one side, and (presumably most) histories of birthdays of famous natural philosophers on the other, is that the former involve contentious philosophical theses, like scientific realism and antirealism, which raise significant questions about the ultimate efficacy of cases in deciding which side is correct. Often, these former cases exhibit more room for interpretation of the evidence, which may then bring prior philosophical commitments into play in interpretation. In recent times, David Hull (1993, p. 472) was among the first to consider the use of cases in “testing” 27

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philosophical views about science, noting that ‘History of science cannot be written from no perspective whatsoever.’ Hull believes that cases can confront philosophical views with recalcitrant evidence, but while this seems uncontroversial, it also leaves open the possibility of multiple interpretations. Joseph Pitt (2002) magnifies this concern: ‘even very good case studies do no philosophical work. … [A]‌t worst, they give the false impression that history is on our side, sort of the history and philosophy of science version of Manifest Destiny’ (p. 373); ‘there is no single fact of the matter of the past’ (p. 379). And while Richard Burian (2001, p. 400) believes that Pitt goes too far, he confesses that ‘Case studies cannot and should not be expected to yield universal … epistemologies.’7 Nothing in what I have said or adverted to here suggests that all case studies are equal in quality, or that they must be judged so, or that one cannot learn things from them; on the contrary.8 My concern here, however, is scientific ontology, and it seems doubtful that a definitive understanding of that can be settled by examining cases. What did Lavoisier really believe, in his heart of hearts, about the existence of caloric—​what were his degrees of belief? That is difficult to say. What was or is, in fact, strictly necessary in order to explain the empirical successes of the theory? That too is open to dispute. Psillos (1994, p.  162) comes clean:  ‘I do not deny that my use of historical evidence is not neutral—​what is?—​but rather seen in a 7. Laudan 1977, chapter 5, considered the evidential weight of cases even earlier, but with the different concern of testing accounts of scientific rationality (e.g., in theory choice) against the history of science, pointing (p.  157) to the phenomenon of ‘self-​ authentication’:  ‘the history we write will presuppose the very philosophy which the written history will allegedly test.’ For more comprehensive discussions of the daunting challenges facing the testing of philosophical theses with cases, see Schickore 2011 and Kinzel 2015, 2016. 8.  See Saatsi 2012 and Vickers 2013, for example, for thoughts on how better case studies might help to advance debates about scientific realism. I agree, with the caveat that advancing a debate is not the same thing as settling it. Advancement often takes the form of more refined views on all sides of a question.

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realist perspective.’ And in the context of scientific ontology, questions about the use and interpretation of case studies are merely the tip of the iceberg, for as I noted at the start of this chapter, it is not uncommon to find that scientists themselves disagree about how best to interpret the ontologies described by the theories and models they employ. None of this should come as a surprise, given the earlier observation that scientific practice is compatible with different ontological commitments, and that the philosophical presuppositions one brings to interpreting the outputs of the sciences, whether as a philosopher or a scientist, inevitably play a role in determining one’s account of scientific ontology. The notion that prior philosophical commitments, whether conscious or unconscious, are substantive factors in the interpretation of cases, is even more transparent in connection with other forms of selective realism. Consider, for example, the view known as entity realism, the contention that under certain conditions, where one appears to have sufficiently detailed causal knowledge of a putative unobservable entity such that one is able (ex hypothesi) to exploit this knowledge so as to manipulate it and intervene on other things in sufficiently impressive ways, belief in the entity is warranted, quite independently of whether other aspects of the theory describing the entity are correct.9 Entity realists are typically skeptical about other such aspects, thus affording a response to the pessimistic induction: while past theories may well be false, one might nonetheless reasonably expect a form of continuity across theory change under circumstances that warrant persisting ontological commitments to certain entities, which can then serve as the basis of a form of scientific realism. In this way, entity realists commit to ontologies of certain entities in spite of what may be regarded as radical changes, over time, in our best theoretical descriptions of them. 9.  Some early, canonical statements of this idea are found in Hacking 1982, 1983, Cartwright 1983, chapter 5, and Giere 1988, chapter 5.

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In order for this to amount to a response to the pessimistic induction, however, one must also hold a rather specific view about what it means to say that significantly different descriptions are properly associated with one and the same thing. That is, the strategy would seem to require that one hold some version of the causal theory of reference: the view that terms pick out things in the world in virtue of certain causal connections; the original user of a term employs it to dub or “baptize” an entity that she believes she has detected, and subsequent employment of the term is linked by a causal chain of use back to this original causal interaction (cf. Putnam 1985/​1975, ­chapter 12, Kripke 1980). A number of refinements of this view have been suggested, some of which incorporate elements of description in characterizing the way terms “hook onto” the world, but none are acceptable to those who think that more comprehensive descriptions are the basis of successful reference to scientific entities. After all, one might worry that only a fatally denuded conception of linguistic practice could allow that we have the same referent in mind today when using the term ‘electron’ as physicists did at the end of the nineteenth century, given that beliefs about electrons have gone through extraordinary transformations since then. The relative merits of causal and descriptive theories of reference are not decided by case studies of science, and adopting one view of reference or the other promotes very different interpretations of them. Perhaps the most dramatic illustration of the inefficacy of case studies in settling debates about scientific ontology comes from discussions of yet another form of selective realism known as structural realism. This view identifies certain structures or relations as the aspects of the world described by scientific theories to which realists can commit, as opposed to the unobservable entities that putatively stand in these relations. Ironically, the contemporary debate surrounding this position grew initially from John Worrall’s (1989)

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appeal to a case study which offered a prima facie demonstration of its plausibility, and many versions of the view (and the case) have appeared since. The case study concerns the transition in nineteenth-​ century theories of light from the wave optics of Augustin-​Jean Fresnel to the electromagnetic theory of James Clerk Maxwell. It quickly became clear, however, that the tenability of structural realism was not so much informed by the case as hostage to a number of logical, conceptual, and metaphysical challenges concerning the proper expression of structural knowledge, the definition and nature of the relevant structures, and the coherence of a number of the proposals for structuralism to emerge. The question of whether these challenges can be met in a convincing way seems remarkably insulated from the intricacies of the cases to which the view is intended to apply. The details are so much fun that rather than explore them here, I will make them the subject of my own case study, in chapter 5. In this chapter, I have argued that scientific ontology is underdetermined by the sciences and case studies thereof. As a consequence, debates about what if any ontologies are described by our best scientific theories are inherently meta-​scientific. In order to understand these debates, one must understand the criteria for ontological commitment that yield different scientific ontologies. These criteria are informed by philosophical commitments:  views concerning the epistemic reach of scientific investigation and the epistemic power of what I have called metaphysical inferences. Different conceptions of this reach and power yield different assessments of the proper limits of scientific ontology, and we have traversed a number of the most influential views of these limits, from the deflationary inclinations typical of historicist, sociological, and pragmatic approaches to ontology, to the non-​deflationary perspectives associated with certain forms of empiricism and scientific realism. In the next two chapters, I will attempt to elaborate these claims. First, in chapter 2, I will

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defend the no doubt controversial thesis that if the sciences are to afford any ontologies at all, we must employ metaphysical inferences of some kind or another. In chapter 3, I will begin the task of spelling out the result: a conception of naturalized metaphysics—​ontological theorizing informed by science. Let us begin.

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Science and Metaphysics, Then and Now

2.1 ONTOLOGY AND THE NATURE OF METAPHYSICAL INFERENCE In chapter 1, I  suggested that scientific ontology is meta-​scientific. This is to say that understanding what the sciences are telling us about what things and kinds of things exist, and what they are like, is a project that incorporates philosophical presuppositions and metaphysical inferences that go beyond the strict execution of scientific practice. This view may be thought to conflict, however, with what are often presented as two truisms about science. The first is the idea that whatever the natures of the earlier endeavors from which the modern sciences arose—​amalgams of empirical techniques of observation and experiment with generous helpings of philosophy, theology, and perhaps even superstition—​contemporary science includes none of these latter, non-​empirical ingredients. This is not incompatible, of course, with the view that scientific ontology involves philosophical presuppositions that are not essential to contemporary scientific practice, but some are tempted to slide from the idea that science is philosophy-​free to the idea that scientific ontology is (or should be) too. This slide is especially tempting for those who advocate the second putative truism: that there are some conceptions of scientific 33

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ontology that do not involve any philosophical presuppositions or, at the very least, none that are metaphysical. I believe that both of these supposed truisms are false and, in this chapter, I will explain why. Let me first take a moment to clarify the use of some terms, confusion about which might otherwise obscure what follows. The focus of this book is scientific ontology, but in speaking of how scientific ontologies are given, through interpretation, I have made reference to metaphysical inferences. What is the relationship between ontology and metaphysics? Some philosophers use the terms fairly interchangeably, because much of metaphysics focuses on straightforwardly ontological questions and much of the rest can also be described, with some strain or ingenuity, as exercises in ontology. The term ‘metaphysics’ originates from the classification of Aristotle’s works three centuries after his death by Andronicus of Rhodes (and others), who placed certain works just after his Physics. ‘Meta-​‘ (‘after’ in Greek) commonly carries connotations of underlying or lying behind or beyond something else and often, thereby, belonging to a higher order of thought. One of Aristotle’s main foci here, the study of being qua being, the most general nature of existence and the natures of things that exist, corresponds directly to what I am calling ontology. Another Aristotelian focus is theology and the study of first causes, the ultimate cause for him being God, the unmoved mover; this might be redescribed as a rather divine form of ontology. Other Aristotelian topics here, such as the study of the laws of logic, are more difficult to describe as ontological per se. Leaping from Aristotle through the intervening centuries to the present, one finds a jumble of subjects under the banner of metaphysics, some of which are more or less easily described as ontological—​ the natures of things like properties and substances, time and space, mental and physical and abstract entities, and laws of nature, as well as the natures of certain relations of things such as causation, constitution, identity, and fundamentality. Other topics, such as the nature 34

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of probability and modality (necessity, contingency, and possibility) overlap significantly with contemporary logic, and yet others, like the question of whether humans or other creatures have free will and if so what kind, are less straightforwardly ontological, though they are closely connected to a number of ontological issues. It turns out that what unifies these various projects associated with metaphysics, apart from their focus on or significant attachment to ontological issues, is more methodological than anything else. The unifying principle, central to ontological and other metaphysical concerns, is a commitment to the use of what I have called metaphysical inferences. So, what are metaphysical inferences? Reasoning in metaphysics from data to conclusions—​the process of making inferences—​has a significant a priori dimension. That is, it is reasoning that is fueled primarily by non-​empirical considerations, as opposed to empirical or a posteriori considerations, ones that are directly informed by or especially sensitive to observations and experiences. Commonly, the largely non-​empirical considerations involved in making metaphysical inferences are explanatory: thoughts about how best to optimize the sorts of features often associated with good explanations. Thus, a good metaphysical inference is generally conceived as one that yields a good (ideally, the best one can produce) explanation of the data, and the criteria most commonly cited in evaluating such goodness are the simplicity, internal consistency, and coherence with other knowledge of the relevant theory or hypothesis, as well as the scope of the phenomena that are unified by it. The a priori character of this reasoning is manifested in a number of ways, by emphasizing, for example, the analysis of one’s concepts, and by taking seriously one’s intuitions about how best to optimize the explanatory virtues mentioned above. Typically, the goal of a metaphysical inference is to provide an explanatory account of some observable phenomenon or phenomena in terms of some underlying, unobservable thing or things. 35

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As it happens, it is easier to characterize what a metaphysical inference is than to get philosophers to agree on whether specific examples count as metaphysical inferences. The reason for this is that several of the terms I have just used to describe these inferences are open to interpretation, and agreement regarding how best to interpret them is hard to come by. Consider the idea that what sets metaphysical, a priori, non-​empirical reasoning apart from non-​metaphysical, a posteriori, empirical reasoning is the extent to which the former is fueled by, informed by, or sensitive to observation and experience. In the strictest sense, observation and experience refer only to the employment of the unaided senses. Thus, on the strictest interpretation, any ontological claim that goes beyond what one observes or experiences is metaphysical. As I  intimated earlier, however, many philosophers have more liberal views about what it means to reason in a way that is ‘fueled by,’ ‘informed by,’ or ‘sensitive to’ observation. Scientific realists, for instance, generally do not think of inferences to the existence of strictly unobservable entities like bacteria or atoms as metaphysical—​or at least, not to the same degree as metaphysical inferences to the existence of things like abstract entities or possible worlds, as discussed in the metaphysics seminar. Talk of degrees is useful here, and I will return to it in section 4. In the meantime, let us turn now to the first of our tasks at hand. This, recall, is to examine the notion that the modern sciences are unlike the investigations into the natural world that preceded them regarding connections to philosophy in general, and metaphysics in particular. The seventeenth-​century ancestors of contemporary science, a collection of forms of inquiry often gathered under the heading of ‘natural philosophy,’ combined a number of what are now usually regarded as separate things:  empirical investigations in the form of observation and experimentation, frequently interwoven with theorizing and modeling; philosophy; and theology. Between then and now, the natures of each of these components of natural 36

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philosophy have evolved, and the modern sciences, philosophy, and theology have come to possess largely exclusive identities, not least professionally and vocationally. Looking back from the perspective of the present, though, it is often unclear how best to describe what came before. Historians of philosophy and historians of the sciences, in describing the early modern origins of their respective disciplines, are often concerned with exactly the same people and texts (cf. Lüthy 2000, pp. 164, 173–​174). Early modern physicists and chemists were referred to as ‘experimental philosophers.’ Galileo’s title was ‘court philosopher.’ Their microscopes and telescopes were considered philosophical instruments.1 Natural philosophy covered a lot of ground. While some of these endeavors were predominantly metaphysical, focusing on questions passed down through scholastic lineages connected to Aristotelian philosophy, others were more empirical and experimental, as in the cases of a great deal of work in optics, alchemy, metallurgy, medicine, and astronomy. Even in the latter cases, however, if one looks carefully, it is easy to discern the traces of the former. To take one example, it is widely held that during the seventeenth century, mechanistic explanations (those citing laws understood to govern the motions and collisions of bits of matter) rose to displace scholastic explanations in terms of final causes (in Aristotle, the natures, purposes, or goals of things in virtue of which they behave in characteristic ways). But Margaret Osler (1996) argues that this widespread story of the triumph of the mechanical philosophy over scholasticism is misleading. Final causes, she contends, were simply reinterpreted in the context of the mechanical philosophy as external to matter instead of immanent in it, in accordance with the design of the laws by the creator. Descartes may have rejected final causes because he did 1.  For examples of some iconic figures from the history of philosophy who made contributions to the sciences of their day, see Callender 2011, footnotes 1 and 11, pp. 51–​52.

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not believe that humans could presume to understand God’s intentions, but Gassendi, Boyle, and Newton all incorporated final causes into their work as constraints imposed by divine design (see also Ross 1998). If something like this version of the narrative is correct, what we have here is a story of metamorphosis as opposed to one of eradication. No doubt in some such cases the distinction is subtle, and one might be forgiven for thinking that a severe enough metamorphosis is tantamount to the eradication of something. Even so, one might well wonder whether something analogous to metamorphosis has taken place in the transformation of natural philosophy into modern science. Granted, striking differences abound. It would hardly be considered a proper part of physics today to consider the nature of divine providence or the soul as relevant to the study of atoms. Nobody doing cosmology or investigating the nature of spacetime these days is expected to engage with the question of whether God could have created the entire contents of the universe just as it is, but five meters to the left. All of this said, one might still wonder whether it is merely particular metaphysical concerns such as these that have been eradicated in the modern context, as opposed to metaphysical inference itself. In the next few sections I  will argue that, on reflection, it is clear that metaphysical inferences are still with us in the sciences, even if they look rather different today than they did in centuries past.

2.2 IS MODERN SCIENCE INHERENTLY METAPHYSICAL? There are two sides to the question of whether any sort of metaphysics is part and parcel of contemporary science. These sides are strongly opposed and the arguments in favor of each are, I  think, 38

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open to serious questioning. Regarding the anti-​metaphysics side, one may wonder whether the picture of science presented is so out of touch with what scientists actually appear to be doing (on the surface, at any rate) as to amount to an overzealous redescription by philosophers. On the pro-​metaphysics side, there is often significant vagueness or indeterminacy regarding whether the putative instances of metaphysical commitments in the sciences suggested are, in fact, metaphysical after all. Let us consider these opposing sides in turn. The most thoroughgoing denunciations of metaphysics in connection with the modern sciences have come from positions that I  earlier identified as forms of instrumentalism or strong forms of empiricism. Both camps have been known to contend that any exercise in scientific ontology that ostensibly produces knowledge of unobservable objects, events, processes, or properties, or that aims to do so, is metaphysical. Since both typically recommend against this aim let alone the putative production of knowledge of this sort, metaphysics in the scientific domain is strictly off limits. This general idea was shared by many philosophers who identified with logical empiricism, the highly influential “founding” movement of the philosophy of science during its emergence as a recognized subdiscipline of philosophy in the early twentieth century. Inspired in part by nineteenth-​century work in French sociology and the pronouncements of a number of natural philosophers, scientists, and social theorists, this ‘positivism’ represented science as a mode of engagement with the natural world that had superseded prior religious and metaphysical modes in virtue of its emphasis on experience in the form of observation and experimentation. As per the strong empiricist credo, in order to avoid lapsing into these prior and inferior modes of engagement, unaided sensory experience should delimit the appropriate range of scientific knowledge. As one might guess, there are many specific criticisms of specific versions of instrumentalist and strongly empiricist accounts 39

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of the sciences. Logical empiricism, for example, faced a barrage of criticism over its so-​called verifiability criterion of meaning, which many on both sides viewed as central to the position. According to this doctrine, unless there is an empirical procedure whereby a supposedly factual proposition can be verified or confirmed, it will sadly amount to metaphysics instead. Many argued that verifiability, as a criterion for what counts as meaningful, is itself a piece of metaphysics or essentially tied to certain metaphysical commitments (e.g., Alston 1954). This and other concerns are important, but I will not dwell on them here, in part because it is arguable that the strongly empiricist take on scientific knowledge is robust under critiques of idiosyncratic elements of any very particular formulation of it. If one were forced to give up on the verifiability criterion of meaning, for instance, that would not by itself entail that the empiricist approach more generally is fatally undermined, only that this particular conception of it is. Therefore, let me focus on a more general worry that appears relevant to instrumentalist and strongly empiricist approaches in any guise. Prima facie, given the large scope of what the advocates of these views would classify as metaphysical inferences, the sciences are littered with them, because most sciences appear to take a very strong interest in unobservable objects, events, processes, and properties that are hypothesized to underlie the phenomena that scientists observe. If one takes scientific discourse at face value, scientists apparently and routinely attempt to study things like particles and fields and genes and enzymes and market forces and levels of happiness in societies and all manner of other things that cannot be detected as such using the unaided senses. By ruling out inferences to the existence and natures of unobservables in the context of the sciences, instrumentalists and strong empiricists are driven to what might well seem a radical redescription of the apparent aims and results of scientific investigation. Now, to be fair, it may be claimed 40

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that it is the job of philosophy, inter alia, to reveal to us the ways things are quite independently of how they may appear on the surface, and I  am sympathetic to that reply here. The empiricist’s (and instrumentalist’s—​I will take this inclusion for granted in what follows) recasting of surface descriptions of scientific practice is potentially worrying, I will now suggest, not because it requires that one view the sciences in a way that seems surprising, but rather because of the extent of the surprise, the enormity of which, I think, has not yet been widely appreciated. Recall that even strongly empiricist approaches advocate a conception of scientific ontology: an ontology of observable objects, events, processes, and properties. Now recall my earlier contentions that any exercise in scientific ontology involves the application of philosophical commitments in interpreting the practice and outputs of scientific work, and that this process of interpretation involves making metaphysical inferences.2 If one accepts this contention, it follows that if the empiricist is nonetheless intent on refraining from metaphysics altogether in the context of the sciences, she must do so at the cost of any sort of investigation into scientific ontology at all. It is doubtful that many empiricists would be happy to pay this cost. Indeed, the cost is too dear for anyone who views the sciences as affording ontological knowledge, for it requires that one view science itself as a thoroughly non-​ontological activity—​not impossible, but surely startling. To take such a view would be to identify science itself with whatever zombies who behaved like actual scientists but lacked their aims and mindful engagement (since zombies have none) would do. One might well regard this as an implausibly severe conception of science. 2.  The idea that even empiricist ontologies are underwritten by metaphysical inferences is controversial and calls for more argument than I have given thus far. I will return to this idea in section 4 and, until then, ask the reader to consider this a promissory footnote.

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What about the opposing view, that the modern sciences incorporate metaphysics as a matter of course? Edwin Burtt (1959/​ 1925) documented the ways in which metaphysical concepts such as substance, essence, and form played central roles in the work of Copernicus and Kepler, but as the protagonists of his study (additionally: Galileo; Descartes; Hobbes; Boyle; Newton) suggest, these reflections on the metaphysical foundations of science are confined to the early modern period (see also Buchdahl 1969, Woolhouse 1988). R.  G. Collingwood (1998/​1940) gave a famous account of the nature of metaphysics in which he described several arguably metaphysical assumptions underlying physics from Newton’s mechanics to Einstein’s theories of relativity, which brings us up to the contemporary period. As mentioned in chapter 1, Thomas Kuhn (1970/​1962) held that metaphysical commitments, such as preferences for teleological or mechanistic explanations, are one of the main ingredients constituting the paradigms that govern most of science. The tangled nature of science and metaphysics is also a theme of some more recent work. Consider this representative assertion by Craig Callender (2011, p. 48): [W]‌hat we conventionally call science in ordinary affairs is inextricably infused with metaphysics from top (theory) to bottom (experiment). Metaphysics is deeply important to science. Laying bare the metaphysical assumptions of our best theories of the world is a crucial and important part of understanding the world.

Interestingly, all of these declarations concern the presence in modern science of metaphysical assumptions of one kind or another. This suggests metaphysical inferences that are implicit in or even prior to the relevant science, but presumably this does not preclude such

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inferences being made explicit or occurring in the regular course of scientific work.3 Again, leaving aside very specific critiques of particular views, let me raise a more general concern that seems applicable to any claim to the effect that modern science is infused with metaphysics. The worry stems from what I earlier suggested is a kind of vagueness or indeterminacy in deciding whether certain putatively metaphysical commitments are, in fact, metaphysical, as opposed to empirical. There is significant disagreement among philosophers regarding what it could mean to say that the supposedly metaphysical content is insulated from empirical considerations and, thereby, a product of a priori reasoning. The challenge is one of knowing how to make judgments concerning how indirectly informed by or insensitive to empirical considerations an element of scientific ontology must be in order to qualify as metaphysical. The very idea of what it could mean to be “closer to” or “further away from” observation and experimentation is the subject of chapter 3, but given that the challenge of knowing how to judge these things is relevant to the question of whether the sciences are inherently metaphysical, let me give a couple of examples here of how this challenge can arise. In the early twentieth century, American physicist Robert Millikan conducted a series of experiments to investigate whether there is a fundamental unit of electric charge. He suspended ionized droplets of oil between two charged plates and, using the Stokes equation, measured their charge, ultimately concluding that all of the results were integral multiples of (approximately) 1.602 × 10−19 coulombs, and suggested this as the fundamental unit. Meanwhile, 3.  This brings to mind the discussion in chapter 1 of Carnap’s deflationary account of scientific ontology, in which the linguistic frameworks used to describe these ontologies are chosen pragmatically. Some commentary, such as Friedman 1999, characterizes this as exemplifying a neo-​Kantian view of a priori principles (more on which in chapter 3).

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Austrian physicist Felix Ehrenhaft was conducting similar experiments using tiny metal spheres, and his results indicated ever smaller measurements of electric charge, suggesting no fundamental quantity as such. Barry Barnes, David Bloor, and John Henry (1996, chapter 2) suggest that Millikan and Ehrenhaft reached different conclusions in part because they operated with different (arguably metaphysical) assumptions which informed their interpretations of the data. With excitement about quantum hypotheses more generally rising in his scientific community, Millikan assumed that electric charge must be quantized, whereas Ehrenhaft was committed to the previously popular notion of a continuous electric field or fluid. Barnes et  al. argue that different interpretations of Millikan’s data were possible, citing historian Gerald Holton’s analysis of his notebooks. But given that history ultimately favored Millikan’s results, should one classify his assumption as a metaphysical presupposition, or as an empirical hypothesis that ultimately won the day in light of further evidence? The weight of subsequent history is significant in the Millikan-​ Ehrenhaft case. It might make it seem all too easy (or perhaps easier) in the minds of some people to rule out the case of electric charge as involving metaphysical inferences. So let us consider another example, this time from contemporary science. In a study of the development of cancer research, J.  A. Marcum (2005) argues that in recent decades, two conflicting metaphysical presuppositions—​ reductionism and organicism—​have shaped scientific investigation and have been shaped by this research in turn. Reductionism here is related to the idea of genetic determinism, the view that certain biological states and processes can be explained largely in terms of genes and gene function, whereas organicism is the view that emergent phenomena at higher levels of biological organization are in fact crucial to explanations of the relevant phenomena. An organicist explanation in this sphere, for instance, might causally link cancer cell production to certain forms of abnormal tissue organization. 44

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Again, one might wonder whether these competing hypotheses are properly characterized as metaphysical assumptions, or whether they are in fact empirical hypotheses that are being tested in the course of cancer research, as may be suggested by the claim that the hypotheses themselves have been reformulated as a consequence of this research. I have just reviewed some of the messy details of arguments on opposite sides of the same question. On the one hand, empiricist denials of the presence of metaphysical inferences in the context of the modern sciences may seem difficult to sustain, on pain of a rational reconstruction of what science entails that makes it appear alien next to what we actually see unfolding in the work of scientists today. On the other hand, one may worry that it is not entirely clear whether strikingly metaphysical aspects of science can be distinguished from empirical aspects, given that putative examples of the metaphysical appear to be jumbled up with the empirical in intricate ways. I believe that the former conclusion—​that metaphysical inference is inescapable in this context—​is correct, but this leaves open the question of how best to understand these inferences in a way that does justice to the manners in which a priori reasoning makes contact with the a posteriori content of science. Let us turn to this question now.

2.3 EPISTEMIC STANCES REGARDING SCIENTIFIC ONTOLOGY Assiduous readers will recall my serving notice from the start that one of the themes of this work would be that differences among various philosophers and scientists regarding ontological commitment are a function of differences in some of the epistemic commitments these individuals are wont to make. This was the basis of my claim that scientific ontology is deeply interwoven with issues in epistemology. 45

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It is time now to begin unpacking this claim, for in doing so we will gain a better understanding of why it is that scientific ontology in all of its forms presupposes at least some metaphysics, as well as an understanding of how varying commitments to different “degrees” of metaphysical inference function to separate those who advocate different kinds of scientific ontology into their respective camps. Let me begin by recalling the strongly empiricist tradition that I previously introduced as posing, historically and presently, a significant challenge to the very idea of metaphysical inquiry. Earlier I canvassed some specific examples of these views, but let me refer simply to ‘empiricism’ henceforth, by which I will intend any position of this strong sort. The opposition of empiricism to metaphysical inferences is helpfully described by one of the foremost contemporary champions of empiricist philosophy of science, Bas van Fraassen (2002), in his characterization of empiricism as a philosophical stance. Van Fraassen’s discussion suggests that stances can be very broad sorts of things, potentially relevant to a wide variety of subject matters and forms of inquiry, but given that my interest here is focused rather narrowly and squarely on questions of knowledge regarding scientific ontology, I myself will engage with the notion of stances in a more focused way. My interest here is in what I will call epistemic stances, namely, stances regarding the production of knowledge. As we will see, this interest stems from the ways in which different epistemic stances in the context of the sciences generate different scientific ontologies. Perhaps the simplest way to understand the concept of epistemic stances—​I will simply use the term ‘stances’ henceforth—​is to contrast them with what are commonly referred to as propositions, or claims regarding presumptively factual matters. Presumably, there are facts of the matter about whether grass is green, whether chlorophyll (the molecule responsible for the greenish hue) facilitates photosynthesis (a process in which light is converted into chemical 46

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energy), and whether carbon dioxide is used in the process. There are facts of the matter about whether the moon is made of green cheese and whether Santa Claus lives at the North Pole or, as some conspiracy theorists maintain, at an undisclosed location. If endorsed, the appropriate attitude toward propositions is belief. Stances have a rather different character, for unlike propositions, they are not claims about the world. A  stance is an orientation, a cluster of attitudes, commitments, and strategies relevant to the production of allegedly factual beliefs. They determine how human agents go about generating claims about the world that they may then believe. Stances themselves are not believed, but rather adopted by people, held by them, and expressed in their actions. Unlike propositions, their relation to those who seek knowledge cannot be understood in terms of belief in any strictly propositional content, but their adoption can eventuate in belief. Consider the stance typical of empiricists. Granted, empiricism is often (and traditionally has been) described in straightforwardly propositional terms as the view that the only source of knowledge of the world is experience and, furthermore, where strong empiricism is concerned, that this knowledge is ultimately about such experiences. Defining ‘empiricism’ in an alternative way in terms of a stance, as van Fraassen prefers, may be somewhat idiosyncratic, but this is of no concern here. Quite independently of how best to define the term ‘empiricism’ (an argument that empiricists are welcome to have among themselves), it is fair to say that a certain stance is characteristic of empiricists generally. Let us call this the ‘empiricist stance.’ The commitments typical of this stance are ones that follow from an austere attitude toward ontology and, in particular, a distaste for what is perceived to be the excessive nature of metaphysical inference. Those who hold the empiricist stance often describe the use of a priori reasoning in formulating ontologies as profligate and philosophically repellent. 47

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They view the appeal to explanatory virtues in such reasoning as epistemically impotent and, indeed, reject the very idea that observable phenomena require explanation at all, since this would involve explaining things that we already understand in terms of putative things that we understand less well if at all. They dismiss the demand for explanation in terms of underlying unobservables as irrelevant to scientific ontology. Conversely, what I will call the ‘metaphysical stance’ is very much inspired by the perceived importance of seeking explanations of the phenomena that we observe with our unaided senses, no doubt driven in this context by a strong sense that the investigation and provision of such explanations is surely part of what the sciences are intended to achieve. Those who adopt the metaphysical stance thus find themselves diametrically opposed to their empiricist counterparts in taking seriously the quest to reveal facts about underlying unobservable objects, events, processes, and properties as a means to scientific ontology. As a consequence, they happily engage in the project of attempting to provide the relevant explanations by theorizing about the unobservable, and seek to optimize explanatory virtues such as simplicity, internal consistency, coherence with background knowledge, and unificatory scope as a guide to inference. A dramatic conflict between these empiricist and metaphysical stances lies at the heart of many of the epic, perennial battles of philosophy down through the ages, and is central to a significant part of our mission presently:  to understand how and why different philosophers and scientists manage to end up with such different conceptions of scientific ontology. The idea of opposed stances in the context of the sciences raises many questions, and my ultimate interest here is not merely to understand how different scientific ontologies arise, but also whether and how conflicts regarding scientific ontology can be

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resolved. The former issue is the subject of the rest of this chapter and the next; the latter will be the focus of Part III. Before continuing with the current assignment, however, it is worth taking a moment to flag some of the issues that will come up for deeper consideration later, as they will surface again here and there en route. Perhaps the most obvious questions concern the basis on which different stances are adopted and how they are to be assessed, one against the other. Van Fraassen (2002) identifies two criteria for adoption and, with certain caveats that will emerge later regarding whether these criteria are exhaustive, I  am inclined to agree with him. The first criterion is rationality:  a stance should be rational, where this is understood in a broadly pragmatic way as internal coherence. As van Fraassen (2004, p.  184) puts it, the ‘defining hallmark’ of irrationality is ‘self-​sabotage by one’s own lights.’ So long as the adoption of a stance is not demonstrably self-​defeating according to its own standards of success, its adoption and the epistemic project associated with it are rational. The second criterion for stance adoption is one’s values, in the sense that one may value certain kinds of information and forms of explanation, for example, informed by one’s sense of the importance of these things and the likelihood of success in acquiring them. As is no doubt obvious immediately, this is a very permissive account of rationality. Prima facie, it would appear to allow that different and mutually incompatible stances could be rational. Those adopting the empiricist and metaphysical stances (for instance), respectively, clearly have incompatible values, but on the conception of rationality just indicated it would seem that neither is irrational so long as their proponents are each, so far as they can ascertain, succeeding by their own lights in doing what they set out to do, or at the very least, have no cause for concern that their stances are promoting epistemic inquiries that are doomed

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to failure. They have very different views, of course, regarding what sorts of phenomena call for further explanation and what explanations are genuinely illuminating as opposed to obscure or otherwise unhelpful, but contrary views on these matters do not by themselves suggest that either party is irrational in his or her choice of stance. This suggests, as a consequence, a kind of pluralism about scientific ontology. I expect that some readers will be worried about even the possibility of pluralism regarding ontology, but lest anyone be concerned unnecessarily, it is worth pointing out that the kind of variance in ontologies that such a pluralism would allow is not one according to which the holders of different stances are licensed to hold mutually contradictory beliefs regarding matters of putative fact. This is precisely the result feared by those who object to epistemic relativism, in which one person asserts a proposition, P, another asserts not-​P, and there are no grounds even in principle on which to conclude that either is mistaken. The possible pluralism licensed here in connection with stances is not relativistic in this way. Where someone adopting the metaphysical stance may be tempted to affirm certain propositions regarding unobservable objects, events, processes, and properties, the holder of the empiricist stance does not deny such claims. Rather, the empiricist simply has no beliefs at all concerning such propositions. Where a certain kind of scientific realist might affirm the existence of quarks, the empiricist does not deny their existence but simply remains agnostic about them. In this way, the latter’s scientific ontology may be a subset of the former’s, and this should assuage much of whatever concern there may be regarding the nature of rationality in this context, since there is no question of sanctioning contradictions. There is more to be said about all of this and, as promised, there is more to come. In the meantime, however, I will take the possibility

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of different but nonetheless rational stances for granted in order to return to the question of how metaphysical inferences function to produce scientific ontologies. With the current discussion of the nature of epistemic stances in hand, we are now in a position to redeem the promise made earlier to explain why it is that, the protest of some philosophers notwithstanding, any sort of scientific ontology at all involves the making of or, minimally, the tacit acceptance of at least some metaphysical inferences.

2.4 METAPHYSICAL INFERENCES: LOWERCASE ‘m’ VERSUS CAPITAL ‘M’ On a few occasions now I have mentioned that what different philosophers accept as falling under the heading of ‘metaphysical inference’ can vary rather significantly. The reason for this is an unwitting tendency among many to classify certain metaphysical inferences that they view as acceptable as non-​metaphysical, thereby reserving the term ‘metaphysical’ for certain kinds or extents of metaphysics that they find unacceptable. Perhaps a partial explanation of this phenomenon stems from the disfavor with which metaphysics has sometimes been regarded in some quarters, historically. For example, in the philosophy of science, much of the twentieth century was dominated by logical empiricism, and many logical empiricists applied the label ‘metaphysics’ as a term of disapprobation or even derision to identify claims that they regarded as falling outside the bounds of good sense or meaningfulness. In such a climate, perhaps it is not surprising that if one thought that scientific evidence yields good reason to believe in subatomic particles, one would prefer not to describe one’s beliefs in terms of metaphysical inference! If pressed, one might concede perhaps that there are metaphysical inferences involved but,

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surely, if this be metaphysics, it is metaphysics with a small ‘m,’ not Metaphysics with a big ‘M.’4 I have suggested that a common, de facto criterion for designating a given inquiry as metaphysical is the extent to which the subject matter is perceived to be removed from the sorts of familiar or everyday things the perceiver takes for granted. The greater the use of metaphysical inference to get from the commonplace to the less familiar, the more likely it is, it seems, to fall on the side of being labeled with a capital ‘M.’ Given that this sort of classification is in the eye of the beholder, it is tempting to dismiss it entirely. I believe, however, that subjective classifications aside, the practice of contrasting not-​very-​ metaphysical inferences with very-​seriously-​metaphysical inferences is on to something. The difficulty with it, as it stands, is that it gives the impression that there is something like an objective boundary separating little ‘m’ from big ‘M’ metaphysics, the precise location of which is no doubt subject to disagreement and debate, but which is there to be found nonetheless. Given my description of how these judgments are often made, this is doubtful, and I propose that we see the situation for what it is instead. There is no boundary. Rather, there is something like a continuum ranging from lesser to greater magnitudes of metaphysical inference, and disagreement regarding which parts of this continuum are epistemically solid enough to serve as a basis for scientific ontology. Let me unpack this suggestion a bit further. Recall that a metaphysical inference is one that has a significant a priori dimension, being fueled by non-​empirical considerations, namely, considerations that are not themselves directly informed by or sensitive to empirical

4.  We will encounter this sort of attempt to divide metaphysics into two camps—​a laudable camp and a reproachable one—​with a vengeance in the next chapter, where we will find that (for instance) some authors aim to separate laudable “naturalized” metaphysics from reproachable “non-​naturalized” metaphysics.

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investigation. These are typically considerations of the explanatory virtues of a given theory or hypothesis, where the latter is presented to give an account of some object, event, process, or property putatively underlying the relevant empirical information. Now, imagine a spectrum of metaphysical inferences ranging from the smallest ‘m’ at one end to the largest ‘M’ at the other. (Granted, this is something of an abstract exercise, but I will add some substance to it in chapter 3.) Perhaps reasoning about what one can infer by using a light microscope—​the sort used by students in school, for example, putatively to examine microscopic organisms—​involves a lesser degree of metaphysical inference than reasoning about what one can infer by using a particle accelerator, putatively to probe the natures of the smallest bits of matter. Both sets of inference begin with empirical information in the form of observations made or empirical data generated, but what follows is an interpretive exercise to determine what these observations and data can tell us about the ontology of things underlying them. This post-​production is significantly more elaborate in the latter case than in the former. As it happens, it is not uncommon for those inclined toward the empiricist stance to think that they are avoiding metaphysics altogether, and thus avoiding the spectrum I have described above entirely, even at the extreme limits of the smallest ‘m’ of metaphysical inference. This common view is, I  think, generally mistaken. For the most part, empiricists simply employ metaphysical inferences that are of a smaller magnitude than those they oppose. For example, consider ‘Humean’ or ‘neo-​Humean’ philosophical positions, grouped as such in acknowledgment of the inspiration (if not usually the precise emulation) of the great Scottish empiricist David Hume. Humean views of laws of nature, for instance, identify them with regularities in the world, and deny that there is anything more to be said about them apart from the various ways one might (or should) classify descriptions of them. But regularities are 53

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fascinating things from an ontological point of view. A  regularity is not something that anyone observes; it is a pattern that is exemplified without exception, past, present, and future. Furthermore, denying that laws involve yet further ontological ingredients, such as any sort of de re necessity (necessity in nature itself) or special properties like dispositional properties, is a metaphysical claim. The metaphysics inherent in these assertions and denials—​the Humean metaphysic—​may be modest, and it is certainly less grand than some others, but it is supported by metaphysical inferences nonetheless. Very much the same thing is evident more broadly with respect to empiricist accounts of scientific ontology. Those inclined toward the empiricist stance generally hope to avoid metaphysical inference altogether in interpreting the outputs of scientific practice, but cannot escape engaging in at least some metaphysics. The relevant inferences, however, are often hidden from view, and thus perhaps it is no surprise that they often escape notice. Admittedly, there are some forms of empiricism that may escape this diagnosis and resist metaphysical inference entirely. These forms are of significant historical interest, but it is fair to say that they have not been considered live options in debates about scientific ontology for over a century. Take perhaps the strongest version of empiricism imaginable, for instance: a strict phenomenalism of the present moment, according to which the extent of one’s knowledge is exhausted by one’s current sensations. By restricting itself so severely, it is arguable that this kind of view makes no recourse to metaphysical inferences. There are interesting questions here about whether this could amount to a coherent epistemology, but I will leave them aside. For present purposes, it is sufficient to note that in recent times, those who adopt the empiricist stance are not so stingy when it comes to knowledge. They extend the remit of what is knowable beyond impressions and ideas to an ontology of observables. 54

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Let us be as clear as possible about what an ontology of observables is, exactly. What I earlier called ‘strong’ forms of empiricism are not versions of idealism that deny the existence of an external world—​that is, a world that is independent of human cognition concerning it (but is nevertheless the subject of such cognition). They are also not versions of quietism (positions that offer no comment, usually for some principled reason) regarding what in that world lies beyond our sensations and ideas where observable objects, events, processes, and properties are concerned. Rather, they are epistemologies of science according to which empirical evidence yields good reason to believe in at least some facts about observable things whose existence does not depend on human sensation or thought. Though beliefs such as these are so commonplace as to be taken for granted, on reflection, even so minimal a prescription for knowledge requires metaphysical inferences. For in reaching toward an ontology of items beyond those acceptable to the phenomenalist, it quickly becomes evident that not all of one’s experiences are straightforwardly indicative of truths. The connection between experience and facts about observables is often complex. In some cases it is a simple matter to move from one to the other, as when one perceives that the cat is on the mat. At other times things are not so simple, as when one perceives that the straw is bent in the glass of water, all the while knowing it to be straight. The complex relationship between experiential evidence and truths about observables entails a number of things. It requires that one be able to recognize when appearances are deceiving and to distinguish deceitful experiences from veridical ones in a highly systematic way, not least in the context of the sciences. In scientific domains, it generally requires the application of metaphysical inferences in which theories or hypotheses about things underlying the apparently observable phenomena play a role. Many a sasquatch has turned out to be a calculable, optical effect of shadows 55

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and light filtered through the trees in interesting ways (or so they claim). The recourse to metaphysical inference is important not only to distinguish straightforward, ontology-​guiding experiences from optical illusions and hallucinations, but also to help in determining the quality of the empirical information one does acquire. Not all observations are created equal, whether in the lab or in the field. Differentiating good from bad and better from best once again typically requires the employment of metaphysical inferences involving theories or hypotheses concerning things (e.g., the functioning of instruments of detection and measurement) beyond the realm of the observable. Lest anyone worry that suggesting the importance of metaphysical inferences to the integrity of one’s knowledge of observable phenomena is somehow outré, it is probably worth noting that this suggestion is not entirely new. Indeed, though perhaps underappreciated in the present context, a number of related suggestions have surfaced in a number of important and influential works of philosophy of science this past century.5 Wilfrid Sellars (1956), for instance, is famous for arguing against what he called ‘the myth of the given,’ maintaining (among other things) that no cognitive state, including experiential states, can serve all by itself as a foundation from which facts about the world are simply or transparently read. Similarly, in part comprising the historical turn in the philosophy of the science mentioned in chapter 1, Norwood Russell Hanson (1958, chapter 1), Paul Feyerabend (1975), and Kuhn argued that scientific and even everyday observations are theory laden in the sense that theoretical beliefs held prior to observation significantly shape how they are experienced and described.

5.  For practically the only detailed, recent discussion of the challenges faced by empiricism in this regard, see Nagel 2000. Relating some of these challenges to the present discussion, see Ribeiro 2015, pp. 69–​70, and Robus 2015, pp. 854–​855.

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The notion of theory ladenness indicates yet a further way in which advocating an ontology of observables might require the use of metaphysical inferences, as I will now contend somewhat speculatively. In making the kinds of judgments indicated above, regarding what counts as bona fide observation and how to assess the quality (and thus the evidential force) of such observations, one inevitably makes use of a multitude of categories and classifications of objects, events, processes, and properties. Carving up the world in this way is an essential part of science. It is a basic requirement for coordinated action in scientific practice and otherwise, not least, for example, in the form of successful communication between scientists and others about the content of empirical evidence. Add to this a multitude of shared principles within subdomains of the sciences regarding how properly to extrapolate from empirical evidence in epistemically sensible ways so as to formulate generalizations about observable phenomena, and how to use this evidence to test and confirm hypotheses and theories. It seems that in order for these practices to function effectively in a scientific community, startling degrees of agreement are required concerning how they are done correctly. Where does all of this background knowledge come from? Kuhn has an answer to this question, and though many of the details of his account of scientific knowledge have been subjects of enduring debate, this particular answer is widely accepted. The forms of background knowledge that serve collectively as a necessary precondition for scientific ontology, even in so limited a form as an ontology of observables, cannot be acquired simply by making observations. This kind of knowledge is possessed by scientific communities, the members of which have been trained in such a way as to absorb the relevant information and thereby learn how to do science in a particular way. This background, which is in part constitutive of what Kuhn has in mind when talking about paradigms governing scientific activity, furnishes shared answers to questions regarding how 57

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to execute scientific practices correctly. For many authors of the historical turn, this kind of knowledge is viewed as largely ‘tacit’: it is not something that can be written down or communicated in terms of a set of clear instructions and neatly catalogued; it is learned via practice while immersed in a scientific community (more like learning to ride a bicycle than to add or subtract). Van Fraassen himself (2002, p. 130) agrees that the shared ‘traditions’ underwriting scientific practices such as those described above are not ‘formulable as a text.’ One must know how to experience things before one can derive knowledge from experience. Now, what sorts of things are these pools of background knowledge, or traditions? They are, I  submit, unobservable entities with complex natures:  cognitive, heuristic, culturally transmitted entities underlying the practices of observation and extrapolation from experience on which empiricist (and other) epistemologies of science rest. These complex social entities are posited to explain a number of observable phenomena, including the success of the various practices described here in terms of making and using observations in the sciences. Positing and theorizing about these entities is compelling largely because the successful performance of these activities involving observation, which is there for all to see, seems inexplicable otherwise. We find ourselves bereft of an understanding of how such success could be possible were it not for the existence of such things. As a consequence, and in this way, it would appear that even those drawn to the empiricist stance have reason to engage in a little bit of metaphysical inference after all. I characterized this line of argument as ‘speculative’ because it is fair to wonder, I think, whether a social, inter-​subjective thing such as a pool of tacit knowledge is appropriately described as an entity per se, let  alone an unobservable one. On reflection, however, it is unclear why either contention should be denied. Surely, the mere

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complexity of some of the entities studied in the social and human sciences should not bar them from a discussion of scientific ontology. And it seems clear that tacit knowledge (or for that matter any knowledge), while demonstrable and no doubt amenable to scientific investigation, is not strictly observable. It is evident that the numerous conventions that scientists bring to the world of experience make substantive contributions to their understandings of the natures of things that exist: they determine the ontological categories employed and how the coherence and confirmation of scientific claims are assessed. The conventions themselves are not read, like a recipe or an algorithm, from observation, and in attempting to explain how successfully coordinated scientific activities involving observation are possible, it seems only natural to theorize about underlying social entities—​aspects of paradigms, or traditions—​that serve as frameworks for experience itself. If this picture is right, it gives yet another reason to think that metaphysical inference is essential to scientific ontology.

2.5 THE (POSSIBLE) AUTONOMY OF (SOME) METAPHYSICS FROM SCIENCE In this chapter I have been examining connections between science and metaphysics. After considering the relationship between ontology and metaphysics generally, and the relationship between scientific ontology and metaphysical inference more specifically, I  have reflected on the popular notion that the modern sciences, unlike their predecessors in natural philosophy, have left philosophical considerations in the dust. This notion, I argued, is false. For one thing, it is difficult to conceive of the sciences themselves independently of at least some aspiration to inquire into at least some aspects of the

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ontology of the world. Once one accepts this premise, even the most minimal conceptions of what it could mean make recourse to metaphysical inferences. In working to establish the indispensability of metaphysical inference to the least ambitious conceptions of what scientific ontology might look like, however, I  have not said much about the more expansive ontologies of interest to those inclined toward the metaphysical stance. As ambitions for scientific ontology increase, one moves along the spectrum I described earlier in terms of magnitudes of metaphysical inference. It will be the task of the next chapter to spell out this metaphor of lesser and greater “magnitudes” in more detail. To prepare the ground for this next task in one last way, let us leave the minimalist end of the spectrum of metaphysical inference inhabited by those attracted to the empiricist stance and consider for a moment the opposite end. We have been preoccupied with the question of whether scientific ontology need involve metaphysics. Let us now turn this question around and ask whether metaphysics need involve scientific ontology. In effect, this is a question about just how big the ‘M’ in our most thoroughgoing metaphysical inferences can and should be. It is an extremely important question not least in our time, in an age during which the sciences have become the ultimate arbiter of our prospects for knowledge of the natural world. There was a time when metaphysicians ruled in ontology, but increasingly, throughout the transition from the period of natural philosophy to the present and outside the cloistered halls of departments of philosophy, more intensive a posteriori investigation has ascended the throne at the expense of more purely a priori reasoning. Is there is anything left for metaphysicians to do now apart from facilitating scientific ontology? As mentioned in passing at the start of chapter 1, the most common response to the question of what might make philosophical ontology (in contrast to ontological concerns in other domains) a 60

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genuine subject matter in its own right is that it concerns more general or fundamental questions of existence than those one might find in other places. Where scientists and philosophers of science, for example, are interested in specific objects, events, processes, properties, the various types or kinds of these things, laws of nature, causes and effects, and so on, metaphysics apart from science concerns more general or fundamental things and kinds of things, of which scientific subjects of interest are exemplifications. This is a widespread view among metaphysicians, well expressed by Laurie Paul (2012): the subject matter of metaphysics is ‘systematic, general truths concerning fundamental facts’ (p. 4), describing ‘features of the world that are metaphysically prior to those of the scientific account (p. 5).’ On the other side of the balance, there are skeptics. As Kyle Stanford (2017, p. 134) contends: ‘The most pressing worry here, I think, is whether these metaphysical proposals are really adding anything to the conception of the fundamental constitution of the natural world offered by the relevant scientific theories themselves.’ The question of whether there is sui generis work to be done in metaphysics is a difficult one to settle, in part because those on either side appear to be divided, ultimately, by strongly opposed intuitions the assessment of which is difficult to fathom. The best case, I believe, for thinking that when it comes to facts about the natural world, there is no domain of ontology that is neatly separable from ontological concerns elsewhere—​a case I take to be suggestive but not conclusive—​stems from what I will call the exclusivity problem. One might wonder whether the meaning of ‘generality’ or ‘fundamentality’ in this context is sufficiently clear as to allow a clear-​cut demarcation between a somehow purified metaphysics and other concerns about ontology. Historians are interested in the moon landing of 1969, but they are also interested in space missions more generally. The latter collection of events forms a category to which the former event belongs; thus, shifting from the former to the latter involves 61

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a shift from something more specific to something more general. Indeed, one may iterate this observation: historians are also interested in major ventures of space agencies of any sort, and ventures of high technology of any sort, and … In each case one reaches for a higher level of generality. ‘Aha!’ says the defender of pure metaphysics, ‘but none of this involves a consideration of the very notion of what an event is in the first place.’ That question, presumably, is purely metaphysical. But is it? The nature of historical events is undeniably a question of historiographical interest, and this more general sort of reflection is by no means unique to history. When Einstein formulated his special theory of relativity, describing the simultaneity of spatially separated events in terms of light signals arriving from them at the same time at the point from which their simultaneity is judged (different points of assessment leading to different judgments, thus yielding the relativity of simultaneity), he was articulating part of a theoretical description of the nature of events in terms of their relations to one another in spacetime. A physicist might well contend that it is difficult to imagine a more general reflection on the nature of events, but let us play devil’s advocate: perhaps, as in the historian’s conception of events, the physicist is merely engaging in a form of theorizing about a specific kind of event—​in this case, physical events—​which should be regarded as a distinct category from events simpliciter, theorizing about which more generally is the proper domain of philosophy. An obvious question then presents itself. What is this more general concept of an event, the study of which is the private domain of a purified metaphysics? This is where the exclusivity problem bites. If indeed there is a maximally general or fundamental concept of event simpliciter to be found, it must earn its generality or fundamentality by being appropriately related—​as more general or fundamental—​to all the other conceptions of events (historical, physical, psychological, etc.) found 62

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in all the other domains of ontological concern where events are an important category. In order to theorize about an appropriately general concept of event simpliciter, it would thus seem important to generalize from these more specific conceptions, in which case the general concept would be intimately, methodologically connected to facts about the more specific ones, not separable from them. It is hard to guess what further, exclusive work would then remain for a purified metaphysics to do. Or perhaps the sui generis project could go a different way, by first developing accounts of events potentially to serve as general, and then comparing candidate general concepts to more specific ones to see whether any of the general candidates will serve. Metaphysicians generally do the first part, but not the second. What tests of generality one finds are typically brief examinations of everyday cases or thought experiments, not systematic investigations into whether claims of generality are vindicated. Intuitions about whether such vindications are really there to be had are what separate those who believe that there is sui generis work for philosophical ontology to do, and those who do not.6 Given my own particular focus here on issues of scientific ontology, it is not crucial that we resolve once and for all the question of whether there are, in fact, genuine ontological matters to be contemplated of a more general or fundamental sort than those arising in the sciences. For what it is worth, I would suggest that in the tug of war between the relevant intuitions on opposite sides, given the exclusivity problem, the burden of proof rests with the metaphysical

6.  It is worth noting that the question of whether some conception of pure metaphysics is viable as a direct means of generating facts about the world is independent of the question of whether highly metaphysical inferences may be potentially, indirectly useful as heuristics for ontology in other domains. For a general discussion of the former question, see Tahko 2015, c­ hapter 9. Baron 2016, pp. 2250–​2254 offers an argument to the effect that metaphysics should be informed by the sciences. The question of the possible heuristic functions of “purer” metaphysics will surface again in chapters 3 and 5.

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purists, but be that as it may. To the extent that the question remains open, it is a useful primer for a more pressing concern presently. One might wonder whether it is possible to demarcate genuinely scientific ontology from ontological theorizing that may begin to appear, in light of the magnitudes of metaphysical inference involved, so tenuously connected to the empirical content of the sciences that it is effectively cut off from a serious consideration of scientific objects, events, processes, and properties (in which case it would belong, at best, to a domain of purely philosophical investigation). Is there a line to be drawn somewhere along the spectrum of metaphysical inference, beyond which the ontology is no longer scientific? Let us turn to this question now.

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[ 3 ]

Naturalism and the Grounding Metaphor

3.1 IN HOPES OF A DEMARCATION OF SCIENTIFIC ONTOLOGY The adjective ‘scientific’ in the expression ‘scientific ontology’ conveys a clear intent. It is intended to designate a particular subject matter of ontological concern as distinct from other possibilities, which comprise fields of inquiry into the nature of the world apart from the sciences. Given the conclusions of the previous two chapters, however, a significant challenge faces any ambition to identify all and only those ontological concerns that deserve the label ‘scientific.’ I  have argued that different philosophical presuppositions—​in the form of different epistemic stances regarding the reasonable scope of human knowledge—​are commonly applied to the very same scientific theories and models by different scientists and philosophers. As a result, any hope that the “true” or “proper” scope of scientific ontology is something that could be revealed simply by staring at scientific practices and their outputs, with the expectation that a scientific ontology will just tumble out of its own accord, is bound to be disappointed. These practices and outputs yield nothing ontological without interpretation, and when it comes to interpreting what the sciences are telling us about the world, the appropriate motto is ‘no stance in, no 65

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ontology out.’ Combine this with my assertion earlier that different stances may be rational, and one might well wonder whether a demarcation of scientific ontology is even possible. If this were all that could be said about scientific ontology, it would be worth knowing if perhaps a bit dispiriting. Thankfully, there is more to be said. Even though different views concerning the reasonable extent of scientific ontology are rationally defensible (a claim whose full articulation will be the focus of Part III), I  believe that a common principle of demarcation is shared by these different yet defensible interpretations—​a principle that speaks to the question of how best to draw a line between metaphysical inferences that are good bets for producing knowledge and those that are not (so far as we can tell presently). The key here is to appreciate that a shared principle of demarcation does not by itself entail a shared view of where to draw the line. This is because even a common principle of demarcation for scientific ontology is compatible with different judgments concerning how best to apply that principle and, more specifically, what sorts of inferences actually exemplify it. In this chapter I aim to elucidate this shared principle, which I will call the norm of naturalized metaphysics, and illuminate how those who hold different stances are apt to apply it in different ways, some more conservatively and others more liberally, resulting in some more conservative and other more liberal conceptions of scientific ontology. So, what is this shared principle, the norm? Recall that metaphysical inferences are ones having a significant a priori dimension as a consequence of their substantial reliance on non-​empirical considerations, typically involving an assessment of how the explanatory virtues of a given theory or hypothesis stack up, and where the explanations themselves are often accountings of observable phenomena in terms of underlying objects, events, processes, or properties. I have portrayed metaphysical inferences as constituting a spectrum, locations in which are determined by just how metaphysical an inference 66

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is, relatively speaking, as determined by an assessment of relative “magnitudes” of the a priori reasoning involved. The notion of magnitudes here is, of course, metaphorical, and as we will see, there are a number of suggestive metaphors commonly employed in this sphere. In this case, the idea of a magnitude of metaphysical inference is meant to suggest the degree to which an inference is (or is not) directly informed by, or sensitive to, scientific-​empirical investigation; the former is inversely proportional to the latter. The norm of naturalized metaphysics is the principle that scientific ontology is properly delimited by metaphysical inferences and propositions that are sufficiently informed by or sensitive to scientific-​empirical investigation as to provide or constitute ontological knowledge relating to the sciences. As just stated, several aspects of the norm of naturalized metaphysics stand in need of clarification. For one thing, one might wonder how this principle is connected to the many philosophical positions that have gone by the name of ‘naturalism’ in philosophy more generally. For another thing, one might wonder why the principle as stated suggests ‘scientific-​empirical investigation’ as opposed to science simpliciter as a constraint on metaphysical inference. For yet another thing, one might wonder how exactly relative judgments of the degrees to which metaphysical inferences and propositions are constrained by empirical investigation can be made, if indeed such thing is possible at all. Before digging into these questions, let us take a moment to appreciate some of the ways in which the norm of naturalized metaphysics is applied de facto, which will provide something of a backdrop against which these clarifications can unfold. It is fair to say that almost everyone interested in scientific ontology, when examining ontological theorizing very broadly, comes to a point in the spectrum of metaphysical inference beyond which they feel that the connection between the theorizing on the one hand, and scientific-​empirical content on the other, is simply too weak to 67

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shed any helpful light on the ontology of the sciences. In chapter 2 we considered a conception of this point favored by adopters of the empiricist stance, for whom the domain of the observable defines the proper scope of scientific ontology. On such a view, any claim about objects, events, processes, or properties that goes beyond that which is detectable using human observational capacities alone is too weakly connected to empirical evidence to merit ontological commitment. In contrast, in chapter 1 we considered some versions of scientific realism, the view according to which our best scientific theories yield knowledge of both observable and unobservable aspects of the world. In different ways, in accordance with their own precise recipes for realism, scientific realists view many of the unobservable things putatively described by the sciences as elements of ontologies to which they can commit. Given that there are different forms of empiricism and scientific realism, it will come as no surprise that even within these camps there are differences of opinion regarding where the epistemic potency of metaphysical inferences runs out. The possibilities for scientific ontology do not end with versions of empiricism and scientific realism, however. Both are associated with endorsements of bits of ontology comprising what one might call the explicit subject matters of scientific investigation. In molecular biology, for example, scientists are explicitly concerned with putative phenomena including gene transcription, in which sequences of segments of DNA molecules are copied in producing RNA molecules. In nuclear physics, scientists are likewise explicitly concerned with putative phenomena such as the process of beta decay, in which protons are converted into neutrons (and other particles which then leave the nucleus) and vice versa. These subject matters are explicit in the sense that, taking descriptions of the relevant scientific endeavors at face value, they are putatively investigations into the natures of the phenomena described. Beyond the explicit subjects of scientific theorizing, modeling, and experimentation, however, there is also 68

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what one might call implicit subject matters. These are things whose natures are not the face-​value targets of scientific work, but which are rather mentioned in passing. Scientific descriptions make explicit reference to certain properties, causal relations, laws of nature, possibilities and necessities, and so on, but the sciences make no attempt to describe the nature of causation itself, for instance, as opposed to the natures of putative instances of causation found in specific domains. Arguably, the implicit subject matters of science are also possible aspects of scientific ontology. After all, one might argue, given that the sciences investigate (for instance) so many things commonly referred to as laws of nature, it is reasonable to think that reflection on what the sciences reveal about specific laws is a good starting point for metaphysical inferences concerning the nature of laws themselves, more generally. The same would go for the natures of objects and events, the natures of their properties, the natures of categories of things into which nature is classified, and so on. This is not to assume, of course, that any one account of these subjects is tenable. Perhaps there are necessary and sufficient conditions for causation, or perhaps there is no one nature here and, instead, lots of different causal relations with different natures. Perhaps the entities described in biology and chemistry are ultimately reducible to entities described in physics, or perhaps they are not. These sorts of issues are not pondered in laboratories, yet one might think that their very proximity to the sciences, as features of the world that are implicated in descriptions of scientific phenomena, makes them good targets for ontological theorizing. Much recent philosophy of science has aimed to do precisely this: to grapple with the ontological underpinnings—​the implicit subject matters—​of our best science. It is now obvious, I suspect, why many different conceptions of the proper scope of scientific ontology are not merely possible but actual. Among scientific realists, for example, there are different conceptions of where along the spectrum of metaphysical 69

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inferences one should draw the line demarcating scientific ontology, for once one opens the door to the implicit subject matters of science, it is difficult to avoid the potential hazard of a slippery slope, and scientists and philosophers alike are apt to dig in their heels in different places. Recall that the metaphysical stance is motivated in part by an aspiration to explain certain phenomena in terms of further, underlying things. A  slippery slope here is difficult to avoid because demands for explanation can always be iterated—​in the course of explaining things, it is always possible to convert a given explanation (an explanans) into something that is itself subject to explanation (an explanandum) and carry on down the slope. The norm of naturalized metaphysics is intended to arrest one’s fall at precisely the point at which one would begin to make inferences whose connections to scientific-​empirical evidence have become so attenuated that they are no longer good bets for scientific ontology. Many and perhaps most philosophers of science are tempted to say more at this juncture, suggesting that wherever the norm of naturalized metaphysics is absent, metaphysical inferences yield nothing worth having, since all that remains are empty metaphysical pursuits. Some feel very strongly about this contention.1 With my own attention focused obsessively on the prospects of scientific ontology, I am not as interested here in further judgments concerning non-​naturalized metaphysics as I  am in the question of what it could mean to apply the norm of naturalized metaphysics at all, for it seems to me that this principle, while itself tempting, has yet to be articulated in a clear or compelling manner. Our current understanding of it is, I think, undermined by what might be fairly 1.  For statements to this effect, see Maudlin 2007 and especially Ladyman & Ross 2007, chapter 1. For a reply to the latter, see Dorr 2010. For an exploration of some of the ways in which metaphysics may suffer as a consequence of being disconnected from the sciences, see Humphreys 2013.

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described as a debilitating vagueness. In the rest of this chapter I hope to begin the process of sharpening it. As a start, let us return briefly to the ways in which scientific ontology requires metaphysical inferences, as a means of clarifying what it is about some of these inferences that raises the temperatures of some philosophers of science.

3.2 ON CONFLATING THE A PRIORI WITH THAT WHICH IS PRIOR Earlier, in describing how metaphysics enters into the sciences, I mentioned two possibilities. The most commonly suggested way is in the form of metaphysical assumptions or presuppositions. The idea here is that certain metaphysical concepts or principles are assumed as part of the background that one must have in place, functioning as a sort of launching pad, in order for it to be possible to engage in any concerted scientific investigation in the first place. Hence the notion of a framework or a paradigm of such concepts and principles, without which scientists would be lacking the conceptual infrastructure—​shared definitions of basic concepts, shared commitments to methods of investigation, shared standards of analysis for assessing and extrapolating from the data—​that makes science possible. On the other hand, I have focused much of my discussion on metaphysical inferences made in interpreting the outputs of science such as theories and models. These inferences are processes of reasoning having a significant a priori dimension, emphasizing non-​empirical considerations as opposed to empirical ones. Before wrapping our heads around the norm of naturalized metaphysics, it will be helpful to clarify whether this apparent distinction between presupposing and inferring is consequential for an understanding of scientific ontology. 71

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The notion that presuppositions are involved in the production of scientific knowledge has surfaced on several occasions now. Perhaps most famous outside of philosophical circles is the Kuhnian idea that the normal practice of science incorporates metaphysical assumptions as parts of paradigms, but this is just one of many accounts of how scientific inquiry depends on prior agreement regarding the categories of entities, evidence, methods, and analysis that allow scientific questions to be posed and then investigated. Many have sought to describe the sciences in terms of historically or contextually relativized a priori principles, and some are inspired directly or indirectly by Immanuel Kant’s contention that certain categories of human understanding are preconditions for investigating empirical reality.2 The principle that Euclidean geometry is the correct geometry for describing spatial relations is presuppositional for Newtonian physics. The idea that the speed of light is the same in all directions is presuppositional for Einstein’s formulation of his theory of special relativity. Without presuppositions like these, it would be impossible to describe empirical phenomena, to design experiments to probe them, and to forge the results into a system of knowledge. They make certain ontological possibilities intelligible, which then allows hypotheses to be formed and tested. Interestingly, the notion of a priori presuppositions furnishing ontological molds for scientific theorizing, modeling, and experimentation is widely spread even among those who are opposed to the idea that metaphysical inference should have anything to do with interpreting scientific knowledge. This is puzzling, for it suggests that metaphysics is both fine as a guide to scientific ontology, in the form

2.  See Hacking 1991 on ‘styles of reasoning,’ Jardine 1991 on ‘scenes of inquiry,’ Friedman 2001 on the ‘constitutive a priori,’ and Stump 2003 on the ‘functional a priori.’ This list would grow very long if we included antecedents such as Rudolph Carnap, Michel Foucault, Henri Poincaré, Hans Reichenbach, and more.

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of presuppositions of scientific inquiry, and not fine as a guide to scientific ontology, in the form of subsequent inferences based on the outputs of science. It seems contradictory to suggest that metaphysics is both fine and not fine here, so what gives? I believe that there are two possible ways out of this puzzle for those who are opposed to metaphysical inference in the context of scientific ontology. The first is to deny that the kinds of presuppositions that serve as the necessary background of scientific work are, in fact, metaphysical after all. The second is to accept that these presuppositions are, in fact, metaphysical, but to maintain that they represent a different kind of metaphysics with respect to the sciences than is involved in making metaphysical inferences—​a presuppositional metaphysics that, unlike metaphysical inference, is unobjectionable. Let us consider these possibilities in turn. Granting that presuppositions regarding the sorts of things we canvassed above as preconditions of scientific work (certain definitions, views of taxonomy, evidence, and analysis, etc.) are prior to scientific work, does this by itself make them a priori, and thus metaphysical? Is it right to identify what is prior in these ways with that which is a priori? At first glance, it may seem that the obvious answer to this question is ‘no,’ for it may seem that there is nothing to preclude these presuppositions being the outcomes of previous empirical investigations and thus a posteriori, not a priori after all. On a second glance, however, this answer seems problematic. A  quick survey of the kinds of principles that are commonly cited as a priori in the context of scientific practice reveals that they are difficult to characterize as the immediate upshots of any directly empirical inquiries. When the gold standard for explaining the behavior of an entity shifted away from citing, in Aristotelian fashion, the ultimate objective or aim (the telos) of that kind of thing, it was not because teleological explanation had been found wanting in some sort of observation or experiment. It was found wanting by means of 73

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metaphysical inference. Likewise, it was not because the geometry of spacetime was somehow empirically detected to be non-​Euclidean that Einstein ushered in a new way of thinking about spacetime with his theory of general relativity. Accepting, then, that the relevant presuppositions are a priori, since they cannot be viewed in any direct or straightforward way as empirically assessable, might one contend that this acceptance points to a different kind of metaphysics than that which is entailed by engaging in metaphysical inference? There are, I think, two things that one might intend in making such a claim. The first is an assertion to the effect that presuppositional metaphysics, unlike metaphysical inference, does not concern ontology. This is a difficult trick, however. Of course, if one espouses a deflationary view of scientific ontology (recall chapter 1, section 2), one will regard both metaphysical presuppositions and metaphysical inferences as relevant to and indicative of something other than ontology as traditionally conceived.3 But this is no help to the view that metaphysical inferences concern ontological matters while presuppositional principles do not, for if one accepts that metaphysical inferences are undertaken with the aim of producing facts about ontology (even if one fails in that aim), it is hard to see how presuppositional metaphysics could play a different role. For the non-​deflationist, after all, the relevant presuppositions concern ontological categories of things, techniques for evaluating evidence in the service of ontological conclusions, and so on. The presuppositions are infused with ontological claims and implications.

3.  For example, as discussed earlier, Carnap fits here. More generally, anyone who, in a neo-​ Kantian spirit, views these presuppositions as conventions fits here too. Though relatively uncommon, there is another way that one might label some views in this vein: as opposed to traditional metaphysics but not (neo-​)Kantian metaphysics, which holds that the world is, in part, a product of our ways of understanding it, which includes substantive shaping by frameworks of a priori principles.

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Here is another way in which one might hope to combine an acceptance of presuppositional metaphysics with a disavowal of metaphysical inference. One might contend that while both are metaphysical, the former is metaphysical in an innocuous way whereas the latter is not. This contention requires a telling difference between the two. One obvious difference is that while metaphysical inferences are always explicit bits of reasoning, presuppositional metaphysics is sometimes implicit, in the sense that even if the relevant assumptions were originally conclusions of past metaphysical inferences, such past reasoning is often invisible to those who are educated in a given scientific context. When learning science, metaphysical presuppositions are often presented simply as definitions or axioms upon which the rest of one’s scientific work depends. In some cases it might even be impossible to reconstruct the prior thinking that gave rise to the relevant presuppositions (in the absence of some illuminating history of science). In other cases the thinking involved may be learned tacitly in the process of training and perhaps even inexpressible explicitly (e.g., learning how to describe phenomena in terms of appropriate kinds of objects, events, processes, or properties is sometimes described this way). Since tacit or otherwise implicit metaphysical presuppositions shape descriptions of scientific ontology no less than explicit metaphysical inferences, however, this difference does not make the right sort of difference. It is difficult to imagine what could. I suspect that the reason some philosophers are less concerned about presuppositional metaphysics than they are about metaphysical inference is that while the former seems to be necessary for the very practice of science itself, the latter runs the risk of falling uncomfortably far down the slippery slope of ontological issues, each seemingly more distant from science than the last. If I am right about this, the motivating idea here is that the best hope for satisfying the norm of naturalized metaphysics is to expose oneself to metaphysical 75

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questions as minimally as one can in thinking about scientific ontology. For those who are inclined toward more conservative stances regarding scientific ontology, this sort of motivating sentiment is perfectly natural, but as we will see, if the intended aim is ontological caution, merely favoring presuppositional metaphysics over metaphysical inference in interpreting scientific theories and models is not the way to go. The measure of how metaphysical an aspect of scientific ontology may be is a function of how directly informed by or sensitive to the relevant empirical evidence it is, not whether it is presupposed in the course of scientific work as opposed to being later inferred. In the next couple of sections, we will turn at last to the question of what this could mean.

3.3 HOW NOT TO NATURALIZE METAPHYSICAL INFERENCES Earlier I  described the norm of naturalized metaphysics as a principle demarcating scientific ontology as a particular form of ontology—​one whose subject matter is metaphysical inferences and propositions that are informed by, or sensitive to, scientific-​ empirical investigation. Since being informed and sensitive here are presumably things that admit of degrees, I added the qualification that satisfying this criterion is a matter of meeting it sufficiently for the purpose of shedding light on the ontology of the sciences, however that threshold is to be determined. While there have been a significant number of voices in recent years advocating a preference for naturalistic or scientific metaphysics over projects in metaphysics that are judged to be non-​naturalistic or non-​scientific, relatively little has been said in a compelling way about what the former is, exactly. I believe that the most obvious and generic way of understanding naturalized metaphysics is incoherent, and while 76

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this charge of incoherence can be answered, the answer comes at a price. In this section I will attempt to explain this charge, consider how a naturalistic metaphysician should respond, and explore the consequences of this response for our understanding of the norm of naturalized metaphysics. To begin, let us ask what the reference to ‘naturalism’ here is meant to convey. The term itself is associated with several different philosophical positions and stances, from very broad and somewhat vague sentiments (e.g., a blanket deference to the sciences regarding knowledge of the world) to more specific and technical theses (e.g., the claim that there is no such thing as a priori knowledge of the world). Together these commitments comprise a family of inequivalent theses and attitudes, many of which are nonetheless unified by a generally positive assessment of the sciences and a generally negative assessment of non-​empirical methods for producing knowledge. I will make no attempt here to review systematically the many flavors of naturalism, but will focus instead on the two formulations that seem initially most relevant to an explication of the norm of naturalized metaphysics. The first of these, though often cited in discussions of possible connections between science and philosophy, turns out to be largely unhelpful in illuminating the norm. The second formulation, as we will see, is more promising. The first conception of naturalism of potential relevance here is the idea that some considerations of ontology are best viewed as progressing over time, as thinking about them matures, from a state in which they are contemplated in philosophy quite apart from the sciences to a state in which they are investigated by the sciences themselves. W. V. Quine is perhaps most famous for advocating this idea, according to which philosophy can play a preparatory role, theorizing in a more conceptual way, until such time as the sciences are able to tackle the issues at hand in a more empirically engaged sort of way. Thus his suggestions, for example, that epistemology, 77

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the philosophical study of knowledge, should ultimately give way to empirical psychology (1969, chapter 3), and that theorizing about natural kinds, the philosophical study of categories of things in nature, should ultimately give way to scientific classification (­chapter  5). This should not be taken to suggest that the prior philosophical work is uninteresting or unimportant, for it is often acknowledged that philosophy sometimes plays a crucial role in preparing the ground for science by developing concepts that prove useful to, or serve as a heuristic for, later scientific work. Theorizing about atoms, elements, corpuscles of light, the aether, and principles of conservation and determinism was part of philosophy long before these subjects became targets of empirical inquiry.4 This kind of naturalism, however, according to which certain areas of philosophy should give way to corresponding areas of science, is of no help in spelling out the norm of naturalized metaphysics. Doing metaphysics as a guide to scientific ontology in the present requires that one engage in metaphysical theorizing that is suitably connected to scientific-​empirical considerations now, not as a potential precursor to some different sort of theorizing at some indefinite future time (a time which, for all we know, may never come). As a consequence, this heuristic conception of metaphysics cannot help to explain how one might distinguish ontological theorizing that exemplifies the norm from that which does not. Chasing the ghosts of philosophy past to identify inspirations for science that were subsequently derived from it is historically and otherwise fascinating, but the temporal disconnect between earlier (philosophy) and later (science) clearly marks this conception of naturalism as incidental to our present concern. What we are after is a normative guide to ontological theorizing now, as opposed to a diagnosis in retrospect, 4.  Examples are ubiquitous. For a nice list pertaining mostly to physics, see Ladyman 2012, pp. 47–​48.

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in order to judge whether metaphysical inferences and propositions currently under consideration are appropriately connected to science in the present. Another highly influential form of naturalism is usually presented with the slogan that philosophy is, or should be, continuous with science. The slogan is cashed out in various ways, but here is a list of the most common things advocated as candidates for continuity between philosophical and scientific inquiry:  aims; methods; subject matters; and criteria of evaluation for theories and hypotheses. It is this conception of naturalism that is most relevant, I think, to explicating the norm of naturalized metaphysics. And indeed, all of the items on this list—​except for one—​come for free in light of the discussion we have had already regarding the nature of scientific ontology. Ontological investigation in both the sciences and philosophy aims to describe what exists, what kinds of things exist, and what they are like. Furthermore, given our earlier discussion of the ways in which a priori presuppositions and reasoning are inescapable in scientific ontology, it seems that there is at least some continuity of methods as well (though clearly not in toto). As for criteria of evaluation, I have mentioned the sorts of criteria that are operative in metaphysical inference, such as simplicity, internal consistency, coherence with other knowledge, and the capacity to unify otherwise disparate phenomena, and these criteria are no less operative in thinking about scientific theories and hypotheses. That leaves just one thing:  the subject matters of science and philosophy. Now, scientific ontology is often concerned with what I  earlier called the explicit subject matters of the sciences, which comprise the apparent foci of scientific practice. But what could it mean for this explicit content to be continuous with the implicit subject matters of the sciences that comprise the other targets of scientific ontology? Recall that doing ontology in a way that is appropriately connected to the sciences is supposed to prevent one from falling down the slippery 79

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slope into metaphysical issues that cannot plausibly be counted as relevant to what the sciences are telling us about the world. If there were, in fact, some sort of continuity between the explicit and the implicit subject matters of science, that might serve as an appropriate connection, but this sort of continuity is not easy to define. What is “the continuity,” exactly, between (say) the study of the evolutionary development of a species by biologists and the debate about whether evolutionary parameters like natural selection are forces that act causally or rather statistical outcomes of causal processes at other levels of description, as conducted by philosophers of biology? Continuity is a metaphor here in want of an analysis and, unfortunately, our common understandings of it are couched in loose talk: naturalized metaphysics is “based on” or “constrained by” or “derived from” our best science, which thus “grounds” scientific ontology. Tightening up some of this talk will be the goal of the next couple of sections, but it is critical that we first address a tension here that threatens to undo the project of naturalized metaphysics before we begin. The conception of naturalism just outlined advocates continuities between science and philosophy, such that the former is something that serves as a basis of, or a constrainer of, the latter. The norm of naturalized metaphysics, however, suggests that scientific ontology should be delimited by metaphysical inferences and propositions that are sufficiently informed by or sensitive to scientific-​ empirical investigation, as opposed to science simpliciter. One might overlook this difference on the assumption that scientific inquiry simply is empirical inquiry—​an assumption so widespread that one might think it banal. But is it true? Most sciences are empirical in a number of ways: novel predictions are made and observations and experiments are devised to test them; hypotheses and theories associated with these predictions are thereby appraised; instruments are built and techniques developed in order to detect, measure, and

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manipulate putative entities. None of this happens in philosophy.5 Saying that most science has empirical content is not the same thing as saying that science is thoroughly empirical, however, and this has important repercussions for understanding the norm of naturalized metaphysics. As we have seen, the sciences are permeated with a priori content in the form of metaphysical presuppositions and inferences. Thus, any attempt to ground the a priori theorizing of scientific ontology somehow straightforwardly in a posteriori knowledge cannot take science simpliciter as the relevant ground, for science as a whole is an inextricable mixture of the two. Exacerbating this difficulty is the fact that there is enormous variation within the sciences regarding their empirical credentials. Some areas are primarily concerned with developing models to accommodate already known data, as opposed to making novel predictions that can be tested. Some are highly theoretical—​essentially mathematical theorizing at a significant remove from observation and experience. Some cannot hope to investigate their subject matters experimentally because their targets are empirically inaccessible (consider the ‘strings’ of some theorizing in fundamental physics) or otherwise beyond our capacities of interaction and manipulation (consider the scale and distance from us, spatiotemporally speaking, of the subjects of cosmology!). The ways in which and degrees to which science is empirical is highly variable. This, combined with the observation that the sciences are infused with a priori content to begin with, exposes the naiveté of thinking that one could simply point to science as an a posteriori foundation for, or constraint on, scientific ontology. 5.  An exception is the small corner of philosophy occupied by so-​called ‘experimental philosophy’, or ‘X-​Phi,’ which has until now focused on areas (such as philosophy of mind, action theory, and epistemology) other than scientific ontology.

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The upshot is that there is something incoherent about thinking in a coarse-​grained way about the norm of naturalized metaphysics. One cannot hope to sanction a priori theorizing with a posteriori knowledge simply by waving the flag of science and gesturing toward “continuity” between subject matters. To escape this incoherence, one must first think of naturalized metaphysics in terms of an appropriate connection between scientific ontology and the specifically empirical content of the sciences, not science simpliciter. This move will not amount to much, though, if one cannot say more to spell out the metaphors of continuity—​basing, constraining, deriving, grounding, and so on—​that are supposed to delimit scientific ontology specifically. This is the cost of a clear understanding of the norm, and if left unpaid, trivial satisfactions of it become a serious threat. Consider: Plato observed that the objects of his experience were similar and different in myriad ways. The empirical evidence was abundant. In order to explain these phenomena, he “derived” the theory of the Forms, according to which the properties of these objects are abstract entities (‘universals’) enjoying an independent existence. The theory is motivated by and thus arguably grounded in empirical data. But this sort of consistency with observation is true of all metaphysical theorizing. So much for applying the brakes somewhere down the slippery slope! If it happens that every project in metaphysics as they are currently undertaken automatically counts as an instance of scientific ontology, something has gone terribly wrong. Though it is fair, no doubt and in some sense, to describe Platonism as a theory whose genesis can be traced to empirical observations, there is something deeply unimpressive about the nature of this connection from the point of view of scientific knowledge. At the risk of failing to make any distinctions at all between scientific ontology and other possible ontological concerns, it is necessary to move beyond vaguely

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specified links to empirical content and a posteriori investigation. This is where we must go next.

3.4 UNPACKING THE METAPHORS: “GROUNDING” AND “DISTANCE” In the previous section I argued that the norm of naturalized metaphysics cannot be satisfied by the mere possibility of future heuristic uses, in scientific work, of prior work in metaphysics. The distinctive character of scientific ontology has something to do with its continuity with empirical inquiry here and now. So how, then, is this continuity to be spelled out? To initiate an answer to this question, it will help first to translate the metaphor of continuity into some of the other metaphors that often surface in this context: the notions of “grounding” and “distance.” To say that one thing is continuous with something else is to say (inter alia) that they occupy adjacent locations in a series (an unbroken series, but this detail is superfluous here). Think of empirical inquiry as marking a position in a series—​a position that serves as a reference point for assessments of scientific ontology. Exercises in scientific ontology can be closer to or further away from this point of reference, hence the notion of distance. The reference point is thus a ground of such measurement, in just the way that the ground beneath one’s feet is a place from which one can measure one’s height. It is also a ground in the sense that it forms a basis for judgments concerning whether a given exercise in ontology counts as scientific ontology—​a judgment which, I will contend, is a function of the relevant distance. On reflection it seems that all of the metaphors frequently bandied about with gay abandon in this context can be understood in terms of the notions of ground and distance. When one says that an

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exercise in scientific ontology is “based on” empirical inquiry, one means that the ground of empirical inquiry is the inspiration or motivation for certain metaphysical inferences which take place at a distance from observations and experiments. When one says that some metaphysical inferences are “constrained by” empirical inquiry, one means that the ground of empirical inquiry is being taken seriously as setting limits on the viable conclusions of those inferences. When earlier, on a number of occasions, I spoke of different “magnitudes” of metaphysical inference constituting a spectrum, where different locations in the spectrum are associated with different “measures” of how directly these inferences are informed by empirical inquiry, or how sensitive they are to empirical inquiry, I was in effect talking about the distances of metaphysical inferences from the ground of empirical inquiry. In this way, all of the now familiar loose talk that has come before can be translated into much more focused loose talk in terms of grounding and distance. This is a useful first step. In the terms just discussed, the key to understanding the norm of naturalized metaphysics, it seems, is an answer to this question: what is being measured when one speaks of distances from empirical inquiry and associated magnitudes of metaphysical inference? The answer, I believe, is this: epistemic risk. As I intend it, epistemic risk is a feature of propositions (and the inferences generating them, as conclusions) that determines how confidently one is able to judge whether they are true or false; that is, whether and to what extent they are conducive to knowledge. If one says that a proposition—​say, ‘there are electrons,’ or ‘there are Platonic universals’—​is epistemically risky, one is saying that one is not in a position to judge with confidence whether it is true or false. Conversely, to say that a proposition is not especially epistemically risky is to say that one has confidence in one’s judgment that it is true or false. To borrow from the language of probability theory, the more likely one takes the relevant proposition to be, the higher one’s degree 84

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of belief in it (imagine a range from 0, indicating certainty that it is false, to 1, indicating certainty that it is true, and all the intermediate degrees of confidence in between). When degrees of belief are sufficiently high or low, most people happily count themselves as having knowledge; when degrees of belief are stuck in the middle, one cannot really say one way or the other and knowledge is not on the cards. In scientific ontology, as in any other domain in which knowledge is sought, the less epistemic risk the better. The norm of naturalized metaphysics, recall, states that the proper subject matters of scientific ontology are metaphysical inferences and propositions that are sufficiently informed by or sensitive to (scientific-​) empirical investigation. What is the rationale for this principle? The reason that empirical inquiry—​in the first instance, observation, but also including forms of intervention, manipulation, and experimentation on objects, events, processes, and properties—​ is a ground for scientific ontology is that, when it comes to knowledge of the world (as opposed to certain formal propositions in logic or mathematics, which are necessarily true), empirical inquiry is our best bet for knowledge. This is not to say that it is infallible, for it is always possible to be mistaken even in observation, and neither is it to say that our conceptions and descriptions of observable phenomena do not contain a priori content, for as discussed in chapter 2, they do. It is, however, to say that this is the place where the world itself can resist our descriptions of it. It is the place where the inadequacy of false descriptions is most evident. This resistance is what marks empirical inquiry as a reference point for assessments of the epistemic riskiness of the metaphysical inferences and propositions of scientific ontology. Measures of epistemic risk are thus inversely proportional here to what one might call empirical vulnerability, which concerns how susceptible a proposition is to empirical testing. It is important to clarify that as I intend it, the empirical vulnerability of a proposition 85

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is something that is assessed on the basis of one’s actual empirical evidence concerning it. One might easily imagine different (including more prospective) uses of the term ‘empirical vulnerability’: one might say that even though no one has yet performed some potentially relevant empirical investigation that is within our current power to perform, a given proposition is empirically vulnerable in principle, for there would seem to be ways of testing it empirically; or one might say that a proposition is empirically vulnerable in principle because we can envision the advent of instruments or experiments capable of testing it one day in the future. I have something more restrictive in mind, however, and hereby restrict the scope of judgments of empirical vulnerability to assessments made in connection with the evidence one has, pertaining to what one believes in the present. Regarding matters of fact about the world, the more vulnerable a metaphysical inference is in the face of one’s empirical evidence, the better the evidence one has in determining whether one is in a position to know something.6 Consider the claim that there are electrons. While the inferences that may lead one to assert (or deny) this claim are inescapably metaphysical, the hypothesis that there are such things is implicated in a large number of predictions regarding observable phenomena which have been tested in the laboratory. The hypothesis is thus vulnerable in the face of empirical evidence. Now consider the hypothesis that properties are Platonic universals:  abstract entities that exist independently of the concrete things that have them. There is no possible observation that one could make that would add to or subtract from

6.  This brings to mind Popper’s (1989/​1963) different but related suggestion that ‘falsifiability’ (susceptibility to empirical confirmation or disconfirmation) is the mark of genuinely scientific theories and hypotheses. For reasons that I have mentioned already, though, concerning the diversity of the sciences, and for further reasons that will become clear in Part III, I think it would be a mistake to stipulate that empirical vulnerability is the sine qua non of science.

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one’s confidence that there are such things. It is thus unsurprising that no one has ever made such an observation. The hypothesis is completely invulnerable in the face of empirical inquiry and, as a consequence, the epistemic risk of the hypothesis is all the greater. The lower the degree of empirical vulnerability associated with a proposition, the higher its epistemic risk, ceteris paribus. Thus we see how it is often the case that the norm of naturalized metaphysics is better satisfied in contexts of high empirical vulnerability. If this were all there was to assessing epistemic risk, scientific ontology would be a much simpler thing to grasp than it is, in fact. As it happens, empirical vulnerability is only one factor relevant to assessing epistemic risk. There is another, and it turns out that this further feature plays a dramatic role in disputes concerning where the line should be drawn, in the spectrum of metaphysical inference, between putative instances of scientific ontology on the one hand and exercises in metaphysics that arguably shed no light on science on the other. This additional feature is explanatory power, which is (in this context, and as I intend it here) a measure of how well a metaphysical inference or resulting proposition satisfies the criteria typically associated with good explanations of the data of observation and experience that we canvassed earlier, including simplicity, internal consistency, coherence with other knowledge, and the capacity to unify otherwise disparate phenomena. Like empirical vulnerability, explanatory power varies inversely with epistemic risk:  the greater the explanatory power of a theory or a hypothesis, the smaller the epistemic risk associated with it, ceteris paribus. Unlike empirical vulnerability, however, the power of explanatory power to affect epistemic risk is hugely contested. In chapter 2, we encountered the idea of epistemic stances and the epic confrontations in philosophy they have fueled. Those attracted to the empiricist stance are generally skeptical of the need to explain the observable world in terms of underlying realities at all, 87

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let alone well. Why attempt to explain things that are fairly evident in terms of other things whose putative natures are inevitably much less clear? On the flip side, those attracted to the metaphysical stance are generally optimistic about the prospects of describing underlying realities and greatly value the explanations these descriptions provide as furnishing, in some cases, genuine insight into what the sciences are revealing about the nature of the world. Explanatory power can serve as a massive counterweight to a lack of empirical vulnerability in dissolving epistemic risk, but only if it does, in fact, have weight. And if it does, the question of precisely how much weight it should be given is a very difficult one to answer univocally, as we will see. Ultimately, epistemic risk is determined by weighing the contributions of empirical vulnerability and explanatory power. The resulting determination is what yields an answer to the question of how far a given exercise in ontology is from the ground of empirical inquiry and, in turn, the question of whether the norm of naturalized metaphysics has been satisfied.

3.5 ON THE DISTINCTION BETWEEN THEORIZING AND SPECULATING Having spelled out the metaphors in terms of which the idea of naturalism figures in scientific ontology, we are now in a position to see how, more precisely, the notions of grounding and distance play out in arguments concerning empirical vulnerability and explanatory power. The issue before us is that of how trade-​offs between these factors relevant to epistemic risk can be judged in such a way as to identify supposed instances of scientific ontology as bona fide, as opposed to, at best, belonging to a different sort of philosophical inquiry or, at worst, amounting to what some authors would describe as a frivolous

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expenditure of time and energy. The assumption that there is a distinction to be drawn here is so deeply entrenched as to be taken mostly for granted. The assumption is commonly framed in terms of a distinction between theorizing, characterized as a noble pursuit in the service of human knowledge, and speculating, described as something more like a purely intellectual exercise, or even a parlor game for those locked in ivory towers, without serious implications for knowledge. Statements to this effect are pervasive. Consider Harold Kincaid’s (2013, pp. 21–​22) take on a broadly shared commitment in contemporary approaches to naturalized metaphysics: [S]‌cientific ontology goes beyond just what scientists explicitly are committed to. … However, those interpretations are still constrained by well-​established results and widely accepted standards of scientific evidence, unlike speculative ontology. So traditional metaphysics in the sense of speculative ontology has no place in an objective scientific understanding of the world.

In the remainder of this chapter, I  will contend that the putative distinction between theorizing and speculating about ontology is largely empty. There is no objective distinction between theorizing and speculating in the context of scientific ontology. At least some gentle readers may now be thinking that something has gone badly off the rails. Is it really the case that one cannot distinguish between genuine attempts to clarify scientific ontology and ineffectual attempts? Let me highlight two caveats with respect to the seemingly positive answer to this question given above, which may go some way (if not all the way) toward assuaging this concern. This is not a case of “anything goes.” In saying that the distinction between theorizing and speculating is ‘largely’ empty and that there is ‘no objective’ distinction, I  mean to suggest some recourse for those

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who are convinced of a distinction. I would not deny the legitimacy of drawing one. Rather, what I  deny is that there is a distinction; in fact, there are many, for there is no one, objective assessment of thresholds of empirical vulnerability and explanatory power, in relation to the empirical content of science, beyond which an exercise in ontology counts as genuinely scientific. Let me now illustrate this by examining three key variables in any such assessment. The first is the commonly assumed privilege of theories or hypotheses that make novel predictions, as opposed to ones that simply accommodate data that are already known. The second is the perceived susceptibility of theories and hypotheses to the (so-​called) problem of underdetermination. The third is the perceived epistemic risk associated with increasing degrees of what I will call “experiential distance.” Some scientific theories yield detailed predictions regarding their target phenomena in terms of precise, observable consequences that have yet to be investigated, or yield predictions concerning data that were available but unknown to, or simply not taken into account by, whoever formulated them. It is commonly held that theories that make such ‘novel’ predictions are more empirically vulnerable than theories that do not. When novel predictions are borne out in observations and experiments, the relevant theories are deemed to have passed a test of empirical vulnerability that lowers the epistemic risk associated with them. Conversely, when theories make no novel predictions, but only predictions of data that were already known and taken into account in formulating the theories themselves—​in some cases, being formulated precisely to the end of making such predictions—​there is no comparable lowering of epistemic risk. One might, therefore, think it a straightforward matter simply to apply the norm of naturalized metaphysics and judge the entities described in impressive novel predictions (which come to pass) as genuine subjects of scientific ontology, in virtue of being close to the ground of empirical inquiry. By the same token, one might disqualify theoretical 90

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objects, events, processes, and properties that are proposed merely to accommodate already known data from belonging to a properly scientific ontology. This sort of straightforward qualifying and disqualifying is not what happens as a rule, however, and there are good reasons why this is so. For one thing, there is at least some controversy regarding whether evidential relations between data and theories are sensitive to the distinction between novel prediction and mere accommodation.7 But even if one were to grant the power of novel predictions (that are subsequently borne out in experience) to reduce epistemic risk—​the right thing to do, I suspect—​we have yet to factor in here the other major determinant of epistemic risk, namely, explanatory power. In principle, if the explanatory power of a theory or a hypothesis in relation to the relevant empirical phenomena is sufficiently great, it may reduce the epistemic risk involved to such an extent that it overrides considerations of novel prediction versus accommodation. This much is clear in principle, but what about in practice? What one finds in practice is that there is no rule to which one can appeal to deliver unequivocal verdicts concerning the impact of explanatory power on epistemic risk in specific cases. The awe-​inspiring unificatory power of the idea of natural selection in evolutionary biology, which brings a huge wealth of data from paleontology to population genetics into a common theoretical framework, is undoubtedly the primary reason for its acceptance as scientific fact, despite its relative inefficacy for making precise predictions due to the uncontrollable effects of other biological processes at work in evolution. Unification, recall, is one of the hallmarks of

7.  Horwich 1982, chapter 5, and Schlesinger 1987, for example, emphasize predictive power over novelty in assessing evidential strength. For representative arguments in support of the view favoring novel prediction over accommodation, see Lipton 2004/​1991, ­chapter 10, and Leplin 1997.

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good explanation. But even the amazing unificatory power and, hence, explanatory power (not to mention predictive successes) of the Standard Model in particle physics, collecting electromagnetic and strong and weak nuclear interactions into a single theoretical framework, is insufficient to convince some who adopt the empiricist stance that the particles and forces there described are aspects of scientific ontology. Shifting from the explicit subject matters of science, like biological mechanisms and physical forces, to the implicit subject matters of science, like laws and properties, the same diagnosis applies. Most theories of the nature of scientific properties (we will examine some in chapter 4), for instance, offer no novel predictions and are completely invulnerable to empirical testing. And yet, there is no unassailable criterion on the basis of which to rule them in or out as instances of scientific ontology. Explanatory power, and its significance for epistemic risk, is indefeasibly in the eye of the beholder. Exactly the same moral emerges from reflections on the nature of underdetermination in the context of scientific ontology. The notion of the underdetermination of theory by data, originally inspired by extrapolating work by Pierre Duhem (1954/​1906, chapter 6) and Quine (1953, chapter 2), suggests that any given set of empirical data is compatible with different theoretical accounts of underlying entities whose natures and behaviors might explain it. This may lead to skeptical worries about believing any one account given that no choice between rivals can be determined on the basis of the data alone and, inevitably, in reply, considerations of explanatory goodness are telling.8 Acknowledging this, some naturalistic metaphysicians appear to suggest that paying attention to 8.  This points to larger debates that I cannot engage here. Underdetermination is sometimes cited as a reason to doubt scientific descriptions of unobservables generally, and this is hotly contested. Relatedly, it would seem that scientific ontology is contingent on a reply to concerns about different accounts of the data in the form of historical discontinuities in scientific knowledge. For recent versions of the view that historical discontinuity is compatible

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“degrees” of underdetermination will furnish a criterion with which to demarcate genuinely scientific ontology, for it may appear that at least some metaphysical inferences, though underdetermined by our current data, stand a good chance of becoming empirically evaluable in due course via the extension of experimental instruments and techniques. Thus James Ladyman (2012, p.  46) holds that ‘[w]‌e have inductive grounds for believing that pursuing simplicity and explanatory power in science will lead to empirical success, but no such grounds where we are dealing with distinctively metaphysical explanations, since the latter [are] completely decoupled from empirical success.’ As we have seen, however, attempting to differentiate metaphysical inferences that enjoy low epistemic risk purely on the basis of empirical vulnerability is doomed to fail. Those inclined toward a strict empiricist stance draw the line separating out aspects of putatively scientific ontology, worthy of belief, in a different place than less strict empiricists, whose domain of scientific ontology is larger but still small in comparison to those who adopt a modestly metaphysical stance, who themselves are conservative in comparison to those who are more metaphysically optimistic. These differences are a function of differing assessments of the epistemic potency of explanatory power. Indeed, the challenge facing anyone who seeks a rigid demarcation criterion for scientific ontology is even more severe than this suggests, for as I  have argued, scientific practice underdetermines metaphysical inferences and their conclusions across the board. It would be a mistake to think that naturalized metaphysics, which aspires to metaphysical theorizing that is based on

with partial continuity (which might then serve as a basis for scientific ontology), see Worrall 1989, Psillos 1999, French 2006, and Chakravartty 2007. For a different approach to identifying the most defensible parts of physics in particular, see Ney 2012, and for caution regarding metaphysics in connection with physics, see Monton 2011.

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or constrained by empirical inquiry, can ever produce conclusions that are entailed by scientific practice. Metaphysical inferences, whether they are close to the ground of empirical investigation or further away, are not somehow implicit in the data, simply waiting to be revealed. They are interpretations and explanations of the data. The ways in which empirical vulnerability and explanatory power factor into assessments of epistemic risk also helps to illuminate a third and final way in which many would like to demarcate scientific ontology, in terms of degrees of what I earlier labeled ‘experiential distance.’ Seated at my desk, I can hear a baby laughing directly beneath my office in the apartment below. The baby is detectable by me using only my unaided senses and, consequently, her experiential distance in relation to me is small. The electrons whizzing around inside the liquid crystal display of the computer monitor I am staring at presently are not detectable in this way: their experiential distance is greater; I would need to rig up some instruments in order to detect them, indirectly. These instruments would mediate the connection between the electrons and my senses. In some cases the experiential distance is so great that such mediation is impossible, as when undetectable objects, events, processes, and properties are simply posited for theoretical or explanatory reasons. In the 1930s, Enrico Fermi and Wolfgang Pauli hypothesized the existence of a new subatomic particle, the neutrino, to allow for conservation of mass-​energy and angular momentum in certain processes of atomic decay. The neutrino was undetectable at the time, but became detectable in experiments two decades later by Frederick Reines and Clyde Cowan, which thereby reduced their experiential distance. It is not uncommon to find the limits of scientific ontology described in terms of experiential distance. At a certain point, the

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distance is judged to be sufficiently great that empirical vulnerability is seriously compromised. That said, and as we have noted, how one judges the spectrum of magnitudes of metaphysical inference in terms of epistemic risk is very much a function of the attitude toward explanatory power that is partially constitutive of one’s epistemic stance. Many putative subject matters of scientific ontology are not merely undetectable now but are very likely undetectable in principle. Presumably there will never be a means by which to detect empirically whether laws of nature are simply regular patterns as opposed to something more metaphysically meaty, such as relations between certain kinds of properties. Neither will we ever be in a position to detect other possible worlds, conceived as concrete entities that are causally inaccessible to us, whose existence is entertained by some who theorize about them as a guide to scientific ontology in the actual world. But neither will we ever be in a position to detect directly (let  alone observe, given the configuration of our sensory modalities) the non-​Euclidean geometry of spacetime, as opposed to inferring it on the basis of the central role this supposition plays in the theoretical framework of our best physics. Metaphysical inferences will always require leaps of epistemic faith from the data of observation and experience, no matter how they are naturalized. There will always be ultimately irresolvable differences in assignments of epistemic risk based on subjective differences in assessments of the interplay between empirical vulnerability and explanatory power in particular cases. Understanding the norm of naturalized metaphysics requires an appreciation of the fragile yet undeniably inspirational character of our scientific quest for knowledge of the world. The sciences are complex human practices, and like anything fitting this description, their nature and epistemic significance are subjects of interpretation. Employing the conceptual tools introduced over these past few chapters, I hope that we are now

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in a position to see more clearly how different appraisals and probabilities of success associated with this quest—​rather than uniquely rational or objective determinations of epistemic risk—​generate our different understandings of what the sciences can reveal about the world via metaphysical inference. That is the nature of scientific ontology.

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PAR T II

ILLUSTRATIONS AND MORALS

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Dispositions Science as a basis for scientific ontology

4.1  HOW DISPOSITIONS MANIFEST IN THE PHILOSOPHY OF SCIENCE Part I of this book was dedicated to the task of understanding the idea of scientific ontology through an examination of the relations between science and metaphysics and the hope of combining them in the form of a suitably naturalized metaphysics. The overriding theme was that of different assessments of epistemic risk in deciding how to demarcate adventures in scientific ontology from other metaphysical pursuits. In Part II, we will turn our attention to more detailed illustrations of putative exercises in scientific ontology, with the aim of revealing how the morals of previous chapters are exemplified in cases. I will focus on what might be regarded as the two most provocative examples—​viewed in different quarters as laudable and infamous examples, respectively—​of recent metaphysical theorizing in the intended service of scientific ontology. In this chapter we will consider a prime example of the attempt to use scientific knowledge and practice as a basis from which to theorize further about ontology. In chapter 5 we will examine a case in which scientific knowledge functions not merely as a basis but also as an ostensible constraint on ontological theorizing.

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Before digging in, it is worth noting that both cases of metaphysical theorizing explored here in Part II concern what I earlier called the implicit content of scientific theories, models, and experimentation—​that is, content regarding things that, while seemingly important, are generally mentioned in passing as opposed to being the explicit subjects of direct scientific investigation. The motivation for focusing here on this more implicit content is twofold. First, the status of the more explicit content, including the existence of unobservable scientific entities such as electrons and molecules of DNA as well as their properties, has been the focus of specific debates between scientific realists and antirealists of various stripes for a very long time. These debates are certainly part of the larger landscape of thinking about scientific ontology, but since there is already a vast literature exploring this more specialized terrain featuring well-​developed arguments and counterarguments, it will be more illuminating here, I think, to focus our attention on examples of implicit content, which have received significantly less attention, comparatively, until recently. Second, given that this implicit content is widely considered to engender greater epistemic risk, it is all the more controversial and, as a consequence, especially juicy and thereby (hopefully) more starkly exemplary of morals for scientific ontology. Thus we come to the subject of this chapter:  the invocation of a particular kind of property, dispositional properties, in interpretations of scientific knowledge and practice. The term ‘disposition’ is one of a handful of terms used to describe the ancient idea of a “causal power,” namely, a property that empowers something to behave in the way or ways that it does. Other terms commonly used in this way, such as ‘capacity,’ ‘propensity,’ and ‘tendency,’ are sometimes employed by philosophers with careful distinctions in mind, but for our purposes the subtleties are immaterial, and I will simply use the term ‘disposition’ as a surrogate for the idea of a causal power in what 100

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follows. According to the standard history of the career of disposition concepts in descriptions of the natural world, after a heyday in Aristotelian and medieval scholastic philosophy, dispositions fell on hard times in early modern natural philosophy. Like a phoenix with a propensity to rise from the ashes, however, dispositions have made a serious comeback in much recent philosophy of science. As one might expect, the merits of this comeback are highly contested. Our target here is the currently debated status of ontologies of dispositions in connection with the sciences. Historically, the most popular argument in favor of dispositional properties has been the contention that by positing their existence, one gains explanations of phenomena whose explanation seems important and which would be lacking otherwise. This argument is familiar, of course, from a number of long-​standing disputes in metaphysics. Why do entities behave in regular or law-​like ways or figure in the same sorts of causal relations in similar circumstances? Why is it reasonable to believe that such regularities would obtain in various counterfactual circumstances? One answer to these questions is that things are disposed to behave in these ways, in virtue of their dispositional properties. The ideas that having such explanations is important and that an ontology of dispositions is in fact explanatory, however, are controversial. Many who are inclined toward the empiricist stance reject the demand for explanation here generally, and explanations in terms of dispositions in particular. On the general point, one might hold that the desire for such explanations is inappropriate—​perhaps there is simply nothing to be said beyond the fact that there are such phenomena, because (as per Hume) there are no necessary connections between ‘distinct existences’ (states of affairs) of the sort suggested by dispositional properties. On the specific point, perhaps these explanations are undesirable because the very concept of a disposition is too mysterious or occult to be helpful in explanation. 101

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In the context of the sciences, the disputed benefits of believing in dispositions go well beyond those associated with the traditional metaphysical issues to which I have just alluded. With the notion of a scientific ontology firmly in view, my aim in this chapter is to focus on recent arguments for the reality of dispositions arising in the philosophy of science.1 In the next section we will consider what might be described as a triumph of unification in debates about how best to formulate the idea of scientific realism, where the invocation of dispositions suggests a synthesis of two leading versions that are generally viewed as diametrically opposed, as well as a beautifully unified account of the core metaphysical assumptions of scientific realism itself. Next, we will examine the putative requirement of an ontology of dispositions in order to make sense of scientific practices of explanation and the extrapolation of knowledge concerning “isolated” systems into non-​isolated domains. Finally, we will investigate the possible use of dispositional property ascription in resolving a serious challenge to the integrity of scientific knowledge stemming from the frequent use of apparently incompatible scientific descriptions of one and the same phenomenon. As we will see, while the arguments are new, the ancient oppositions between stances including those associated with empiricism and metaphysical inquiry are never far away. In preparation for these arguments to come, it will be helpful to have a better sense of what it means to posit the existence of dispositional properties or, as I will put it, to be a dispositional realist. Dispositions are generally described in contrast to ‘categorical’ properties:  dispositional properties are usually characterized in terms of what happens to things having these properties under certain

1.  This focus on metaphysical issues arising distinctively in the context of the sciences is also exemplified in contributions to further topics which exceed my ambitions here, such as in Bird 2007 and Morganti 2013.

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conditions, and categorical properties are usually characterized in terms of the static features of things, without reference to any further happenings or conditions. Everyday examples of dispositions are properties like fragility and solubility, which are described in terms of what typically happens to things having these properties when they are treated roughly (they break) and placed in solvents (they dissolve), respectively. Everyday examples of categorical properties are dimensions (e.g., length, area, volume), shapes (e.g., square, cylindrical, tetrahedral), and configurations or arrangements (e.g., a given molecular structure). The intended difference here is that between properties whose natures are properly described in terms of the powers they confer on the things having them to behave in particular ways in particular circumstances, and properties whose natures involve no such empowerment. This is an ontological distinction.2 It is important to note, however, that the use of dispositional language, including the ascription of dispositions to various entities, does not entail a realism about dispositions all by itself, because many who are happy to ascribe dispositions to things also maintain that this sort of talk should be given a purely linguistic interpretation, as opposed to an ontological one.3 J.  L. Mackie (1973, ­chapter 4.2), for instance, held that dispositional ascription is simply a way of describing categorical properties—​that is, in terms 2.  Having made this distinction, there are several possibilities for dispositional realism. Some hold that dispositional properties are “anchored by” or “grounded in” categorical properties, without which the former would be ontologically unstable or incomplete. Some hold that dispositions can exist without being grounded (independently of whether categorical properties exist). Some hold that one and the same property has both categorical and dispositional aspects (see the discussion of Martin’s view in Armstrong, Martin & Place 1996, and Heil 2003, ­chapter 11). The discussion of dispositional realism to follow is neutral with respect to these options. 3.  Relatedly, for a history of attempts to define disposition concepts using conditional statements, thus analyzing them away in favor of categorical predicates and properties, see Malzkorn 2001. There is no clearly unproblematic account of this sort (cf. Mumford 1998, chapter 3, and Bird 2007, ­chapter 2.2), but the semantics of dispositional terms is hardly straightforward even for the dispositional realist (see Lipton 1999).

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of the sorts of behaviors typical of things having those categorical properties—​and not suggestive of a separate ontological category of properties per se. On this view, dispositional descriptions are co-​extensive with categorical descriptions; they pick out the same things in the world. For example, in a given context, ‘soluble,’ a linguistic predicate that may appear to name a dispositional property, is actually elliptical for a given molecular structure, which is a categorical property. On Mackie’s view only categorical properties are real, but one can describe them in different ways, and these different descriptions reflect a distinction between predicates only, not a distinction between ontological categories. Thus, a linguistic acceptance of dispositional predicates must be distinguished from an ontological acceptance of dispositional properties. With this wrinkle in mind, let us proceed to consider what work dispositions can do for interpretations of science.

4.2 EXPLANATORY POWER I: UNIFYING ASPECTS OF SCIENTIFIC REALISM Perhaps the most central epistemological debate in the philosophy of science is the perennial conflict between scientific realists and antirealists. This debate concerns the question of how best to understand the knowledge that is embodied in scientific theories and models, and as we will see, the metaphysical posit of dispositional realism forges some significant overall unity between what would otherwise remain disparate elements of widely discussed aspects of scientific realism. Thus, it is hardly surprising, perhaps, that a number of proponents of scientific realism have made dispositions the cornerstone of their view. This unity comes in two distinct forms, the first of which is a surprising rapprochement (partial but nonetheless impressive) between two of the leading versions of scientific realism 104

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which, absent dispositional realism, appear to offer entirely incompatible conceptions of scientific knowledge. The versions of realism at issue, entity realism and structural realism, were introduced briefly in chapter 1. A second instance of unification here fuses together the component parts of many scientific realist accounts of knowledge concerning scientific properties, causation, laws of nature, and categories of scientific classification. Let us consider the role played by dispositional realism in each of these cases, in turn. Scientific realism, recall, to a first approximation, is the view that our best scientific theories and models correctly describe (or describe in a way that is “close to” the truth, if not wholly or precisely true) both observable and unobservable features of the world. Recall further that one of the most widely cited challenges to scientific realism is the pessimistic induction: the argument that given the historical record of past theories that enjoyed significant acceptance and empirical success only to be replaced in due course by newer theories that often differ substantially in their descriptions of unobservable objects, events, processes, and properties, comprising a record of ontological discontinuity over time, one should be skeptical about scientific realism even in the present. Among the many replies to this concern, the most common response has been to refine scientific realism in such a way as to suggest that while it is the case that some successful theories have ultimately proven false, the success they enjoyed is usually attributable to the fact that aspects of these theories were and are, in fact, true (or close to the truth; I will dispense with this qualification henceforth). By being more discriminating, the more selective scientific realist hopes to identify particular aspects of theories that are better warranted than others and thus, eo ipso, more likely to stand the test of time. In chapter 1 we considered a highly influential form of realism, entity realism, the view that when one’s putative causal knowledge of an entity is sufficiently detailed as to allow apparently successful 105

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manipulations of it and, even more impressively, the ability to use the entity itself as an experimental tool to intervene on other things, belief in it is warranted. Entity realists are typically skeptical regarding other aspects of theories, thus affording a response to the pessimistic induction: many past (and present) theories may be false, but under the right conditions it is reasonable nonetheless to expect continuity across theory change regarding certain ontological commitments. Conversely, in recent years, another form of selective realism, structural realism, has come to significant prominence. Structural realism is likewise selective, but in contrast to entity realism it offers a rather different prescription for knowledge:  what our best theories truly describe, it says, are not entities but rather the structure of the world, including that of the unobservable world, often in terms of relations between entities (a detailed consideration of this view is coming in chapter 5). Note that structural realism affords an answer to the pessimistic induction that seems diametrically opposed to the one suggested by entity realism. The structural realist endorses only the structural or relational aspects of our best theories and expects to see continuity there, while throwing the entities that ostensibly stand in these relations under the bus. It is here, I  believe, that dispositional realism can be harnessed with dramatic effect, saving realist blushes by unifying the best insights of entity realist and structural realist approaches to scientific knowledge. The most compelling insight of entity realism is its exemplification of the principle that our best bet for knowledge in the scientific domain comes from interacting with the world. The greater one’s ability to act in such a way as to affect something, to manipulate, to intervene, often in highly intricate and amazingly detailed ways, the better the warrant for the existence of the relevant entity or entities, causal knowledge of which underlies one’s ability to act in these ways. However great or small this warrant may be, it seems only reasonable to think of it as enhanced by this kind of interaction. 106

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Conversely, the most compelling insight of structural realism is its recognition of the fact that certain relations described by theories, often in the form of mathematical relationships between certain parameters, are often preserved in some form or other as theories are revised over time.4 Given that descriptions of these relationships often continue to serve fruitfully in scientific predictions and explanations even when underlying ontologies appear to shift, it seems only sensible that the scientific realist should invest some epistemic warrant there too. The scientific realist thus has serious motivation to join the seemingly disjoint forms of selectivity suggested by entity realism and structural realism. Enter dispositional realism. Dispositions are quintessentially causally relevant properties—​they empower the things that have them to behave in certain ways in certain circumstances. According to the dispositional realist, masses, charges, accelerations, chemical valences, volumes, and various other properties of scientific interest can be described in terms of the dispositions of things to behave in certain ways in the presence or absence of other properties. The property of mass confers, inter alia, the disposition of a body to be accelerated when it is subject to a force. The property of volume possessed by a gas confers, inter alia, the disposition of that gas to become more highly pressurized when it is heated. It is precisely this sort of knowledge that entity realists hold to be important in establishing the existence of certain kinds of entities, for it is this sort of knowledge that allows one, ex hypothesi, to detect and manipulate the entities in specific ways and to use them to interact with other entities. Knowledge of the relevant dispositions underwrites all of these interactions and thus, dispositional realism and entity realism are easily woven together. So far so good. 4. For some nice case studies of structural continuity, see Post 1971 and French & Kamminga 1993.

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From here it is a short step to the idea that the very knowledge of dispositions used to explicate entity realism is tightly interwoven with a knowledge of structures, as advocated by structural realism. Dispositional realism, after all, characterizes properties of scientific interest as dispositions for specific kinds of relations—​a knowledge of which facilitates experimental detections, manipulations, and interventions. The behaviors that entities display in virtue of the dispositions they possess are generally described in scientific theories and models as relations, often in the form of mathematical equations, for example, relating variables whose values are magnitudes of the relevant properties. Dispositional realism reveals an intimate connection between properties of scientific entities and their structural relations and, in this way, the most compelling insights of entity realism and structural realism are fused together: the kind of knowledge that is required in order to interact with unobservable entities in highly systematic ways, as per the former, is structural knowledge, as per the latter. Dispositions are dispositions for relations. Structures are “encoded” in the properties of entities, because these properties confer dispositions for precisely those relations that the sciences describe in terms of structure. Dispositional realism thus facilitates a rapprochement between the best insights of entity realism and structural realism. There is another way in which invoking dispositions in the sphere of scientific realism does striking explanatory work, and this further work may also be viewed in terms of unification. It is common in scientific realist discussions of scientific knowledge to hear claims to the effect that the sciences reveal information concerning a number of features of the world; not only entities, properties, and relations, but also causal processes, laws of nature, and the numerous categories of things that populate the natural world. A  little reflection on the natures of these bits of ontology would remind us that they are all subjects of metaphysical presupposition and inference 108

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(as discussed in Part I), and while they mostly comprise the implicit content of scientific theorizing, modeling, and experimentation, they are explicitly center stage in descriptions and defenses of scientific realism. Dispositional realism furnishes a unified ontological framework for these different metaphysical concepts, and as we have noted on several occasions now, the ability of a theory to unify phenomena that would otherwise remain disparate is generally considered an explanatory virtue. The organization of the metaphysical concepts underpinning scientific realism into a unified ontological framework is, I submit, no mean feat, and as we will see, the hypothesis of dispositional realism achieves it with notable elegance. Let us begin once again with the observation that ‘disposition’ is typically regarded as a causal concept par excellence. A number of different descriptions of the nature of causal interaction are compatible with a realist attitude toward dispositions, but one such view naturally suggests itself: entities are engaged in continuous processes of causal interaction in which the dispositions they possess are manifested in accordance with the presence and absence of other entities and properties. Entities with disposition-​conferring properties are, on this view, in a continuous state of causal interaction, a state in which relations between the relevant properties obtain.5 Consider, for example, a sample of gas that comes into contact with a source of heat. The gas expands in virtue of the dispositions it possesses, conferred by properties such as volume, temperature, and pressure, and in accordance with their relations to the properties of the heating source. As it expands into other regions of space the gas may encounter further entities and properties. The property instances present in these new regions together with those of the original sample determine how

5.  For an elaboration of this sort of view, see Chakravartty 2007, chapter 4. Though different in important respects, a process-​type view of causation and dispositions is also presented in Mumford & Anjum 2011.

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both are further affected, and so on. In this way, dispositional realism can be employed to unify our concepts of entities and properties with the causal processes in which they participate. With some such understanding of causation in hand, the scientific realist is then nicely placed to offer an integrated account of laws of nature and scientific categories, or kinds. The idea of “natural” kinds, which suggests that nature comes prepackaged into objective categories of things, has a long and storied history. But quite independently of whether one subscribes to this particular view of kinds, arguably the primary motivation for theorizing about them more generally, among scientific realists, is to connect the classificatory practices of our best sciences to successful practices of inductive generalization and prediction regarding the observed natures and behaviors of the members of these categories. A number of philosophers have suggested that the primary goal of scientific systematizations of nature into categories is to demarcate groupings of things that allow for reliable generalizations and predictions of scientific phenomena (cf. Kornblith 1993, Boyd 1999, Hacking 2007, Magnus 2012). The ambition here is to explain how taxonomic practices in the sciences facilitate this success. As we will see, this connection between taxonomies of kinds and successful inductive practice is suggestive of a further connection between scientific categories and laws of nature—​in terms of dispositions. It is presumably because of the fact that the members of a given kind share certain properties and behaviors that they are grouped together, and it is precisely this sort of knowledge regarding specific classes of entities that is traditionally identified with laws. Now, a neatly unified account of kinds and laws follows immediately from dispositional realism and the concomitant view of causation described above, for in the sciences, statements of laws are often simply descriptions of relations between properties (e.g., Newton’s second law of motion, F = ma; the ideal gas law, PV = nRT). In these 110

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expressions, as noted earlier, relations between properties are often described mathematically, with variables representing the properties in question, and where properties are shared across the members of a kind, the dispositions these properties confer generate shared behaviors. Of course, sometimes laws are stated more directly in terms of the behaviors of members of kinds (e.g., ‘things having opposite electrostatic charges attract’) rather than in terms of relations between properties as such, but for the dispositional realist this works just as well, because once again, the properties shared by the members of these kinds dispose them to behave in the shared ways they do. In this way, dispositional realism unifies talk of properties not only with talk of causation but also with talk of kinds and laws. The unificatory work made possible by the hypothesis of dispositional realism in discussions of scientific realism is remarkable. But now one may ask: what does all of this unification buy? The astute reader will have noticed just how many metaphysical inferences were taken for granted here in bringing dispositional realism to bear. In order that one find the unification of aspects of entity realism and structural realism impressive, presumably one must already find the idea of scientific realism in some such forms attractive or defensible, but since this requires the prior acceptance of a number of metaphysical inferences, there is an air here of preaching to the converted. Similarly, unless one is already seriously invested in the metaphysical concepts I have identified as important to defenses of scientific realism (properties, causation, kinds, laws), the fact that they can be unified by means of dispositional realism might well strike one as fanciful as opposed to a revelation of naturalized metaphysics. The impressiveness of the unifications facilitated by dispositional realism in this arena is subject to the calculus of epistemic risk: the weighing of empirical vulnerability and explanatory power. There is no empirical observation that tells in favor of dispositional realism or against it. Hence, here, explanatory power is king, and the epistemic 111

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potency of this power in connection with dispositional realism has long remained a matter of unresolved disagreement.

4.3 EXPLANATORY POWER II: GIVING SCIENTIFIC EXPLANATIONS Admittedly, there is one approach to thinking about dispositions that threatens to nullify my contention that there is no empirical evidence that is telling with respect to dispositional realism. Traditional metaphysical disputes pitting the reality of dispositional properties against deflationary analyses of dispositional ascription have waxed and waned for centuries now, and one might be forgiven for thinking that this dialectic is a prime example of a philosophical stalemate. Interestingly, however, recent philosophy of science has generated different arguments for the reality of dispositions which depart from their predecessors.6 These newer arguments generally take the form, explicitly or implicitly, of transcendental arguments (cf. Clarke 2010). Generically, the first of two premises in a transcendental argument, call it P1, asserts something that is readily accepted as evident on the basis of experience or otherwise uncontroversial, perhaps even undeniable. The second premise, P2, is an assertion to the effect that in order that P1 be true, some other less obvious and usually controversial assertion, Q, must be true. In the present context, P1 is presented as an unobjectionable claim regarding an aspect of scientific practice, namely, some common explanatory practice. P2 is the claim that the giving of the relevant explanations presupposes Q, the reality 6.  I would distinguish these arguments from another involving science, about whether the dispositions associated (by some authors) with elementary particles in physics can exist independently of categorical properties. For a discussion of the latter issue with comprehensive references to earlier discussions, see Williams 2011. My focus here is on the prior question of whether there are dispositions at all.

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of dispositional properties. The conclusion, then, is dispositional realism. These arguments concerning explanatory practice in the sciences come in two flavors, and I will consider each of them in turn. The first focuses straightforwardly on explanations of scientific phenomena and admits of a couple of distinct sub-​flavors, which I will label the dispositional regress argument and the dispositional exercise argument, respectively. The second sort of explanatory practice that is germane here concerns worldly phenomena more obliquely, focusing in the first instance on the methodological issue of explaining how abstract descriptions and models in the sciences are applied to systems of interest in the world. Let me call this the argument from abstraction. The dispositional regress argument starts with the common recourse to dispositional concepts in explaining the behaviors of entities investigated by the sciences. In elaborating these explanations, it is not uncommon to hear the word ‘because’ used immediately prior to the ascription of a disposition. Many chemical reactions in the cells of living things, for example, only occur at the rates that are required to sustain the life of a cell because they are, when necessary, catalyzed (accelerated) by enzymes—​molecules disposed to enhance the rates of these reactions under certain conditions. It is reasonable, of course, to seek to unpack this dispositional explanation in terms of a finer-​grained description of the relevant phenomenon; in this case, in terms of the precise biochemistry of how a given enzyme lowers the activation energy of a given reaction so as to accelerate it. In this manner, one might hope to dissolve apparently dispositional explanations into finer-​grained explanations that cite only categorical properties. The dispositional regress argument maintains that however one attempts to dissolve dispositional explanations, finer-​grained explanations inevitably invoke yet further dispositions. In the process, the unpacking of dispositional explanations simply results in a regress of appeals to dispositional properties. 113

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Consider an example suggested by Brian Ellis (2001, pp.  115–​ 116), concerning the scientific explanation of the brittleness of a crystal. Clearly, brittleness seems like a dispositional property, associated with things that are hard but which break or shatter easily under certain kinds of stresses. Citing the internal geometry of a crystal, one might hope to explain its brittleness in terms of its planar structure, which many would consider a categorical property. However, this by itself would not explain why the crystal is brittle. One would have to add that the crystal is highly disposed to break along some of these internal planes, the cleavage planes, under stress. Perhaps this further disposition talk could be replaced with further information regarding electromagnetic bonding forces, which are substantially less between cleavage planes than elsewhere in the internal structure of the crystal, and again, one might conceive of the magnitudes of the relevant forces as categorical properties. But even here, in order that one have an explanation, one must presumably add something about the different dispositions of attraction that hold between different planes, which are correlated with different magnitudes of force. The pattern here seems iterable, and Ellis (p.  116) concludes that ‘there never seems to be any point at which causal powers can just drop out of the account.’ In order to explain why the crystal is brittle, one inevitably makes recourse to dispositional properties. Now, is this recourse to dispositional realism really inevitable, as suggested above? It is, no doubt, a substantive matter whether these explanations must be couched in terms of dispositions at all, but for the sake of argument let us grant that there are contexts of scientific explanation in which dispositional ascription is not merely useful or colloquial, but indispensable. Even on this assumption it is unclear why dispositional realism should follow, for as we have noted, even skeptics about dispositions routinely use dispositional language, where convenient, without thereby committing themselves to the reality of dispositional properties. Having adopted this sort of 114

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linguistic deflationism, even assuming the indispensability of dispositional language, one commits only to an acceptance of dispositional predicates. For again, dispositional description can always be taken as elliptical for categorical description, whether or not science has yet revealed a description that would qualify as the latter. Thus it appears that the dispositional regress argument is another instance of preaching to the converted. It strikes a chord among those sympathetic to dispositional realism, but even under a most charitable interpretation, it succeeds at best in establishing the necessity of a linguistic acceptance of dispositional predicates as opposed to an ontological acceptance of dispositional properties. A second argument premised on scientific explanations of target phenomena in the world, the dispositional exercise argument, focuses on the striking fact that sometimes ostensibly dispositional properties are described as “acting” (i.e., presently being causally efficacious), even in the absence of an observably manifest behavior. Let me use the term ‘exercising’ to label this idea of a disposition being active, or being triggered, quite independently of whether a manifestation is evident. Thus, we might speak of a disposition (or an entity having this disposition) exercising its power, or of the power associated with that disposition being exercised. Consider an example of this described by Nancy Cartwright (2009, pp. 151–​155): two negatively charged particles whose gravitational attraction, which they experience in virtue of their mass, is exactly balanced by their electrostatic repulsion, which they experience in virtue of their charge. It seems uncontroversial to describe this situation as one in which the dispositions to attract, gravitationally, and the dispositions to repel, electrostatically, are exercised. Indeed, this is the basis of an explanation of why the particles do not move with respect to one another, despite the forces in play. It is because the associated dispositions of attraction and repulsion, while exercised, are equal and opposite to one another, that there is no manifest motion. 115

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How does this amount to an argument for dispositional realism? Cartwright suggests that if one does not appeal to the notion of dispositions exercising without manifesting, one is left without an explanation of what is going on in cases like this, where a balance between forces and, ex hypothesi, associated dispositions produces a situation in which the manifestations typically associated with those dispositions are absent. That the manifestations are absent in the present case seems clear: it would seem peculiar to describe this example as one in which the relevant manifestations associated with mass and charge—​motions in line with gravitational attraction and electrostatic repulsion, respectively—​are both manifested. After all, in this case, there is no motion whatsoever. Thus it appears that an explanation of what is going on requires an appeal to the exercising but not the manifestation of the relevant dispositions. The result is an argument for dispositional realism, for dispositions are the only sorts of properties that are capable of exhibiting this fascinating behavior of exercising without manifesting. The very notions of exercising and manifesting are alien to descriptions of categorical properties, since unlike the natures of dispositions, the natures of categorical properties are not described in terms of happenings—​like exercising or manifesting. Once again, however, as in the case of the dispositional regress argument, there is something slippery about the dispositional exercise argument. Clearly, the explanation just given of the stationary behaviors of the two particles may appeal to the dispositional realist, but there is nothing here, I suggest, that compels an ontological commitment to dispositional properties. On reflection, while the explanation given succeeds in drawing one into a story about the nature of dispositions, it is far from clear that this particular story is the right one to tell. The appeal to notions such as the exercising and manifesting of dispositions is not an option for dispositional skeptics. What might they say instead? From the perspective of the skeptic, it is far 116

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from clear that there is anything here that requires explanation. From the perspective of someone who adopts the empiricist stance and is suspicious of the ontological import of disposition talk, for instance, there are no dispositions whose apparent inabilities to manifest can result in perplexity, which is then resolved by theorizing about how dispositions are exercised. Rather, there are simply states of affairs that follow one after the other. When there are net forces, there are motions. When there is no net force, as in the case considered here, there is no motion. That is simply the way things are. There is no further demand for an explanation. Earlier I mentioned that arguments for the reality of dispositions based on considerations of explanatory practice in the sciences come in two forms. Having reviewed arguments that focus on explanations of scientific phenomena directly, let us turn now to the second, more indirect form, associated with what I earlier called the argument from abstraction. ‘Abstraction’ here refers to a selective attention to certain features of a target system of scientific interest for purposes of modeling or experimentation. The phenomena we hope to understand are often complex, and efforts to grapple with them scientifically often take the form of model building that focuses on certain parameters and ignores others that may be relevant to the system’s behavior, and experimental setups in which only the relationships between certain parameters are studied and the experimental system itself is shielded from other, potentially interfering factors. The argument here is again transcendental, but this time focused on explanations of the efficacy of scientific methodology in cases of abstraction. The basic idea is that the effective use of abstractions in scientific practice would be inexplicable were it not for the fact that they yield information about dispositions. Roy Bhaskar (1975) was an important early advocate of the argument from abstraction though, to be fair, he did not himself elaborate much support for the conclusion. What Bhaskar did is turn a 117

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spotlight onto what he called the “closed” conditions under which scientists routinely attempt to learn about specific causal relationships in the laboratory, where effectively shielding the experimental systems from influences that might alter those relationships is crucial. In this way, experiments often abstract from naturally occurring phenomena in the world. Granting that this sort of experimentation yields knowledge of certain causal relationships, one may then wonder what this tells us about the more complex systems inhabiting the world. As a scientific methodology, abstraction is only useful beyond the laboratory if learning things under closed conditions is in some way relevant to understanding different and more complex kinds of phenomena. While keen on the idea that an ontology of dispositions would help to explain why and how causal knowledge produced in the lab can be exported to considerations of more complex systems, Bhaskar himself gave little indication of how this explanation might go. The task of spelling out the explanation has been taken up by Cartwright (1989) and, developing similar insights yet further, Andreas Hüttemann (1998, 2013), who argues that the physical laws we describe are generally abstract. As a consequence, strictly speaking, they only describe the behaviors of “isolated” systems, but as these authors note, it is nonetheless common scientific practice to apply this knowledge to non-​isolated systems. It is the efficacy of this practice of applying or bringing scientific knowledge to bear beyond the abstract contexts it describes that the argument from abstraction seeks to explain, and the suggestion here is that this explanation requires that one interpret the laws as describing dispositions. The central idea is that in explaining the behaviors of more complex systems, one often makes reference to knowledge of how parts of the system are disposed to behave in isolation. Such dispositions often play a role in the more complex situations, even if the precise manifestations they produce in isolation are mitigated or altered when 118

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combined with other dispositions. As Hüttemann (2014, p.  1721) puts it: ‘[i]‌n part-​whole explanations the behavior of compound systems is explained in terms of the behavior the parts would display if they were on their own’; these explanations ‘presuppose that the properties of the parts of the compound are dispositional properties.’ No doubt, there is a sense in which the dispositionalist’s description of the use of abstractions in scientific practice is attractive. Imagine that an enzyme that appears not to be functioning in the cells of a patient is found to catalyze the desired chemical reaction successfully in vitro. The knowledge that the enzyme is disposed to function well in more isolated circumstances may serve as a heuristically useful starting point for exploring what is going on in vivo, suggesting an investigation into the factor or factors that are interfering with the desired manifestation. But is this really an example of the successful application of knowledge generated in isolation to a more complex situation? One might think it the opposite: it is often the case that the putative dispositions of isolated systems are not manifested at all in more complex ones. Thus, while perhaps methodologically useful in some ways (for example, suggesting avenues for further research), the notion that abstract laws describe dispositions hardly guarantees success in exporting knowledge of these laws to more complex systems. Whether the knowledge at issue is applicable more broadly depends on whether conditions elsewhere are sufficiently similar to the conditions one finds in the lab, and there is nothing about a dispositional ontology that can guarantee this. And so, when it comes to explaining successful scientific practice in cases of abstraction, dispositions have mixed credentials. Be that as it may, there is a more serious difficulty with the argument from abstraction which threatens to undermine it entirely. The problem is that it is not at all clear why an ontology of dispositions is required to explain even the investigative, heuristic practices alluded to above, which one might want to count as part of a successful 119

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scientific methodology. To return to the example considered, it is unclear why talk of the disposition of an enzyme to catalyze a reaction in vitro could not be redescribed, alternatively, simply in terms of the behaviors of enzymes and their substrates instead, without any mention of dispositions as such. Behaviors like these are surely amenable to dispositional description, but they are also surely amenable, if one is that way inclined, to description simply in terms of entities with categorical properties and processes which comprise successions of events involving those entities and properties. Thus, realism about dispositions does not seem to be any sort of requirement in accounting for the methodological success of practices of abstraction in scientific modeling and experimentation. The further question of whether external conditions are sufficiently similar to the conditions under which scientific knowledge is often formulated to allow extrapolation is also one that can be answered independently of whether there are dispositions. If there were dispositional properties, simply knowing this would offer no assistance regarding the inductive challenge of working out which circumstances are favorable to their manifestations and which are not. In the course of advocating dispositional realism, Cartwright (2009) suggests that our very ability to make useful predictions and manipulate systems of interest and, thus equipped, to make good policy decisions of importance to ourselves and the world in which we live depends on the assumption that we have a knowledge of dispositions. But there is nothing here to suggest that one could not do all of these things if there were only categorical properties instead. Gilbert Ryle (1949) made a similar point long ago when he described dispositional ascriptions as ‘inference tickets.’ Their function, he said, is merely to indicate that we are licensed to make certain inferences about what will happen to things with certain categorical properties in certain circumstances. Scientific abstraction, I submit, suggests no telling argument for the reality of dispositions. 120

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4.4 EXPLANATORY POWER III: CONSOLIDATING SCIENTIFIC KNOWLEDGE Over the previous two sections, I have pondered the explanatory power of dispositional realism in connection with a unification of aspects of scientific realism, and with respect to explanations of certain phenomena of scientific interest and the use of abstraction in modeling and experimentation. In each case I  have concluded that an assessment of the weight of this explanatory power is susceptible to conflicting judgments, informed by prior attitudes toward the tenability of dispositional realism. In this section I will examine one final appeal to dispositional properties in interpreting scientific practice. Specifically, I  will consider the role that dispositions can play in defusing a challenge to the coherence of scientific knowledge in light of an everyday scientific practice, namely, the use of mutually inconsistent descriptions and models, across different contexts of use, of one and the same phenomenon. Seemingly incompatible models, incorporating apparently incompatible assumptions about the natures and behaviors of subjects of scientific investigation, are perhaps surprisingly common. This presents an obvious provocation to anyone who might hope to consolidate these different descriptions into unified pictures of the subjects at issue. Need one accept this provocation? The idea that theories and models sometimes yield inconsistent descriptions of one and the same thing does not worry everyone. In chapter 6 we will consider one recently popular understanding of this feature of scientific practice—​the idea of “perspectivism”—​according to which incompatibility is not properly regarded as any sort of challenge to the integrity of scientific knowledge per se. Let me simply note here that on most (even vaguely) realist conceptions of scientific knowledge, 121

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inconsistent description seems worrisome prima facie, and proceed for the moment on the assumption that resolving different and conflicting descriptions into a unified picture might be a good thing to do, if at all possible, for the sake of knowledge. It will be useful to have an example. One case discussed by a number of authors (Morrison 1999, Teller 2001, Rueger 2005) recently is that of different models of fluids, which are used in order to make predictions and give explanations of phenomena involving fluidic motion. Models that are employed to explain how water flows, or how water waves propagate, describe water as a continuous, incompressible medium. Conversely, models that are employed to explain how molecules can spread by diffusion in a fluid, like dye dropped into a glass of water, describe fluids as collections of discrete particles in motion. Thus arises an obvious challenge, for water cannot be both a continuous medium and a collection of discrete particles. The two models, on their face, would seem to attribute mutually incompatible properties to one and the same thing. In the example just given, while the behaviors considered (propagation and diffusion) are both behaviors of fluids, the respective phenomena may appear rather different. But apparent inconsistency is also sometimes evident in different displays of a single type of behavior. Take fluid propagation, for example. Models of how fluids flow around solid objects, along solid walls, and in various other ways typically adapt and apply the relevant mathematical description (the Navier-​Stokes equations) in very different ways. The result of this is, again, the apparent attribution of incompatible properties to one and the same fluid. Now, what if it were possible to translate these different and apparently conflicting descriptions of the properties of a fluid, used in different contexts of prediction and explanation, into a set of consistent descriptions of the fluid instead? This is the promise of a dispositional ontology. For a disposition, recall, is a property that is (or that confers) the power to behave in particular ways in particular 122

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circumstances, and this is compatible, of course, with things having dispositions to behave differently under different circumstances. The dispositional realist is thus in a position to translate what may appear on the surface as incompatible descriptions of a target system into descriptions of the different dispositions of that system instead. In this way, the inconsistency is revealed as merely apparent and dissolvable into attributions of dispositions for different sorts of behavior, all of which are compatible with one another. Under certain conditions, often associated with a particular explanatory context, a particular disposition may be manifested, while under different conditions, other dispositions are manifested. Water is disposed to behave in the manner of a continuous medium in some contexts (e.g., in wave propagation) and in the manner of a collection of discrete particles in other contexts (e.g., in cases of diffusion), and the dispositions of fluids to behave in these different ways are perfectly compatible with one another. Is this a case of dispositions to the rescue, or is it a trick? No doubt some will worry that the dispositional realist’s consolidation of seemingly incompatible models and descriptions comes at a cost. In our example of different models of fluids, if one reads the relevant descriptions non-​dispositionally, one does at least appear to be given a straightforward account of what a fluid is. It is an incompressible medium. Or it is a collection of discrete particles. Conversely, the dispositionalist may appear to be making a claim, not so much about what a fluid is, as opposed to a claim about what a fluid is disposed to do. This is to distinguish between the nature of a fluid and its behavior—​in the present example, what that behavior is like. Thus, in describing wave propagation, the dispositional realist does not say that the fluid is a continuous medium but rather that it behaves like one. From the perspective of dispositionalism, it is a mistake to identify (naïvely) the surface features of scientific models and descriptions with putatively categorical natures of the things they represent. 123

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One might worry that on such a view, one has sacrificed what many would naturally take to be part of the job of science: to tell us about the natures of things, about what they are. Here I believe we have returned, via an interesting but circuitous route, to the now familiar division between those who invest the hypothesis of dispositional realism with genuine explanatory power and are thus keen to admit dispositions into an ontology of science, and those who asses the weight of this power for scientific ontology rather differently. For the dispositionalist, there is no price to be paid (or at least, no price not worth paying) for their consolidation of scientific knowledge across seemingly inconsistent models and descriptions. There is no lack of ambition here to explain what the subjects of these descriptions are, for according to dispositional realism, the properties of entities of scientific interest—​on some versions of the view, many such properties, on other versions, all of them—​simply are dispositions. Thus, a description of the dispositions of something to behave in the ways it does, under the kinds of circumstances that elicit those manifestations, is unavoidably part of a description of the nature of the thing. Historically, the overriding source of suspicion regarding the explanatory force of dispositional realism has been the concern that dispositional ascription is empty with respect to ontology. It is, at best, a placeholder awaiting the development of further science, which will reveal the underlying natures of things that dispositional descriptions merely gesture toward. It may be convenient to talk about putatively dispositional properties like solubility and fragility—​ associated with manifestations of dissolving in solvents and breaking under the application of moderate force, respectively—​but these ascriptions are merely placeholders for properly scientific descriptions of some underlying facts. For example, chemistry explores the molecular structures of solutes and solvents and inter-​and intra-​molecular

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forces, which involve electromagnetic properties and types of bonds and bond angles formed between atoms, underlying behaviors such as dissolving. But now one might reasonably ask: are these suspicions about the seriousness of explanations citing dispositions telling? The existence of underlying events, processes, and mechanisms in terms of which solubility can be explained does not, by itself, entail that solubility is not a property of solutes; this latter claim is a substantive and disputed one. And even if one were to accept it, the underlying explanations might themselves involve or require dispositional ascription (recall our discussion of the brittleness of a crystal). As it happens, it is a luxury to be able to debate the question of whether talk of dispositions can be safely immunized against serious ontological challenges while at the same time having some agreed, underlying explanations ready to hand, as in the cases of solubility and fragility and brittleness. In stark contrast, some talk of dispositions occurs in situations that are remarkably resistant to scrutiny of what lies beneath. Nineteenth-​century theories of the nature and behavior of light described its propagation in terms of models that were inspired by prior understandings of the oscillations of things like water waves and sound waves. On this basis, explanations of light propagation involved the ascription of various dispositions to behave in wave-​like ways during processes of diffraction, refraction, and constructive and destructive interference. These dispositions of light to behave much like a classical waveform in these particular situations survived into subsequent theorizing about the nature of electromagnetic radiation more generally and, to bring us up to the present, work in contemporary field theory. Through all of this change and development, there is still no consensus on an underlying categorical story regarding why and how wave-​like manifestations occur in the behavior of light. Arguably, the same can be said, mutatis mutandis, regarding various properties

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of entities in physics such as the charge or spin of an electron, or the color of a quark, where all one can say about their natures is exhausted by descriptions of how things having them (are disposed to) behave, and no further insight in terms of underlying categorical natures, assuming they are there to be apprehended, are available. For the dispositional realist, to attribute the relevant dispositions of light is to describe the ontology of light. For the dispositional skeptic, to attribute these dispositions is either to invoke a placeholder for some deeper story to come, or to give an elliptical description of the ultimately categorical nature of light, stripped of any connotations of powers. Which approach to scientific ontology is correct? If the history of philosophy is any guide, there is mileage yet in a perennial debate, but one thing seems clear: there is nothing in the dispositional realist’s approach to apparently inconsistent models and descriptions that settles it. Given that our best contemporary descriptions of the natures of at least some properties are given in what seem to be exclusively dispositional terms, the dispositional antirealist’s hope of discovering the categorical properties that will eventually serve as the truthmakers of these dispositional ascriptions is something of a promissory note. But since no one thinks that contemporary science is complete let  alone wholly correct in its descriptions of the world, and since we have much to learn, a promise may be good for something. As we have seen, the concept of dispositions can be employed to do significant work in interpreting scientific knowledge and practice. In contemplating the ontology of science, the dispositionalist may view the skeptic’s deflationary approach as having all the virtues of theft over honest toil, reaping the benefits of dispositional explanation while skirting the cost of genuine, ontological commitment. From the point of view of the skeptic, however, this may be one of those occasions on which theft is a virtue.

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4.5 PROPERTY IDENTITY AND THE ACTUAL POWER OF EXPLANATORY POWER I have aimed in this chapter to examine arguments that take scientific knowledge and practice as a basis for theorizing about the implicit content of scientific theories and models, specifically concerning the hypothesis of dispositional realism. Given the invulnerability of this hypothesis to empirical testing, is its explanatory power sufficient to earn dispositions a place in a scientific ontology? In all of the considerations we have mulled over, focusing on the role of dispositions in unifying aspects of scientific realism, in giving explanations, and in consolidating seemingly inconsistent descriptions of phenomena of scientific interest, one answer to this question has prevailed: different conclusions are viable, fueled by prior commitments suggestive of the empiricist and metaphysical stances described in Part I, with their concomitant attitudes toward demands for, and the value of, certain kinds of explanation. This reflects my earlier suggestion that it is only in virtue of the philosophical intuitions one brings to bear in interpreting the outputs of the sciences that one is able to formulate a scientific ontology. Is this all that one can say? While I suspect that, at the level of some basic intuitions, there is an irresolvable impasse between the dispositional realist and antirealist with respect to traditional metaphysical arguments and the arguments from science canvassed here, one last strategy for a possible resolution remains. I have argued that scientific knowledge and practice are compatible with both realism and antirealism about dispositions, but this leaves open the possibility that, nevertheless, these positions are not equally suited to or appropriate to the context of the sciences. Those who are drawn to the empiricist stance often suggest that the empirical invulnerability

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of the hypothesis of dispositional realism renders it foreign or alien to the context of the sciences, and this fits nicely with their discounting of the kinds of explanatory power that are championed by dispositional realists. In closing this chapter let me consider an argument to the contrary, to the effect that it is, in fact, the dispositional hypothesis that is more in tune with the spirit of scientific inquiry after all. In traditional metaphysical discussions of properties, one topic of significant interest is that of the ultimate natures of properties with regard to their identities. What is it that makes a given (causally efficacious) property the property that it is, as opposed to another? Transposing this traditional topic into the domain of the sciences, one might well wonder about the natures of the properties of objects, events, and processes subject to scientific investigation. What is it that makes a property like the electric charge of a proton, or the fitness of an allele on a strand of DNA, the properties that they are? One family of answers to this question, proposed by a number of authors though differing in the details, is that what makes a property the property that it is are the dispositions it confers on the things that have it.7 On this account of the natures of properties, their identities are determined by and constituted by dispositions. Entities having positive charge are disposed to repel other entities that are likewise positively charged and to attract entities having negative charge; these dispositions are part of the nature of charge itself. Along with the various other dispositions that are associated with positive charge, they constitute the identity of that property. Now, obviously, antirealists about dispositions are not in a position to accept the idea that the identities of properties are determined, whether wholly or even in part, by dispositions. What is the

7.  Shoemaker 1980 and Swoyer 1982 are canonical sources of this type of view, and there are many subsequent discussions. For one of the latter and further references, see Chakravartty 2007, chapter 5.

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alternative? The traditional view of property identity standing in opposition to the view that dispositions play a role is that what makes a property the property that it is is a primitive principle of property identity, a ‘quiddity.’ On this sort of view, in contemplating the identity of a property like positive charge, one must ultimately rest content with the thought that whatever the behaviors of entities having it, and whatever the laws may be that are taken to describe these behaviors, the nature of the property itself is fundamentally unknowable. There is really nothing more that can be said about the identity of the property apart from the fact that its quiddity is different from those of other properties. Just as I indicated a stalemate between dispositional realists and antirealists elsewhere, I  suspect that there are no non-​question-​ begging ways to resolve this particular dispute regarding property identity if the problem is conceived in the terms of traditional metaphysics. Conceived as a dispute within the metaphysics of science, however, one might think that progress could be made by reflecting on the question of which picture of property identity fits more naturally into the context of scientific theorizing, modeling, and experimentation. The sciences are, ostensibly, investigations into the natures of various bits of the world. In our time they are widely regarded as comprising the most promising forms of inquiry yet devised for learning about their target systems and phenomena. As I will now suggest, this generates an argument for a kind of pragmatic incoherence on the part of anyone who is sympathetic to this scientific worldview and yet, at the same time, skeptical about dispositional accounts of property identity. Recall that dispositional antirealism is the default position of some empiricist-​ minded philosophers who reject dispositional ontologies as, at best, ontologically profligate, and at worst, mysterious or occult. As it happens, those attracted to the empiricist stance also commonly champion the scientific worldview just sketched, 129

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and thus consider empirical science the gold standard for inquiry into its subject matter. As noted above, however, in thinking about the natures of scientific properties, the dispositional antirealist-​cum-​ empiricist adopts the view that the identities of such properties are ultimately empirically inscrutable. Is this a coherent combination of views? On the one hand, the sciences are regarded as our best bets for learning about aspects of the natural world; on the other hand, the sciences are regarded as powerless to describe the differences between the properties they investigate. There is nothing inconsistent in this, strictly speaking, for one’s best bets may be unsuccessful, but one might reasonably worry about the pragmatic coherence of regarding empirical science as the exemplary means of producing knowledge of scientific properties while simultaneously holding that these efforts are guaranteed to fail. In order to avoid this charge of incoherence, one might consider simply avoiding the recourse to quiddities, which by their nature cannot be described in qualitative terms, when confronted with the issue of property identity. Thus steering clear of ontological commitments to both dispositions and primitive principles of property identity, our imagined empiricist would then simply refrain from saying anything at all about what makes properties like positive charge the properties that they are. It is unclear, I think, whether this will suffice. From the perspective of a certain kind of metaphysical stance, on which questions of property identity call for an answer, it is doubtful that remaining quiet offers much if any help in evading the worry of incoherence, because it is doubtful that refusing to say anything about property identity sits much if any better (than appealing to quiddities) with the view that empirical science is the exemplary means of knowledge production regarding properties of scientific interest. Put abstractly, the question of what constitutes the identities of properties may not sound like one that falls within the remit of scientific ontology, but more concretely, the question of what constitutes the identities of 130

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properties like charge and fitness surely does. From this perspective, the assertion of pragmatic incoherence has not been defeated here, merely reformulated. From quite another perspective, however, say that of a certain kind of empiricist, one might wonder whether the very question of the ultimate determinants of property identity, whether posed abstractly or even more concretely in the context of the sciences, is merely a fine example of a metaphysical question that does not properly admit of a response. Some questions, one might think, are symptomatic of an ambition to look for answers that reach beyond our ability to know things on the basis of scientific knowledge and practice. It may be that the sciences are our best bets for producing knowledge of the natural world, but that is not to say that scientific ontology can be expected to answer all conceivable questions regarding it. Some questions can only be answered by means of metaphysical inferences of such magnitude that they are, viewed from the empiricist stance, utterly incapable of producing knowledge. Here, once again, we see the deep divide between more and less metaphysical stances, and between fundamentally opposed conceptions of the demand for explanation.

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Structures Science as a constraint on scientific ontology We often don’t have the faintest idea what entities and properties are being posited by our foundational physical theories. It is just those fundamental theories that are notorious for leaving us befuddled as to what kind of a world they are talking about. Our foundational theories usually exist in a scientific framework in which they are subject to multiple, apparently incompatible, interpretations. (Sklar 2010, p. 1123)

5.1 THINKING ABOUT ONTOLOGY IN THE DOMAIN OF FUNDAMENTAL PHYSICS In chapter 4, we considered an example of metaphysical theorizing about the content of scientific theories, models, and experiments that takes science as a basis for thinking about ontology. The notion of a basis here suggests some substantive inspiration or motivation for the ontological view proposed (in that case, an ontology of dispositions). In this chapter we will consider an example of metaphysical theorizing that takes science not merely as a basis for ontology but also as a constraint. The hypothesis here is that taking our best science seriously sets some limits on properly scientific ontologies. As before, what I have labeled ‘the norm of naturalized metaphysics’—​the principle that scientific ontology is properly delimited by metaphysical

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inferences and propositions that are sufficiently informed by or sensitive to scientific-​empirical investigation—​looms in the background. In the last chapter I illustrated how different judgments concerning how best to exemplify this principle can and do stem from different epistemic stances. In this chapter I  will illustrate how, even when views regarding which ontological projects are worth tackling are largely shared, the underdetermination of scientific ontology by our best science presents a serious challenge to naturalized metaphysics. The case study to follow concerns a view of scientific knowledge that has cropped up on a couple of occasions already, namely, structural realism, which maintains that the most promising interpretation of the knowledge that scientific theories and models contain is that of certain structures or relations between things, as opposed to any putative (non-​structural) knowledge of the things that ostensibly stand in those structural relations. At issue here is the interpretation of the theory known as the Standard Model in fundamental particle physics, one of the great achievements of twentieth-​century physics, fully established by the 1970s, which describes all the known varieties of subatomic particles and many of their interactions (those identified as the electromagnetic, weak, and strong interactions, but not including gravitational interaction). For reasons that I will mention briefly momentarily, however, despite its talk of particles, the theory itself is rather unclear with respect to certain ontological questions. The precise nature of the particles it describes, conceived as aspects of the world, is not at all straightforward, and a great deal of debate has focused on the question of how best to characterize them as elements of physical reality—​for example, as things that can participate in the sorts of causal or modal behaviors that the term ‘interaction’ is often held to connote. In what follows, in keeping with this common connotation, I will employ the idea of being causally efficacious as a proxy for the idea of being part of the fabric of the physical world. This is not to say with 133

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any absolute conviction, though many would think it uncontroversial, that the abilities to affect and to be affected by other aspects of the world are a sine qua non of parts of physical reality. Talk of causal efficaciousness here is simply a convenient way to pick out aspects of the world that are thought to be concrete, or that have, for lack of a better term, some physical “oomph,” as opposed to things that are abstract and thus not part of the physical world as such (assuming that there are such things). Thus, while causal oomph is often taken as a proxy for physical oomph, all of the arguments to follow here are compatible with a deflationary understanding of causal talk, according to which locutions of cause and effect are simply elliptical for facts about the behaviors of genuinely physical objects, events, and processes, such as behaviors comprising the temporal evolutions of physical systems, without any necessary attachment to any particular, metaphysically weighty conception of causation.1 If we are resolved here to being quite this easygoing about what causation is, exactly, why invoke the idea at all? For one thing, many philosophers do think that causal efficaciousness is an important attribute of bits of the physical world, one that distinguishes the concrete from the abstract, and which is thereby relevant to a consideration of the ontology of even very small bits such as subatomic particles. This thinking is reflected in the views of some of the most prominent advocates of structuralist understandings of fundamental physics. Steven French (2010), for example, describes the ontology of this domain as comprising a ‘web of relations’ that is ‘inherently modal and, in particular, causal’ (pp. 92–​93); ‘the quantum structure that we are concerned with … can be considered to be ‘causally

1.  There is a long-​standing debate about whether metaphysically substantive as opposed to deflationary accounts of causation are applicable to the interpretation of physics, especially fundamental physics, but I will not take a stand on this issue here. See Frisch 2012 and 2014 for considerations of recent skepticism about causation in this arena, and a rebuttal.

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empowered’’ (p. 98; cf. French 2006, 2014, ­chapter 8.8). Likewise, in advocating his version of structuralism, Michael Esfeld (2009, p. 180) maintains that ‘fundamental physical structures are causal structures.’ In light of these sorts of commitments, it is possible to identify a shared ontological project: to describe the ontology of fundamental physics in a way that is compatible with the notion that it has some causal or physical oomph. This shared project will serve as the case study of this chapter. Even while being easygoing, for present purposes, about the precise nature of causation and causal talk, it is important to recognize at least one commitment that seems common to what I will call “traditional” views of causation. This is the idea that whatever causation may be, precisely, it involves objects, or events involving objects, or their properties. This commitment surfaces in different ways, depending on the view under consideration. Some hold that causation is a sui generis relation between certain objects or events. Others maintain that causation is a process in which objects transmit certain quantities through spacetime, and whereby the trajectories of different transferences can intersect and sometimes facilitate an exchange of these quantities. Yet others describe causation in terms of the manifestations of the dispositions of objects. Some contend that causation is a form of counterfactual dependence between objects or events which entails that if one such object or event had been different, something else would have ensued. Deflationary accounts of causation typically unpack causal locutions in terms of the behaviors of objects or sequences of events. In sum and very generally, traditional views describe or analyze causation in terms of the relations of, or properties of, or relations between the states or properties of objects or events involving them. Objects and events are the locus of causal oomph. Now, admittedly, given that they are regularly used as terms of art in discussions of ontology, this talk of ‘objects’ and ‘events’ is vague, 135

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but it will suffice for present purposes simply to think of objects as the referents of both count nouns (e.g., ‘octopus,’ ‘cell,’ ‘nucleus’) and mass nouns (things that cannot be counted as such; e.g., ‘foliage,’ ‘oil,’ ‘oxygen’). Objects thus broadly construed are generally considered to be causally efficacious according to the traditional views mentioned above. Likewise, it will suffice for present purposes to construe the term ‘event’ broadly as well, to refer both to changes in objects (e.g., lighting a match) and, as the term is sometimes used more generally, to refer to temporal durations of objects whether or not they undergo change as such (so that the mere exemplification of a property at a time would qualify). In one final act of liberal terminological stipulation, let me refer to objects and events here as entities. Entities are central to traditional accounts of causation as the repositories of the oomph of causation—​the causal modality, as described more fully on each account. The centrality of entities in traditional accounts of causation raises an immediate concern regarding the compatibility of causation with structuralist views of fundamental physics. As a family of positions concerning the ontology of things like subatomic particles, structuralism is generally associated with the idea that the ontological status of entities should be downgraded in favor of some significantly greater ontological status for relational structures. On some interpretations of structuralism in this sphere, only relations exist, not entities, while on others, entities exist but are ontologically dependent on their relations in ways that clash with more traditional pictures of causal efficacy. As we will see, this immediately raises questions about whether downgraded entities can be causally efficacious, or whether causal efficacy can be relocated. In the next section I will provide some motivation for an ontological investigation of subatomic particles in particular. While it is certainly possible to resist this motivation, the background it furnishes will give some context for the ontological project under 136

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scrutiny here. Next, I  will consider structuralist approaches to this investigation, dividing them into what I  take to be two exhaustive categories: eliminative and non-​eliminative structuralism.2 In each case I will explore the issue of what could serve as the locus of causal efficacy in comparison to more traditional views. Ultimately, the upshot will be this:  whatever approach to structuralism one takes, serious metaphysical challenges are inevitable. I  will contend that in these cases, which serve as examples of a conundrum that is likely characteristic of most if not all inquiry into fundamental ontology, one faces choices between ontologies that require the acceptance of contentious primitive notions on the one hand, and skepticism on the other. I will suggest that a dissolution of this choice is possible by means of a principled combination of belief and less committal attitudes toward scientific ontology in any given domain. Let us begin.

5.2 SITUATING AN ONTOLOGICAL INQUIRY INTO SUBATOMIC “PARTICLES” Elaborated as a means of clarifying the ontology of fundamental physics, structuralism has appeared in a number of guises throughout the twentieth century and has attracted significant attention in recent philosophy. I have proposed to focus here specifically on a shared ontological project concerning the natures of subatomic particles, and this calls for a little bit of scene setting.

2.  The term ‘eliminative structural realism’ was first used by Psillos (2001, pp. S18–​S19) in contrast to ‘restrictive structural realism,’ a label for the position commonly attributed to Worrall 1989, often called ‘epistemic structural realism.’ At that time, what I  call ‘non-​eliminativism’ had not yet been clearly articulated in the contemporary literature. Eliminative and non-​eliminative structuralism are both attempts to describe the ontology of fundamental physics and, as such, are often described as versions of ‘ontic structural realism,’ in contrast to the epistemic project, as distinguished in Ladyman 1998.

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The term ‘particle’ in this domain has always been problematic, for it can easily be taken to suggest certain ontological connotations that are unwarranted in the context of modern physics. For those unfamiliar with this context, it is only natural to think of particles on the model of, or as analogous to, particle-​like things in everyday experience or in classical physics: billiard-​ball-​type objects that interact by bouncing off of one another. Once initiated, however, this classical picture is revealed to be highly misleading. In quantum field theory one effectively describes subatomic particles as modes of excitation of a quantum field, and the state of a field does not sound much like a particle in any classical or everyday sense. Thus it is important to recognize here at the outset that talk of ‘particles’ in this context is loose—​it is a placeholder for whatever has the properties associated with them by the theory, like mass, charge, and spin. It will suffice to be noncommittal here: perhaps, as broadly construed above, a state of field excitation might qualify as an object or, perhaps better still, as an event. Either way, on a traditional realist reading, at least, it is an entity of some sort. The descriptions of quantum theory, our most fully developed theory of the very small, do no better than to offer the prima facie suggestion that a particle is something object-​and/​or event-​like. This will serve as a starting point. Accepting that the ontological nature of subatomic particles is slippery from the get-​go, another issue presents itself regarding whether further ontological inquiry here is properly identified as pertaining to “fundamental” physics. Contemporary research programs exploring theories of quantum gravity—​attempts to unify theorizing about the behavior of quantum particles and gravitation—​may be thought to be yet more fundamental, since they aim to describe the world at a “lower level” of physical organization than that represented by the particles of the Standard Model. I will not consider these research programs here but mention them in order to stave off a potential worry that their very existence may 138

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suggest. This is the thought that only the “lowest level” of theorizing is properly the subject of serious ontological consideration, since anything at “higher levels” of organization simply reduces to the subject matter of the lowest, which some take to suggest a reductive skepticism about the reality of composite or higher-​level entities generally. This brand of reductionism is controversial and I will simply assume, as is common among those who are interested in scientific inquiry in fields other than quantum gravity, that societies, aardvarks, proteins, and electrons are no less real than whatever more fundamental theorizing may reveal, and no less worthy of ontological scrutiny. With these caveats and assumptions laid bare, we are ready to face up to the significant challenge that particles present to any hope of rendering them ontologically intelligible. The precise ontological natures of the particles described by the Standard Model are notoriously difficult to understand, in ways that go beyond the mere object-​ event ambiguity mentioned above. In experimental setups, particles appear to behave much like everyday or classical objects in having properties that can be detected, and whose values or magnitudes can be measured. On the other hand, they appear to be utterly unlike everyday or classical objects in the sense that it is unclear whether these properties, values, and magnitudes are well defined at all times during which the particles with which they are associated may be thought to exist. Furthermore, quantum theory describes particles as exhibiting a form of ‘permutation invariance’: in contrast to what one would say about everyday or classical things, swapping one particle with another of the same type within a system of particles does not constitute a new physical arrangement, which raises intriguing questions about their individuality. There is no established consensus on the matter of whether particles can be individuated or distinguished from one another on the basis of any of their properties or otherwise. 139

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What does all of this uncertainty suggest for an investigation of the ontology of particles? The preceding challenges have dissuaded at least some philosophers (including many attracted to the empiricist stance) from belief in these entities. Most scientific realists, however, hold that there is ample evidence for belief in this domain. One might, perhaps, walk a middle road by suspending belief in subatomic particles for the time being, pending some further developments in physics that would render their ontology less opaque, but this is a lonely road. If one is genuinely committed to the empiricist stance, one is not apt to be moved by further ontological theorizing, and the realist is not, I submit, in a position to wait, for subatomic particles satisfy extremely well the sorts of criteria that are standardly cited in arguing for realism generally. Interpreted from the perspective of a sufficiently metaphysical stance, particles have been detected in huge numbers of experiments. The values and magnitudes of their properties have been measured with tremendous accuracy and precision. They have been causally manipulated in intricate ways, to such an extent that they have been used to interfere with and probe the natures of other entities. Theorizing about particles has produced novel predictions that have then been confirmed in subsequent experiments. These criteria are the bread and butter of realist arguments in favor of ontological commitment to unobservable entities. In light of the impressive extent to which particles pass the realist’s standard tests for ontological commitment, she is in no position to deny their persuasiveness in this arena, on pain of undermining their authority very broadly and thereby threatening the tenability of realism more generally. As we have seen, however, the precise ontological status of these things to which it seems realists cannot help but commit is largely up for grabs, which also threatens the tenability of realism, from a different angle. Hence the motivation (from the realist point of view) for grappling with an ontology of particles. Enter structuralism. In the next section I will give an overview of the 140

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different forms of structuralism—​different takes on the shared ontological project of describing the ontology of fundamental physics in a compelling manner—​that have been proposed in connection with particles, all of which I take to be inescapably controversial. Let me foreshadow the moral I intend to draw from this discussion to come: ontological commitment is possible and defensible, I believe, even in situations where the finer-​grained natures of the things to which one might commit are very much up for grabs. The trick, I will suggest, is to appreciate that belief in the reality of something at one level of description is compatible with a suspension of belief regarding how its ontological nature is properly characterized at finer-​grained levels of description, even while admitting the potential pragmatic value of theorizing about the latter. It is only natural to wonder whether this is a stable combination of doxastic states, but recalling the notion of a spectrum of metaphysical inference from Part I, I  will suggest that metaphysical inferences of lesser and greater magnitudes sometimes pertain to one and the same thing, and that it can be reasonable to accept the conclusions of the former as true while nonetheless withholding belief in the conclusions of the latter. Driven by one’s epistemic stance, one may well draw a line separating subject matters that are suitable for belief and suspension of belief, respectively, between these two sets of inference. Let us see now how this framework for thinking about the nature of scientific ontology plays out in the example of particles and structuralism.

5.3 STRUCTURALIST INTERPRETATIONS OF THE METAPHYSICS OF PARTICLES Among the different strategies one might take in grappling with the ontology of subatomic particles, the most discussed approach over 141

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the past couple of decades has been the structuralist approach, comprising a collection of views aiming to describe the ontology of fundamental physics. The self-​avowed starting point of many of these accounts is to take contemporary physics as an explicit constraint on metaphysical responses to the challenges inherent in particle ontology outlined above, by downplaying or recasting the ontological status of the particles themselves. Thus, in very general terms, what these different forms of structuralism share is the goal of reorienting what I will call the “standard” (i.e., the common or received) picture of the relative ontological status of entities and their relations. On the standard picture, physical entities have what may be described as a non-​derivative ontological status vis-​à-​vis the physical relations (I will simply speak of ‘relations’ henceforth) in which they stand: their existence is independent of these relations. Conversely, relations have a derivative status vis-​à-​vis the entities they relate: their existence depends on some things of which they are relations. Consider an arrangement of chairs around a table. The arrangement, which is a particular set of spatial relations between those items of furniture, clearly depends on the existence of the table and chairs. If one were to destroy the table and chairs there would be no arrangement of them at all, let alone any particular arrangement. Any given physical arrangement, or structure, is thus ontologically derivative of the relevant entities. Conversely, one could destroy the arrangement simply by moving the table or chairs this way and that, but otherwise leaving them intact. This asymmetry of dependence between relations and relata exemplifies the standard picture. As it was originally framed, structuralism in the domain of fundamental physics sought to downplay the ontological status of particles by inverting this picture of ontological dependence. The properties associated with particles in the Standard Model are described mathematically in terms of certain quantities that are invariant under certain (so-​called ‘symmetry group’) transformations, such as translations through space, 142

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time, spacetime, and rotations. Quantities that are unchanged under the action of these and other transformations are identified with properties such as mass, charge, and spin, and the structuralist inversion takes these properties and, concomitantly, the entities that have them, to depend on the relevant (group) structures for their very existence. On the structuralist picture, then, the relations of particles and their properties carry a greater ontological “weight” than the particles or properties themselves, and this interpretation of the physics is offered as being both “closer” to it than the standard picture and, in virtue of its demotion of the ontological heft of particles, helpful in avoiding concerns about the ontology of particles that one would otherwise face. For reasons given in Part I (and elsewhere, e.g., Chakravartty 2007, chapter 3), I  am doubtful about both of these claims, but let us remain focused here on the task at hand: examining the shared, structuralist project of describing the ontology of fundamental physics in such a way that it has some causal or physical oomph. This seems an obvious desideratum for anyone attracted to the metaphysical stance. Can it be met? A number of variations of structuralism have surfaced and it is not my intention to consider each of them in detail. Thankfully, the ontological landscape of structuralism admits of a natural division into two versions of the position, and it is possible to investigate the compatibility of structuralism with causal efficacy by examining the ontologies described by each of these camps, thus affording an exhaustive consideration of the variations they contain. As mentioned earlier, I will refer to these versions as eliminative structuralism and non-​eliminative structuralism.3 Let us consider each in turn. 3.  For a comprehensive survey of different forms of structuralism, see Ladyman 2014/​2007. I will assume here that eliminative and non-​eliminative structuralism are distinct options, but it is arguable (see Chakravartty 2012) that non-​eliminativism ultimately collapses into eliminativism.

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Eliminative structuralism is the more ontologically revisionary proposal of the two as measured against the standard picture. Indeed, the inversion of ontological dependence it proposes is so revisionary that, strictly speaking, talk of ontological dependence here at all is somewhat misleading. True to its name, eliminativism asserts that the very notion that particles exist is, in fact, illusory. Rather, these “entities” should be conceived merely as convenient ways of talking about various structural relations described by physics, which are themselves ontologically subsistent. Thus, strictly speaking, the dependence of relata on relations proposed here is not, in fact, an ontological dependence, because (ex hypothesi) there are no relata to play the role of the dependent entities. Rather, the dependence pertains only to our concepts. The notion of an entity-​ type particle may be a useful concept, but it is one that has no referent in the world. As a consequence, on this view, particle talk cannot be taken literally, and however reasonable or helpful it may be in contexts of scientific practice, description, and pedagogy, it is, in the end, simply a useful manner of speaking which should be construed non-​literally. In claiming that terms like ‘electron’ and ‘neutrino’ should be construed non-​literally, eliminative structuralism immediately turns a spotlight onto whatever it is that is supposed to constitute the ontology of particle physics instead, for which particle talk is properly construed as elliptical. Certainly, it is not difficult to point toward descriptions of relations involving putative particles in the physics, such as, for example, the mathematical relations in terms of which certain transformations and invariant quantities are described, in hopes of shedding light on how an apparently misleading conception of the properties of particles might arise. But then, given that this conception is taken to be misleading, the obvious question becomes: what is the seat, on this picture, of causal efficacy? On the standard picture, entities play a crucial role here. On the eliminativist picture, 144

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causal efficacy will have to be located in systems of relations that have no physical relata as such. The locus of causation, then, will have to be the structural relations all by themselves, absent those entities in the world that the standard picture views as dance partners. Hold that thought, gentle reader; we will return to it in the next section. The option of attributing causal efficacy solely to relations (independently of relata) is also available on the non-​eliminative version of structuralism, but what is intriguing about this position is the possibility of a distinctive approach that renders it closer to the standard picture than eliminativism. Unlike eliminative structuralism, non-​ eliminativism proposes an ontology of ‘particles’ literally construed, as referring to entities in the world. This suggests the possibility that entities of some sort might serve as the locus of causal efficacy after all and, thereby, the tantalizing further possibility of straightforward compatibility with traditional views of causation. While non-​eliminative structuralism maintains that particles are ontologically dependent on their relations, thus downplaying the ontological status of entities in comparison to the standard picture, it does not eliminate them from its ontology entirely.4 The precise notion of ontological dependence at issue here is an important topic unto itself, but not one that I  will digress to consider. There are several possible, candidate notions (supervenience, composition, constitution, and more besides) and it is fair to say that different conceptions of non-​eliminativism likely have different dependence relations 4.  There are two variants of the view: one according to which particles depend on their relations and not vice versa; and one according to which they are symmetrically dependent. On the second variant the ontological status of relations and relata are on a par, and one might wonder whether such a position is properly viewed as a form of structuralism per se. For example, Esfeld & Lam 2011 suggests that the distinction between particles and their relations is merely conceptual rather than ontological, inspired by Spinoza’s substance monism. Traditionally, this sort of holism has gone by names other than ‘structuralism.’ Cf. French 2003, Esfeld 2003, 2004, Pooley 2006, p.  98, Rickles 2006, pp.  188–​191, Esfeld & Lam 2008, and Floridi 2008, pp. 235–​236.

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in mind. All that is required for present purposes is the observation that non-​eliminative structuralism posits an ontology of entities that might serve as a locus for causal efficacy and, as a consequence, physical oomph. Before getting carried away, however, it is important to appreciate just how significantly non-​eliminativism departs from the standard picture of ontological dependence. While it is true that according to this version of structuralism, particles are genuinely part of the furniture of the world, their existence is nonetheless derivative of their relations. This is commonly explicated by saying that the identities of the particles, that is, their natures, or what makes them what they are, is relational. (To adapt the locution I used earlier of one thing depending for its existence on something else, one might put this in terms of particles depending for their existence qua particles on their relations.) And this is to say that the identity of a given particle is wholly determined by something external to itself, or something extrinsic: the various things to which it is related. In other words, the identity of the particle is exhausted by its place in a system of relations, as opposed to any intrinsic property or properties. As Simon Saunders puts it (2003, p. 163): ‘a particular body is no more than a particular pattern-​position.’ Similarly, James Ladyman and Don Ross (2007, p.  131) describe their position this way:  ‘there are objects in our metaphysics but they have been purged of their intrinsic natures, identity, and individuality, and they are not metaphysically fundamental.’ One last clarification is needed here, because there are different notions of identity and it is unclear what sort is at stake in claims to the effect that the identity of a particle depends on its relations. One might take ‘identity’ to refer to the individual identity of a particle—​ whatever it is that makes it a particular individual, distinct from others. Indeed, much of the recent discussion of structuralism regarding

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physics is concerned with questions of individual identity. This is a fascinating issue in its own right, but I submit that it is irrelevant to our present concerns. As noted earlier, the term ‘entity’ in this context should be construed broadly so as to include the referents of count nouns and mass nouns, objects, events, and states. Since not all of these things are obviously individuals, and since there is some question as to how best to classify particles, and since the issue of whether their natures are wholly extrinsic would remain regardless of how one classifies them, the issue of individuality is a tangent. Furthermore, recall that the matter before us is that of whether structuralism is compatible with causal efficacy. If there are abstract objects (e.g., concepts, numbers, propositions), presumably some of them are individuals but not causally efficacious. Therefore, since concrete things can be causally efficacious whether or not they are individuals, and since abstract things can be individuals without being causally efficacious, the notion of identity at stake here is clearly not that of individual identity.5 For present purposes, it is the kind identity of particles that is relevant. These putative entities behave causally in the ways that they do in virtue of the properties that they have. These properties mark out divisions between different kinds of particles and, concomitantly, their different causal profiles. It is precisely these kind-​relevant properties, such as different values of mass, charge, and spin, that non-​eliminative structuralism views as extrinsic properties. Thus, on the non-​eliminative view, leaving aside the possibility shared with eliminativism that causal efficacy resides in systems of relations alone, it seems that causal efficacy must be attributed to the extrinsic 5.  See Caulton 2013 for an overview of the recent literature on whether particles are relationally discernible as individuals. On my setting the issue aside here, cf. Wolff 2013, p. 614 on the singlet state of two electrons: ‘The question is not so much whether electrons are individuals, but whether they are reducible to the role they play.’

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properties of entities. With these understandings of eliminative and non-​eliminative structuralism in hand, let us turn now to a consideration of whether or not these views are tenable.

5.4 REASONING ABOUT ONTOLOGICAL BEDROCK: AN UNAVOIDABLE DILEMMA It is fair to say that there is no consensus regarding the persuasiveness of structuralist approaches to the ontology of fundamental physics, and both eliminativism and non-​eliminativism have been challenged in various ways. In what follows I  will outline certain metaphysical challenges faced by these approaches as a means to the end of my ultimate focus: a reflection on the nature of theorizing about fundamental ontology. The challenges that I will outline have appeared in a number of forms (again, Ladyman 2014/​2007 is helpful here). What I aim to add to this is a diagnosis, for I believe that upon examination, there is good reason to think that arguments concerning basic aspects of scientific ontology are by their very nature inconclusive, exemplifying a pattern of reasoning that leads inevitably to irresolvable disagreement. In the specific case of structuralism and causal efficacy I will contend that the arguments inexorably draw one into a dilemma, each horn of which represents a different ontological conclusion, and neither of which is properly regarded as following from any constraint imposed by physics let alone metaphysics. I will argue nevertheless that ontological commitments at some “levels” of description can be shared by those who disagree about yet further ontological details, and that such a commitment to particles is compatible with even a pragmatic attitude toward their finer-​grained ontology. To begin, let me sketch the pattern of reasoning and the dilemma that I believe are typical of debates about structuralism in the case 148

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of particles. As intimated above, both this pattern and dilemma are likely instances of a generic phenomenon, whose further instances might be obtained simply by substituting ‘structuralism’ and ‘causal efficacy’ below, mutatis mutandis, with whatever is at stake in analogous debates concerning issues of fundamental ontology. In our present case, the pattern and dilemma take the following form: A. Given a version of structuralism, one determines the locus/​ loci of causal efficacy. B. In evaluating the tenability of this view, one faces a metaphysical challenge. C. In replying to the challenge, one posits a contentious ontological primitive. D. Dilemma: accept the contentious posit, or reject this version of structuralism.

As I will attempt to show momentarily, the metaphysical challenges faced by versions of structuralism are significant but not insurmountable. What is interesting here are the costs of surmounting—​a possibly troubling hypothesis can always be saved by adding beliefs that render it coherent. Both versions of structuralism can be rendered coherent, I suggest, at the cost of an ontological posit that is justifiably contentious. In either case one may accept the posit, but there is no irresistible calculus of explanatory power according to which this is the right thing to do, epistemically speaking. On the other hand, if one finds the relevant posit absurd or otherwise unacceptable all things considered, one may reject the version of structuralism at issue, and this too is a kind of choice. At this level of ontological theorizing, neither course engenders ontological beliefs that are directly empirically testable as such. And so, once again, different assessments of the explanatory power of the posits involved result in different accounts of scientific ontology. 149

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Let us consider first the case of eliminative structuralism. Recall that eliminativism licenses the use of particle locutions and concepts for all practical purposes, but with the understanding that this sort of talk is ontologically misleading if taken at face value. This is to say that particle talk does not, strictly speaking, refer to particles in the world. Instead, it is elliptical for systems of relations that are understood to be ontologically subsistent in the absence of ‘particles’ literally construed, and these relations must then serve as the repository of causal efficacy. It is in this spirit that French (2010, p. 98) says that ‘the quantum structure that we are concerned with does not exist independently of any exemplifying concrete system, it is the concrete system and as such it can be considered to be ‘causally empowered.’’6 A metaphysical challenge then arises immediately. On the standard picture, it is the fact that there are entities that stand in relations to one another that makes a system of relations concrete. If one were to take the entities away, there would be nothing concrete left over. On this picture, absent relata, relations are at best abstract. They only become part of a story of causal efficaciousness when they are physically realized as relations between entities, their relata. How can a system of relations be concrete in the absence of entities, whose being related is what makes it so? Thus, the challenge for eliminative structuralism is to locate causal efficacy in something concrete—​something that is spatiotemporal and thus capable of participating in causation (one might add: without assuming that these locations are always determinate, since particles are tricky things, or any classical sort of picture on which concrete things are found “in the container” of spacetime). As noted, on the eliminativist view, the locus of causal efficacy is systems of relations having no physical relata. As a consequence, the

6.  French assumes that this structure is amply described using the mathematics of group theory. See Bain 2013 for a recommendation of category theory instead and, for criticisms of this view, Lam & Wüthrich 2013 and Lal & Teh 2014.

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only option here for locating causal efficacy in something concrete is to reify structural relations absent relata, contra the standard picture according to which relations without relata are at best abstract. Let me call these reified relations ‘relations-​in-​themselves’ to distinguish them from the standard picture’s relations of entities. By positing relations-​in-​themselves in contrast to the more familiar relations of the standard picture, eliminative structuralism introduces a new ontological category. Given that the concreteness of relations-​in-​ themselves cannot be explained on the standard picture—​the idea does not seem amenable to explanation in terms of prior ontological concepts—​the plausibility of the idea (for those drawn to it) has an intuitive and stipulative character. One can think of it as a primitive notion of the eliminativist view. Now, let us superimpose these thoughts onto the pattern of reasoning outlined above in A  through D.  Eliminative structuralism locates causal efficacy (and thus physical oomph) in relations without relata. It thereby invites the challenge of clarifying how relations can be causally efficacious all by themselves, in contrast to the standard picture. In response to this challenge, it posits a new ontological category of relations-​in-​themselves, which is in effect a primitive of the theory. There is no algorithm for the acceptance or rejection of primitive notions in ontological theorizing. The viability of such notions is commonly assessed on the basis of the roles they play in theories overall, such as the conceptual unity they afford, as well as answers to questions about whether the systems of concepts they help to unify are important for some explanatory or predictive purposes, whether they are more or less appealing than the alternatives (as judged by the same criteria), and so on. Intuitive judgments are made using these admittedly vague parameters, and thus it is hardly surprising to find that responses vary. One response to the positing of a primitive is simply to accept that there is something here about which nothing further can be said (cf. Ladyman & Ross 2007, p. 158). Another is to 151

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regard the posit as failing to provide any insight into something that calls for better understanding. When presented with this sort of choice regarding very basic questions of ontology, between accounts that are (so far as one can tell) internally consistent, the decision as to whether to place a bet or fold one’s hand splits the world into two kinds of people. Embracing the new ontological category may save the hypothesis at issue—​in this case eliminative structuralism—​but those who cannot bring themselves to accept relations-​in-​themselves may reject this hypothesis for failing to make causal efficacy intelligible. The cost-​benefit analysis of accepting or rejecting ontological propositions in these kinds of circumstances may vary between sincerely engaged inquirers, and decisions one way or another cannot be forced by any presumptive canons of ontological reasoning. Likewise, given that eliminativism is simply one among other apparently consistent interpretations of the physics of particles, the choice here cannot be forced on scientific grounds either. In Part I of this work I contended that all claims of scientific ontology involve the application of some or other (explicit or implicit) metaphysical presuppositions or inferences. Now we may add to the complexity of the task of scientific ontology the further complication that ontological posits are themselves underdetermined by the methods of metaphysical inquiry. Let us turn now to the second of our two versions of structuralism: non-​eliminativism. Recall that the non-​eliminative structuralist has the option of following the eliminativist in associating causal efficacy with relations-​in-​themselves. However, since non-​eliminative structuralism is unlike eliminativism in that the former but not the latter recognizes entities as part of the ontology of the world, non-​ eliminativists have the further and rather different option of locating causal efficacy in these entities themselves, in a manner analogous to traditional accounts according to which the oomph of causation is associated in various ways with entities and their properties. 152

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Having just explored what the previous option of causally efficacious relations-​in-​themselves entails, let us now consider this further option of causally efficacious entities, understood in the manner of non-​eliminative structuralism. In contrast to the standard picture on which physical relations are ontologically dependent on their relata and not vice versa, non-​ eliminativism takes particles and their properties to be dependent on their relations to other things. This is to say that their kind identities are extrinsic. The very nature of a particle—​its existence qua particle—​is constituted by an extrinsic system of relations as opposed to any intrinsic property or properties. Now, much can and has been said about the distinction between intrinsic and extrinsic properties, but I will simply proceed here with a widely shared conception of it: an intrinsic property is one that something has in virtue of what it is in itself. To attribute such a property is to indicate something about it as considered in isolation, as opposed to considering it in relation to something else. Consider, for example, the character of the different property attributions suggested in talking about an object ‘being cylindrical’ as opposed to ‘having a larger volume than the cylinder next to it.’ Rae Langton and David Lewis (1998, p. 334) summarize this common conception neatly (with respect to qualitative, non-​disjunctive properties) by describing an intrinsic property as one that is compatible with the entity having it being accompanied by other entities (to which it may be related, as in having greater volume) or not so accompanied (as in a cylinder considered in vacuo). As they put it, an intrinsic property is one regarding which ‘having or lacking the property is independent of accompaniment or loneliness.’7

7.  Some challenges to the notion of intrinsicality in connection with the properties of particles can be found in French 2013, pp. 6–​8. For a discussion of these challenges see Chakravartty 2013, pp. 43–​45.

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In describing the identity of a particle exclusively in terms of its relations to other things, non-​eliminative structuralism describes the nature of a particle wholly in terms of its extrinsic properties—​ properties that something has solely in virtue of such relations. The term ‘relational property’ is sometimes used in this context, but I will stick with the term ‘extrinsic’ to emphasize the point that the relevant relations here are relations to other things. This terminological caution stems from the fact that entities are sometimes thought to have relational properties regarding which the relations are not to some other thing or things, in which case they are generally considered to be intrinsic. For example, take the relational property of having longer fingers than toes, which may be intrinsic to a person, or the relational property of having twice as many hydrogen atoms as oxygen atoms, which may be intrinsic to a puddle of water. Using the term ‘extrinsic’ as opposed to ‘relational’ helpfully underlines the fact that the relations that we are interested in presently are relations to something beyond the entity in question. This characterization of particle identity in purely extrinsic terms, however, raises a worry. On the standard picture, intrinsic properties are typically part of any description of the nature of an entity and this is hardly surprising, for a description of intrinsic properties conveys what a thing is in itself. Knowledge of such properties is, ipso facto, knowledge of the entity itself. If, however, as non-​eliminative structuralists contend, the only properties relevant to the identity of a particle are extrinsic—​properties of standing in a relation of this sort and that sort—​doubts inevitably arise about whether something analogous to the kinds of knowledge and understanding of entities afforded by the standard picture is even possible. Since a list of extrinsic properties merely tells one that something stands in certain relations to some other things, one seems bereft here of a clear grasp of what that thing is that stands in these relations in the first place. The worry is that this leaves one with an account of identity that reveals 154

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everything about an entity except that which one most wants to know: a conception of something with prior reference to which something else might count as external and, thus, as a potential partner in an extrinsic relation. The failure to fulfill this desideratum represents a prima facie concern about non-​eliminative structuralism. One way of expressing this concern is in terms of a worry about circularity or regress in attempting to understand the natures of particles. Non-​eliminativists maintain that these natures can be understood by appeal to extrinsic features:  in answer to the question of what a particle is, one is told that it stands in some extrinsic relations. The natural reaction from the point of view of the standard picture is to wonder what this thing is that stands in these relations, but the only response that the non-​eliminativist can give will appeal to yet more of the same:  the same or perhaps further extrinsic relations. This does not satisfy the initial request for enlightenment, of course, for the questioner is left still wondering what the it is that stands in these relations—​the nature of the thing that is related to other things, in virtue of which one is able to speak of extrinsic features at all. To answer by citing extrinsic features yet again merely extends the circle or regress of dissatisfaction.8 In sum, one may ask: on the non-​eliminativist view, where particles are to serve as the locus of causal efficacy, how does one apprehend their nature? The answer is to posit entities whose kind natures are constituted exclusively by extrinsic properties, contra the standard picture according to which something intrinsic seems crucial. Let me label the entities thus envisioned by the non-​eliminativist

8.  This challenge bears a family resemblance to others historically suggesting a circularity or regress in, for example, versions of functionalism in the philosophy of mind, and dispositional essentialist views of properties. Moore 1919, pp. 47–​49, can be read as a classic argument against extrinsic identity. Heil 2012, chapter 7, holds that all relational facts have non-​relational truthmakers. Lam 2014, p. 1163, contends that some concerns about circularity in the context of fundamental physics are ‘mere prejudice.’

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as ‘internally extrinsic entities,’ to distinguish them from what is given in the ontology of the standard picture. In positing internally extrinsic entities, the non-​eliminative structuralist introduces a new ontological category the likes of which is mysterious, judged from the standard perspective. Given that this ontological posit does not seem amenable to explanation in terms of prior ontological concepts, the plausibility of the idea once again (recall our earlier discussion of relations-​in-​themselves) has an intuitive and stipulative character. Given this character, one can think of the idea of internally extrinsic entities as a primitive of non-​eliminativism. One area in which the notion of extrinsic identity has received significant attention is the philosophy of mathematics, where certain mathematical entities have been described by some authors simply as “nodes” of certain kinds of relations, having no properties other than those associated with being a “place” or a “location” in the structure comprising those relations. Consider, for example, the mathematical concept of a graph, which is a structure composed of two things: nodes (also called ‘vertices’), and edges between nodes which can be taken to represent relations. A directed relation is one between nodes joined by an edge that is taken to be asymmetric (e.g., ‘larger than’); an undirected relation is symmetric (e.g., ‘the same size as’). Taken as a whole, a graph itself may be asymmetric, in which case each node in the structure is related to the others in a unique manner, thus allowing for a conception of its identity—​its place in the overall structure—​purely on the basis of extrinsic relations. A question then naturally suggests itself. This may be well and good for certain mathematical entities, where some think it intuitive to say that there is nothing more to being the number 7 than having a certain place in a mathematical structure, but is this an appropriate model for physical identity? One thing that would guarantee that mathematical structuralism supplies a fitting description of the physical world is if the physical 156

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world were, in fact, a mathematical structure: an asymmetric graph. In that case, entities would simply be identified with nodes or subsets of nodes of the world graph. This “world is math” view has been proposed (see Dipert 1997, Tegmark 2008) but with little credulous uptake. Less radically, one might take the suggestion not literally but as furnishing an analogy for how to think about internally extrinsic entities (cf. Ladyman 2007). But even thus understood, the suggestion would serve merely to re-​describe, not to resolve, the impasse between the standard and non-​eliminativist pictures. On the former, a place in a system of relations is simply a location in a structure. Until and unless that location is occupied by an entity, there is nothing here that is recognizable as an aspect of the physical world. Unpopulated structures are at best abstract—​they lack causal or physical oomph. To be told that a particle has only the properties of standing in various relations does nothing to distinguish a mere location in a structure from something that might occupy it (cf. van Fraassen 2006, pp. 294–​295). The question of whether the identity conditions for something that physically occupies a place in a structure can be the same as the identity conditions for the place itself is precisely what is at issue. The analogy of mathematical structuralism thus yields only a description, not a resolution, of our impasse. As before, let us superimpose this result onto the pattern of reasoning outlined above in A through D. Non-​eliminative structuralism goes beyond eliminativism in allowing the possibility of causally efficacious entities, as in traditional views of causation. In allowing this possibility, however, it invites the challenge of clarifying the natures of these entities in terms of an account of their kind-​constitutive properties. In response, non-​eliminativism proposes a new ontological category of internally extrinsic entities, which is effectively a primitive of the theory. It seems appropriate to note here again that the viability of such primitive notions in ontological theorizing is hardly amenable to any straightforward calculus of assessment. One possible 157

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reaction to the prospect of internally extrinsic entities is to add them to one’s ontology and then bite whatever bullets are required regarding their putative intrinsic mysteriousness or the apparent inability to distinguish them from the nodes of abstract, mathematical structures. Another possible reaction is to reject non-​eliminativism for the very same reasons. Our best intuitive judgments concerning which route is preferable in interpreting the physics—​concerning which option best satisfies desiderata such as conceptual unity or explanatory power—​are all we have. This choice between alternatives once again splits the world into two kinds of people. Internally extrinsic entities allow for something that sounds closer to traditional conceptions of causal efficacy (and thus physical oomph) than eliminativism, but those who find the ontology of these entities too difficult to swallow will regard this apparent closeness as superficial and uncompelling. Once again, there would seem to be no obvious canons of ontological reasoning or strictures imposed by the relevant science that require one choice over the other. Where does one go from here?

5.5 DISSOLVING THE DILEMMA: THE VARIABILITY OF BELIEF AND SUSPENSION Structuralism regarding fundamental physics was supposed to deliver an ontology of particles that is appropriately constrained by the outputs of our best science. What we have found instead is that even when the aims of ontological inquiry are largely shared—​in the case at hand: formulating a structuralist ontology that is compatible with the causal efficacy of “particles”—​clear-​cut demonstrations of the ultimate superiority of any one view of the fine-​grained ontological

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details are hard to come by. There are often different, apparently internally consistent proposals, each of which is underdetermined by the relevant science.9 The fact of this underdetermination is reflected in the dilemma we have just explored: for each version of structuralism one appears to face a choice between accepting a contentious ontological primitive or rejecting the view. Debates about structuralism exemplify in miniature a challenge facing the project of scientific ontology very generally, and by confronting this challenge here, I mean to link the discussion of naturalized metaphysics in Part I to the epistemological issues of Part III to follow. Recall from Part I the idea that metaphysical inferences comprise a spectrum of increasing magnitude from small ‘m’ metaphysics to larger ‘M,’ locations in which are assessed by the degrees to which these inferences are informed by or sensitive to empirical investigation. Thus I spoke of the norm of naturalized metaphysics, the principle according to which scientific ontology is properly delimited by inferences that are sufficiently “close” to the empirical content of the sciences, and of different conceptions of how far one can go along the spectrum before ceasing to engage in properly scientific ontology at all. The case of structuralism beautifully illuminates how, on some occasions, different magnitudes of metaphysical inference pertain (ostensibly) to one and the same thing. One may entertain the hypothesis that there are subatomic particles, conceived as entities subject to various detections, measurements, manipulations, and novel predictions. But one may also entertain the hypothesis that there are subatomic particles conceived as entities having the finer-​grained 9.  It is all too easy to forget this in the cut and thrust of arguing for a specific view. For example, consider Dorato & Morganti’s (2013, p.  592) suggestion that fine-​grained ontology can be ‘straightforwardly extracted from the relevant scientific description.’ Cf. Arenhart & Krause’s (2014) observation that “extractions” inevitably make recourse to metaphysical assumptions.

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ontological characters described by eliminative and non-​eliminative structuralism. Is it tenable to believe at one level of ontological description while refraining from or suspending belief at finer-​grained levels? Some scientific antirealists say ‘no, belief at coarser levels of description is hostage to settled accounts of description at finer-​grained levels’; thus, to the extent that dilemmas of the sort described above (in A through D) are genuine, there can be no justification for realism at any level of ontological description. Some scientific realists are seduced by this into thinking that their particular accounts of underlying ontology are required for the salvation of scientific realism itself. But surely, this is all a mistake. It is simply not the case that every last question regarding the ontological natures of things must be settled in order for realism about them to be viable! If it were, the project of scientific ontology would cease before it began. Those inclined toward the empiricist stance would have no grounds for belief in observable entities until and unless they also believed (in violation of their stance) some account of the underlying unobservable entities explicitly described in scientific theories and models. Realists about these latter entities would have no grounds for belief in them without concomitant beliefs regarding all of the implicit subject matters of science, including scientific properties and laws of nature. Ontological commitment does not proceed this way, by putting the cart before the horse. The case study of this chapter has focused obsessively on interpretations of fundamental physics, so let me offer another example, briefly, in hopes of driving the point home. Consider the rather less fundamental domain of molecular biology and an example cribbed from chapter 4. Here one finds descriptions of processes in which chemical reactions are catalyzed by proteins called enzymes. A realist about enzymes may come to believe in them—​that is, to add enzymes to her ontology—​on the basis of an assessment of the 160

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evidence presented for the reality of these proteins, their chemical properties, and processes in which they catalyze chemical reactions in virtue of these properties. This assessment need hardly take into account (let alone incorporate decided views on) yet further ontological facts underlying the reality of enzymes. What is a process, exactly? Are those in play here causal processes or some other sort, and what is the difference, precisely? What is the nature of the relevant properties? Are they intrinsic, or extrinsic? These are examples of questions at finer-​grained levels of ontological inquiry. Deciding once and for all how best to answer them, however, is not required for justified belief in enzymes. In just this way, knowledge of the ultimate natures of particles is detachable from the knowledge that they exist which, lest this be undersold, rests on some significant (putative) knowledge of what they are like. The moral is this: it is in the nature of scientific ontology that one may contest the inferences made at any point along the spectrum of metaphysical inference. It is the fact that different agents do so at different points that serves as one of the major determinants of different conceptions of scientific ontology, reflecting prior epistemic stances. Shared belief at one level of description is compatible with disagreements about whether to believe or suspend belief in the context of others, further down the line. This suggests an alternative way of understanding dilemmas such as those facing versions of structuralism which I have elaborated here. One might view them not as dilemmas at all, but as identifiers of branching points, or decision points, in scientific ontology. On the view I have proposed, belief in one ontological picture or another at a given level of description is a function of how one assesses and weighs the parameters of empirical vulnerability and explanatory power, as explored in Part I. Thus one may, for example, take particle talk in physics seriously qua ontology and, understanding the costs and benefits of so doing, spell this out further by adopting the 161

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ontology of eliminative structuralism or non-​eliminative structuralism or the standard picture or, no doubt, by denying all three in favor of something else. One may also, though, if not inclined in the direction of any of these finer-​grained ontologies by one’s assessment of the arguments for and against, take particle talk seriously while simultaneously suspending judgment with respect to claims at deeper levels of ontology. If one’s considered judgment is that, on the basis of the evidence, it is difficult or even impossible to argue definitively for the one true account of fine-​grained particle ontology, one may view these attempts as reaching for conclusions that extend beyond the kind of support that scientific theories, models, and experiment can give. Suspension of belief is then a rational option. All of these choices reflect the judgments of agents who must decide which (if any) metaphysical challenges are pressing, and whether and how they can be resolved. In the chapters to come, I will reflect on this in more detail. The idea of suspension of belief concerning ontology opens the door to other epistemic attitudes with which it is compatible. The most apposite example in the context of structuralism may well be a pragmatic attitude toward theorizing about the finer-​grained, ontological natures of subatomic particles. Different versions of structuralism may be viewed as making up a collection of fine-​grained ontologies, all of which are compatible with a coarser ontology of particles. This sort of plurality has uses, and thus utility. It helps to elaborate conceptual pictures of the ontology of fundamental physics in different ways, which may then be heuristically fruitful for scientific investigation down the road. The history of natural philosophy and the modern sciences is full of examples of how theorizing about ontological issues has served as a primer for theorizing and experimentation in future science. And as we will see in the next chapter, different ontological pictures are often useful in different contexts of scientific work, especially when modeling the behaviors of systems 162

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of scientific interest under different conditions or with different explanatory goals in mind. With a helping of pragmatism regarding descriptions of objects, events, processes, and properties that fail to cross an agent’s threshold for belief, these descriptions may be useful all the same. Of course, most philosophers and scientists alike interpret the outputs of scientific work as yielding some genuine knowledge of the world, but there is no universally compelling formula for identifying what that knowledge is, precisely. Across this multifarious group, judgments concerning the efficacy of different sorts of metaphysical inference vary enormously. Most inquirers who embark along the spectrum of metaphysical inference find that, at a certain stage, digging ever deeper into the bedrock of ontology, they reach a point at which they find the questions being asked and the answers being given too far removed from contexts of empirical investigation to be capable of transformation, via considerations of empirical vulnerability and explanatory power, into knowledge of the world. Let us turn now to confront the very nature of this variability at the heart of scientific ontology.

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VOLUNTARIST EPISTEMOLOGY

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6.1 INCONSISTENT ONTOLOGIES AND INCOMPATIBLE BELIEFS One may engage in scientific ontology—​in giving an interpretation of what scientific theories and models are telling us about what things and kinds of things exist, and what they are like—​without thereby engaging with questions of how this proposed knowledge of scientific ontology is acquired. Questions of knowledge acquisition are, of course, questions of epistemology, the study of knowledge. As soon as one starts to think more deeply about the nature of the pursuit of scientific ontology, however, one inevitably grapples with issues in epistemology:  issues concerning the epistemic risk involved in making an ontological claim, and how this risk is affected by considerations of empirical vulnerability and explanatory power. The inextricability of the ontological and the epistemological in this sphere was a recurring theme in Parts I and II. Now, in the final part of this book, we are ready to consider the epistemological dimensions of this understanding of scientific ontology in more detail. The idea that there are different “magnitudes” of metaphysical inference associated with ontological claims at different locations along a spectrum, with lower degrees of epistemic risk at one end 167

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and higher degrees at the other, was central to the account of naturalized metaphysics presented in Parts I and II. Throughout that discussion I  suggested that assessments of where (if anywhere) a line should be drawn between small ‘m’ and big ‘M’ metaphysics, or magnitudes of metaphysical inference that are conducive to knowledge and those that are so large as to suggest a suspension of belief instead, are ultimately and ineluctably in the eye of the beholder. Granted, this variability leads to significant, collective uncertainty in scientific ontology across the opinions of those who draw these lines in different places or not at all, and perhaps even feelings of uncertainty within individuals who feel the weight of these differences of opinion strongly. Uncertainty is at least one natural reaction upon coming to appreciate the voluntary nature of the act of drawing lines in the spectrum of metaphysical inference. That we should not fear this kind of voluntarism, but instead recognize and accept it as part of the nature of scientific ontology, is the theme of Part III. Before exploring in more detail what the notion of a voluntarist epistemology in the realm of scientific ontology amounts to, some clarification is in order, for throughout the preceding chapters we have in fact encountered two distinct forms of ontological uncertainty. One form concerns the question of where if anywhere to draw lines between domains of ontology in which belief is appropriate and, conversely, in which suspension of belief is appropriate. For instance, one may believe certain claims about gene transcription—​the process whereby segments of one sort of nucleic acid, DNA, is copied in the production of another, RNA—​and yet hold that finer-​grained questions and answers about what processes themselves are, as conceived more generally in ways discussed by some metaphysicians, go beyond what is required to give an account of a scientific ontology of DNA, RNA, and gene transcription. One might even worry that answers to questions regarding the nature of processes generally, in themselves, so to speak, exhibit a degree of epistemic risk that makes 168

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them unpromising candidates for knowledge per se. The nature of this particular kind of ontological uncertainty will be the subject of chapters 7 and 8. In the meantime, let us focus on the other form of ontological uncertainty, which has also been lurking in the preceding chapters if perhaps less transparently. This further uncertainty concerns different accounts of ontology, not in connection with different domains of ontological theorizing but in connection with a given object, event, process, or property considered within a domain. For example, some philosophers think that properties like hardness or electric charge are abstract entities which exist independently of any concrete thing or things that may be said to have, instantiate, or exemplify them; others think that properties are abstract but exist only when instantiated; yet others think that they are not abstract at all but rather concrete entities which (typically) form groups, thereby forming other entities. These different views of properties—​as transcendent universals, immanent universals, and tropes, respectively—​are contested within one and the same domain of theorizing. Likewise, scientific theories and models sometimes offer different characterizations of something within a domain; chapter 4 gave the example of different descriptions of fluids according to which they are continuous media and collections of discrete particles, respectively. Once again, differing accounts may produce collective and perhaps even individual uncertainty regarding the relevant ontological claims. This chapter is about this kind of uncertainty. The distinction between uncertainty regarding where to draw the line between domains in which different doxastic attitudes (belief or suspension of belief) are appropriate, on the one hand, and uncertainty within a given domain, on the other, rests upon the notion of “domains” of ontological theorizing. In hopes of clarifying this distinction one might hope for an analysis of how domains are demarcated. This is a tall order, but luckily, all that is required presently is 169

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that we be able to distinguish one form of ontological uncertainty from the other, and this much is easy to do. There are two clear contrasts. In the former case, the different endeavors in theorizing are addressed to different ontological questions—​for example, ‘what is gene transcription?’ versus ‘what is a process?’ In the latter, intra-​ domain case, all of the relevant theorizing is addressed to one and the same question, as in ‘what is the nature of a fluid?’ And strikingly, in the former case, the different epistemic commitments involved are plainly compatible with one another—​there is no inconsistency in believing claims about gene transcription while refraining from beliefs regarding the nature of processes more generally. But in the intra-​domain case, one confronts a prima facie choice between inconsistent ontologies and, concomitantly, incompatible beliefs. A property cannot be both a transcendent universal and a trope, any more than water can be both a continuous medium and composed of discrete particles. Certainly, human beings are famous for holding beliefs not all of which are compatible with one another, but no one thinks that this is something of which to be proud. Consistency is an epistemic virtue and to the extent that one can help these things, one’s beliefs should not lead one into contradictions. Now, as we have seen, there are approaches to scientific ontology on which the apparent inconsistency of different descriptions is merely apparent. Consider the deflationary accounts of ontology discussed in chapter 1 (section 2). Since deflationists do not take ontology at face value as an investigation into what things and kinds of things there are and what they are like, but instead dissolve such talk or recast it in terms of something else—​as merely elliptical for historically contingent relations between ideas, socially sanctioned ways of speaking, pragmatically helpful choices of language, and so on—​inconsistent descriptions need not pose them any difficulty. If inconsistent descriptions are

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simply elliptical for different historical, social, or pragmatic conventions of linguistic practice, no problem of incompatible beliefs arises, because in each such case one may simply recast what appears as conflict in terms of descriptions of different conventions of practice, each of which has whatever value it affords in its own historical, social, or pragmatic context. Likewise, anyone who suspends belief in connection with a given domain of ontology will hardly be fazed by inconsistency there. Inconsistent descriptions only present a challenge where incompatible beliefs threaten, via the uncontroversial thought that holding incompatible beliefs is something to avoid. In the remainder of this chapter I  will consider the idea that healthy ontological beliefs are possible and incompatibility is avoidable, even in the face of inconsistent descriptions, if one adopts an appropriately perspectival view of scientific ontology. Inspiration for this view comes from recent work on the idea of ‘perspectival realism’ in the philosophy of science, or what I will simply refer to here as perspectivism. While I will contend that in the end, this proposal generates more heat than light, it is nonetheless helpful in suggesting to those who are looking to invest belief in the arena of inconsistent descriptions what they should say instead.

6.2 BELIEF AND ONTOLOGICAL PLURALISM: PERSPECTIVAL KNOWLEDGE? The idea of perspectival knowledge in connection with the sciences has come to recent prominence, both in specific considerations of how to interpret conflicting models of a given target of scientific interest, and in more general considerations of how to

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interpret conflicting theoretical approaches to one and the same subject matter.1 While these discussions are concerned with the suggestion that scientific knowledge has a pluralistic character broadly speaking, let us home in here on the issue of our present concern, namely, the prospect of ontological knowledge. In giving seemingly mutually inconsistent ontological characterizations of things, different models as well as conflicting assumptions built into different methodological approaches sometimes raise the specter of potentially incompatible beliefs for anyone who aspires to ontological knowledge. The question before us, then, is whether the notion of perspective is a helpful means to the end of avoiding incompatibility. In what sense might different models and approaches furnish different perspectives? In everyday use the notion of a perspective suggests a vantage point from which something is viewed or an angle of approach—​one that differs from others from which the same thing is or could be regarded. In artistic representation, perspective refers to the rendering of three-​dimensional subjects on a two-​dimensional surface with the intention of eliciting in the viewers of this surface the same sorts of visual impressions of features, such as relative positions and magnitudes, as they would have if they were in fact viewing the subjects depicted instead. Unlike the everyday use, however, the artistic use of the term often pertains to cases in which what is depicted does not actually exist in the world so far as we know, but is rather imagined. Insofar as perspectivism may offer a guide to

1.  Giere 2006 provides the label ‘perspectival realism.’ On the shared theme that human purposes and actions are central to scientific observation, measurement, and representation, see also Teller 2001 and van Fraassen 2008 (but note the exceptions, p. 86). Several approaches to pluralism about scientific aims, methods, and descriptions are collected in Kellert, Longino, & Waters 2006, but as in the case of perspectivism, not all versions of pluralism suggest explicit consequences for ontology (see Cat 2012).

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scientific ontology, then, the sense of the term mirrors the everyday use, not the artistic—​it should afford an answer to the question of what or what kinds of things exist. The scientific use shares with both the everyday and artistic uses the connotation that the ways in which things appear from a given perspective need not match the ways in which they appear from another. One explanation of this is that typically, in virtue of taking a certain perspective, our representations unavoidably leave out aspects of, obscure, or otherwise misrepresent their subjects in various ways. Consider, for example, the different ways in which the continents and oceans of the earth are represented in different types of maps. Meeting the technical challenge of mapping the three-​dimensional surface of the earth onto a two-​dimensional surface that one can place easily on a table or in one’s pocket requires a mathematical projection from three dimensions onto two, and this can be done in different ways. The most familiar to most people is the Mercator projection, but there are others such as the Gall-​Peters projection, each of which generates visual representations in differing ways. The Mercator projection, for instance, functions extremely well for navigational purposes because straight lines drawn on a Mercator map correspond to lines of constant compass bearings, allowing navigators to plot simple, straight-​ line courses. At the same time, it gives a highly misleading sense of the relative sizes of land masses due in part to the way it increasingly distorts their dimensions as one approaches the poles. Disliking the incorrect impression this gives of northern hemisphere lands being proportionately large in comparison to their southern hemisphere counterparts, some prefer the Gall-​Peters projection, which is highly accurate in depicting the areas of these lands but nonetheless exaggerates horizontal distances near the poles and vertical distances near the equator, thus distorting their shapes. There are many other projections in use, all having their own idiosyncrasies of representation.

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So long as different perspectives are regarded as sharing the same subject matter—​say, the distribution of land masses on the surface of the earth—​the different representations one may associate with them pose no challenges to ontological claims regarding what exists per se. After all, different representations of this sort would seem to permit entirely consistent answers to questions about what things there are, even across the various perspectives of them one might take. That is, one may well think that different perspectival characterizations nonetheless refer to one and the same thing. Mere existence, however, is just the tip of the ontological iceberg, for we are commonly further interested in what these things are like, and here, as we have seen, one faces the challenge of inconsistent models and, thereby, the threat of incompatible beliefs. Before proceeding to consider whether perspectivism can diffuse this challenge and threat, it is important to note that not all cases of inconsistent models give rise to the worry of incompatible beliefs. There are at least three cases in which the former does not entail the latter. The first is one in which there is an underlying theory or model (or some combination of theories or models) that explains why apparent differences in the natures of things represented are merely apparent, which is to say that there is an underlying explanation of how one and the same nature, itself known, appears differently in different circumstances. One might hold that the Mercator and Gall-​Peters projections generate appearances of the shapes and sizes of land masses while simultaneously holding that the shapes and sizes themselves are independent of these projections. The projections are simply means by which different maps are generated, and the variability of the resulting appearances may be explained in terms of actual shapes and sizes and the mathematics of projections. In just the same way, the appearances of a straw as straight in the air and bent in a glass of water are explainable in terms of the actual shape of the straw combined with theories of optics and the human visual system. 174

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Where underlying theories and models can be employed to explain away inconsistencies of appearance, there is no worry of incompatible belief. Another case in which inconsistent accounts of the nature of something produces no concern for belief is the scenario in which conflicting models or approaches are not regarded as being on a par, epistemically speaking. There are substantive differences, for example, between the classical conception of gravity due to Newton, as a force whose mechanism of action (if any) is unknown, and the conception of gravity furnished by Einstein’s theory of general relativity, as the curvature of spacetime in the presence of matter and energy. Here the concern of believing two conflicting descriptions does not arise because Einstein’s theory is regarded as having superseded Newton’s. If one were tempted to theorize about the ontology of gravitation one would hardly look to both theories as guides; rather, one would start with the theory that is regarded (by those who see promise in such theorizing) as closer to the truth concerning the nature of gravity. This immediately suggests a third case in which mutually inconsistent models do not threaten to give rise to incompatible beliefs—​cases in which one is disinclined to believe anything at all. Consider once again, for instance, the historically important notion of underdetermination, which suggests that choices of which among (at least some) conflicting theories or models one should believe cannot be decided solely on the basis of empirical evidence. Anyone who withholds belief from inconsistent models for reasons of underdetermination is, of course, safe from the threat of incompatible beliefs. What these three cases of equanimity in the face of inconsistency have in common is that they present obvious strategies for dissolving the prospect of incompatible beliefs. Not all cases are so easily resolved, however. In some, an apparent plurality of ontological characterizations is disconcerting for anyone who aspires to ontological belief precisely because we know of no underlying facts or states of 175

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affairs, revealed or represented by underlying theories or models, in terms of which to unify disparate appearances, and neither is it clear that just one theory or model is epistemically preferable. It is here that perspectivism might be thought to offer a solution, for if ontological knowledge in these problematic cases is knowledge relative to a perspective, the scope of ontological commitment in these cases is thereby confined to different perspectives and, thus confined, the relevant commitments never come into conflict.2 This is the promise of perspectivism for scientific ontology that we must now consider. Let us tailor our definition of ‘perspective’ with the scientific arena in mind, where the vantage points or angles of approach from which something is considered are constituted by particular contexts of scientific practice. To be more precise, one might say that a context of this sort comprises the kinds of things readily identified with distinct investigations in the realm of scientific activity: an agent or agents; a target system under consideration; a predictive or explanatory goal or goals; some characterization of properties of the target that facilitates (one hopes) the realization of these goals; and no doubt more, including specific techniques and/​or instruments of investigation. While the identities of particular agents are not essential to a context—​agents come and go—​some fairly determinate collection of the rest of these elements may be thought of as definitive of a given context. And now, armed with this conception of scientific perspectives and contexts, let us formulate the perspectivist thesis vis-​à-​vis ontology. How might one find ontological knowledge to be bound by separate perspectives? Let me suggest two straightforward ways of achieving this balkanization:  a way that asserts limitations on the 2.  Cf. Giere 2006, p.  81:  ‘For a perspectivist, truth claims are always relative to a perspective.’ For related thoughts on the perspectival assessment of such claims, see Brown 2009, pp. 214–​215.

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scope of scientific knowledge simpliciter, which is to make a purely epistemic claim; and a way that goes further in attributing the source of these limitations to the nature of the world, which is to piggyback an epistemic claim on an ontological claim. Let me express these two assertions as follows, in the form of P1 and P2 (taking ‘facts’ and ‘states of affairs’ to refer to true propositions and things in the world, respectively): P1 Knowledge of scientific ontology is bound within specific contexts because our epistemic abilities do not extend as far as perspective-​transcendent knowledge. P2 Knowledge of scientific ontology is bound within specific contexts because there are no perspective-​transcendent ontological facts or states of affairs to be known.

It should be clear that while P1 and P2 are distinct theses, they need not be mutually exclusive. Both associate the perspectival nature of scientific ontology with limitations on what can be known, but while P1 says nothing at all about the ontology of the world itself—​that is, the world apart from our ways of knowing it—​P2 goes further, asserting that there are no ontological states of affairs in the world apart from those that inhabit different perspectives. Thus, P2 implies P1, for if there is nothing non-​perspectival to be known, it is hardly surprising that we lack the ability to know such things. (This claim must be read in a particular way: there is a trivial sense in which if P2 is true, no epistemic abilities will extend as far as non-​perspectival facts, simply because there are none. This is analogous to saying that no epistemic abilities would allow one to plot a continuous walk that fully traverses all the seven bridges of Königsberg, Prussia, crossing each bridge only once. Leonhard Euler proved in 1735 that given the layout of the city, such a walk is impossible.) P1 does not imply P2,

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however, since P1 is compatible with the idea that there are, in fact, non-​perspectival states of affairs, in which case it would amount to the thought that we simply lack the epistemic wherewithal to grasp them. In the next section I will examine a number of suggestions that have been made in favor of perspectivism and argue that none of them establishes P1 or P2. This leaves intact the challenge to those who aspire to ontological knowledge emanating from mutually inconsistent theories, models, and approaches to scientific investigation. The news is not all bad, though, for as we will see, there are options remaining to those who aspire to ontological knowledge in these circumstances nonetheless.

6.3 A TRILEMMA FOR PERSPECTIVISM: IRRELEVANT; UNSTABLE; INCOHERENT There is no consideration of science that renders perspectivism about ontology plausible, or so I will suggest. The basis of this contention is that all such considerations are suspect in at least one of three ways, insofar as they are taken to be relevant to ontology. The first concern is one of relevance: there are surely ways in which the sciences are perspectival, some of which are interesting and important, but they are typically ontologically inconsequential. It is true, for example, that different contexts of investigation produce data and descriptions of scientific phenomena that can only be generated idiosyncratically. The use of different investigative techniques, instruments, and experimental setups, applications of different models to target systems, and analyses of systems at different scales or “levels” of organization (e.g., cells, tissues, organs), all represent different means of investigation. But as we will see, perspectival investigation, which highlights the contextuality of knowledge acquisition and justification, does

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not entail perspectival ontology.3 In some cases the notion of perspectival ontology has some initial plausibility but collapses under scrutiny into views that are either non-​perspectival about ontology or deflationary about ontology altogether. These cases exhibit a kind of instability. Finally, some suggestions of perspectivism are simply incoherent as proposed understandings of ontology. Let us see how these charges attach to common claims of perspectivism. One feature of scientific knowledge that has been the subject of significant recent attention in studies of modeling is the extent to which even our best theories and models are often approximations at best and admit of different kinds of abstraction and idealization. By ‘abstraction’ I refer to a process (or a model resulting from such a process) in which only some aspects of the phenomenon of interest are actually represented. The motivation for this is perhaps obvious: representing every last feature of any interesting part of the world is generally beyond our capabilities and also unnecessary for most purposes of prediction and explanation. Nevertheless, the inevitable result is a partial representation, and frequently one that excludes aspects of the target that may be relevant to its nature or behavior. By ‘idealization’ I  refer to a process (or resulting model) in which aspects of something in the world that are represented in a model are represented in a distorted fashion, perhaps even in a way that they could not be given the laws of nature (Chakravartty 2007, chapter 7). No doubt the motivation for this is also clear, since the complexity of the subject matter often exceeds our abilities to represent them in anything other than a distorted way, given the descriptive 3.  For an account of perspectivism in terms of scientific investigation specifically, see Massimi 2012, and for further thoughts on triviality, see Votsis 2012, p. 95. It is all too easy to slip tacitly but without warrant from acknowledging the perspectival nature of investigation into suggesting that all scientific representations are perspectival in a deeper sense (e.g., Elgin 2010).

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(e.g., mathematical) tools at our disposal. With respect to some of their features a model may be both abstract and ideal, in that omitting something may constitute a significant distortion. One might think that abstraction and idealization in scientific modeling invites a perspectival analysis. After all, in omitting and/​ or distorting aspects of the world, is it not fair to say that a representation takes a certain perspective with respect to its target? This suggestion becomes all the more plausible when one appreciates that in scientific practice one often uses different models in different contexts of description, prediction, and explanation, each of which abstracts or idealizes in different ways in connection with the same subject matter, thus arguably and collectively presenting a variety of perspectives. All by itself, however, this appeal to perspectives is either irrelevant or unstable in relation to ontology and thus incapable of establishing P1, the claim that ontological knowledge is limited to specific contexts, or P2, the further claim that the ontology of the world is context-​relative. It is sometimes irrelevant in that while there is no doubt that different contexts of scientific work employ models that focus on different aspects of a phenomenon of interest, in cases of abstraction that are not also cases of idealization—​cases where models furnish incomplete but otherwise correct descriptions of some aspects of something:  objects; events; processes; properties; whatever—​these different contexts of investigation generate ontological claims about what exists and what these things are like which, if true at all are true simpliciter, not merely in those contexts. The fact that certain aspects of the world are postulated and considered in specific contexts of scientific practice does not somehow bind knowledge of their existence and natures to those contexts alone. Anyone who learns facts about ontology in such a context is at liberty to carry this knowledge with her wherever she goes. Thus, the mere contextuality of investigation offers no support for P1, and since P2 is an 180

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even stronger claim, there is no support for it here either. This kind of perspectivism amounts to the truism that we are finite creatures and, as such, when learning things about the world, we must start somewhere. When idealization is involved the situation is more complex, but here too there is no support for P1 or P2, this time for reasons of instability. What does it mean to say that a given theory or model is a representation of something that distorts its nature? Prima facie, it is to say that the theory or model represents some thing, but in a way that is untrue. On the surface this amounts to a claim of mixed success from the point of view of ontology: success in that the existence of some target in the world is affirmed, but failure in that by our own admission, questions regarding the nature of that thing do not seem answerable in a wholly veridical way—​the degree of deviation from the truth here depending on the extent of the idealization. When one idealizes an inclined plane as frictionless in theorizing about how a ball rolls down its surface, one employs a distorted representation of actual planes (since no surfaces in the world are completely frictionless), but this hardly compromises one’s belief in the existence of worldly planes. Population genetics models in evolutionary biology often assume infinite populations of organisms in order to eliminate the effect of random drift in the frequencies of gene variants (alleles) on gene frequency calculations (the smaller the population, the larger this effect), but in idealizing an actual population this way one does not thereby doubt the existence of the population itself. That said, perhaps one could imagine cases in which a representation is so out of touch with our best scientific judgment concerning what things exist that one finds oneself doubting that there is anything in the world of which it reasonably qualifies as an idealization. This would be to say that the extent of the distortion is so great that one does not actually think it plausible to interpret the representation as denoting anything in the world. In this case one has ceased to treat 181

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the model as supporting ontological claims at all; one has deflated the surface appearance of an ontological characterization of a target and recast it in terms of whatever virtues one attributes to the use of the model in its scientific context, say, perhaps its usefulness in making predictions regarding some parameter of interest. But neither of the interpretations of idealization just suggested—​taking the representation to be indicative of an existential claim while being circumspect about the extent to which it describes the nature of something (in proportion to the severity of the idealization), or deflating the ontological credentials of the model altogether—​amounts to support for P1 or P2. In the former case, there is no reason to think that knowledge of the existence of the entity in question cannot transcend the context in which the model is used, thus violating the context-​ relativity of ontological knowledge suggested by both P1 and P2. In the latter case, P1 and P2 are simply irrelevant, since there is no question of ontological commitment to begin with. This idea that certain cases of seemingly perspectival representation collapse, either into a view of scientific ontology that is non-​ perspectival or one that is deflationary about ontology altogether, is nicely illustrated by yet another perspectivist suggestion, this time arising from considerations of detection and measurement. In fact, there are two separate thoughts here. The first is that scientific instruments used to these ends are only ever sensitive to specific aspects of the things they detect—​they detect only certain aspects of them. And as Ronald Giere (2006, p. 66) notes, ‘the only way any particular model could exhibit an exact fit to the world is if it were a complete model that fits the world exactly in every respect.’ But the issue of completeness simply returns us to the observation that models are generally abstract and thus partial. The more interesting thought here is that scientific instruments of detection and measurement condition their outputs such that they appear in different ways in different contexts. As van Fraassen (2008, p.  9) puts it, ‘what measurement 182

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shows is not directly what the measured is like but how it appears in that particular measurement set-​up’; thus, it would be a mistake to believe that ‘what is represented is simply like what is presented in the representation.’ Let us stipulate that the use of a particular kind of instrument under some specifiable conditions of application in detecting or measuring some feature or features of a given target constitutes a context of investigation. Furthermore, let us grant that varying instruments or conditions in application to a target can produce different characterizations of ostensibly one and the same thing. This sort of variability is widespread, of course, not merely in scientific practice but more broadly. Animals with different kinds of visual systems see objects in different ways. The outputs of telescopes which are sensitive to radiation emanating from distant galaxies are represented in glorious color images that are produced by arbitrarily assigning colors to different wavelengths of radiation. But once again, if the visual images formed in either case, though variable, are taken to represent one and the same thing, it follows that belief in the existence of that thing is not context-​relative, in which case neither P1 nor P2 obtains. A more pressing matter is whether anything can be said about what these objects of detection and measurement are like, and here we have an illustration of the sort of instability and collapse suggested above. In some cases we have underlying or background knowledge that allows us to infer from different representations of things to an underlying nature that transcends perspectives. In other cases, such inferences are more challenging. What follows? In cases where one may work with the appearances, data, or representations generated in a specific context, combining it with further knowledge so as to answer the ‘what is it like’ question in a way that goes beyond the perspective in which it is generated, P1 and P2 gain no traction. For example, though there are many kinds of detections one may perform and kinds of images one may produce 183

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using telescopes, taking the data they yield together with information about how they work and the conventions we employ in producing images reveals perspective-​independent facts about what distant galaxies are like. In cases where one is unable to make such inferences to non-​perspectival facts but has grounds nonetheless for thinking that different representations share a common target, one is left with the more modest success of non-​perspectival existence claims. Perhaps there are even cases in which the outputs of detections of what one previously took to be one and the same thing are so wildly divergent that one is unsure, upon reflection, whether the supposition of a unique referent was appropriate to begin with. In such cases, to the extent that these models are useful at all, they are useful for reasons other than ontology. In none of these cases is ontological knowledge irreducibly perspectival. In our discussion of perspectivism thus far, all of the considerations offered in favor have been linked directly to P1, the idea that ontological knowledge stops at the boundaries of scientific contexts due to our epistemic limitations. Since P2 asserts the same limitations, in denying P1, I have simultaneously sought to undermine P2. The latter thesis goes further, however, in offering an ontological diagnosis of these limitations in terms of an absence of non-​perspectival states of affairs in the world, and there is at least one perspectivist consideration that would seem to offer direct support to P2 by facilitating this ontological picture: a consideration of meaning and reference. Before giving up on the idea of perspectivism altogether, let us consider this putative support carefully. In chapter 1 (section 2), I  described Kuhn’s historicism about scientific knowledge as an example of deflationism about ontology. The idea was that by thinking about the meanings of scientific concepts as exhausted by their relations to other concepts in specific historical contexts, one binds these meanings within such contexts. It is this contextual view of meaning or meaning holism that leads to the 184

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incommensurability of scientific descriptions across different historical periods of practice. Bent on perspectivism, one might be tempted to extend this idea, from the notion that talk of scientific ontology is merely a way of parsing historically contingent relations between ideas concerning the nature of the world, to the notion that the nature of the world itself is in some sense a function of different contexts of scientific description. That is, one might extend a perspectivist-​ friendly thought about meaning into the realm of reference—​to the states of affairs that scientific descriptions ostensibly describe. The later Kuhn (2000, pp.  244–​246, 264)  was explicit that his own understanding of how different paradigms shape the world is neo-​Kantian and, indeed, this is a common reading of the role of different linguistic frameworks for describing the world according to at least some logical empiricists as well. In relation to ontology, however, this sort of prescription is, once again, unstable. If one interprets it merely as indicating that there are different, historically or pragmatically chosen ways of describing the world, without taking these descriptions to have any ontological significance beyond such practices, one has deflated the project of ontology in just the way indicated in chapter 1. Talk of ontology here is simply a way of talking about one’s—​or a scientific community’s—​choice of paradigm or framework for describing the world. On this picture, the question of whether things (especially unobservable things) that are ostensibly the subject matters of scientific investigation are part of the world itself is at best confused about what we can know. This is an echo of Kant’s contention that our knowledge of the world is limited to the phenomenal world, the world of our experience; it is not knowledge of the world in itself (the noumena). On this interpretation, P2 is deflationary about ontology. On the other hand, if one interprets P2 literally as an ontological thesis, incoherence beckons. It is one thing for Kant to claim that the world we know is both a product of our human ways of knowing, 185

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namely, our ‘categories of the understanding,’ and at the same time empirically real. For on this view, despite our having no knowledge of the noumenal world, there is at least a coherent picture of something that is intersubjectively accessible to all humans:  a shared world of scientific (and other) investigation that is fixed in virtue of the fact that certain aspects of human cognition, such as experiencing the world in terms of time and space and causal relations, are fixed as part of what it is to be human. For the neo-​Kantian perspectivist, however, there is no fixed world to know. In the words of Peter Lipton (2001, p. 30; 2007, p. 834), this is ‘Kant on wheels.’ Worldly states of affairs have no inherent stability. They are as fluid as our changes in conceptions, paradigms, or linguistic frameworks. In the case of mutually inconsistent models, it would follow that empirical reality exhibits an almost psychedelic fluidity. In virtue of conceptualizing the world in conflicting ways, scientists would somehow create a fundamentally conflicted reality. They would create a mishmash world of Frankenstein facts or states of affairs, without the benefit that even Frankenstein’s monster enjoyed of having all of his otherwise incongruous parts working together in consort, as though seamless. The idea that the world is inhabited by incompatible states of affairs is plainly incoherent. Even if one were to accept that scientific contexts somehow create incompatible states of affairs, it is impossible to insulate them from one another in the way that a literal reading of P2 suggests. One cannot say, for example, as an interpretation of apparently inconsistent models, that fluids are both continuous media and collections of discrete particles but in different contexts, because in both the sciences and in everyday life, we take a fluid to be the same thing across different contexts of investigation. This implies a certain stability of ontological profile across contexts. Stability does not entail that a target of investigation should behave in exactly the same ways in different circumstances, of course, but it does reflect 186

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the fact that it only makes sense to talk about one and the same thing in different contexts precisely because one assumes that something with the same nature is present in each. Having fundamentally different natures precludes this kind of identity. One could avoid the incoherence suggested here by biting the bullet and accepting that a fluid in one context of investigation is simply not the same thing or kind of thing as a fluid in another, but the violence this would do to basic assumptions of scientific practice is ample reason not to.4 These reflections on where perspectivism about ontology leads may be startling to those who are sympathetic to perspectivism simpliciter. Giere (2013), for instance, goes so far as to describe the work of Hans Reichenbach and the later Kuhn as exemplifications of perspectival realism. But as representatives of the tradition of logical empiricism and the historical turn, respectively, both appear to exemplify the notion of Kant on wheels and, as we have seen, the upshot of this for ontology is either deflationism or incoherence. In a recent examination of different approaches to studying human aggression and sexuality, Helen Longino (2013, pp. 7–​8, 125–​133, 206) suggests that quantitative behavioral genetics, molecular behavioral genetics, social-​environmental studies, and neurobiological studies render the subject matter in ways that are ‘incommensurable’ with one another, admitting of no shared ontology. Claims such as these are music to the ears of perspectivists, some of whom self-​identify as ‘pluralists,’ but what do they mean? The more precise ontological implications are usually left unspecified. I have argued that where ontology is concerned, perspectivism is either irrelevant, or unstable

4.  One can find disagreement with this if one looks hard enough. Arguably, Goodman 1978 is an example, though his support for the view is obscure (see Wieland 2012, pp. 12–​16). Without arguing that there are in fact such things in the world, Colyvan 2008 suggests that scientific realists should accept the idea of inconsistent objects, but this rests inter alia on an assumption that realists should regard idealized descriptions as true, which is itself peculiar given that deviating from truth is definitive of idealization.

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(collapsing into deflationism or non-​perspectival claims about what exists), or in the worst case, utterly incoherent. Dispensing with perspectivism, let us turn now to a positive account of what pluralism about ontology could mean after all.

6.4 TWO KINDS OF CONTEXT-​ TRANSCENDENT PLURALISM ABOUT ONTOLOGY I submit that whatever intuitive appeal the idea of perspectivism may enjoy, it stems largely from an observation that I have characterized as being irrelevant to ontology: ontological knowledge is gained in contexts of scientific practice. These contexts may involve different ways of viewing a domain of phenomena and often include the use of different techniques of modeling and experimentation, or different instruments of detection and measurement, or analysis of systems at different scales resulting in different kinds of descriptions. The label of irrelevance here is not at all intended to suggest a lack of interest or importance more generally, since sometimes what is most fascinating in a given area of science are the different forms of investigation, justification, and description that different contexts afford. The charge of irrelevance applies to perspectivism in connection with ontology because, as we have noted, these differences lend no support to theses like P1 or P2. Nonetheless, different perspectives may generate a plurality of descriptions that are useful in different areas of the sciences, and this is surely a good thing. One example of this sort of pluralism, which evades what I earlier called the threat of incompatible beliefs due to inconsistent ontologies of one and the same thing, occurs in cases in which some domain of entities (objects, events, processes, or properties) are aggregated

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in different ways so as to form larger-​scale entities of scientific interest. In some cases the adoption of one or another scheme of aggregation is favored as better facilitating different predictive or explanatory purposes, all of which may be desirable and well motivated from a scientific point of view. For example, this is a common understanding of different concepts of biological species, which arrange organisms into different species groups according to different membership criteria, resulting in different collections of organisms. This is an excellent example of how shared ontologies at lower levels of description—​in this case, concerning various properties of organisms and typically (but not always) facts about which organisms there are to begin with—​are compatible with significant variation in the kinds of these entities that exist, where the kind (e.g., species) groupings are themselves putative entities. In some cases the question of how best to package properties into an object, event, or process in the first place is open to different but nonetheless well-​motivated scientific answers.5 There is an intriguing issue here regarding whether different higher-​level entities exist in the world apart from our concepts of them, or whether they are instead merely reflective of human conventions of classification. I will take no stand on this issue here, for whatever stand one takes, the threat with which I  am concerned presently—​ of inconsistent descriptions leading to incompatible beliefs about one and the same thing—​does not arise. If one holds that alternative ontological descriptions of a domain are merely conventional, one thereby adopts a form of deflationism in which

5.  For arguments relating to ontological pluralism in the much discussed case of biological species, see Kitcher 1984, Dupré 1993, Ereshefsky 1998, Chakravartty 2007, chapter 6, Magnus 2012, pp. 83–​96, and Slater 2013, chapter 7. For a nice example of how properties can be grouped in different ways to constitute particular objects, see Danks 2015 (pp. 3612–​3613) on ‘ocean indices’: large regions that have effects on other regions and terrestrial weather patterns.

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ontological talk is merely elliptical for different taxonomic conventions. If instead one takes these contrasting descriptions at face value as referring to ontologies of things in the world (as I and others do; see footnote 5), they are properly regarded as compatible descriptions of different entities—​compatible precisely because they describe different things—​not inconsistent descriptions of the same entities. This is a profound form of pluralism, suggesting that different ontologies of entities at a given level of analysis are sometimes revealed by the sciences, which further suggests that in these cases, no one description of ontology is uniquely correct or privileged. Let us call this pluralism about packaging, since the idea is that entities and kinds of entities may come in different sorts of packages, corresponding to different aggregations, even at one and the same level of analysis. Returning now to our overarching interest in the challenge of mutually inconsistent theories and models, there is at least one further form of pluralism about ontology that suggests itself. This view emerged implicitly in Part II where we considered some case studies of naturalized metaphysics in depth. I will call this proposal pluralism about behavior. Let me extract this idea now from the relevant case examined earlier and elaborate it in the remainder of this section. One of the examples discussed in chapter 4 and mentioned again above is that of mutually inconsistent models of fluids. Depending on the fluidic phenomenon for which one hopes to furnish predictions or explanations, such as wave propagation or the diffusion of dissolved substances, one models fluids in different ways—​for example, as continuous media, or as collections of discrete particles. The fact that nothing can be both a continuous medium and a collection of discrete particles, since this would involve having incompatible properties, presents the sort of prima facie challenge to ontology that perspectivism was (in part) intended to meet, but could not. Our previous discussion of this example focused on the suggestion that a dispositional ontology might nullify the challenge. (A dispositional 190

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property, recall, is one whose possession confers on the possessor the power—​ability, capacity, propensity, etc.—​to behave in certain ways in certain circumstances.) In that earlier discussion the goal was to evaluate this suggestion as an argument from explanatory power to the reality of dispositions, but in exploring the notion of pluralism about behavior, dispositional realism is merely suggestive, not a requirement. Whether one is a realist about dispositions or rather takes a deflationary attitude toward dispositional talk (say, as code for counterfactual conditionals about what would happen under certain conditions), the important point here is simply that the sciences may be regarded as producing knowledge of how things behave. How does this observation lead to a form of pluralism about ontology? Since having a disposition to behave one way in a given set of circumstances does not entail that something having this property will behave in that way in all circumstances (since some may not be the sorts of circumstances in which the relevant behavior is manifested), the dispositional idiom permits an easy diagnosis of at least some apparently mutually inconsistent models: they harbor no threat of incompatible beliefs after all, for a correct interpretation of them involves no attribution of properties that would be, if attributed to one and the same thing, incompatible. What these models reveal is the plurality of ways in which one and the same thing behaves, associated with the different conditions in which these behaviors occur. Water is not properly described in any circumstances as a continuous medium, but it is correctly described as behaving much like a continuous medium in certain circumstances. Similarly, it may be something of an idealization to describe the liquid contained in a glass of milk as comprising a strictly discrete collection of particles in motion with respect to one another, but it certainly behaves much like a collection of discrete particles when one heats it up and stirs in delicious cocoa for dissolving and diffusing and, ultimately, drinking pleasure. 191

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Pluralism about behavior is a pluralism about the kinds of events or processes—​that is, behaviors—​that one associates with something in the world. It takes for granted an ontological commitment to there being something that is present under different conditions and (thus) across different contexts of investigation, and focuses on a different sort of ontological commitment: an answer to the question ‘what is it like?’, which informs our conception of its nature. In scientific practice, attempts to answer this question take the form of attempts to observe or otherwise detect the range of behaviors of a target system under a variety of conditions, often by creating new and interesting conditions in experimental contexts, exposing the target to them and seeing what happens. The resulting index of contexts and behaviors constitutes a significant part—​sometimes the whole—​of our ontological characterization of something. What is striking about this kind of pluralism is that by focusing on behavior, it is often inherently analogical in its characterizations of things. To say that something behaves like a continuous medium under certain conditions does not entail that it is, in fact, continuous, any more than saying that someone is behaving selfishly in a specific circumstance entails that he or she is, in fact, a selfish person. (Conversely, if something or someone behaves like a continuous medium or selfishly in all circumstances, this might suggest stronger ontological conclusions.) This common recourse to analogy makes pluralism about behavior intriguing from an ontological point of view, and the more extreme the differences in behaviors we attribute to one and the same thing the more intriguing it becomes. As noted earlier, for example, light behaves in a way akin to various kinds of waves in certain kinds of circumstances. In these cases, as in considerations of phenomena like diffraction, refraction, and interference, one typically describes the behavior of light in terms of processes involving electromagnetic fields. In other circumstances light behaves in a way akin to particles. In these situations one typically describes light 192

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as comprising distinct entities, or photons, as when describing the operation of instruments like photodetectors. These wave-​like and particulate descriptions are both genuinely scientific ways of populating the index of contexts and behaviors in terms of which a pluralist about behavior characterizes the nature of light. Even cases that are so familiar to most people as to seem mundane are sometimes striking instances of this sort of pluralism. In everyday chemical phenomena, for example, across different combinations of temperatures, pressures, and other environmental conditions, one and the same thing may behave in radically different ways through changes in phase from solid to liquid or liquid to gas. Of course, the cases that offer the greatest challenge to the prospect of belief for those interested in scientific ontology are those in which there is little or no consensus regarding why something to which one is ontologically committed behaves so differently in different contexts, as in the case of light. But belief is possible even so. Perhaps a unifying explanation awaits the development of future science; perhaps it is a mistake to think that everything has an explanation. In another testing case, Margaret Morrison (2011, pp. 347–​348) considers mutually inconsistent models on a large scale in the form of extant descriptions of the atomic nucleus, where over thirty models are used in application to different nuclear phenomena, offering a dizzying array of utterly different and conflicting descriptions including characterizations of nucleons (protons and neutrons) as point particles that orbit the nucleus, as entities with volumes, as probability waves, and as composing something like a classical fluid in which the nucleons move randomly with respect to one another. The highly attenuated nature of possible belief in such a case—​a belief in the existence of something whose nature can only be characterized by our best science in terms of so many seemingly inconsistent descriptions—​is surely a factor in deciding whether to extend belief to a given (putative) entity at all. The extent to which one is 193

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willing to extend belief in these cases is a measure of one’s assessment of the reasonable scope of pluralism about behavior. Let me wrap up these pluralistic thoughts with a final note on how both of the forms of ontological pluralism described here, regarding packaging and behavior, differ from the ontological perspectivism of P1 and P2. On either reading of perspectivism, knowledge of scientific ontology is bound to specific contexts. But this seems an inapt way to describe the forms of ontological pluralism just considered. In recognizing different collections of properties, objects, events, or processes as constituting different kinds of things, as the pluralist about packaging is wont to do, one does not thereby suggest that knowledge of these things is somehow confined to contexts in which they are subject to practices of detection, experimentation, prediction, or explanation. They simply exist, without qualification, and the fact that different packages are of interest in different contexts hardly restricts knowledge of their existence to those contexts. Neither is pluralism about behavior contextual, for knowing that something behaves one way in one context is entirely compatible with knowing that it behaves another way elsewhere and, taking the dispositional idiom seriously, it is true in every context that if one were to alter the circumstances appropriately, one’s target of interest might behave differently. In these ways and as understood here, pluralism about ontology, unlike perspectivism, is context-​transcendent.

6.5 ONTOLOGICAL EXPLANATION AND CONTRASTIVE WHAT-​Q UESTIONS The notion that the ontology of the world should admit of any sort of pluralism is unintuitive to many. The preceding remarks notwithstanding, it would be understandable if even now, some felt a certain 194

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unease at the very idea. There are, I  suspect, deeply entrenched sources of this unease. One is the worry that by stepping onto the path of pluralism, one enters a dangerous road leading to an unbridled relativism. The road to the horror of “anything goes,” one might think, is paved with good, pluralistic intentions. Neither pluralism about packaging nor pluralism about behavior seem susceptible to this worry, however, and anyone interested in the idea of scientific ontologies should be especially skeptical of it. Regarding packaging, the relevant groupings of properties, objects, and so on that yield different conceptions of entities are all motivated by the exigencies of scientific practice. It is difficult to imagine there being a more compelling test of when an entity or kind of entity is properly recognized as ontologically significant—​for anyone inclined toward such belief in the first place—​than an assessment of the role that positing these things plays in scientific practices of induction, prediction, explanation, and so on. And since pluralism about behavior ultimately amounts to the identification of different kinds of behavior with one and the same thing, and this sort of correlation is again subject to empirical investigation, it is difficult to imagine what more one (who is open to belief) could wish for beyond an assessment of this kind of evidence. Another source of unease concerning pluralism about ontology is the ancient idea that the world is naturally divided up into entities in a way that is correctly described in terms of a unique taxonomic scheme: the one true structure of the world. But this too is revealed as outmoded by the modern sciences, and if the worry is cast again in terms of a fear of unbridled relativism, it is worth noting (again) that there is nothing in the idea of pluralism to suggest that scientific ontology is vulnerable to an uncontrolled explosion in the number of taxonomic schemes, since successfully facilitating the kinds of scientific practices mentioned above is hardly a trivial matter. Even if mere imaginings of aggregations of properties and other entities 195

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are constrained only by the powers of our imaginations, discovering aggregations in the world that successfully facilitate scientific practice and knowledge is extraordinarily difficult. Not just any imaginings will do. Having already pointed in the direction of some of the literature engaged with these long-​standing issues in philosophy, let me turn our attention now to a third and more immediate source of unease about ontological pluralism: a lingering concern that having granted the importance of contexts in scientific investigation, justification, and the resulting generation of knowledge, I have made scientific ontology somehow dependent on human thoughts, actions, and intentions after all. There is no denying that given the forms of ontological pluralism discussed here, contexts of scientific practice (which I  earlier described as comprising agents, goals, descriptions of properties of target systems, techniques, instruments, etc.) are central to how knowledge of scientific ontology is produced and articulated. They are means to the end of generating knowledge, but they also determine, assuming that all goes well, which ontological facts (again, taking facts to be true propositions) about the world are expressed. This is to say that human choices governing precisely which scientific contexts are created and explored inevitably have a dramatic impact on what we take ourselves to know about the ontology of the world. We know, at best, only what these contexts reveal. We know only about those ontological packages that have proven sufficiently successful as posits in these particular contexts. We know only about the sorts of behaviors we take to be manifested in them. That human intervention may be regarded as revealing ontological facts as opposed to creating facts that depend on human intervention is revealed in two ways, however. The first is by noting that nothing in scientific practice precludes the existence of other packages and behaviors that are unknown to us and, indeed, the hubristic image of our own ontological powers that would be required to think 196

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otherwise should arguably give one pause. The second is by noting, as we have done already, that all of these different packages and behaviors are compatible with one another in a trans-​perspectival sort of way. They may all co-​exist in the world, but more than that, while questions about which entities and behaviors exist are often answered in different ways in different contexts, if these answers express facts, they may be true of the world quite independently of knowers and across whatever perspectives knowers take. Investigative contexts afford perspectives, which in turn facilitate knowledge of non-​perspectival facts. The insight that a context may be important in allowing one to pick out which among a number of non-​perspectival facts is relevant there is a familiar lesson in work concerning the nature of explanation. A  number of authors have observed that often, a question of the form ‘why P?’ admits of different but nonetheless correct answers, depending on the way the question is read or understood. (Alternatively, one might think that the different understandings are correlated with different albeit homonymous questions, in which case one would rephrase the observation here by saying that the surface form of a question may be shared by distinct sentences.) These different understandings of a why-​question are often associated with different contexts, which determine what sort of answer is relevant in the sense of being genuinely explanatory.6 Crucially, however, different answers may be correct and entirely compatible with one another—​the appeal to context serves only as a marker of the relevance of any given answer for purposes of explanation. Taken together, the different contexts in which a question may be posed

6.  For recent discussions of this approach to explanation see van Fraassen 1980, chapter 5, Garfinkel 1981, chapter 1, and Lipton 2004/​1991, chapter 3. Bromberger 1992, p. 160, footnote 34 argues that emphatic stress on different components of sentences having the same surface structure produces different sentences.

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can be regarded as making up a ‘contrast space’ or class of perspectives from which the question may be answered appropriately and, thereby, an explanation given. Consider a famous example. Why did Willie Sutton, the well-​ mannered and well-​dressed American master of disguise—​not to mention infamous mid-​twentieth century bank robber—​rob banks? As the old joke goes, when asked this question (by reporter Mitch Ohnstad), Sutton replied: ‘Because that’s where the money is.’ (Many years later Sutton confirmed that he had, in fact, never said this, but thankfully the philosophical moral is unaffected.) In a context where one is inquiring into why Sutton robbed banks as opposed to, say, libraries, this response may constitute a helpful explanation, but in a context where one is inquiring into why Sutton robbed banks as opposed to, say, merely depositing and withdrawing funds in the usual way, this response proves woefully inadequate. It may express a fact, but it is irrelevant to the context of inquiry and, as such, does not furnish a helpful explanation. Different answers to this why-​question are true independently of investigative contexts and compatible with one another, but only some are relevant to giving an explanation in a given context. Often the context itself is implicit in how a question is posed. For example, the utterance ‘Why did Sutton rob banks?’ indicates that one’s inquiry is directed toward the locations of the robberies, whereas ‘Why did Sutton rob banks?’ focuses on the kinds of activities he performed there. Different contexts of investigation call for different answers. In these reflections on how context figures into the analysis of what makes for an explanation in response to a why-​question, we have a ready-​made analogy for what constitutes an explanation in response to a what-​question. Our interest here is in scientific ontology: in questions regarding what things and kinds of things exist, and what they are like. Ontological pluralism about packaging suggests that the entities and kinds that are relevant to the sorts of inquiry 198

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pursued within a domain of science may vary across different contexts of investigation. It is for this reason that conceiving of a particular species as a group of organisms demarcated by the reproductive boundaries of actually or potentially successful interbreeding populations (the interbreeding species concept), and conceiving of it as a historical lineage of organisms whose boundaries are marked by speciation and extinction events (the phylogenetic species concept), represent different but compatible answers to a what-​question. Interbreeding species and phylogenetic species both exist quite independently of context, but one or the other may be relevant or more relevant to explaining the different kinds of phenomena examined in different contexts of biology. Likewise, pluralism about behavior suggests that when inquiring into what a given entity or kind of entity is like, different contexts of investigation may reveal different forms of behavior of one and the same thing. An index of these behaviors contributes substantially to our conceptions of what these things are like, even in cases where the best we can manage is an analogical description (‘in this situation, water behaves like a continuous medium’). Adopting the dispositional idiom, one may say that while a given entity is disposed to behave in different ways in different contexts quite independently of whether any particular context is realized in practice, the behaviors that most interest us are those that are manifested in scientific contexts of investigation. In this way, a genuinely explanatory answer in response to an inquiry into the nature of something can be tied to a context, even though the truth of that answer transcends the context itself. Thus, ontological explanation may be context-​dependent even when the ontological facts that compose the explanation are not. It is a failure to understand this distinction between truths and explanatory truths, I suspect, that leads some philosophers into thinking that scientific ontology is inevitably perspectival. 199

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In keeping with the nature of analogies, there are limits to the extent to which the contextuality of what-​questions mirrors that of why-​questions. For instance, as we have seen, in the case of why-​ questions the relevant contrast space of contexts is easily illuminated by giving emphasis to different parts of the question. In asking ‘Why did Willie Sutton rob banks?’, for example, one might stress ‘Willie Sutton,’ or ‘rob,’ or ‘banks.’ There is no obvious parallel in the case of questions of the form ‘what is x?’ Questions such as ‘what is an electron?’ do not admit of the same heuristic for determining relevant contrasts. In other ways, though, the analogy is tight. It is sometimes said that in the case of why-​questions there is an implicit contrast built into any given act of questioning, such that a request for an explanation of P has the implicit form ‘why P rather than Q?’ (e.g., ‘why did Sutton rob banks rather than libraries?’). By making the relevant contrast explicit one may, with luck, identify an answer that is explanatory in the context in which the question is posed. In just the same way, there are implicit contrasts between contexts of investigation built into questions like ‘what is the subspecies Canis lupus familiaris?’ or ‘what is the nature of an electron?’ In any given context of scientific investigation, implicit in the act of questioning and standing in contrast to others, one or another ontological package or range of behaviors may be relevant to providing a genuinely explanatory answer.

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The Nature and Provenance of Epistemic Stances

7.1 AN INDEFEASIBLE PERSISTENCE OF ONTOLOGICAL DISAGREEMENT We saw in the previous chapter how a consideration of certain epistemological issues can shed light on how ontological commitments are made in connection with the sciences, which in turn reveals a number of interesting features of these commitments and interpretations of scientific theories and models. We were concerned there with the sort of ontological uncertainty that results from having conflicting accounts of an object, event, process, or property in the guise of mutually inconsistent theories or models. Many apparent conflicts of this sort are produced by different answers to questions regarding the ontological nature of an entity of scientific interest, such as the nature of a fluid, or a species. As noted there, however, this is but one form of ontological uncertainty. Another form, with which much of this book has been concerned very directly, concerns the question of where one should draw lines, if anywhere, between domains of ontological theorizing in which prospects for knowledge and (thus) belief are good, and domains in which it seems more appropriate to suspend belief with respect to ontological propositions altogether. Let us turn now to this second form of ontological uncertainty. 201

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Readers with good memories will recall our earlier discussion of how different magnitudes of metaphysical inference, associated with theorizing about what there is and what these things are like, form a spectrum, and that locations along this spectrum are amenable to judgments of epistemic risk. The notion of risk here is understood in terms of a measure of one’s confidence in being able to judge correctly whether a proposition is true or false; the greater one’s confidence, the smaller the perceived risk. It is the fact that different agents are apt to judge this kind of risk differently, in accordance with different assessments of the relevance and impact of what I called empirical vulnerability (the susceptibility of an ontological posit to empirical testing) and explanatory power (the extent to which an ontological posit satisfies criteria commonly associated with good explanations of things for which explanation is sought), that explains why there are conflicting views about the proper scope and limits of scientific ontology. It is one thing to subscribe to what I  called the norm of naturalized metaphysics—​the principle that this scope is properly identified with ontological theorizing that is sufficiently informed by or sensitive to scientific-​empirical investigation—​but it is quite another thing for subscribers to agree on which precise adventures in ontology qualify as satisfying the norm. Is it not possible simply to resolve these differences? Perhaps, as in many areas of philosophy, it is too much to hope for that questions of such complexity should admit of easy resolutions, but one might hope nonetheless that ultimately, incisive arguments will show the way. I  have hinted on several occasions throughout, though, that there are principled reasons to expect that questions about the proper limits of scientific ontology cannot, in fact, be settled this way. If I am right about this, we have reason to expect that these particular questions and disagreements concerning their answers will persist. This chapter is about the idea that underlying different judgments concerning the genuine scope of scientific ontology we find deeper 202

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commitments, to what I have called epistemic stances (introduced in chapter 2, section 3), which both sustain these different judgments and are themselves immune to the kind of damage that is sometimes within the power of philosophical arguments to inflict. As a result and as we will see, the resulting impasse between different conceptions of scientific ontology is philosophically indefeasible. Hints of this sort of deadlock between stances relevant to scientific ontology arose decades ago (and no doubt earlier) in related discussions of debates between scientific realists and antirealists. Recall that scientific realism, to a rough, first approximation (and subject to refinement in various ways, some of which we considered in chapters 1, 4, and 5), is the view that our best scientific theories and models yield knowledge of both observable and unobservable aspects of the world, where this demarcation of aspects is conceived in terms of what is and is not detectable using our unaided senses. Conversely and in different ways, scientific antirealists oppose this interpretation of theories and models, most commonly by limiting scientific knowledge to the observable. In a reflection on the dialectic between these positions, Alison Wylie (1986) observed that sophisticated versions of them have different standards for assessing philosophical theories of science which are internal to the positions themselves, and that as a consequence they are ‘essentially incommensurable modes of philosophical practice’ (p. 287), which shifts the emphasis of the dispute from disagreements about the kind of knowledge science delivers to ‘a more comprehensive meta-​philosophical disagreement about the principles that govern the formulation and evaluation of these theories’ (p. 291). In a similar vein, John Worrall (2000, pp. 230, 234) argued that what are often viewed as powerful arguments in favor of scientific realism and antirealism are, in fact, not compelling arguments so much as considerations that seem probative only to those who are already committed one way or the other. For example, one of the most 203

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cited “arguments” in favor of scientific realism is the thought that it is difficult to imagine how our best theories could be so empirically successful, facilitating all manner of predictions which are borne out in observation, experiments, and the construction and use of technologies, were they not at least approximately true. This is commonly referred to as the ‘miracle argument’ (or ‘no miracles argument’), the idea being that it would take a miracle to explain such empirical success were not theories (approximately) true, but Worrall suggests that this kind of thinking is only convincing to the extent that one makes recourse to assumptions that prejudge the debate about scientific realism. Likewise, one of the most cited considerations in favor of scientific antirealism, which we have come across already—​the pessimistic induction, offering the falsity of past, successful theories as a reason to doubt the (approximate) truth of current theories—​is not a decisive argument so much as a challenge to which scientific realists can respond in ways that may satisfy themselves if not their challengers. These intimations to the effect that there is something ultimately question-​begging about disputes between scientific realists and antirealists are indicative of something important at the heart of the project of scientific ontology more generally. As we have seen, questions regarding ontological commitment in connection with the sciences go well beyond those typically debated by scientific realists and antirealists. While these latter debates are concerned primarily with the ontological status of what I have called the explicit subject matters of scientific investigation, which are the presumptive targets of these investigations taken at face value (subatomic particles, DNA molecules, etc.), there are also decisions to be made about whether theorizing about the merely implicit subject matters of scientific theories and models (the nature of properties, laws of nature, etc.) is also a defensible or desirable part of genuinely scientific ontology or, for that matter, any ontology. These larger debates, with their broader 204

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scope, are no less susceptible to the suspicion that there is something more to them than is obvious on the surface. Thus, when Wylie suggests that commitments to different principles give rise to different positions regarding scientific ontology (in the form of scientific realism and antirealism), this naturally invites a detailed consideration of what these principles are exactly. When she suggests that they operate at a meta level, this invites an articulation of the ways in which they differ from the ontological assertions to which they give rise and how these different levels are related. When she suggests that they are incommensurable, indicating that there is a sense in which they incorporate different standards of assessment, this invites a consideration of whether and how one can adjudicate between rival principles. When Worrall suggests that what appear on the surface as arguments are more like reflections that are telling only for those who are already inclined at some deeper level to accept their conclusions, this again invites a consideration of the relation between these different levels of commitment and the question of what inhabits them, precisely. In what follows I will contend that the relevant principles here—​the ‘meta-​level’ or ‘deeper-​level’ commitments from which different approaches to and claims about scientific ontology follow—​are epistemic stances.

7.2 STANCES REVISITED: DEFLATIONARY; EMPIRICIST; METAPHYSICAL In everyday speech the term ‘stance’ refers to the way one stands, one’s posture, or one’s attitude with respect to something in particular. The idea of having a certain attitude toward something is reflected in the figurative notions of taking a stand or having a posture in relation to a subject of reflection. The philosophical use of the term borrows from 205

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everyday language, taking philosophical questions, propositions, or positions as the relevant subjects of interest. In this very general sense a stance on a philosophical issue might be any view concerning it, but here I will have something more specific in mind. Sandy Boucher (2014, p.  2319) gives us a clue regarding this more specific intention in connection with his general characterization of philosophical stances as ‘perspectives, or ways of seeing,’ when he explicates this further in terms of ‘particular orientations on the world, or ways of seeing facts.’ By referencing orientations with respect to the world, the focus is sharpened in the direction of ontology, and by referencing ways of viewing claims about the world (‘seeing facts’), we sharpen it further still. My interest here is not in the very general idea of a philosophical stance, which may simply comprise claims about a subject matter, but in the more specific idea of a stand, orientation, or attitude regarding ontological claims. In chapter 2 I used the term ‘epistemic stances’ to label stances that are relevant to understanding how purported knowledge of scientific ontology is generated, and when I speak of stances henceforth I will have this subcategory in mind. Let us recall the basics of what these stances are before considering a few examples. In contrast to propositions or claims about matters of fact, such as whether male ruby-​throated hummingbirds can flap their wings up to two hundred times per second during courtship displays, or whether Elvis Presley is alive and well and singing in Las Vegas, stances are not subject to belief, disbelief, or agnosticism. Stances are not claims about the world but rather collections of attitudes, commitments, and strategies that determine how one goes about producing ontological claims. As such, they are not believed (disbelieved, etc.) but rather adopted and exemplified in attempts to generate putative knowledge. In shaping the way that individuals or groups interpret the outputs of scientific work, stances reflect different assessments of empirical vulnerability and explanatory power, which determine the degrees of 206

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epistemic risk one associates with ontological claims. A proposition is either true or false and may be judged as such; a stance is neither true nor false but incorporates (inter alia) a guideline—​like a set of instructions, or policies—​for how to behave, epistemically.1 A few such stances have operated in the background of many of our previous discussions, sometimes transparently and sometimes more covertly, producing differences of opinion regarding the various ontological propositions under consideration. Three in particular have been especially influential, and in making the contrasts between them stark for purposes of illustration, it is important to remember that the lives of actual epistemic agents can be messy in practice and often are. Each of the stances I will codify below admits of more complex and nuanced formulations in the actual thinking of specific individuals, and it may be that no two people think about (if they do) or apply these guidelines (knowingly or tacitly) in exactly the same ways, the result being some inevitable variation even among those sharing what I will describe as a given stance. Still, it is possible to consider the kernel of each of these approaches to scientific ontology which is broadly shared by its subscribers, and that is what we will do. I will call these core sets of attitudes, orientations, and commitments the deflationary stance, the empiricist stance, and the metaphysical stance, respectively. As we have noted now on several occasions, some philosophers approach the idea of scientific ontology with a certain amount of wariness. While it is common to think about ontological projects in a literal way, taking them at face value as engaged with questions of what things and kinds of things exist and what they are like, it is also 1.  This description has elements in common with Teller’s (2004) characterization of stances as ‘policies,’ which he offers as an exegesis of van Fraassen 2002. Rowbottom & Bueno 2011a describes an even more determinate conception in which stances are made up of modes of engagement (e.g., dogmatic, open-​minded), styles of reasoning (e.g., inferential techniques and tools), and propositional attitudes (e.g., hopes and desires).

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possible to conceive of them as ultimately reducible to something rather different, which is in effect to regard the unreduced conception as wrongheaded or naïve in some way. The result is a deflation of literal interpretations of ontological claims in favor of a different conception of them which recasts them in other terms. Thus, some historicist philosophers deflate the face-​value conception of ontology by redescribing it in terms of historically contingent relations between ideas; some social constructivists redescribe it in terms of propositions and beliefs that are produced and sanctioned by social processes; and different sorts of pragmatically inclined philosophers recast ontological claims simply as ones that are formulated within linguistic frameworks that are preferred for their pragmatic benefits in describing scientific work, theories, and models, thereby helping to systemize scientific knowledge. Given the diversity of deflationary understandings of ontology just described, it may seem unlikely that those sympathetic to them would share a common stance. That said, many deflationists in this sphere are motivated in part by a kind of unease with what I  will call the “traditional” philosophical approach to understanding the nature of ontological theorizing, commonly associated with forms of realism (not merely scientific, but more generally). This discomfort often manifests as doubts or reservations about our capacities to make sense of ontological pursuits in terms of traditional realist explications of them—​for example, in terms of discovering facts about a mind-​independent world (i.e., a reality that exists independently of human thoughts concerning it), or putative abilities to refer to specific aspects of this world using scientific concepts. Reflecting this, it is perhaps no surprise that the deflationary approaches mentioned above emphasize historical, sociological, or pragmatic ways of understanding scientific knowledge instead. Some who respond to traditional ontological theorizing in these ways simply lose interest in the traditional approach and are inclined to remain silent about it 208

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altogether. Let us refer to this cluster of attitudes as the ‘deflationary stance,’ whose core epistemic policies one may summarize as follows: D1 Reject traditional philosophical (i.e., realist) understandings of scientific ontology. D2 A fortiori, reject the analyses of truth and reference with which they are typically explicated.

It is easy to see how the deflationary stance resonates with some who especially value the pragmatic dimensions of the sciences. If one’s primary mode of thinking about scientific knowledge is framed by considerations of utility, the question of where to draw lines between domains of theorizing in which one makes ontological commitments versus those in which one is agnostic instead may seem uninteresting or peculiar, since a theory or a model can be useful entirely independently of whether it is viewed as describing an ontology in the traditional, realist sense. If one takes the meanings of propositions to be exhausted by their practical consequences for human experience, as some within the philosophical tradition of pragmatism are wont to do, the traditional conception of ontology is not merely peculiar but confused, since it is (ex hypothesi) befuddled about how to think about the meanings of terms for scientific entities.2 Likewise, the quietism inherent in the idea of remaining silent about traditional ontological concerns fits neatly here. Consider Arthur Fine’s (1996/​ 1986, chapters 7, 8) rejection of the traditional ontological picture in favor of his ‘natural ontological attitude’ (NOA), which he (1998, p. 583) describes in a way that echoes our notion of a stance: ‘NOA is … simply an attitude that one can take to science … minimal, 2.  Blackburn 2002 illustrates this nicely in connection with certain debates between scientific realists and antirealists: some of their disputes collapse if one deflates the ontological claims sanctioned by each camp in a pragmatic way.

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deflationary … accepts ‘truth’ as a semantic primitive … rejects any general theories or interpretations of scientific truth.’ In its various incarnations the deflationary stance has played an important role in the history of the philosophy of science, but having paid it due attention and respect, I mention it here primarily so as to set it aside. Though it is certainly possible to view all of the conclusions for which I have argued through the lens of a given deflationary approach (‘when I say ‘there are mitochondria’, this is elliptical for …’; ‘when I say ‘there are mitochondria’, don’t interpret this in the way that realists about mitochondria do’; etc.), our focus throughout has been on taking the project of scientific ontology at face value in an unvarnished, literal sort of way as an investigation into what things and kinds of things exist and what these things are like. Continuing in this vein, let me turn now to the two stances most relevant to illuminating the face-​value project as conceived by its practitioners, and to the question of how decisions are made about the proper scope of scientific ontology so conceived. Here I will be brief, for we have encountered both of these stances before. The empiricist stance, widely emblematic of empiricist thinking about scientific ontology, comprises a cluster of attitudes representing a cautious approach to ontological theorizing, in which the limits of reasonable caution are drawn at the boundary of what we can detect using our unaided senses.3 This is a relatively austere approach, disavowing the kinds of metaphysical inferences that would lead one to extend ontological claims beyond the realm of the observable (with ‘observation’ understood as indicated here, in terms of human sensory capabilities). 3.  Van Fraassen 2002 is the source of much contemporary discussion of what he calls the ‘empirical stance,’ though it is likely that he has something broader in mind than the strictly epistemic stances I aim to discuss here. Critical commentary has followed in the form of collections such as Monton 2007 and Rowbottom & Bueno 2011b. For some contextualization of van Fraassen’s conception within his philosophy more generally, see Okruhlik 2014.

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It encapsulates the feeling that to extend belief further, to putative unobservable entities that are the apparently explicit subject matters of scientific theorizing, modeling, and experimentation, let alone to the sorts of claims found in theorizing in the metaphysics of science about the natures of properties, natural kinds, modality, and so on, is to extend belief too far. It reflects an intuition that such claims incur too much epistemic risk to be believed, owing to their insufficient vulnerability to empirical investigation, and the uncompelling nature of the idea that the explanatory power that one may associate with these posits amounts to a form of epistemic warrant. Let me summarize the core epistemic policies of the empiricist stance this way: E1 Reject demands for explanation in terms of things underlying the observable. E2 A fortiori, reject attempts to answer these demands by theorizing about the unobservable.

The reference here to demands for explanation reflects a key point of divergence between those who gravitate toward the empiricist stance and those who find it too restrictive. At stake are questions of what sorts of things call for explanation and what would qualify as genuinely answering that call. Some empiricists are doubtful that observable phenomena need to be explained at all, as opposed to (merely) predicted, where doing so seems important or interesting, for the simple reason that what they care most about are the observable phenomena themselves. Some feel that the further one moves along a spectrum of increasing magnitudes of metaphysical inference, the lesser the extent to which the candidate explanations produced are genuinely explanatory, since in their estimation, explanations produced by certain kinds of metaphysical theorizing are significantly less comprehensible than the observable phenomena they may be 211

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adduced to explain, and in some cases so alien as to be barely comprehensible. By adhering to the epistemic policies associated with the empiricist stance, one avoids this concern. This does not bar scientists, of course, from seeking explanations of experienceable things in terms of underlying unobservables—​this is, after all, part of scientific practice and not for philosophers to decide—​but it does suggest that this seeking should not be regarded as producing ontological knowledge per se. Departing from the relative ontological austerity inherent in the empiricist stance, those with more expansive ontological ambitions gravitate toward the metaphysical stance. In very general terms, those moved by such ambition see the empiricist stance as precluding at least some knowledge of the world which they not only seek to possess, but think is within our grasp. As a result, they are interested in the pursuit of explanatory investigations that aim to furnish descriptions of, among other things, unobservable objects, events, processes, and properties. They take explanatory power seriously as having evidential force in the assessment of hypotheses concerning these entities and seek to understand things that are too small, or too large, or too distant from us in space or time to be detected using human sensory modalities alone. Taking a cue from their own readings of scientific practice, they explore possibilities for belief using techniques and instruments that extend beyond the range of human sensation to otherwise unimaginable parts of the world. Some pursue this quest for ontological knowledge well beyond our abilities to test assertions directly, or even indirectly, using empirical methods. Let me summarize the core epistemic policies associated with the metaphysical stance as follows: M1 Accept demands for explanation in terms of things underlying the observable. M2 Attempt to answer these demands by theorizing about the unobservable. 212

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At the risk of over-​emphasis, it is important to point out just how much variability of ontological commitment is compatible with the metaphysical stance. I have described this metaphorically in terms of different “magnitudes” of metaphysical inference, with small ‘m’ and big ‘M’ metaphysics contrasted in accordance with where along the spectrum of these inferences a proposition or bit of theorizing falls. Some subscribe to metaphysical inferences and assertions only insofar as they pertain to ontological claims regarding the explicit subject matters of scientific investigation, or in some cases, for those who are even more circumspect, to smaller subsets of these claims. One might be impressed, for example, by the much greater empirical vulnerability of assertions about common chemical compounds as compared to claims about the superstrings of current theorizing in the physics of quantum gravity; the former are tackled in classroom experiments, but the latter only by means of highly abstract, mathematical models. Some go further, adopting the metaphysical stance in application to some or all of what they take to be the implicit subject matters of the sciences (causation, laws, etc.) which are of interest to metaphysicians of science. Yet others have an affinity for the metaphysical stance in all parts of the spectrum of metaphysical inference; for them, the distinction between small ‘m’ and big ‘M’ may seem ill conceived or, in any case, epistemically irrelevant. Thus we see just how complex the application of stances to questions of ontology can be. A given stance may generate different extents of ontological commitment depending on how precisely it is conceived and wielded. This is yet another reminder of the fact that the epistemic lives of actual people are messy in practice. One and the same person may be drawn to a particular stance in connection with metaphysical inferences occupying one region of the spectrum of metaphysical inference, and another stance in what she judges to be a region that is properly assessed in a different way, epistemically speaking. (As an illustration of this, recall the case study 213

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of chapter 5, in which we considered the prospect of adopting the metaphysical stance with respect to one domain of theorizing while simultaneously adopting the deflationary stance with respect to another.) These are the sorts of complexities that are revealed in the details of cases and, more personally, in the intensity of reflection that one can only bring to bear on one’s own epistemic attitudes and conduct.

7.3 A VOLUNTARIST PRIMER ON CHOOSING STANCES AND BELIEFS Having presented a sharp contrast between the core epistemic policies associated with the empiricist and metaphysical stances, which play pivotal roles in determining where lines are drawn between, on the one side, domains of ontological theorizing that are viewed as amenable to belief, and on the other side, domains that are viewed as amenable only to suspension of belief instead, let us turn now to the question of how different agents come to have a stance in the first place, as a prelude to considering whether and (if so) how one stance can be judged superior to another. How does one adopt a stance? We have encountered a number of examples of different agents assessing the epistemic risk of an ontological proposition in different ways. In the previous section I described the stances that fuel these judgments, codified in part by means of contrasting epistemic policies, in terms of a variety of attitudes and orientations toward ontological theorizing that are not themselves well described as inherently truth-​apt (i.e., admitting of truth or falsity): feelings of doubt, unease, or reservation; affinities for austerity or expansiveness corresponding to desires for fewer explanations or more; caring deeply about the pragmatic dimensions of science, or knowledge of the observable predictions of science, or the potential of science to reveal or 214

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shed light on otherwise hidden features—​unobservable aspects—​of the world; the sensation of proffered explanations seeming alien or occult, or helpful and illuminating; the intuitive sense that one is skating on unbearably thin ice, or that the ice is thick enough to support ontological assertions after all. I submit that all of these attitudes and orientations have something in common. They may be described in terms of what, for a given agent, has value, or what one values most about the outputs of some scientific or other investigation into the ontology of the world. The thought that what one values, which is reflected in one’s hopes, preferences, and inclinations, is a determinant of what one believes and how one acts—​in forming a belief or suspending belief, for instance—​is a hallmark of what is often referred to as voluntarism: the idea that the relevant beliefs and actions are freely chosen, or voluntary, as opposed to being forced in virtue of reason alone. This notion of free choice arises in different contexts and, as a consequence, the idea of voluntarism has several rather different applications. Very generally, the notion of choice suggests that the human will has an important function in bringing about belief and action, where the will is conceived as the faculty or capacity one has for believing or acting with a sense of deliberate control. While I have nothing invested in the question of whether the idea of voluntarism is compelling in other spheres, as I  will now suggest, it would certainly appear to furnish an excellent characterization of the nature of scientific ontology as I have described it here, as intimately linked to the epistemic stances one may adopt. Let us therefore consider in more detail the idea of voluntarism in epistemology as a way of making sense of the fact that, as we have seen, different people can and do value different things and think about scientific ontology differently as a result. Unsurprisingly, voluntarism in epistemology is concerned with the notion of choice in relation to knowledge, but this pithy 215

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observation glosses over much, since the concept of knowledge is itself multi-​faceted. Luckily, it will not be necessary here to enter into the mire of ongoing debates in the field of epistemology about how best to analyze the concept of knowledge. For present purposes it will be sufficient simply to note the almost universal (and thus uncontroversial) consensus that, whatever knowledge is, exactly, it generally involves beliefs and justifications for those beliefs in some form or other. Accordingly, most discussions of voluntarism in epistemology are concerned with the thesis that it is possible to exercise some sort of voluntary control over one’s doxastic states: belief; disbelief; and suspension of belief. In opposition to doxastic voluntarism, the doxastic involuntarist contends that these states are not in fact subject to choice but simply follow, for example, as a consequence of the application of reasoning—​ideally, proper reasoning—​to whatever evidence is relevant to a proposition under consideration. In this opposition lies one of the great historical debates of epistemology.4 Perhaps the most powerful crystallization of the idea that some beliefs are chosen is William James’s (1956/​1897) famous suggestion that between the extreme of believing too much in an overly zealous pursuit of truths, which results in believing falsehoods, and the extreme of believing too little in an overly zealous attempt to avoid believing falsehoods, which results in missing out on truths one would otherwise believe, one must somehow chart a path. Crucially, said James, there is no one way for agents such as ourselves to do this; the path one walks is inevitably a reflection of the kinds of epistemic risks one is willing to accept in the pursuit of truth and the avoidance of falsity, which he describes in terms of an agent’s ‘temperament.’ This could well serve as a motto for the characterization

4.  For some important recent defenses of the thesis that human beings have control over at least some of their beliefs, see Winters 1973, Steup 2000, and Ginet 2001. For denials, see Williams 1973 and Alston 1988.

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of scientific ontology I have given here, where the generic concept of temperament is spelled out further in terms of the sorts of attitudes and orientations highlighted above. My contention is that the kind of variability James envisioned with respect to belief is no mere assertion, for we see it in practice. Taken together in the form of a giant case study, disagreements about the genuine scope of scientific ontology amount to a demonstration in practice of James’s principle. All of this notwithstanding, it is only natural that some hesitation should remain. Some of this is fueled by taking note of beliefs that seem to arise via processes other than those involving conscious deliberation, such as perceptual beliefs, where one believes something simply in virtue of seeing, hearing, or otherwise employing one’s senses. Here the idea of choice may seem inapposite given that choice is commonly taken to imply a considered appraisal of options, which is typically absent in cases of perception. (Weighing evidence for and against the hypothesis that what one is ostensibly seeing is an optical illusion would be an example of considered appraisal, but this of course does not describe what happens in most cases of perception.) Taking perceptual belief as a model, it does seem intuitive to many to say that a conscious consideration of whether to believe, disbelieve, or suspend belief regarding a proposition is not something that is properly described as subject to choice, for the simple reason that, arguably, we simply manifest doxastic states “autonomically,” as it were, not by choosing. That is, we simply manifest doxastic states that best fit and thereby “emerge” from our evaluations of the evidence, as though “seen” (note the figurative analogy here to perception) by the light of reason. These hesitations are understandable, but dissolvable. First let us note that the cases at issue in thinking about where to draw lines between belief and suspension of belief regarding scientific ontology are unlike cases of perception. One does not literally see (or fail to see) that electrons have negative charge or that charge is 217

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a dispositional property (cf. chapter 4, section 1). That said, there is surely nothing wrong in saying that, armed with an appropriate set of values inclining one toward a particular version of the metaphysical stance, there is a figurative sense in which one “sees” that forming these beliefs is consonant with how one should behave, epistemically. But here we must ask: what is it that propels one toward this conclusion? It is no mere reasoning about the evidence for and against the propositions that electrons have charge and that charge is a dispositional property. This evidence is relevant, of course, in the sense of furnishing candidate beliefs, since if there were no readings of the evidence that made propositions about electrons and their properties candidates for belief in the first place, the question of believing them would never arise. But it is one’s stance that determines where lines are drawn between belief and suspension of belief with respect to candidates such as these. This is the figurative sense in which stances allow us to “see.” Given the crucial role thus played by stances in determining what one believes, it should be immediately clear that it is overhasty simply to conflate (as suggested in the hesitation above), on the one hand, the idea that one’s doxastic states follow as a matter of course given one’s stances and a consideration of the evidence, and on the other hand, the idea that there is no choice involved. As we have seen, different and conflicting stances are adopted by different people, which allows for the possibility at least that different stances are chosen. Now, recall my previous descriptions of the adoption of stances, involving (for instance) affinities for, desires for, and inclinations toward certain kinds of ontological austerity or expansiveness with which to facilitate explanation. These are the sorts of things in terms of which one may describe the phenomenon of being drawn toward or repelled by, as the case may be, a given stance. Affinities, desires, and inclinations are commonly invoked in describing the phenomenon of choice more generally—​indeed, in any sphere in which, to put 218

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it philosophically, the will takes us in one direction or another. I will have more to say momentarily about what this could mean, which may further motivate the appeal to a notion of choice. Even so, as we will see, the more precise nature of this particular form of choice is likely to remain elusive. Having clarified the role of stances in relation to ontological belief, much concern about voluntarism in epistemology here is revealed as following from a misunderstanding of what is involved in making choices. The idea of voluntary commitment in the context of scientific ontology applies to stances in the first instance, and only thereby, secondarily or indirectly, to belief. There is nothing inaccurate in saying that there is a sense in which doxastic states such as belief and suspension of belief are chosen, but this statement all by itself threatens to mislead if it is not understood as a simple consequence of the fact that there is something voluntary in the adoption of stances, and it is stances that in part determine our doxastic states, in virtue of the attitudes, orientations, and epistemic policies they afford regarding whether certain kinds of ontological propositions are amenable to belief. The sense in which beliefs are chosen is thus derivative of choices of stance. This should go some way toward allaying, I hope, the most pressing concerns of doxastic involuntarists, at least in the context of belief and suspension of belief regarding scientific ontology. Many who instinctively balk at the idea that belief is subject to choice are relieved to hear that what is (directly) chosen is something “upstream” from, or in some sense prior to or distinct from, the manifestation of a specific doxastic attitude toward a specific proposition—​that choice here pertains more directly to (for example) questions of what would constitute telling evidence, how this evidence is obtained, and how it is assessed (cf. Clarke 1986). The sort of voluntary commitment I intend is not, in the first instance, to beliefs such as ‘electrons have (or do not have) negative charge,’ or ‘negative charge is (or is not) 219

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a dispositional property,’ though such beliefs may of course follow in the wake of one’s stance. The relevant choice in the first instance concerns whether propositions like these belong to domains of ontological theorizing whose propositions are regarded as belief-​apt. We are dealing not with a choice between ontological propositions P and ~P, but with a choice concerning whether to believe propositions like P and ~P at all. If one’s answer to this latter question is ‘yes,’ then one believes accordingly. If it is ‘no’—​if one cannot bring oneself to believe propositions like P nor ~P—​then one is agnostic. As intimated a moment ago, in the course of all of this clarification of the nature of voluntaristic choice, I have yet to say much about the issue of how these choices are made, exactly. How does one go about choosing a stance? Here, however, it is unclear that there is much of anything one can say. The stances of agents reflect the things they value, epistemically, including certain kinds of information and explanation, certain kinds of evidence and argument, and intuitive judgments about what kinds of information, explanation, evidence, and argument support inferences to ontological claims and to what degrees, all of which then translates into certain epistemic policies. But this seems merely to push the question back one step: how exactly does one come to have the values one has? And here it is difficult to say more, because it is hard to imagine that there is anything like a decision procedure or an algorithm that could be made somehow explicit to demonstrate how a given agent ends up with his or her values. When someone shows an affinity for a particular stance by carrying out the epistemic policies associated with it, this tells us something about what she values in connection with ontological investigation, but nothing about why or how this person came to have these values in the first place. This is not to say that one cannot speculate about relevant factors. For example, what one values epistemically may well be influenced

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by one’s background in the form of ambient cultures and training, including the influence of teachers, mentors, and peers. A sociological account of how stances are adopted seems ultimately unpromising, however, since it is all too evident that these kinds of influences underdetermine the stances that people adopt. Often, those with similar backgrounds interpret the outputs of scientific theorizing, modeling, and experimentation in different ways, which suggests that background notwithstanding, one is at liberty to choose. Furthermore, in the self-​consciously critical settings of scientific and philosophical practice, the purely passive, unconscious absorption of ambient values seems a doubtful vector for stance adoption because agents are regularly pressed to defend and consider alternative interpretations of ontology by those with conflicting stances. This inevitably leads to explicit discussions of how certain values and stances resonate with different individuals which, again, suggests a notion of choice—​but without further illumination of the driver or mechanism of choice itself. There are, no doubt, forms of analysis of human experience and cognition that might be brought to bear here, but they are equally unpromising. Phenomenology, the philosophical study of conscious experience from a subjective, first-​person perspective, may generate more detailed articulations of how precisely different stances strike one as appealing, unappealing, or uninteresting (see Ratcliffe 2011; cf. Rosen 2001, p. 88), but this kind of articulation merely fleshes out the explanandum, namely, facts that taken together describe what one values in terms of felt qualities of attraction, aversion, or disinterest, which is simply a finer-​grained way of describing what one values. It does not furnish an explanans—​an account of the source of these affective states (for lack of a better term) concerning which are the right and wrong ways to go, epistemically, or how we come to have them. Similarly, empirical

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psychology or cognitive science may one day—​this may seem far-​ fetched, but who knows?—​reveal correlations between certain cognitive features of individuals and the stances they adopt. To rest with an analysis of the nature of choice in these terms, however, would appear to court a similar unhelpfulness: such information would amount to interesting facts in the neighborhood of what we value, but it is difficult to see how it would answer the question of why we value certain things at the expense of others. Perhaps the question of why one adopts the stances one does is simply wrongheaded. Many who advocate the idea of naturalized epistemology, according to which epistemology conceived as a branch of philosophy should ultimately be given up in favor of scientific analysis, hold that the traditional epistemological quest for an account of the justification and warrant of beliefs should be replaced with a scientific quest to describe causal processes or laws pertaining to the relevant cognitive processes. According to some ‘non-​ normative naturalists,’ there is in principle nothing further to say about normative concepts like justification; analogously, one might hold that there is nothing further to say about the nature of choice. I will take no stand on these issues here but raise them so as to reveal an important upshot concerning voluntarism: the naturalist position does not answer the question of the ultimate nature of choice; it simply dissolves it. Whether there is something more to be said regarding the nature of voluntariness and the will, which we are unable to say for lack of knowing, or whether there is simply nothing further to be said—​either way—​we have now run out of illumination. Let us rest content, therefore, for the time being at least, with what we have.5 5.  There is an inevitable parallel here with Wittgenstein’s (1963, §217) advice regarding intractable questions:  ‘If … I  have reached bedrock, and my spade is turned … Then I  am inclined to say, ‘This is simply what I do.’’ Cf. Richardson & Uebel 2005, p. 77. Shah 2002, p.  442 characterizes doxastic voluntarism simply in terms of ‘the capacity to be moved’ upon considering evidence.

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7.4 EPISTEMIC STANCES IN CONFLICT: RATIONALITY AND ROBUSTNESS I have maintained that in the context of scientific ontology, the kinds of knowledge, explanation, and inference to which one is most inclined, or that one most values, has a significant bearing on one’s assessment of where to draw lines between domains of theorizing that generate beliefs and those that do not. This immediately suggests a notion of choice, for as we have seen, there are different stances in play associated with different epistemic policies, all of which are live options. Saying that there is an element of choice involved, however, is not to suggest that it is acceptable to form beliefs in any old way—​ for example, in haphazard, random, or arbitrary ways. Voluntarism in epistemology is not a license to behave carelessly or erratically when it comes to belief. If we are to manage our epistemic lives defensibly and well, there must be constraints on belief even if one allows for voluntarism, because the formation of (healthy) beliefs cannot be a matter of “anything goes.” Constraints of this sort are usually taken to be furnished by an appropriate theory of rationality, that is, an account of what it is rational for someone to believe given their evidence. And so the question arises: what is rational given voluntarism? If we regard the scope of ontological commitment as something that may vary, rationally, as a function of different stances, the conception of rationality at issue will have to be “permissive” in the sense that it allows (potentially) more than one stance and resulting set of beliefs, given evidential considerations, to count as rational. What is called for is thus an understanding of rationality that is appropriately permissive but that does not thereby open the door to epistemic behavior that would count as undesirable in a neutral or stance-​transcendent sort of way. In chapter 2 (section 3) I invoked van Fraassen’s proposal to the effect that rationality amounts to

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a constraint of internal coherence. Let me now press this into service as an account of the rationality of adopting a stance. A rational stance is one that does not lead inexorably to the logical incoherence of beliefs that contradict one another, or degrees of belief that violate the basic axioms of probability; furthermore, a rational stance is one that does not lead inexorably to beliefs that are in tension with the attitudes and orientations that constitute the stance itself, since subscribing to such a combination would be self-​defeating and thus pragmatically incoherent. ‘Self-​sabotage by one’s own lights,’ as van Fraassen expresses it, is surely a bad thing whatever one’s stance. Let us understand rationality and irrationality with respect to stances in terms of internal coherence and incoherence (respectively) construed in this way. Two questions immediately present themselves. While limiting the constraint imposed by rationality to internal coherence opens the door to the possibility that more than one stance will count as rational, since it seems at least possible that more than once stance could be internally coherent, a question inevitably comes to the fore about whether this inherently permissive constraint is strong enough to rule out epistemically pathological stances. This is to ask whether mere internal coherence is a strong enough account of rationality when considered in a neutral or stance-​independent way. Let me assign the discussion of this important question to the next section. In the meantime, let us focus on another important question whose consideration will complete the present discussion of what it means to choose a stance, by examining what it means to adopt one in the face of opposition. What debate can there be between those holding conflicting stances on the assumption that rationality is exhausted by internal coherence? When parties to a disagreement hold positions that are mutually incompatible and yet which appear defensible given the values and standards of

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assessment adopted by each, a certain robustness of disagreement seems a predictable result. Under these circumstances, what is a meaningful debate? One obvious way to resolve a conflict between those who adopt different stances would be to demonstrate that only one of the stances at issue is rational—​in other words, show that only one is coherent. Productive debate might thus take the form of attempts to reveal and rebut charges of incoherence regarding stances that are incompatible with one’s own and, of course, to subject one’s own to the same kind of scrutiny. The proof of this pudding is in the eating, and without examining all such imaginable attempts and rebuttals, there always remains the possibility that judgments to the effect that certain stances are rational could be undermined. That said, regarding well-​established stances such as the deflationary stance, the empiricist stance, and the metaphysical stance, the simple fact of their unfaltering persistence over centuries of debate should give us pause. For reasons that should now be clear, it can be extremely difficult to demonstrate that a stance is internally incoherent. For one thing, recall that a stance is not equivalent to the ontological beliefs that one may form by adopting it and thereby implementing the epistemic policies associated with it. Consider, for example, the metaphysical stance:  whether one tracks the explicit subject matters of the sciences or the implicit subject matters discussed by metaphysicians of science, beliefs concerning the existence of various kinds of objects, events, processes, and properties have changed over time, in some cases dramatically. It is evident historically that for a variety of reasons, both empirical and non-​ empirical, when many who adopt a given stance have judged their ontological beliefs to be mistaken, they have reformed them, all the while preserving their stance. Stances are not identifiable with any

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one set of beliefs because while they clearly facilitate beliefs, they do not of necessity facilitate any one set of them. In this way, stances underdetermine the beliefs they facilitate, and given the option of belief revision, even a demonstration of false or inconsistent beliefs would not by itself demonstrate the incoherence of an associated stance. If revealing incoherence in a set of ontological beliefs cannot serve as an indirect way to demonstrate the irrationality of a stance, why not simply tackle the stance head-​on? Recall, however, the moral of James’s reflection on the nature of pursing truth and avoiding falsity: there is no one way to chart a path between the bad epistemic consequences of doing too much of one at the expense of the other. That is, there is no way to compel by force of plausible constraints of rationality alone the choice of any one particular stance. This was the observation that motivated voluntarism about stances to begin with:  there are, it seems, different ways of coping with the uncertainty of inferring ontological conclusions from the kinds of evidence produced by observation and experimentation. Thus it would appear that the only way to undermine a stance directly is by targeting the source of these different ways of coping, namely, the different values inherent in different assessments of epistemic risk, arising from different assessments of the extent and import of empirical vulnerability and explanatory power, and taking into account factors such as the kinds of things—​predictions, explanations, and so on—​considered important and thus desirable by different agents. Once it is clear that the only way to proceed in the attempt to undermine a stance, however, is to target the values favoring it, it also becomes clear that with respect to well-​entrenched stances that have been subject to extensive scrutiny and discussion for some time, one is doomed before one begins. The sorts of values that we

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have considered in connection with the deflationary, empiricist, and metaphysical stances are not susceptible to any obvious demonstrations of internal incoherence. Consider, for instance, the opposition between the empiricist stance and the metaphysical stance. In what way could it be incoherent to be more or less cautious or more or less adventurous in forming beliefs where the evidence generated by scientific practice entails nothing by itself regarding how cautious or adventurous one should be? A given stance may facilitate beliefs in microscopic spores, or epigenesis, or black holes, or dispositional properties, or concrete relations even in the absence of physical relata, or it may not. The outputs of the sciences are open to more restrained and more expansive ontological interpretations, and these interpretations are not entailed but merely enabled by means of the practice of science. This is not to say that one’s values cannot change, and with a change in values may come a change of heart about which stance or combination of stances to adopt, and where. Imagine that despite having always felt that the most important thing to human inquirers are facts about observable phenomena such as those putatively revealed by the sciences, given that we are ‘creatures bound in a world of sensation’ (Cartwright 2007, p. 37; cf. van Fraassen 2007, p.  344), one grows weary of the limitations this places on one’s epistemic life, such that theorizing about certain unobservable phenomena that once seemed foreign, given one’s habitual epistemic priorities, begins to seem important and compelling after all. Or imagine that despite having always been inclined to interpret scientific theories in a particular domain in a realist manner, one becomes sufficiently frustrated by one’s inability to make sense of the idea of ontological continuity through theory change in this domain historically that one comes to abandon one’s resolve to extend belief in this way (recall the discussion of the pessimistic

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induction in chapter 1, sections 4, 5). Values can change, but note:  this is irrelevant to the prospects of undermining well-​ established stances, since here we are entertaining the thought of trading one rational stance for another, not convicting a stance of irrationality. Thus it turns out that both the direct route of targeting values and the indirect route of targeting beliefs are ineffective strategies for undermining the most influential stances regarding scientific ontology. The result is, I believe, a striking revelation about what it is reasonable to expect of debates that ultimately hinge on the differential adoption of these stances. Disputes between those who are inclined toward the deflationary, empiricist, and metaphysical stances display some of the defining hallmarks of what Gurpreet Rattan (manuscript) calls ‘deep disagreement,’ which ‘concerns fundamental principles, norms, or rules’ and which, as result of this lack of common ground pertaining to fundamental commitments, proves ‘intractable’ and ‘trenchant.’ It is a form of disagreement that ‘does not lead to conciliation but remains uncompromising and committed and can be, or can be expected to be, longstanding.’ Given this reality, the nature of the debate is transformed: we can articulate our stances, put our epistemic values on the table for examination by ourselves and by others, explain how and why they resonate with us, invite others to empathize, and encourage the same with respect to our interlocutors. This is the basis of a collaborative epistemology in the context of voluntarism.6

6.  At this level of depth of disagreement, hints of fundamentality, intractability, and trenchancy have appeared in a number of important discussions of the nature of scientific knowledge. See Laudan 1984, pp. 48–​49 for readings of Popper and Reichenbach in this way; see also Rescher 1985. For intimations of collaborative epistemology see Forbes forthcoming, which argues that historical case studies of science (here, nineteenth-​century electrodynamics) may furnish information that is useful in determining which stances best serve specific epistemic values.

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7.5 IN DEFENSE OF PERMISSIVE NORMS OF RATIONALITY FOR STANCES I have presented voluntarism in epistemology—​more specifically, as applied to stances relevant to scientific ontology—​in a descriptive way. I take it that the voluntary adoption of mutually incompatible stances in this sphere is a fact of life, not something whose existence or relevance to ontological pursuits very generally is uncertain or in doubt.7 The fact that there is voluntarism in practice, though, does not by itself entail that it is ultimately defensible in principle. I have done my best to furnish a persuasive case to the effect that voluntarism is not only actual but inevitable and entirely reasonable given our shared epistemic condition. However, one promissory note left over from the previous section remains to be discharged in the service of this claim. When indicating that the rationality of adopting a stance involves nothing more than meeting a constraint of internal coherence, broadly construed, I noted that one might yet worry that by opening the door this way to certain well-​known and influential stances, one may inadvertently allow epistemically undesirable stances through the door as well, where undesirability is something that can be judged in a stance-​neutral (and thus non-​question-​ begging) sort of way. Let us conclude this chapter by considering whether internal coherence does, in fact, amount to a strong enough account of rationality. Concerns about accounting for rationality in terms of coherence typically stem from the worry that it is too permissive in one or both 7.  Analogously, Lipton (2004, p.  153) describes Kuhn’s account of the assessment of theoretical virtues (accuracy, consistency, scope, simplicity, fruitfulness) by scientists, which is offered as a descriptive account of choices between rival theories, as a ‘constructive proof of voluntarism.’ While different in substance and application, Kuhn’s suggestion that the interpretation and relative importance of these putative virtues are often differently but nonetheless rationally assessed by scientists bears significant similarities to the present case.

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of the following ways: it is either complicit in an unacceptable relativism with respect to judgments of truth and falsity; or it allows for epistemically pathological stances, in the sense that it sanctions stances whose associated epistemic policies are transparently flawed. Consider first the worry about truth, which is substantive but easily laid to rest. If different stances toward ontological commitment are rationally permissible, different agents may rationally hold different beliefs, produced by different judgments concerning specific propositions. As we have noted a couple of times already, however, this sort of pluralism with respect to belief does not have the consequence that many fear in connection with the idea of epistemic relativism: that contradictory beliefs are licensed as rational even in the light of all the same evidence, which is to say that one agent may believe an ontological proposition, P, and another may believe ~P, and that this is all fine so far as rationality is concerned. It is only natural to wonder whether this could be acceptable from the point of view of a plausible epistemology. Could it really be the case that rationality is indifferent with respect to judgments of truth, such that whether an ontological claim is judged true or false may simply depend on one’s choice of stance? The status of this kind of relativism is interesting in its own right and there are arguments on both sides (see Schoenfield 2014), but it is strictly irrelevant to a consideration of voluntarism regarding stances. The contrary doxastic states at issue here, in thinking about ontological claims made by those motivated by variations on the empiricist and metaphysical stances, do not concern belief in propositions and their negations, but rather belief and suspension of belief. Where someone adopting one stance believes P, someone adopting another stance may hold that neither P nor ~P are propositions that she can believe, for they belong to a domain of ontological theorizing whose propositions are unsuitable for belief. In the opposition between those who draw lines separating domains of ontological 230

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theorizing that are appropriate for belief and agnosticism in different places, there is no license to make contradictory ontological claims, only different decisions concerning which magnitudes of metaphysical inference are admitted as generating belief in the first place. Voluntarism with respect to stances requires, at most, that one person’s ontological beliefs across different domains of theorizing may be a proper subset of another person’s, but this is not to sanction contradictions. Whatever its merits or demerits elsewhere, the worry about relativism regarding judgments of truth and falsity gains no traction here. Another worry about rationality as internal coherence is commonly expressed in a number of ways, all of which appear to be fueled by a shared intuition to the effect that so crucial an epistemic notion as rationality must involve more of a constraint on belief formation than mere coherence. Without this something more, the rationality of adopting a stance will surely be compatible with epistemic policies that are problematic—​so goes the intuition. This diagnosis is neatly captured by Paul Dicken (2010, p. 79) when he suggests that the voluntarist conception of rationality ‘is too wildly divorced from our intuitive understanding of rationality to be credible.’ Though one cannot help but appreciate the force of this intuition, I believe that it misdirects those who have it, leading them to draw a mistaken conclusion about rationality in this context. As I will now suggest, the force of the intuition that there is something missing is properly directed toward furnishing a more detailed elaboration of what I have called ‘internal coherence, broadly construed.’ It is not, however, properly thought to undermine the idea that in the context of stance voluntarism, rationality amounts to no more than coherence. Recall that the notion of coherence under consideration has both logical and pragmatic dimensions. The former demands that a rational stance should not require one to form contradictory beliefs, or degrees of belief that fail to satisfy the axioms of probability, and the 231

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latter demands that a rational stance is not self-​defeating, in the sense that it leads one to believe propositions that are in tension with (thus “sabotaging”) the very application of the epistemic values that define the stance itself. (For example, if one judges that theorizing about the existence or non-​existence of concrete possible worlds other than our own is properly met with agnosticism, but the epistemic policies associated with one’s stance generate such claims nonetheless, something has gone wrong in the sense of pragmatic incoherence.) I submit that the intuition that there is something missing in this analysis of rationality fails to do justice to the extent of what a constraint of pragmatic coherence demands, and that charitably understood, it plainly does, in fact, rule out the sorts of problematic epistemic policies that critics of permissivism mistakenly believe to be compatible with it. What critics typically take to be missing in the notion of permissive rationality are features that are, as it happens, properly attributed to it, by way of a more detailed conception of what it means to avoid pragmatic incoherence. For instance, take Stathis Psillos’s (2007, p.  158) concern that voluntarism fails to incorporate a proper deference to evidence in the form of a commitment to ‘regard all evidence that bears on a certain belief (or hypothesis) judiciously.’ In a similar vein, Marc Alspector-​ Kelly (2012, p. 189) worries that ‘voluntarism is so wildly permissive that it countenances as rational … belief-​sets which completely disregard all empirical evidence.’ But does it? Permissivism allows much, as we have seen, but it is difficult to see how it could allow a disregard for evidence. Recall that ‘stance’ here is short for ‘epistemic stance,’ and the adjective is not idle. The epistemic policies associated with stances are implemented with ontological beliefs in mind, in the pursuit of knowledge and thus truth. How could an epistemic stance permit a disregard for evidence, given that evidence is, by definition, anything that serves to indicate, confirm, corroborate, or prove the truth or falsity of a proposition? Any epistemic policy that counseled 232

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such disregard would be antithetical to any stance, and would thus qualify as irrational on the basis of a violation of pragmatic coherence. The same reasoning applies to Psillos’s (p. 162) further recommendation that ‘beliefs should be formed by reliable means or methods.’ Any stance favoring epistemic policies wedded to unreliable methods would be guilty of self-​sabotage, and would thus qualify as irrational according to voluntarism. What these concerns about permissive norms of rationality for stances help to illuminate is that pragmatic coherence is a richer notion than has been appreciated. By articulating these norms in ways that transcend the idiosyncratic characteristics of particular stances, their broader scope is revealed. Since some norms appear to be neutral with respect to individual stances—​they apply to all stances merely in virtue of their shared epistemic character—​theorizing about them may require that one step back from one’s own commitments to think more broadly about the coherence of epistemic projects simpliciter. When James Ladyman (2004, p. 142) suggests that permissive rationality ‘entails that someone who … counter-​inducts cannot be impugned so long as their synchronic degrees of belief remain consistent,’ one must wonder: is it really impossible to judge, in a stance-​neutral sort of way, the epistemic performance of someone who habitually infers conclusions that are at odds with everyday inductive practices (such as generalizing from observed instances)? Coherence is something that can be assessed diachronically, not merely synchronically. If the aim is true belief, and one’s epistemic policies habitually deliver results that demonstrably fail to meet this aim, then surely, at some point the judgment that aims and methods are in tension, that the latter is sabotaging the former, becomes irresistible. To miss this would be to be blind to one’s own pragmatic incoherence. It is a difficult challenge to imagine in the abstract all of the ways in which one might behave incoherently, from an epistemic point of 233

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view, as might be obvious when examining the concrete details of specific cases. Nevertheless, it is a standing principle of voluntarism that wherever incoherence is evident, the stance favoring it is thereby undermined. The permissive account of rationality does not allow that anything goes, and what it excludes is precisely what is problematic. This should furnish a bulwark against intuitive misgivings, but let me end with a final assurance. It is one thing to imagine deviant epistemic practices; now, let us think about the actual practices at issue in extant disagreements about where to draw the line between domains of ontological theorizing that are properly regarded in terms of belief versus suspension of belief. Here we find no advocates for disregarding evidence, or exotic inferential practices, or indeed any practice that is obviously incoherent with respect to the pursuit of knowledge. Ultimately, what is at issue between those who adopt more cautious and more expansive views of scientific ontology has little to do with rationality and everything to do with how far one is willing to go, armed only with uncertain inferences, in an epistemic setting where there is no universal, stance-​transcendent conception of how to chart a course between the poverty of excessive caution and the pitfalls of excessive zeal.

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[ 8 ]

 Coda Ontology with lessons from Pyrrho and Sextus

8.1 GETTING TO THE BOTTOM OF IT ALL, WHILE AWAKE Once I was invited to give a talk at a conference in honor of A. N. Eminent Philosopher. Since I think very highly of this person’s work and the conference was organized to take place on a subtropical island with palm trees, it was hard not to be delighted. Everything was lovely, but the night before my talk I had a strange dream. A few of us were having a wonderful time sailing off the coast and, for no good reason that I  could imagine, A.  N. E.  Philosopher pushed me over the side. If that wasn’t strange enough, despite being a good swimmer in the waking world, in the dream world I began to sink. Luckily, much like Aquaman, I was somehow able to breathe, but disconcertingly, I noticed that while initially I could see everything around me with great clarity on this beautiful, sunny day in gorgeous waters, the deeper I went, the less I was able to see. At long last it felt good, finally, to reach the welcome solidity of the bottom—​as far as I could go, the journey now at an end—​and enjoy the sensation of feeling grounded once more. Yet here I could hardly make out a thing.

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On the surface, the sciences present us with theories and models that appear to describe all manner of things—​quarks and viruses and generalized anxiety disorder and rational economic agents and a Big Bang at the start of the universe. Quite apart from these explicit subject matters of theories and models, some who study the sciences are also tempted to think about the arguably implicit subject matters of scientific work, such as different sorts of properties and laws of nature and ranges of possibility apparently implicated in scientific explanations and predictions. On the surface there is a rich tapestry of objects, events, processes, and properties abundantly illuminated by scientific practice. When one truly appreciates the craft, dedication, and ingenuity exemplified in this endeavor, it is impossible not to luxuriate in the awe-​inspiring practice of science. It is the philosopher’s curse, however, to subject this amazing array of descriptions to deeper consideration. How should one make sense of the fact that some of them appear to conflict, that some of them characterize things in idealized ways we know to be untrue, and that scientists and philosophers alike sometimes disagree about what should ultimately make the cut of scientific ontology? The deeper one goes in grappling with such questions, the more one glimpses the ultimately voluntaristic nature of ontological commitment, which is, in itself, largely unsusceptible to much further illumination. At least, that is how I interpreted the dream. In the preceding chapter I explored the idea that differences in judgment concerning the proper scope and limits of scientific ontology vary, and that some of this variability is in principle indefeasible for the simple reason that at least some of these conflicting judgments are, even though conflicting, nonetheless rationally permissible. This is to say that some mutually incompatible epistemic stances regarding ontology, which determine how agents go about forming ontological beliefs, cannot be faulted for reasons of rationality; they reflect different values of agents in relation to how much epistemic risk they take to be conducive to belief, where risk is conceived in terms of one’s confidence in assessing correctly whether a 236

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proposition is true or false, and where confidence is correlated inversely with perceived risk. Different agents assess risk differently, weighing factors such as susceptibility to empirical testing and the ability to furnish explanations of the phenomena of scientific investigation and everyday observation, in different ways. I have argued that having gotten to the bottom of all of this, what remains in dispute between those who take different stands with respect to the question of which domains of scientific investigation and philosophical consideration are appropriately regarded in terms of belief and which are better regarded in terms of suspension of belief is not amenable to being settled by means of philosophical argument alone. Having come this far, however, I cannot help but worry that some will find this voluntaristic endpoint disconsolately debilitating. Are the powers of philosophical analysis really so limited, powerless to penetrate further? Could we not go further and, in so doing, hold out hope that we may settle the question of how best to conceive the one true extent of scientific ontology once and for all? While I suspect that this may be a natural response, especially among some philosophers and certainly among those who have a great deal invested in debates about scientific ontology, it seems to me that this is not, in fact, the right response. There is no need to be disconsolate. In the current endpoint there is revealed, I  believe, something profound about the nature of ontological inquiry—​something that is not at all impoverished but rather inspiring, the understanding of which we owe to the application of philosophical analysis after all. In this brief, genial coda I hope to convince you, gentle reader, that this is so.

8.2 SKEPTICAL ARGUMENTS: SOME MODES OF AGRIPPA We began this journey all the way back in chapter 1 with the observation that scientific ontology is by its very nature meta-​scientific, in the 237

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sense that scientific practice all by itself does not entail unequivocal ontological commitment. It is only to the extent that both practitioners (scientists) and certain admirers, commentators, and analysts (philosophers of science) bring interpretations to bear—​employing reasoning that is appropriately labeled ‘philosophical,’ whether consciously or unconsciously or explicitly or implicitly—​that ontologies are articulated. Scientific practice all by itself underdetermines scientific ontology. Seeking greater depth of explanation and understanding, one may value a richer ontology. Eschewing the idea of some or all of this kind of seeking, one may value something sparser. Throughout the intervening chapters the revelation of a central role for voluntarism about stances in formulating ontological commitments has served, I hope, as an illustration of the power of philosophy to lay bare the upshot for ontology of the wide-​ranging collection of practices we call sciences. At the risk of being overly bold, let me now suggest that having come this far, what we find is nothing less than a transformative epistemology of scientific ontology. To begin unpacking this claim it will help to draw an analogy to an illustrious and much earlier example of a transformative philosophical project. Pyrrho of Elis, the philosopher of Greek antiquity, is recognized as perhaps the first skeptical philosopher and certainly, at the very least, the inspiration for the philosophical tradition of Pyrrhonian skepticism which arose after his death (in the early third century bce). Pyrrho did not himself record any of his philosophy, and through what little we know of his thought as recorded by his student Timon of Phlius, Pyrrho is not himself perhaps the most helpful source of my intended analogy, in part because what we have of him admits of some potentially complicating ambiguity. One might take him to have a metaphysical agenda, suggesting that in themselves, things in the world have no definite or differentiating features; their (distinctive) natures are thus indefinite or indeterminate. Alternatively, one might interpret him in an epistemological way, to the effect that whatever may be the features 238

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of things in the world, human inquirers are not able to determine or differentiate them. It is the epistemological reading that interests me here, and my analogy is best expressed in terms of Sextus Empiricus’s presentation of skepticism in his Outlines of Pyrrhonism, some five hundred years after Pyrrho. In Sextus’s rendering, Pyrrhonism amounts to the suggestion that one suspend judgment regarding the truth or falsity of all such claims about things in the world. The mere mention of the idea of suspension of judgment no doubt evokes a now familiar appeal throughout the present work to the notion of suspension of belief. Indeed, I take what I have called ‘suspension of belief ’ to be (effectively) what scholars of ancient philosophy have in mind when they speak of suspension of judgment. One might quibble with this: in some usage ‘judgment’ may refer to a process whose outcome is belief, in which case suspending one is not identical to suspending the other, but since in this case suspending judgment would entail suspending belief, and the most obvious route to the latter is the former, this potential quibble is too fine to delay us further here. And of course in other common usage, ‘judgment’ simply refers to the outcome of such a process, namely, a belief, in which case the two suspensions are one and the same. Taking this for granted, now, let me put off elaborating the promised analogy between these two rather different contexts of philosophy—​ancient philosophy and contemporary philosophy of science—​for just a moment longer, in order to clarify first the means by which this kind of suspension arises for Sextus’s skeptic. The strategies that Sextus employs are broadly shared among skeptics of different stripes. They were (and are) commonly used not only by Pyrrhonian skeptics but also by so-​called Academic skeptics, who maintain that we have and can have no knowledge of the world, which is a more forceful claim than the one the Pyrrhonist makes in merely suspending belief with respect to candidate knowledge claims. A key example of these strategies is encapsulated in a 239

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trilemma derived from the “Modes” of Agrippa (another ancient Greek skeptic, also considered by Sextus). If challenged to justify one’s belief regarding a proposition, P, one may give reasons for one’s belief, but the proposition or propositions comprising these reasons (R1 … Rn) will likewise be subject to the same challenge. Iterating this dialectic of challenge and response, one is threatened with a regress ad infinitum. Perhaps at a certain point one may simply insist that further justification is unnecessary; but at precisely this point the skeptical challenge morphs into a charge of dogmatism. Another possibility is that one finds oneself wanting or needing to make recourse to a proposition cited earlier in the chain of justifications so as to reply to the iterated challenge; at this point the challenge morphs into a charge of circularity. Hence the trilemma wielded by so many skeptics: when tempted by belief, how does one escape the worries posed by infinite regresses of justification, dogmatism, and circularity? Much of the history of epistemology can be described as a series of attempts to overcome and reassert the challenges inherent in these Agrippan modes. The charge of dogmatism is often leveled at foundationalist theories of knowledge which appeal to a firm bedrock of basic beliefs, itself requiring no justification in terms of other beliefs, as a platform on which to build knowledge. The charge of circularity is often leveled against coherentist theories, which appeal to the overall coherence of an intermeshing body of beliefs for the justification of any given part of it. It may be tempting to apply these historically storied modes to the context of scientific ontology, to debates about how to draw lines between domains that are ripe for ontological belief and domains in which suspension of belief would be better. After all, there are long-​standing disputes between those who do not extend belief beyond the observable world and those who extend belief (only) as far as some explicit yet unobservable subject matters of scientific work, and those who extend all the way to certain implicit 240

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subject matters of science and perhaps even beyond, to the subjects of some further corners of metaphysics. Objections are raised and reasons given and after a time, the discussions may well seem infinitely prolongable. If ultimately one arrives at conflicting stances about which little more can be said, one may worry about whether their adoption is somehow dogmatic. If stances are defended on the basis of their internal coherence, one may worry about charges of circularity. Though it is tempting to imagine all of this, I do not believe that we should succumb to all such temptation. The present work can be viewed as an extended argument for the idea that there is a sense in which the disputes with which I  have been concerned do, in fact, terminate in the realization that there are different and conflicting (albeit rational) epistemic stances. Thus, one may be rightly tempted to view stances as epistemically foundational, though not in the sense of traditional foundationalist theories in epistemology, which mark out some unique sets of beliefs as privileged above others. Having acknowledged their idiosyncratically foundational character, I would further contend that the adoption and defense of stances does not appear to be susceptible to worries of either dogmatism or circularity, for as I will now suggest, to take such Agrippan worries seriously in the context of drawing lines between domains of scientific ontology apt for belief and agnosticism would seem to require a category mistake.

8.3 A PYRRHONIAN ANALOGY: ISOSTHENEIA AND APHASIA The permissive account of rationality for which I  have argued, on which the constraint of rationality on the adoption of stances is conceived in terms of internal coherence—​avoiding inconsistency, 241

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respecting the probability calculus, steering clear of epistemic projects that are self-​undermining—​may well serve as a contributing factor to the stamina of some disputes about scientific ontology. For even construing rationality in so forgiving a way, it is not always transparent on the surface whether a given stance is, in fact, rational. Furthermore, it is surely healthy to debate whether particular versions of empiricism or scientific realism (for instance), whose advocates are drawn to stances like the empiricist stance and the metaphysical stance, respectively, and which are subject to regular adjustment and reformulation over time, are cogent. These debates do not appear, however, to undermine the underlying stances. To the extent that stances themselves are recognized as rational, the threat of justification ad infinitum is defeated. And since stances are not the sorts of things, like beliefs, about which worries regarding dogmatism and circularity arise in traditional epistemology, it is difficult to see how these concerns could gain traction here. A stance is not something for which one gives justifications as such, but rather something that one adopts because it reflects what one values, epistemically. It is foundational in a manner of speaking, but beyond meeting the basic constraint of rationality, it is not something to be justified so much as an expression of self. Therefore, it is not the application of generic, skeptical arguments to voluntarist epistemology that is the source of the analogy to Pyrrhonism that I promised a moment ago. Rather, I am interested in the distinctively Pyrrhonian conclusion that Sextus draws from his discussion of skepticism. The special knack of a successful Pyrrhonist, says Sextus, is the ability to align the arguments on either side of a proposition, for and against, so as to appreciate their “equal strength”—​isostheneia—​so that it is evident that the support on one side is no more nor less compelling that that on the other. The result of this is a kind of speechlessness—​aphasia—​such that one is unable to say anything 242

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further about the matter let alone the truth value of the proposition. Thus one enters a state of suspension of judgment. It is something very much like this, no doubt, namely, an impression to the effect that no party to a given ontological dispute is more compelling than another, and a resultant inability to say anything further, that often results in agents identifying certain ontological questions or domains of theorizing as ones regarding which we should suspend belief (­chapter 5 gave a detailed illustration of a specific case).1 But quite apart from this observation, here finally is the analogy I most want to draw: when one comes to understand that, ultimately, differences between agents regarding belief and suspension are a function of different stances, the outcome is very much like what Sextus describes. What I am suggesting is that, in a way analogous to Sextus, who in connection with conflicting propositions takes the evidence and arguments before him and argues to a standstill, we have argued the question of where to draw the line between belief and agnosticism about scientific ontology to a number of standstills. Once we appreciate that more than one stance is internally coherent in the ways I have specified, both logically and pragmatically, and that this is the mark of rationality for stances, we have argued to something analogous to isostheneia:  since rationality is the only stance-​neutral criterion for the acceptability of a stance, there are no further grounds on which to prosecute a non-​question-​begging case for the epistemic superiority of one over another; they are, qua rationality, the only relevant measure, “equally strong.” And given this state of affairs, while I  believe 1.  It is worth noting an obvious disanalogy here. Commentators disagree about the intended scope of the Pyrrhonist’s lack of belief. Some take it to be absolute, others hold it to include only philosophical and scientific matters, where reasoning is involved, as opposed to beliefs that are “forced” by experience or acculturation, and others allow only beliefs regarding impressions, as opposed to beliefs about the putative objects of impressions. But all interpretations of Pyrrhonism preclude most of the metaphysical presuppositions and inferences that I have associated with those holding different stances in this work, involving belief in the reality of various entities considered across the sciences and parts of metaphysics.

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that there is great value in what I earlier labeled ‘collaborative epistemology’—​elaborating stances and the values that favor them, entertaining them dispassionately, seeking to understand their purchase on ourselves and our interlocutors—​this must not be conceived as a surreptitious means of arguing for the superiority of any given rational stance, for as we have seen, the relevant mark of strength here is rationality, and all rational stances are rational. Regarding the question of superiority there can be only aphasia, speechlessness, and suspension of judgment.

8.4 EXTENDING THE ANALOGY A BIT FURTHER: ATARAXIA Of course, when one brings one’s values to bear in the context of ontological inquiry, judgment often follows, but this must be understood for what it is. From a neutral epistemological point of view, I  maintain, different but rational stances cannot be judged superior or inferior. Many of us who are interested in questions of scientific ontology are nonetheless passionate about the kinds of ontological theorizing we recognize as worthwhile, and this no doubt fuels the sustained engagement with these questions that is often necessary to produce whatever putative knowledge of the subject matter we are able to generate. One must understand this, however, as work in accord with one’s epistemic values, not as indicative of the inherent preferability of one’s stance. Having internalized this thought, it is credible, I think, to push the analogy to Pyrrhonism a little bit further. Sextus does not end with a description of the speechlessness and suspension of judgment that results from appreciating the equal strength of considerations on different sides. Suspension of judgment elicits, he suggests, a state of ataraxia—​peace of mind, calmness, or freedom from worry in 244

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the face of previously pressing questions—​a state of tranquility. Sextus sees this as following from the skeptic’s appreciation of the fact that no one rival belief is more compelling than another. Analogously, one may come to see that a similar state should attend the appreciation that no stance is more compelling than a rival in any absolute sense, modulo rationality. Is it plausible to think that disputes about where to draw lines between domains of theorizing which admit of belief and those which admit of agnosticism should eventuate in freedom from worry? At first blush, given the intensity of the commitments of many philosophers, the very idea must seem naïve. If the epistemology of scientific ontology that I  have elaborated here is compelling, however, this is precisely the conclusion that beckons. There is plenty of room for dispute: about whether particular stances are, in fact, internally coherent; and as indicated above, about whether more specific prescriptions regarding which particular objects, events, processes, and properties should populate a scientific ontology are convincing (for anyone holding a stance in accordance with which such prescriptions may be appealing, prima facie)—​there are different versions of scientific realism, for example, which espouse different ontologies. At a deeper level, though, any attempt to short-​circuit the persistence of differences at the level of stances is revealed, on this picture, as misconceived. The result is a dissolution of some previously contentious disagreements between those who adopt conflicting stances, and perhaps it is not too much to think that a certain feeling of relief should follow. The disagreements were ill formed. The attempts to resolve them were wrongheaded. With a clearer understanding one is now free to focus attention elsewhere, on issues worthy of philosophical agonizing. One stands relieved. One of the upshots of Parts I and II of this book was that the proper limits of ontology, as recognized by different epistemic agents, vary as a function of different assessments of what magnitudes of 245

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metaphysical inference are belief-​ conducive. At different points along the spectrum of metaphysical inference, the magnitudes of such inference may become too great to allow some epistemic agents to view them as productive of knowledge, given their assessments of the epistemic risk involved in assigning belief to the relevant presuppositions or the conclusions of arguments for ontological claims. At certain points along the spectrum, based on one’s assessment of how strongly empirical vulnerability and explanatory power should bear on the truth or falsity of such presuppositions or conclusions, and the extent to which (in one’s estimation) they do, belief may simply run out. Now, if one cannot shake the judgment that debates about the reality of possible worlds other than our own, each concrete yet causally insulated from one another, are insufficiently informed by or sensitive to the evidence of (scientific) observation, detection, experimentation, and explanatory practice to make a claim in such a way as to command belief—​as one’s own interpretation of the norm of naturalized metaphysics may suggest—​one may not be especially interested in or worried about these debates. If arguments for and against the dispositional nature of properties of scientific interest are viewed in the same way, they should hardly be the cause of one’s insomnia. If one cannot escape the conclusion that quantum theory, superlatively successful vehicle of empirically successful predictions though it undoubtedly is, does not permit ontological inferences regarding the natures of the entities putatively described therein, our continuing struggles to make these inferences need not be a source of consternation. Different epistemic agents may differ in all of these judgments, but according to the extended argument of this book, there is one that they should all share:  insofar as those who draw lines between belief and agnosticism differently nonetheless have genuinely rational stances, these differences should be accepted with tranquility. There is no philosophical basis on which to do otherwise. 246

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8.5 A TRANSFORMATIVE EPISTEMOLOGY OF SCIENTIFIC ONTOLOGY Earlier I suggested that all of this amounts to something transformative. This was intended in both the modest sense in which one understands any transformation as a change, but also in the more lofty or stirring sense of believing that the change involved may be experienced as personally significant and perhaps even inspiring. Lest this seem too grand a suggestion, in closing, let me preach to the converted of those who love philosophy, but hopefully in a way that is helpful to those who are relatively new to philosophy and picked up this work simply out of curiosity regarding the subject matter. Let me suggest that this more ambitious sense of transformation is very much at home in philosophy generally, and that in the context of contemporary philosophy of science, the voluntarist conception of naturalized metaphysics is properly seen as an instance of this sort of philosophy. Many and probably most philosophical projects are intended as transformative in only the modest sense. In saying this I do not mean to downplay their significance even slightly, not least because some of the most important and influential philosophy ever done may be described this way. Rather, I merely hope to facilitate a distinction between philosophy that is insightful and philosophy that furthermore gives us insight into ourselves and others, hopefully for the better. A large proportion of metaphysics and epistemology, for example, fits into the former camp. The aim is to describe or to explain some actual or possible feature of the world (metaphysics) or some actual or possible feature of our knowledge of it (epistemology) and, in doing so, furnish the kind of illumination of these things that only good philosophy can provide. Where possible, one assembles the data of observation, measurement, detection, and experimentation, and leavens it with whatever a priori principles or presuppositions 247

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are necessary in order to collate this information and reason with it. One considers thought experiments and intuitive assessments of how different ways of describing or explaining the targeted feature of the world, or knowledge, stack up against each other, in all the ways that one deems salient. One then derives the best account of the relevant phenomenon one can. The best philosophy in this vein has the power to transform our conceptions of the things it seeks to describe or explain. If one hopes to understand what a property is, or what causation is, or what kind of modal force laws of nature have if any, or if one hopes to determine whether we need to know how precisely a belief is justified before it counts as knowledge, or whether knowledge-​that (e.g., that one is riding a bicycle) is the same sort of thing as knowledge-​how (e.g., of how to ride a bicycle), or whether some knowledge is irreducibly social and not in fact possessed by individual knowers, one may engage with putative instances of the relevant phenomena, philosophically, with the aim to describe or to explain. This is the nature of what one might call descriptive-​explanatory philosophy, producing transformation in the modest sense. On some occasions, however, the change in one’s reckoning of something that comes of philosophical analysis has further repercussions for how one goes on inquiring into matters of philosophy—​ that is, for how one lives, philosophically—​and perhaps even more broadly. This is the sort of transformation I had in mind when I suggested a moment ago that some changes in philosophical points of view may be personally significant in constructive ways.2 As in the

2.  The distinction between different kinds of philosophical transformation to which I  am alluding appears as a recurring theme in the history of philosophy in meta-​philosophical considerations of the nature and purpose of philosophy itself. For a recent articulation of something much like the present distinction, see Gendler 2009, which compares a conception of philosophy as “curve fitting” with one of philosophy as “life shaping.” Cf. Cooper 2009 for some historical perspective.

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modest sense of transformation one begins, no doubt, with description and explanation, but then, recasting this work as preparatory work, one goes further, employing whatever insight has been gained so as to bring about further thinking or ways of acting that have the envisioned personal significance. Certainly, something like this seems to be constitutive of Sextus’s understanding of Pyrrhonian skepticism. The skeptic’s ability to see the arguments on either side of a question as ultimately hanging in a stable balance is not a parlor game for intellectuals, but a way of life, a way of behaving, whose outcome is something of considerable personal import: the peace of mind that makes for tranquility. As the history of the subject attests, Sextus was hardly alone in thinking about philosophy this way. Earlier I noted a central preoccupation of deflationist and pragmatist thinking to the effect that certain philosophical questions are commonly misconceived, and that a better analysis of these questions should relieve the inquirer of the disquiet of grappling with them in a confused way. Infamously, the later Wittgenstein offered to reveal the many pseudo-​problems typical of canonical philosophical inquiry. Once unmasked as confused, these questions could be set aside, which viewed in terms of the present discussion should presumably result in a freedom from at least some of the worries otherwise experienced by many inquirers. The philosophy of science has always sought to engage in projects with transformative agendas, not only in the modest sense but also in the personally significant sense. The motivation of many of the logical empiricists working in the early twentieth century, at a time when the philosophy of science itself was in the process of coalescing into a distinctive, self-​aware branch of philosophical investigation, was to make philosophy an instrument of positive social and political change, and similar motivations were explicit in the work of Karl Popper. Feminist philosophy of science, studies of science 249

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and values, and social epistemology of science all consider the personal, social, economic, political, and other factors that infuse the practice, reception, and impact of the sciences. Much of this is done with the hopeful intention of contributing toward improving the situations of both those who participate in and those who are ultimately affected by scientific investigation. None of this is news and most of it is widely appreciated. But what about debates concerning scientific ontology? So much of the metaphysics and epistemology of the sciences aims to describe and to explain, and this includes many of the approaches to ontological inquiry that we have discussed here, which aim to describe what there is and what those things are like, and to explain the features and behaviors of these things where this seems tenable. For most who undertake this difficult work, that is surely ambition enough. That said, the conclusions of exercises in scientific ontology are often replete with further transformative potential, simply in virtue of representing our best attempts to describe the nature of the world. Our conceptions of the categories of objects, events, processes, and properties that populate this reality have consequences, in just the ways appreciated by logical empiricists, Popperians, feminist philosophers, and those who think about science and values. This is perhaps most transparent in the social sciences, and many have pressed this case regarding the biological and medical sciences. These consequences of scientific ontology, however, can be found across the board, which is evident when one considers how the metaphysical claims and presuppositions inherent to other domains such as physics and chemistry have an impact on (for instance) how resources are allocated for research, and how theories and models informed by these domains end up themselves informing policy on everything from genetic modification to climate change.

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These are important subjects, none of which I have tackled in any direct or explicit way in this book. Nevertheless, I believe that there is something transformative in the sense of personal significance here for anyone who is interested in scientific ontology. Debates between those who think of the proper limits of ontology in different ways are often conducted, I have argued, on the basis of false assumptions. It is a mistake to think that there can be any sort of scientific ontology without recourse to philosophical interpretation in the form of at least some metaphysical presupposition or inference, a fact that is evidenced in part by the multiple interpretability of the outputs of scientific work. The philosophical bases of these different interpretations are often implicit, but they are there nonetheless. It is thus a mistake to suggest that one can derive a favored ontological interpretation from some ground of empirical science that is purified of metaphysical inferences, or that one can take such a ground as a constraint on scientific ontology. We are left with the messiness of assessing epistemic risk for ontological propositions, where different kinds of thinking about the import of empirical vulnerability and explanatory power come into play. These differences reflect different epistemic stances, and the rationality of adopting a stance is inherently permissive—​it does not prescribe any unique way to draw the line between ontological belief and agnosticism. And so, if there is a concluding moral here, perhaps it is this. A  state of affairs in which there are conflicting accounts of scientific ontology is not always epistemically pernicious. Indeed, if what I  have argued here is compelling, it is sometimes an innocuous reflection of our all too human epistemic condition. Those who hold different stances are well equipped to engage in the spirit of a collaborative epistemology, but the intensity of feeling that sometimes attends the desire to prove one of them right and the rest wrong—​to show that a scientific knowledge of ontology must be exhausted by a

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knowledge of observable phenomena, or that it must incorporate the explicit content of scientific theories and models in the form of certain unobservable entities but exclude theorizing about what some regard as its implicit subject matters, and so on—​is fueled by confusions regarding the nature of ontology itself. The norm of naturalized metaphysics recommends that scientific ontology be circumscribed by metaphysical inferences and presuppositions that are held to be sufficiently informed by or sensitive to scientific-​empirical investigation, but as we have seen, this advice all by itself underdetermines the judgment of whether belief or suspension of belief is appropriate in any given domain of ontological theorizing. The sooner we appreciate this, the sooner we will be in a position to let go of a number of ill-​conceived debates about who is right and who is wrong about scientific ontology, the sooner we will be open to a deeper understanding of our own values and those of others, and the sooner we may be ready to take some vital inspiration from it all, with a nod to Pyrrho and Sextus.

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INDEX

agnosticism. See also suspension of belief epistemic stances and, 206, 220, 231, 243, 245–​4 6, 251 isostheneia (equal strength) and, 243 scientific ontology and, 241 Agrippa, 240–​41 Alspector-​Kelly, Marc, 232 Andronicus of Rhodes, 34 aphasia (speechlessness), 242–​4 4 a posteriori reasoning a priori reasoning contrasted with, 36, 45, 60, 73 definition of, 35 empirical considerations as defining quality of, 35–​36, 73 scientific ontology and, 81–​83 a priori reasoning a posteriori reasoning contrasted with, 36, 45, 60, 73 definition of, 35 empiricism and, 47–​48, 85, 247–​48 explanatory virtues and, 48 Kant on, 72 metaphysical inferences and, 35, 43, 45, 52–​53, 66–​67, 71–​74, 81 naturalism and, 77 scientific ontology and, 79, 81–​82 Aristotle, 34, 37, 101 ataraxia (peace of mind), 244–​45, 249

Barnes, Barry, 44 Bhaskar, Roy, 117–​18 big ‘M’ metaphysics, 52–​53, 159, 168, 213 Black, Joseph, 25 Bloor, David, 44 Boucher, Sandy, 206 Boyle, Robert, 38, 42 Burian, Richard, 28 Burtt, Edwin, 42 Callender, Craig, 42 caloric theory, 25–​28 Carnap, Rudolph, 12, 43n3, 74n3 Cartwright, Nancy, 115–​16, 118, 120, 227 categorical properties, 102–​4, 115–​16 causation causal theory of reference and, 30 deflationary accounts of, 135 eliminative structuralism and, 144–​45, 147, 150–​52, 157 entities and, 136 events and, 136 non-​eliminative structuralism and, 147–​48, 152–​53, 157–​58 objects and, 136 structuralism and, 135–​36, 144–​45, 147–​48, 150–​53, 157–​58 traditional views of, 135–​36 Chang, Hasok, 26

265

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INDEX

circularity, 155, 240–​42 collaborative epistemology, 228, 244, 251 Collingwood, R. G., 42 constructive empiricism, 18 Copernicus, Nicolaus, 42 Cowan, Clyde, 94 deflationary ontology context-​transcendent pluralism and, 189–​91 definition of, 8–​9 dispositional realism and, 126 epistemic stances and, 207–​10, 214 historicism and, 9–​11, 31, 57–​58, 184–​85, 208 inconsistent descriptions and, 170–​71 logical empiricism and, 12–​13 perspectivism and, 179, 182, 184–​85, 187–​88 pragmatism and, 12–​15, 31, 43n3, 208 presuppositional metaphysics and, 74 sociology and, 11–​12, 31, 208 degrees of belief case studies and, 28 epistemic risk and, 85 rationality and, 224, 231–​33 scientific ontology and, 16 synchronic consistency of, 233 Descartes, René, 37–​38, 42 descriptive theory of reference, 30 Dicken, Paul, 231 dispositional properties argument from abstraction and, 113, 117–​21 Aristotelian philosophy and, 101 categorical properties and, 102–​4, 115–​16 causality and, 100, 107, 109–​11 contextual behavior and, 199 crystal example and, 114 definition of, 100–​101, 190–​91 dispositional exercise argument and, 113, 115–​17 dispositional regress argument and, 113–​16 empirical vulnerability and, 111 empiricism and, 101, 127, 129–​31 epistemic risk and, 111

epistemic stances and, 101–​2, 117, 127, 129–​30, 220, 227, 246 examples of, 103, 107, 114 explanatory power and, 101, 111–​26, 128, 191 fluidic motion example and, 122–​23 inconsistent descriptions and, 121–​24, 127 as “inference tickets,” 120 light propagation example and, 125 linguistic interpretations of, 103–​4, 114–​15 metaphysical inferences and, 54, 111 ontology of, 101–​4, 109, 118–​20, 122, 124–​25, 129–​30, 132, 190–​91, 194 perception and, 218 property identity and, 128–​30 scientific ontology and, xv, 102, 124, 126–​27 scientific realism and, 102, 104–​6, 109, 111, 121, 127 structural realism and, 108, 111 subatomic physics and, 126 transcendental arguments and, 112–​20 unification and, 110–​11, 127 DNA (deoxyribonucleic acid) logical empiricism and, 13 property identity and, 128 scientific ontology and, 17, 68, 168 Duhem, Pierre, 92 Ehrenhaft, Felix, 44 Einstein, Albert Euclidean geometry and, 74 gravity and, 175 metaphysics and, 42 Newton supplanted by, 9–​10, 175 relativistic spacetime physics of, 9–​10, 42, 62, 72, 74, 175 speed of light and, 72 electromagnetic theory, 31 eliminative structuralism causation and, 144–​45, 147, 150–​52, 157 definition of, 143–​4 4 metaphysical challenges to, 150–​51

266

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INDEX

ontology and, 144–​45, 149–​52, 159–​6 0, 162 physical relations versus physical entities in, 144–​45, 150–​52, 157 Ellis, Brian, 114 empirical vulnerability definition of, 85–​86 dispositional properties and, 111 electron example and, 86–​87 epistemic risk and, 85–​88, 90, 93–​95, 167, 202, 206–​7, 211, 213, 226, 251 experiential distance and, 95 falsifiability and, 86n6 implicit subjects of scientific ontology and, 92 metaphysical inferences and, 86–​87, 93–​94, 163, 246 naturalized metaphysics and, 87–​88, 93–​94 novel predictions and, 90 Platonic universals example and, 86–​87 prospective senses of, 86 theorizing and speculation’s roles in determining, 90 empiricism a priori reasoning and, 47–​48, 85, 247–​48 constructive empiricism and, 18 definition of, 47 dispositional properties and, 101, 127, 129–​31 empirical vulnerability and, 86–​88, 90, 93–​95, 111, 162–​63, 167, 202, 206, 213, 226, 246, 251 as an epistemic stance, 47, 49–​50, 53–​54, 58, 60, 68, 87, 92–​93, 101–​2, 117, 127, 129–​31, 140, 160, 207, 210–​12, 214, 225, 227–​28, 230, 242 instrumentalism and, 18 logical empiricism and, 12–​13, 39–​41, 51, 185, 187, 249–​50 metaphysics and, 43, 45–​48, 51, 53–​58, 68 natural philosophy and, 36–​37 phenomenalism of the present moment and, 54 Pragmatism and, 14 scientific ontology and, 39–​41, 67–​68, 80–​81, 93, 140

scientific realism and, 24–​26, 160, 242 entity realism, 29–​30, 105–​8, 111 enzymes, 160–​61 epistemic commitments. See epistemic stances epistemic risk definition of, 84–​85, 202, 236–​37 degrees of belief and, 85 dispositional properties and, 111 empirical vulnerability and, 85–​88, 90, 93–​95, 167, 202, 206–​7, 211, 213, 226, 251 experiential distance and, 90, 94 explanatory power and, 87–​88, 91–​92, 94–​95, 167, 202, 226, 251 implicit subjects of scientific ontology and, 100 means of evaluating, 214–​15 metaphysical inferences and, 84–​85, 93, 95–​96, 167–​68, 202, 246 naturalized metaphysics and, 84–​85, 88, 95, 167–​68 novel predictions and, 90–​91 scientific ontology and, 85, 87, 94–​96, 99, 167 epistemic stances agnosticism and, 206, 220, 231, 243, 245–​4 6, 251 ataraxia (peace of mind) regarding, 244–​45, 249 attitudes toward evidence and, 232–​33 cognitive science and, 222 collaborative epistemology and, 228, 244, 251 definition of, 46, 205–​6 deflationary stances and, 207–​10, 214, 225, 228 dispositional properties and, 101–​2, 117, 127, 129–​30, 220, 227, 246 empiricist stances and, 47, 49–​50, 53–​55, 58, 60, 68, 84, 87–​88, 92–​93, 101–​2, 117, 127, 129–​31, 140, 160, 207, 210–​12, 225, 227–​28, 230, 242 epistemic relativism and, 50 explanatory power and, 95, 206, 211–​12, 226 isostheneia (equal strength) regarding, 243

267

268

INDEX

metaphysical inferences and, xvi, 53–​56, 60, 68, 95, 161, 231 metaphysical stances and, 48–​50, 60, 70, 88, 93, 102, 130–​31, 140, 143, 207, 212–​14, 218, 225, 227–​28, 230, 242 naturalized epistemology and, 222 phenomenology and, 221 propositions contrasted with, 46–​47 rationality and, xvi, 49–​50, 223–​30, 234, 236, 241, 243–​4 6, 251 scientific antirealism and, 203–​5 scientific ontology and, xiii, 7–​8, 31, 41, 45–​51, 60, 65–​6 6, 84, 202–​3, 206–​7, 213, 215, 219, 223, 228, 243–​45 scientific realism and, 25–​26, 29, 203–​5, 209–​10, 242, 245 skepticism and, 241 subatomic physics and, 140, 143 suspension of belief and, 141, 214, 230, 234, 237, 244 voluntarism and, 215, 218–​32, 234, 238 Esfeld, Michael, 135 Euler, Leonhard, 177 exclusivity problem, 61–​6 4 explanationism, 24–​28 explanatory power definition of, 87, 202 dispositional properties and, 101, 111–​26, 128, 191 empirical success and, 93 empirical vulnerability and, 88 epistemic risk and, 87–​88, 91–​92, 94–​95, 167, 202, 226, 251 epistemic stances and, 95, 206, 211–​12, 226 implicit subjects of science and, 92 metaphysical inference and, 35, 48, 70, 87, 95, 163, 246 natural selection example and, 91 novel predictions and, 91 property identity and, 128–​31 scientific realism and, 104–​12 Standard Model of particle physics example and, 92 structuralism and, 149 unification and, 91–​92

explicit subjects of science epistemic stances and, 213, 225 examples of, 68, 204 implicit subjects of scientific ontology and, xiv, 79–​80, 100 feminism, 249 Fermi, Enrico, 94 Feyerabend, Paul, 9, 56 Fine, Arthur, 209–​10 Forms (Plato), 82 French, Steven, 134–​35, 150 Fresnel, Augustin-​Jean, 31 Galileo Galilei, 37, 42 Gall-​Peters projection, 173–​74 Gassendi, Pierre, 38 genetic determinism, 44 gene transcription, 168 Giere, Ronald, 182, 187 gravity, 175 grounding naturalized metaphysics and, xv, 83–​84, 88 ontological limits and, 82, 84 Hanson, Norwood Russell, 9, 56 Henry, John, 44 historicism, 9–​11, 31, 57–​58, 184–​85, 208 Hobbes, Thomas, 42 ‘How to Make Our Ideas Clear’ (Peirce), 14 Hull, David, 27–​28 Hume, David, 53–​54, 101 Hüttemann, Andreas, 118–​19 implicit subjects of science causation as example of, xiv definition of, 69, 204 empirical vulnerability and, 92 epistemic risk and, 100 epistemic stances and, 213, 225 explanatory power and, 92 explicit subjects of science and, xiv, 79–​80, 100 laws of nature as, 69, 204, 236 ontological limits and, 70 scientific realism and, 160 skeptical trilemma and, 240–​41

268

 269

INDEX

instrumentalism, 17–​18, 39–​41 internal coherence. See under rationality isostheneia (equal strength), 242–​43 James, William, 14, 216–​17, 226, 233 Kant, Immanuel, 72, 185–​87 Kepler, Johannes, 42 Kincaid, Harold, 89 Kitcher, Philip, 25 Kuhn, Thomas historicism and, 9–​12, 184–​85 on metaphysical commitments, 42, 56, 72 paradigms and, 10–​11, 42, 57–​58, 72, 185 perspectivism and, 187 on scientific communities and background knowledge, 57–​58 on scientists’ assessment of theoretical virtues, 229n7 Ladyman, James, 93, 146, 151, 157, 233 Langton, Rae, 153 Laplace, Pierre-​Simon, 25 Lavoisier, Antoine, 25, 27–​28 laws of nature Humean views of, 53–​54 as implicit subject of science, 69, 204, 236 ontology and, 34, 95 philosophical ontology and, 61 scientific realism and, 105, 108, 110, 160 Lewis, David, 153 Litpon, Peter, 186 logical empiricism aims of, 249 critiques of, 39–​4 0 metaphysics and, 51 perspectivism and, 185, 187 pragmatism and, 12–​13 scientific ontology and, 12–​13, 39–​41 verifiability criterion of meaning and, 40 Longino, Helen, 187 Mackie, J.L., 103–​4 Marcum, J.A., 44 Maxwell, James Clerk, 31 meaning holism, 10, 184–​85 Mercator projection, 173–​74

metaphysical inferences a priori dimensions of, 35, 43, 45, 52–​53, 66–​67, 71–​74, 81 big ‘M’ metaphysics and, 52–​53, 159, 168, 213 criteria for, 79 definition of, 35–​36 degrees and magnitudes of, 36, 46, 67, 84, 95, 168, 202, 213, 231, 246 dispositional properties and, 54, 111 empirical vulnerability and, 86–​87, 93–​94, 163, 246 empiricism and, 46–​47, 84–​85, 131, 159, 210–​11 epistemic risk and, 84–​85, 93, 95–​96, 167–​68, 202, 246 epistemic stances and, xvi, 53–​56, 60, 68, 95, 161, 231 explanatory power and, 35, 48, 70, 87, 95, 163, 246 inevitability of, xiv–​xv instrumentalism and, 40 modern science and, 45 naturalized metaphysics and, 66–​67, 70, 76, 80–​85, 132–​33, 167–​68, 252 ontology and, 19, 35, 108 presuppositional metaphysics and, 71–​76 scientific communities’ background knowledge and, 57–​59 scientific ontology and, 31–​34, 38, 41, 46, 48, 51–​60, 64, 66–​68, 71, 73–​75, 132–​33, 152, 161, 168, 234, 251–​52 scientific realism and, 19–​20, 36, 68–​70 small ‘m’ metaphysics and, 52–​53, 159, 168, 213 spectrum of, 52–​53, 60, 66–​70, 84, 87, 95, 141, 159, 161, 167–​68, 202, 246 suspension of belief and, 168 underdetermination problems and, 93 metaphysics. See also metaphysical inference; naturalized metaphysics aims of, 247 big ‘M’ metaphysics and, 52–​53, 159, 168, 213 definition of, 34, 61 dispositional properties and, 101–​2 empiricism and, 43, 45–​48, 51, 53–​58, 68

269

720

INDEX

metaphysical stances and, 48–​50, 60, 70, 88, 93, 102, 130, 140, 143, 207, 212–​14, 218, 225, 227–​28, 242 modern science and, 38–​45 natural philosophy and, 36–​37, 59 ontology and, xiii, 3, 8, 19, 34–​35, 60–​6 4, 82 Pragmatism and, 14 presuppositions and, 71–​76, 79, 81, 108 property identity and, 129 small ‘m’ metaphysics and, 52–​53, 159, 168, 213 subatomic physics and, 141–​48 verifiability criterion of meaning and, 40 Millikan, Robert, 43–​4 4 “Modes” (Agrippa), 240–​41 molecular biology, 160–​61 Morrison, Margaret, 193 naturalized metaphysics continuities with science and, 79–​80, 82–​83 distance metaphors and, 83–​84, 88 empirical vulnerability and, 87–​88, 93–​94 epistemic risk and, 84–​85, 88, 95, 167–​68 explanatory power and, 88 grounding metaphors and, xv, 83–​84, 88 metaphysical inferences and, 66–​67, 70, 76, 80–​85, 132–​33, 167–​68, 252 metaphysical questions and, 75–​76 naturalism and, 67, 77–​80, 88 norm of, 66–​67, 70–​71, 75–​82, 84–​85, 87–​88, 90, 95, 132, 159, 202, 246, 252 novel predictions and, 90 presuppositional metaphysics and, 71–​76, 85 scientific ontology and, 76, 78–​84, 88–​89, 99, 132–​33, 202, 252 scientific realism and, 111 underdetermination problems and, 92–​93, 133 voluntarism and, 247 natural ontological attitude (Fine), 209–​10 natural philosophy dispositional properties and, 101 empiricism and, 36–​37 final causes and, 37–​38

metaphysics and, 36–​37, 59 modern science and, 38, 59 theology and, 36 natural selection, 91 Navier-​Stokes equations, 122 neutrinos, 94 Newton, Isaac Einstein’s supplanting of, 9–​10, 175 Euclidean geometry and, 72 final causes and, 38 gravity and, 175 metaphysics and, 42 second law of motion of, 110 non-​eliminative structuralism causation and, 147–​48, 152–​53, 157–​58 circularity problems and, 155 internally extrinsic entities and, 155–​56, 158 intrinsic versus extrinsic properties and, 153–​55 ontology and, 146, 149, 152–​53, 156–​57, 159–​6 0, 162 physical relations versus physical entities in, 145–​4 6, 152–​53, 157 Ohnstad, Mitch, 198 ontology. See also scientific ontology definition of, xi, 3 deflationary forms of, 9–​15, 31, 43n3, 57–​58, 74, 115, 126, 170–​71, 179, 182, 184–​85, 187–​91, 205, 207–​10 of dispositional properties, 101–​4, 109, 118–​20, 122, 124–​25, 129–​30, 132 eliminative structuralism and, 144–​45, 149–​52, 159–​6 0, 162 epistemic stances and, 207–​14 epistemology and, 180–​81, 184 exclusivity problem and, 61–​6 4 higher versus lower levels of, 8 integration of philosophical and scientific approaches to, xi–​xii, 3–​5 laws of nature and, 34 of light, 126 logical empiricism and, 12 meaning holism and, 10 metaphysical inferences and, 19, 35, 108

270

 217

INDEX

metaphysics and, xiii, 3, 8, 19, 34–​35, 60–​6 4, 82 molecular biology and, 160–​61 naturalism and, 77 non-​eliminative structuralism and, 146, 149, 152–​53, 156–​57, 159–​6 0, 162 ontological pluralism and, 50, 171–​78, 187–​200, 230 philosophical ontology and, 4–​5, 60–​6 4 structural realism and, 107 subatomic physics and, 6, 136–​41, 143–​4 4, 193–​94 theology and, 34 uncertainty regarding, 167–​70 organicism, 44 Osler, Margaret, 37 Outlines of Pyrrhonism (Sextus Empiricus), 239 particle physics. See subatomic physics Paul, Laurie, 61 Pauli, Wolfgang, 94 Peirce, Charles Sanders, 14 perspectivism abstraction and, 179–​80 coherence concerns regarding, 174–​75, 178–​79, 186–​88 definition of, 176–​77 deflationary ontology and, 179, 182, 184–​85, 187–​88 detection and, 182–​84 everyday versus artistic sense of, 172–​73 gravity example and, 175 idealiziation and, 179–​82, 191 inconsistent descriptions and, 121, 171–​75, 190 mapping examples and, 173–​74 ontological pluralism and, xvi, 194 relevance concerns regarding, 178–​79, 188 scientific ontology and, 172–​73, 176, 187, 199 stability concerns regarding, 179, 181–​84, 186 pessimistic induction discontinuity in scientific ontology and, 21, 105, 204 entity realism and, 29–​30

explanationism and, 24–​25 scientific antirealism and, 204 scientific realism and, 21–​23, 105, 204 selective realism and, 23 structural realism and, 106 phenomenology, 221 Pitt, Joseph, 28 Plato, 82, 86–​87 pluralism contexts of investigation and, 197–​200 context-​transcendent forms of, 188–​94 pluralism about behavior and, 190–​95, 197, 199 pluralism about packaging and, 189–​9 0, 194–​95, 197 relativism concerns regarding, 195, 230 scientific ontology and, 194–​96, 198–​9 9 Popper, Karl, 86n6, 249 positivism, 39 pragmatism, 12–​15, 31, 163, 208–​9 presuppositional metaphysics, 71–​76, 79, 81, 108 property identity, 128–​31 Psillos, Stathis on caloric theory and explanationism, 25–​26, 28–​29 on eliminative structural realism, 137n2 on voluntarism and evidence, 232–​33 Pyrrho of Elis, 238–​39 Pyrrhonian skepticism aphasia and, 242–​4 4 ataraxia and, 244–​45 isostheneia and, 242–​43 Sextus Empiricus’s presentation of, 239–​4 0, 242–​4 4, 249, 252 suspension of belief and, 239–​4 0 quantum theory, 138–​39, 246 quiddity, 129–​30 Quine, W.V., 77–​78, 92 rationality degrees of belief and, 224, 231–​33 epistemic stances and, xvi, 49–​50, 223–​30, 234, 236, 241, 243–​4 6, 251

271

72

INDEX

internal coherence and, 49, 224, 227, 229–​33, 241 permissive rationality and, 223–​24, 229–​30, 232–​34, 241–​42 scientific ontology and, 241–​42 testing accounts of, 28n7 voluntarism and, 231–​34 Rattan, Gurpreet, 228 reductionism, 44 Reichenbach, Hans, 187 Reines, Frederick, 94 RNA (ribonucleic acid), 168 Ross, Don, 146, 151 Ryle, Gilbert, 120 Saunders, Simon, 146 scientific antirealism case studies and, 23–​24 definition of, xii, 19 dispositional properties and, 104 epistemic stances and, 203–​5 pessimistic induction and, 204 suspension of belief and, 160 scientific ontology ataraxia (peace of mind) regarding, 244–​45 case study approach to, 20–​31 causal efficaciousness and, 135 deflationary approaches to, 8–​9, 11–​15, 31, 43n3, 74, 115, 126, 170–​71, 179, 182, 184–​85, 187–​89, 191, 205, 207–​10 degrees of belief and, 16 dispositional properties and, xv, 102, 124, 126–​27 epistemic risk and, 85, 87, 94–​96, 99, 167 epistemic stances and, xiii, 7–​8, 31, 41, 45–​51, 60, 65–​6 6, 84, 202–​3, 206–​7, 213, 215, 219, 223, 228, 243–​45 epistemology and, 15–​18, 167, 177, 201 experiential distance and, 94–​95 explicit subjects of science and, xiv, 68, 79–​80, 100, 204, 211, 213, 225, 252 historicism and, 9–​11 implicit subjects of science and, xiv, 69–​70, 79–​80, 92, 100, 109, 127, 160, 204, 213, 225, 236, 240–​41, 252

inconsistent descriptions and, 170–​72, 193 instrumentalism and, 17–​18, 39–​41 isostheneia (equal strength) regarding, 243 metaphysical inferences and, 31–​34, 38, 41, 46, 48, 51–​6 0, 64, 66–​68, 71, 73–​75, 132–​33, 152, 161, 168, 234, 251–​52 meta-​scientific nature of, 6–​7, 31, 33, 237–​38 naturalized metaphysics and, 76, 78–​84, 88–​89, 99, 132–​33, 202, 252 ontological limits and, xv–​xvi, 14–​20, 31, 65–​6 6, 70, 80, 82, 94–​95, 202, 236, 245–​4 6, 251 ontological pluralism and, 194–​96, 198–​9 9 perspectivism and, 172–​73, 176, 187, 199 positivism and, 39 pragmatic approaches to, 12–​14 Pragmatism and, 14 property identity and, 130–​31 rationality and, 241–​42 scientific communities’ background knowledge and, 57–​59, 71, 89, 196 scientific inquiry and, 5–​7, 31, 42–​4 4, 59–​6 0, 65, 99, 132–​63, 238 scientific realism and, xii, 19–​31, 68, 102, 104–​5, 108–​9, 111, 121, 127, 160, 203–​5, 242, 245 skeptical trilemma and, 240 sociological approaches to, 11–​12 suspension of belief and, xvi, 141, 162, 219, 241, 252 theorizing and speculation regarding, 88–​96 transformative epistemology of, 247–​52 underdetermination problem and, 90, 92–​93, 133 voluntarism and, 215, 217–​19, 226, 229, 237 scientific realism case studies and, 23–​32 causal theory of reference and, 30 definition of, xii, 105 deflationary epistemic stances and, 209–​10

272

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INDEX

descriptive theory of reference and, 30 dispositional properties and, 102, 104–​6, 109, 111, 121, 127 empiricism and, 24–​26, 160, 242 entity realism and, 29–​30, 105–​8, 111 epistemic stances and, 25–​26, 29, 203–​5, 209–​10, 242, 245 explanationism and, 24–​28 explanatory power and, 104–​12 inconsistent descriptions and, 121–​22 kind taxonomies and, 110 laws of nature and, 105, 108, 110, 160 metaphysical inference and, 19–​20, 36, 68–​70 miracle argument and, 204 naturalized metaphysics and, 111 observable features of the world and, 19, 68 pessimistic induction and, 21–​23, 105, 204 selective realism and, 23–​24, 30, 106 structural realism and, 30–​31, 105–​8, 111, 133, 137 subatomic physics and, 140 suspension of belief and, 160 unification and, 102, 104–​5, 108–​9, 121, 127 unobservable features of the world and, 19–​20, 68 working posits and, 25 scientific revolutions (Kuhn), 9–​11 selective realism, 23–​24, 30, 106 Sellars, Wilfrid, 56 Sextus Empiricus aphasia and, 242–​4 4 ataraxia and, 244–​45 isostheneia and, 242–​43 Modes of Agrippa and, 240 Pyrrhonian skepticism presented by, 239–​ 40, 242–​4 4, 249, 252 suspension of belief and, 239–​4 0, 243–​4 4 skepticism Academic, 239 ataraxia (peace of mind) emerging from, 245, 249 epistemic commitment and, 26

Pyrrhonian, 238–​39, 242, 249 trilemma (circularity, dogmatism, and infinite regress) suggested by, 240–​41 Sklar, Lawrence, 132 small ‘m’ metaphysics, 52–​53, 159, 168, 213 sociology, 11–​12, 31, 39, 208 stances. See epistemic stances Standard Model of subatomic physics, 92, 133, 138–​39, 142–​43 Stanford, Kyle, 26, 61 structuralism. See also structural realism causation and, 135–​36, 144–​45, 147–​48, 150–​53, 157–​58 eliminative forms of, 137, 143–​45, 147, 149–​52, 157, 160, 162 entities and, 136, 147 explanatory power and, 149 mathematical structuralism and, 156–​57 metaphysical challenges to, 31, 137, 148–​58 non-​eliminative forms of, 137, 145–​49, 152–​57, 160, 162 ontology and, 142–​43, 148–​52, 159–​62 physical relations and, 142–​43 subatomic physics and, 136–​37, 140–​42, 144–​49, 159–​6 0 suspension of belief and, 161–​62 structural realism case studies and, 30–​31 definition of, 30, 106, 133 dispositional properties and, 108, 111 ontology and, 107 pessimistic induction and, 106 theory change over time and, 107 The Structure of Scientific Revolutions (Kuhn), 9 subatomic physics causal efficaciousness and, 134 dispositional properties and, 126 epistemic stances and, 140, 143 experiential distance and, 94 instrumentalism and, 17 metaphysical inference and, 51 metaphysics and, 141–​48 neutrinos and, 94 ontology and, 6, 136–​41, 143–​4 4, 193–​94

273

274

INDEX

permutation invariance and, 139 quantum theory and, 138–​39, 246 scientific realism and, 140 Standard Model of particle physics and, 92, 133, 138–​39, 142–​43 structuralism and, 136–​37, 140–​42, 144–​49, 159–​6 0 suspension of belief and, 140–​41, 162 suspension of belief. See also agnosticism epistemic stances and, 141, 214, 230, 234, 237, 244 metaphysical inference and, 168 ontological inconsistencies and, 171 Pyrrhonian skepticism and, 239 scientific antirealism and, 160 scientific ontology and, xvi, 141, 162, 219, 252 scientific realism and, 160 Sextus Empiricus on, 239–​4 0, 243–​4 4 skeptical trilemma and, 240 structuralism and, 161–​62 subatomic physics and, 140–​41, 162 suspension of judgment and, 239, 243–​4 4 voluntarism and, 215–​19 Sutton, Willie, 198, 200 Timon of Phlius, 238 van Fraassen, Bas constructive empiricism and, 18 on criteria for adopting epistemic stances, 49

empiricism defined in terms of stance by, 47, 210n3 empiricist opposition to metaphysical inference and, 46, 223–​24 on perspectivism and detection, 182–​83 on scientific communities’ traditions, 58 on structures, entities and locations, 157 verifiability criterion of meaning, 40 voluntarism collaborative epistemology and, 228 definition of, 214 doxastic, 216–​19, 222, 230 epistemic stances and, 215, 218–​32, 234, 238 epistemology and, 215–​16, 219, 223, 229 metaphysical inference and, 168 naturalized metaphysics and, 247 perception and, 217–​18 rationality and, 231–​34 relativism and, 231–​32 scientific ontology and, 215, 217–​19, 226, 229, 237 suspension of belief and, 215–​19 temperament and, 216–​17 wave optics, 31 Wittgenstein, Ludwig, 222n5, 249 Worrall, John, 30–​31, 137n2, 203–​5 Wylie, Alison, 203, 205

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