NATURE’S METAPHYSICS This page intentionally left blank Nature’s Metaphysics Laws and Properties by ALEXANDER BIRD CLARENDON PRESS · OXFORD 1 Great Clarendon Street, Oxford ox2 6dp Oxford University Press is a department of the University of Oxford. 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Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above You must not circulate this book in any other binding or cover and you must impose the same condition on any acquirer British Library Cataloguing in Publication Data Data available Library of Congress Cataloging in Publication Data Data available Typeset by Laserwords Private Limited, Chennai, India Printed in Great Britain on acid-free paper by Biddles Ltd., King’s Lynn, Norfolk ISBN 978–0–19–922701–3 13579108642 For Janie and David Fowell This page intentionally left blank PREFACE While writing my first book, on the philosophy of science, I wondered what a world would be like without any laws of nature. Considering first David Armstrong’s view of laws, this is easy to imagine. Laws are higher-order relations among properties. So those higher-order relations would go. But particulars would still have their proper- ties and relations, just as they did with the laws. It is more difficult to imagine a world without David Lewis’s laws, since these are just regularities of a systematic kind. One could remove some of the actual laws by introducing some more facts, ones incon- sistent with the law–regularities; but even then there will be some way of systematiz- ing all the facts, even if very untidily. Nevertheless, the idea of changing and remov- ing laws is still consistent with particulars retaining the properties they have. And in any case, as Stephen Mumford explains, Lewis’s picture is one without laws at all if you have any robust expectations of laws. So for both Armstrong and Lewis the possession of specific properties by things is entirely consistent with there being no laws that govern those properties. But what then differentiates the properties from one another? Such a world is allegedly full of things with different properties, but no thing is causing any other thing to happen. The electron’s negative charge and the positron’s positive charge are said to differ, but without laws concerning charge the two kinds of particle do not differ in their behaviour. Such a world seemed to me hardly to be a genuine possibility. But at the time, the accounts of law provided by Lewis and Armstrong were the two principle contenders in the field. There was something wrong with both, in the divorce between what properties are and what properties do. The behaviour, or rather the tendency towards certain patterns of be- haviour should be built into the properties—or so it struck me. If that is the case, then we do not need laws as external rules telling properties how to interact; the laws would also be built into the properties. At the time I was thinking about such things, circa 1997–8, I was independently beginning to write about dispositions, stimulated first by Lewis’s ‘Finkish Dispositions’ and then by Mumford’s Dispositions.Evenif properties are what they do, a propertied entity does not have to be doing things at all times; it has merely to be capable of doing them. So the intimate link between laws and properties suggests that properties should be considered as dispositions.1 Such thoughts were far from original. The idea that properties have their iden- tities fixed by their causal roles originates with Sydney Shoemaker. The proposal that this accounts for the laws of nature is put forward by Chris Swoyer and devel- oped by Simon Bostock and Max Kistler. A metaphysics with these ideas as central 1That laws could be considered as reflections of dispositions is proposed by Mumford. But that idea struck me as being at odds with his other claim that the dispositional/categorical distinction is a distinc- tion between predicates. Surely laws could not rest on such a metaphysically flimsy foundation. Subse- quently Mumford has developed a more substantial metaphysics of dispositional properties, one which he thinks obviates the need for laws at all. viii Preface components, in particular the thought that properties have dispositional essences— dispositional essentialism as it has become known—is promoted by Brian Ellis. And most recently Mumford argues at length for a similar metaphysics but without laws at all. Not being the first to publish an idea sometimes has its advantages. In this case I have had the opportunity first to reflect on the strengths and weaknesses of my predecessors’ views and secondly, and more importantly, to work at length on the details of a view that is to a greater or lesser degree shared by all those mentioned in this paragraph. It is said that the devil is in the details, but also that God is in the details.2 Both are true. Whether a philosophical or scientific theory stands or falls will depend on how the leading ideas are articulated in detail. I hope to show that there is more God than devil in the details of dispositional essentialism. This book is the result of work carried out over nine years, much of which has been published as individual papers, which were presented in earlier incarnations to numerous audiences. So it is difficult to estimate the number of people who have influenced its outcome, let alone to register them all. I hope that those audiences may nonetheless recognize passages that they have heard and know that I am grate- ful to them for their contribution. However a particularly important group deserves special mention, at whose meetings a large proportion of this book has been pre- sented. The Metaphysics of Science group first gathered at a meeting organized by Johannes Persson in Lund in early 2002. We met later that year in Edinburgh, at a time when I was still at Edinburgh University. And on the strength of those early work- shops, Helen Beebee gained British Academy funding for an International Network which allowed the group to continue its workshops, first in Athens, in 2003, orga- nized by Stathis Psillos. The next meeting was in Reading, 2004, coinciding with the Ratio Metaphysics in Science conference, both organized by Alice Drewery. Subse- quently we met in Ghent, in 2005, organized by Rob Vanderbeeken and Erik Weber, and in Birmingham, in 2006, organized by Helen Beebee. In addition to those men- tioned, the group’s membership includes Anna-Sofia Maurin, James Ladyman, An- nika Wallin, Paul Noordhof, Rebecca Schweder, Katherine Hawley, Joanna Odrowaz- Sypniewska, Samir Okasha, Emma Tobin (who also read the whole of the penulti- mate draft), and Stephen Mumford; to these I am especially grateful, as I am also to quondam members of the group, including Brian Ellis, Sungho Choi, Michael Esfeld, Fraser MacBride, Daniel Nolan, Chris Daly, Toby Handfield, Stephen Barker, and Pe- ter Clark. In addition to several of those already mentioned, the following have also kindly commented on various parts of the book in draft: David Armstrong, Anthony Everett, Jan Hauska, Leon Horsten, Richard Holton, Jon Jacobs, Rae Langton, Amir Karbasizadeh, Hugh Mellor, Finn Spicer, and Tim Williamson. I would also like to remember David Lewis in gratitude for his correspondence with me concerning dis- positions. Much of the work in putting this book together was made possible by an award under the Arts and Humanities Research Council’s Research Leave Scheme, while the final stages of completion have been conducted under the auspices of the Arts 2The latter is attributed to Mies van der Rohe, but also to Gustave Flaubert. The former may be a variant. Preface ix and Humanities Research Council’s Research Grant AH/D503833/1 ‘Metaphysics of Science: causes, laws, kinds, and dispositions’. Parts of this book have appeared in article form or have been developed from such publications. I am grateful to the editors and publishers for their kind permis- sion to use material from the following articles: ‘Dispositions and antidotes’, Philosophical Quarterly 48 (1998): 227–34; published by Blackwell for the Scots Philosophical Club. ‘Laws and criteria’, Canadian Journal of Philosophy 32 (2002): 511–42; published by University of Calgary Press. ‘Structural properties” in Real Metaphysics: Essays in Honour of D. H. Mellor, eds. H. Lillehammer and G. Rodriguez-Pereyra, (2003): 154–68; published by Routledge, by kind permission of Taylor and Francis. ‘Resemblance nominalism and counterparts’, Analysis 63 (2003): 221–8; published by Blackwell for the Analysis Trust. ‘Strong necessitarianism: the nomological identity of possible worlds’, Ratio 17 (2004): 256–76; published by Blackwell.