Theory and Reality : Metaphysics As Second Science Angere, Staffan
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Theory and Reality : Metaphysics as Second Science Angere, Staffan 2010 Link to publication Citation for published version (APA): Angere, S. (2010). Theory and Reality : Metaphysics as Second Science. 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LUND UNIVERSITY PO Box 117 221 00 Lund +46 46-222 00 00 Theory and Reality | Metaphysics As Second Science Staffan Angere Department of Philosophy Lund University ©. 2010 by Staffan Angere ISBN 978-91-628-8207-5 Printed in Lund, Sweden by Media-Tryck in October 2010 For Lucius and Portia, who were lost along the way. Preface This is the day for doubting axioms. With mathematicians, the question is settled; there is no reason to believe that the geometrical axioms are exactly true. Metaphysics is an imitation of geometry, and with the geometrical axioms the metaphysical axioms must go too. |C. S. Peirce, \One, Two, Three: Kantian Categories" This book grew out of my curiosity about what the world is like in its most fundamental aspects. That curiosity got me interested in physics, and later in metaphysics. At first, I was intoxicated by the contempo- rary metaphysics movement and its aims to free metaphysical reasoning from the shackles of epistemology and language. But, gradually, I be- came more and more disillusioned. It seemed to me that standpoints were generally accepted or rejected purely for psychological or social reasons, and the naturalist in me felt that such reasons simply were not relevant to questions of what the world is like. In fact, as I discovered, much of contemporary philosophy is an internal affair: a debate is set up on certain premisses, and these are seldom questioned by the debating parties. As the debate proceeds, it takes on a life of its own, and defines its own norms for evaluating what is a good or a bad argument. Intuitions drive argument, and social groups form intuitions. In the end, the debate can move any distance Preface from the|often quite concrete|questions that motivated it. Perhaps the most well-known philosophical school in which this is said to have occurred was Scholasticism; I suspect that much of what goes on in contemporary analytic and continental philosophy will be described in similar terms in the future. The sciences|both deductive and empirical|are not similarly sus- ceptible. They are generally constrained by fairly stable intersubjective methods of evaluation. These change slower than those of philosophy, so even if much science of the past has been given up, much of it also remains valid. Although purely social factors such as intellectual fash- ion do influence both the sciences and philosophy, the sciences are far less at their mercy. The greater subjectivity of traditional philosophy deprives it of its power to find out what the world is like, and the only way to regain that power, insofar as it is attainable at all, is to limit that subjectivity. I have here tried to sketch an image of what an approach to meta- physics, as far as possible free of these defects, might be like. Ideas are gathered both from the sciences and the arts. On the one hand, this book is intended as a work of scientific naturalism, in that the proper methodology of philosophy is taken to be very similar to that of the sciences. On the other hand, the arts also have a large measure of ob- jectivity by their role as image-providers, detached from questions of truth. An image is, in itself, not anything subjective, even if an inter- pretation of said image may be, and I believe the process of imaging to be crucial both to the sciences and to philosophy. Within philosophy, I have mostly been inspired by the works of the giants of the 20th century: Carnap, Quine, Tarski and Wittgenstein among the dead ones, and Michael Dummett and Bas van Fraassen among those still living. Closer to me, I have received much inspira- tion and support from my supervisor Bengt Hansson, and also from professors Erik J. Olsson and Wlodek Rabinowicz of the Lund philoso- phy department. Furthermore, I would like to thank various attendants at seminars where parts of the book have been discussed, and my co- workers at the department, who were always ready to discuss my ideas, no matter how little sense they made: Robin Stenwall, Martin J¨onsson, Stefan Schubert, Carlo Proietti, and many others. vi An immense thanks goes to Sebastian Enqvist for meticulously read- ing through and commenting on the manuscript, for many enlightening discussions on the nature of philosophy and logic, and for support and friendship. But most of all, I owe infinite and unending gratitude to my wife Saga, and our cats Cassius, Ophelia, Hamlet and Othello, for keeping me sane enough to do philosophy, and for always being there for me. This book could not have been written without you. vii Contents Preface v Introduction xi 1 What Metaphysics Can and Cannot Be 1 . The Last Great Metaphysician . 2 . The Perilous Seas of Language . 9 . What's Wrong with Intuition? . 13 . Naturalistic Metaphysics . 18 . Metaphysics as Model Theory . 25 2 Theories 33 . Logic and Theory . 34 . Truths and Theories as Claims . 42 . Theory Transformations . 48 . Variations on the Theory Theme . 51 .. Formal Theories . 51 .. Many-valued theories . 55 .. Probabilistic theories . 58 . Necessity and Possibility . 63 CONTENTS 3 General Metaphysics 70 . Classical Models . 71 . Abstract Nonsense . 78 . Model Space Mappings . 91 . The Diversity of Model Spaces . 97 .. Theory Space Models . 97 .. Matrix Models . 99 .. Coherence Models . 100 .. Concrete Models . 102 .. Physical Models . 104 . Models and Theories . 106 4 Necessitarian Metaphysics 111 . Necessitation Relations and Possible Worlds . 112 . The Model Space N . 123 . Metaphysical Interpretations . 129 . Probabilistic Necessitation . 138 5 Semantics 147 . Tying Theory to Reality . 148 . Probabilistic and Many-valued Semantics . 155 . Varieties of Semantics . 161 . Necessitarian Semantics . 167 . Truthmaker Theories . 175 . Necessitarian Interpretations . 185 6 The Theory{World Connection 193 . Hertz's Principle . 194 . Necessitarian Semantics are Hertzian . 200 . Algebraic and Probabilistic Theories . 208 . Ontological Commitments . 214 . Commitment in a Necessitarian Semantics . 223 7 Applications 229 . Sentential Logics . 229 . Classical First-order Logic, from Above . 235 . Classical First-order Logic, from Below . 242 ix CONTENTS . Set Theory and Mathematics . 252 . Quantum Mechanics . 259 . Mind and Metaethics . 267 Epilogue: Models and Metaphysics 273 Bibliography 280 Index 293 x Introduction Metaphysics, despite being philosophy's most venerable strain, also re- mains one of its most questioned and criticised. For most part, this criticism is well motivated. Metaphysics was supposed to tell us about the fundamental constitution of reality, but since at least the 17th cen- tury, that has been the work of theoretical physics, and not philosophy. While physics has gone from success to success, metaphysics has seen very little actual progress since Plato: modern metaphysicians still con- cern themselves with problems of universals, instantiation, substance, essences, and the rift between appearance and reality. It is easy to draw the conclusion that metaphysics, as a research programme, has gone into regression, and that the parts of it that were once viable have been taken over by the sciences. Why did this happen? The seeds of the collapse were sown already in the battle between the British empiricists and the continental ratio- nalists during the 17th and 18th centuries. It is safe to say that the progress of science granted victory to the empiricists. Certainly, there was the Kantian programme of trying to show that empirical knowledge was confined to the world of appearances, and that a transcendental metaphysics was necessary to grasp reality as it really is. But the fact remains that the world of things{for{us is what we are immersed in, and it is this world that most directly piques our curiousity. That there may be another world behind the veil of appearance may be an intrigu- ing thought, but perhaps more so for science fiction and theology than Introduction for science and philosophy. Accepting that metaphysics studies the world of things as they are accessible to us should, however, not be confused with the quite different programme of analysing our \common sense" metaphysical concepts, mostly associated with Strawson's descriptive metaphysics (Strawson, 1959). Metaphysics, as it interests us in this book, is a subject pur- portedly dealing with what the world is like, and not primarily about our concepts. If there is a viable notion of descriptive metaphysics, apart from the psychological (and empirical) investigation into how we represent things mentally, we will not have much to say about it here. Our target is the real world, and what we think about it only serves as a stepping-stone, since these thoughts say something about the world only if what they say happens to be true. The best methods for finding out what about this world is true or false are empirical, so it is easy to see why traditional metaphysics in the vein of the presocratics, Plato, Descartes and Leibniz must fail.