THE Conscious Mind PHILOSOPHY OF MIND SERIES Series Editor: Owen Flanagan, Duke University SELF EXPRESSIONS Mind, Morals, and the Meaning of Life Owen Flanagan DECONSTRUCTING THE MIND Stephen P. Stich THE CONSCIOUS MIND In Search of a Fundamental Theory David J. Chalmers THE conscious Mind IN SEARCH OF A FUNDAMENTAL THEORY David J. Chalmers OXFORD UNIVERSITY PRESS New York Oxford Oxford University Press Oxford New York Athens Auckland Bangkok Bogota Bombay Buenos Aires Calcutta Cape Town Dar es Salaam Delhi Florence Hong Kong Istanbul Karachi Kuala Lumpur Madras Madrid Melbourne Mexico City Nairobi Paris Singapore Taipei Tokyo Toronto Warsaw and associated companies in Berlin Ibadan Copyright © 1996 by David J. Chalmers First published by Oxford University Press, Inc., 1996 First issued as an Oxford University Press paperback, 1997 Oxford is a registered trademark of Oxford University Press 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, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of Oxford University Press. Library of Congress Cataloging-in-Publication Data Chalmers, David John The conscious mind : in search of a fundamental theory p. cm. (Philosophy of mind series) Includes bibliographical references and index. ISBN 0-19-510553-2 ISBN 0-19-511789-1 (Pbk.) 1. Philosophy of mind. 2. Consciousness. 3. Mind and body. 4. Dualism. I. Title. II. Series. BD418.3.C43 1996 128'.2—dc20 95-36036 9 10 Printed in the United States of America on acid-free paper. Acknowledgments first became excited by consciousness and the mind-body problem as an undergraduate studying mathematics at the University of Adelaide. I Conversations with a number of people, especially Paul Barter, Jon Bax- ter, Ben Hambly, and Paul McCann, helped form my ideas. Even then, the subject seemed about as fascinating a problem as there could be. It seemed faintly unreasonable that somebody could be occupied full-time thinking about something that was so much fun. Later, as a graduate student at Oxford, I found that the mind was always occupying my thoughts where mathematics should have been, and I decided to switch fields and eventually to switch continents. Many people were pa- tient and supportive during this difficult time, especially Michael Atiyah, Michael Dummett, and Robin Fletcher. Thanks also to all those who were subjected to hearing about whatever my latest theory of consciousness hap- pened to be; the ideas in this book are a distant descendant. My decision to move to Indiana University to gain a grounding in philoso- phy, cognitive science, and artificial intelligence was one of the best that I have made. I owe special thanks to Doug Hofstadter; it was his writing that first introduced me to the mysteries of the mind when I was young, and it was the stimulating and comfortable environment of his research lab, the Center for Research on Concepts and Cognition, that allowed these ideas to develop. Although he disagrees with many of the ideas in this book, I would like to think that at some level what I have written remains true to the intellectual spirit of his work. I wrote the first version of this work (then known as Toward a Theory of Consciousness) in a heady six-month period in 1992 and 1993.1 had useful discussions with a number of people at Indiana around this time: everybody at CRCC, especially Bob French and Liane Gabora, and many in other departments, including Mike Dunn, Rob Goldstone, Anil Gupta, Jim Hett- mer, Jerry Seligman, and Tim van Gelder. Thanks also to members of the consciousness discussion group in the back room at Nick's for many enjoyable Monday afternoon conversations. A two-year McDonnell fellowship in philosophy, neuroscience, and psy- chology at Washington University has provided another stimulating environ- ment, as well as a chance to experience Zeno's paradox in finishing this vi Acknowledgments book. I am grateful to the James S. McDonnell Foundation for their support, to all the participants in my graduate seminar on consciousness for discus- sions that helped to refine the book, and to a number of people for conversa- tion and comments, including Morten Christiansen, Andy Clark, Jason Clev- enger, Peggy DesAutels, Pepa Toribio, and Tad Zawidzki. In the last couple of years, I have had an enormous amount of helpful conversation and correspondence about the material in this book. Among many others, thanks are due to Jon Baxter, Ned Block, Alex Byrne, Francis Crick, Dan Dennett, Eric Dietrich, Avi Elitzur, Matthew Elton, Owen Flan- agan, Stan Franklin, Liane Gabora, Guven Giizeldere, Chris Hill, Terry Horgan, Steve Horst, Frank Jackson, Jaegwon Kim, Christof Koch, Martin Leckey, Dave Leising, Kerry Levenberg, Joe Levine, David Lewis, Barry Loewer, Bill Lycan, Paul McCann, Daryl McCullough, Brian McLaugh- lin, Thomas Metzinger, Robert Miller, Andrew Milne, John O'Leary- Hawthorne, Joseph O'Rourke, Calvin Ostrum, Rhett Savage, Aaron Sloman, Leopold Stubenberg, and Red Watson. I am grateful to too many others to mention for interesting conversations about consciousness in general. A special note of thanks to Norton Nelkin, who returned his copy of the manuscript covered with many helpful comments not long before he died of lymphoma. He will be missed. My broader philosophical debts are many. I developed my initial views on consciousness largely on my own, but these have been greatly enriched by my reading on the subject. One discovers quickly that any given idea has likely been expressed already by someone else. Among recent thinkers, Thomas Nagel, Frank Jackson, and Joseph Levine have done much to empha- size the perplexities of consciousness; their work covers much of the same territory as my early chapters. My work also overlaps with work by Ned Block, Robert Kirk, and Michael Lockwood at a number of points. The metaphysical framework that I develop in Chapter 2 owes much to the work of Terry Horgan, Saul Kripke, and David Lewis, among others, and Frank Jackson has independently developed a similar framework, presented in his marvelous 1995 John Locke lectures. The ideas of Daniel Dennett, Colin McGinn, John Searle, and Sydney Shoemaker have provided stimulat- ing challenges throughout. My greatest debts are to Gregg Rosenberg, for memorable conversations and valuable feedback; to Lisa Thomas, for a book on zombies and moral support; to Sharon Wahl, for expert editing and warm friendship; and above all, to all three of my parents, for their support and encouragement. And thanks to all my qualia, and to the environment responsible for producing them, for constant inspiration. As I was finishing this book, I received a fortune cookie in a restaurant, saying "Your life will be full of delightful mysteries." So far it has been, and I am very grateful. Contents Introduction: Taking Consciousness Seriously xi I FOUNDATIONS 1 Two Concepts of Mind 3 1. What is consciousness? 3 2. The phenomenal and the psychological concepts of mind 11 3. The double life of mental terms 16 4. The two mind-body problems 24 5. Two concepts of consciousness 25 2 Supervenience and Explanation 32 1. Supervenience 32 2. Reductive explanation 42 3. Logical Supervenience and reductive explanation 47 4. Conceptual truth and necessary truth* 52 5. Almost everything is logically supervenient on the physical* 71 II THE IRREDUCIBILITY OF CONSCIOUSNESS 3 Can Consciousness Be Reductively Explained? 93 1. Is consciousness logically supervenient on the physical? 93 2. The failure of reductive explanation 106 3. Cognitive modeling 111 4. Neurobiological explanation 115 5. The appeal to new physics 118 6. Evolutionary explanation 120 7. Whither reductive explanation? 121 viii Contents 4 Naturalistic Dualism 123 1. An argument against materialism 123 2. Objections from a posteriori necessity* 131 3. Other arguments for dualism* 140 4. Is this epiphenomenalism?* 150 5. The logical geography of the issues 161 6. Reflections on naturalistic dualism 168 5 The Paradox of Phenomenal Judgment 172 1. Consciousness and cognition 172 2. The paradox of phenomenal judgment 177 3. On explaining phenomenal judgments 184 4. Arguments against explanatory irrelevance 191 5. The argument from self-knowledge* 192 6. The argument from memory* 200 7. The argument from reference* 201 8. The content of phenomenal beliefs* 203 III TOWARD A THEORY OF CONSCIOUSNESS 6 The Coherence Between Consciousness and Cognition 213 1. Toward a nonreductive theory 213 2. Principles of coherence 218 3. More on the notion of awareness 225 4. The explanatory role of coherence principles 233 5. Coherence as a psychophysical law 242 7 Absent Qualia, Fading Qualia, Dancing Qualia 247 1. The principle of organizational invariance 247 2. Absent qualia 251 3. Fading qualia 253 4. Inverted qualia 263 5. Dancing qualia 266 6. Nonreductive functionalism 274 Contents ix 8 Consciousness and Information: Some Speculation 276 1. Toward a fundamental theory 276 2. Aspects of information 277 3. Some supporting arguments 287 4. Is experience ubiquitous? 293 5. The metaphysics of information 301 6. Open questions 308 IV APPLICATIONS 9 Strong Artificial Intelligence 309 1. Machine consciousness 309 2. On implementing a computation 315 3. In defense of strong AI 320 4. The Chinese room and other objections 322 5. External objections 328 6. Conclusion 331 10 The Interpretation of Quantum Mechanics 333 1. Two mysteries 333 2. The framework of quantum mechanics 334 3. Interpreting quantum mechanics 337 4. The Everett interpretation 346 5. Objections to the Everett interpretation 351 6. Conclusion 356 Notes 359 Bibliography 391 Index 405 This page intentionally left blank Introduction Taking Consciousness Seriously onsciousness is the biggest mystery. It may be the largest outstanding obstacle in our quest for a scientific understanding of the universe. CThe science of physics is not yet complete, but it is well understood; the science of biology has removed many ancient mysteries surrounding the nature of life.