Consciousness Consciousness Confessions of a Romantic Reductionist Christof Koch The MIT Press Cambridge, Massachusetts London, England © 2012 Massachusetts Institute of Technology All rights reserved. No part of this book may be reproduced in any form by any electronic or mechanical means (including photocopying, recording, or information storage and retrieval) without permission in writing from the publisher. MIT Press books may be purchased at special quantity discounts for business or sales promotional use. For information, please email [email protected] or write to Special Sales Department, The MIT Press, 55 Hayward Street, Cambridge, MA 02142. This book was set in Syntax and Times Roman by Toppan Best-set Premedia Limited. Printed and bound in the United States of America. Library of Congress Cataloging-in-Publication Data Koch, Christof, 1956 – Consciousness : confessions of a romantic reductionist / Christof Koch. p. cm. Includes bibliographical references (p. ) and index. ISBN 978-0-262-01749-7 (hardcover : alk. paper) 1 . Consciousness. 2 . Mind and body. 3 . Free will and determinism. 4 . Life. I . Title. B808.9.K63 2012 153 — dc23 2011040572 10 9 8 7 6 5 4 3 2 1 To Hannele Contents Preface ix Acknowledgments xi Chapter 1: In which I introduce the ancient mind– body problem, explain why I am on a quest to use reason and empirical inquiry to solve it, acquaint you with Francis Crick, explain how he relates to this quest, make a confession, and end on a sad note 1 Chapter 2: In which I write about the wellsprings of my inner confl ict between religion and reason, why I grew up wanting to be a scientist, why I wear a lapel pin of Professor Calculus, and how I acquired a second mentor late in life 11 Chapter 3: In which I explain why consciousness challenges the scientifi c view of the world, how consciousness can be investigated empirically with both feet fi rmly planted on the ground, why animals share consciousness with humans, and why self-consciousness is not as important as many people think it is 23 Chapter 4: In which you hear tales of scientist-magicians that make you look but not see, how they track the footprints of consciousness by peering into your skull, why you don’t see with your eyes, and why attention and consciousness are not the same 41 Chapter 5: In which you learn from neurologists and neurosurgeons that some neurons care a great deal about celebrities, that cutting the cerebral cortex in two does not reduce consciousness by half, that color is leached from the world by the loss of a small cortical region, and that the destruction of a sugar cube – sized chunk of brain stem or thalamic tissue leaves you undead 59 viii Contents Chapter 6: In which I defend two propositions that my younger self found nonsense — you are unaware of most of the things that go on in your head, and zombie agents control much of your life, even though you confi dently believe that you are in charge 75 Chapter 7: In which I throw caution to the wind, bring up free will, D er Ring des Nibelungen, and what physics says about determinism, explain the impoverished ability of your mind to choose, show that your will lags behind your brain’s decision, and that freedom is just another word for feeling 91 Chapter 8: In which I argue that consciousness is a fundamental property of complex things, rhapsodize about integrated information theory, how it explains many puzzling facts about consciousness and provides a blueprint for building sentient machines 113 Chapter 9: In which I outline an electromagnetic gadget to measure consciousness, describe efforts to harness the power of genetic engineering to track consciousness in mice, and fi nd myself building cortical observatories 137 Chapter 10: In which I muse about fi nal matters considered off-limits to polite scientifi c discourse: to wit, the relationship between science and religion, the existence of God, whether this God can intervene in the universe, the death of my mentor, and my recent tribulations 149 Notes 167 References 173 Index 179 Preface What you ’ re holding in your hand is a slim exposition on the modern science of consciousness. Within the space of a few hours, you can inform yourself about where we natural scientists stand with respect to unravel- ing one of the central questions of our existence — namely, how do subjec- tive feelings, how does consciousness, enter into the world? “ Through your head ” is the obvious answer. But that answer is not very helpful. What is it about the brain inside your head that makes you conscious of colors, of pain and pleasure, of the past and of the future, of yourself and of others? And does any brain suffi ce? What about the brain of a coma- tose patient, of a fetus, of a dog, a mouse, or a fl y? What about the “ brains ” of computers? Can they ever be conscious? I ’ ll tackle these questions and then some, including free will, a theory of consciousness, and the b ê te noire of my research: the extent to which quantum mechan- ics is relevant to understanding consciousness. This book is not just about science, however. It is also a confession and a memoir. I am not only a dispassionate physicist and biologist but also a human being who enjoys but a few years to make sense of the riddle of existence. I learned over the past years how powerfully my uncon- scious inclinations, my beliefs, and my personal strengths and failings have infl uenced my life and the pursuit of my life ’ s work. I experienced what the novelist Haruki Murakami described in a striking interview: “ We have rooms in ourselves. Most of them we have not visited yet. Forgotten rooms. From time to time we can fi nd the passage. We fi nd strange things . . . old phonographs, pictures, books . . . they belong to us, but it is the fi rst time we have found them. ” You ’ ll learn about some of these lost chambers as they become relevant to the quest I ’ m on — to uncover the roots of consciousness. Pasadena, California May 2011