Darwin's Dangerous Idea

ABOUT THE AUTHOR

Daniel C. Dennett is Distinguished Professor of Arts and Sciences and Director of the Center for Cognitive Studies at Tufts University, DARWIN'S

Massachusetts. He is also the author
of Content and Consciousness
(1969);
Brainstorms
(1978; Penguin, 1997);
Elbow Room
(1984);
The Intentional
Stance
(1987);
Consciousness Explained
(1992; Penguin, 1993); and
Kinds
of Minds
(1996).

DANGEROUS

IDEA

EVOLUTION AND THE

MEANINGS OF LIFE

Daniel C. Dennett

PENGUIN BOOKS

To VAN QUINE

Published by the Penguin Group

teacher and friend

Penguin Books Ltd, 27 Wrights Lane, London W8 5TZ, England Penguin Books USA Inc., 375 Hudson Street, New York, New York 10014, USA Penguin Books Australia Ltd, Ringwood, Victoria, Australia Penguin Books Canada Ltd, 10 Alcorn Avenue, Toronto, Ontario, Canada M4V 3B2

Penguin Books (NZ) Ltd, 182-190 Wairau Road, Auckland 10, New Zealand Penguin Books Ltd, Registered Offices: Harmondsworth, Middlesex, England First published in the USA by Simon & Schuster 1995

First published in Great Britain by Allen Lane The Penguin Press 1995

Published in Penguin Books 1996

3579 10 864

Copyright © Daniel C. Dennett, 1995

All rights reserved

The acknowledgements on p. 587 constitute an extension of this copyright page The moral right of the author has been asserted

Printed in England by Clays Ltd, St Ives pic

Except in the United States of America, this book is sold subject to the condition that it shall not, by way of trade or otherwise, be lent, re-sold, hired out, or otherwise circulated without the publisher's prior consent in any form of binding or cover other than that in which it is published and without a similar condition including this condition being imposed on the subsequent purchaser
Contents

Preface

PART I: STARTING IN THE MIDDLE

CHAPTER ONE

Tell Me Why

1. Is Nothing Sacred? 17

2. What, Where, When, Why—and How? 23

3. Locke's "Proof" of the Primacy of Mind 26

4. Hume's Close Encounter 28

CHAPTER TWO

An Idea Is Born

1. What Is So Special About Species? 35

2. Natural Selection—an Awful Stretcher 39

3. Did Darwin Explain the Origin of Species? 42

4. Natural Selection as an Algorithmic Process 48

5. Processes as Algorithms 52

CHAPTER THREE

Universal Acid

1. Early Reactions 61

2. Darwin's Assault on the Cosmic Pyramid 64

3. The Principle of the Accumulation of Design 68

4. The Tools for R and D: Skyhooks or Cranes? 73

5. Who's Afraid of Reductionism? 80

8 CONTENTS

Contents 9

CHAPTER FOUR

CHAPTER NINE

The Tree of Life

85

Searching for Quality

1. How Should We Visualize the Tree of Life? 85

1. The Power of Adaptationist Thinking 229

2. Color-coding a Species on the Tree 91

2. The Leibnizian Paradigm 238

3. Retrospective Coronations: Mitochondrial Eve and 3. Playing with Constraints 251

Invisible Beginnings 96

CHAPTER TEN

4. Patterns, Oversimplification, and Explanation 100

Bully
for Brontosaurus

262

CHAPTER FIVE

1. The Boy Who Cried Wolf? 262

The Possible and the Actual

104

2. The Spandrel's Thumb 267

1. Grades of Possibility? 104

3. Punctuated Equilibrium: A Hopeful Monster 282

2. The Library of Mendel 107

4. Tinker to Evers to Chance: The Burgess Shale

3. The Complex Relation Between Genome and Organism 113

Double-Play Mystery 299

4. Possibility Naturalized 118

CHAPTER ELEVEN

Controversies Contained

313

CHAPTER SIX

Threads of Actuality in Design Space

124

1. A Clutch of Harmless Heresies 313

2. Three Losers: Teilhard, Lamarck, and Directed

1. Drifting and Lifting Through Design Space 124

Mutation 320

2. Forced Moves in the Game of Design 128

3. CuiBono? 324

3. The Unity of Design Space 135

PART III: MIND, MEANING, MATHEMATICS, AND MORALITY

PART II: DARWINIAN THINKING IN BIOLOGY

CHAPTER TWELVE

CHAPTER SEVEN

The Cranes of Culture

335

Priming Darwin's Pump

149

1. The Monkey's Uncle Meets the Meme 335

1. Back Beyond Darwin's Frontier 149

2. Invasion of the Body-Snatchers 342

2. Molecular Evolution 155

3. Could There Be a Science of Memetics? 352

3. The Laws of the Game of Life 163

4. The Philosophical Importance of Memes 361

4. Eternal Recurrence—Life Without Foundations? 181

CHAPTER THIRTEEN

CHAPTER EIGHT

Losing Our Minds to
Darwin

370

Biology Is
Engineering

187

1. The Role of Language in Intelligence 370

1. The Sciences of the Artificial 187

2. Chomsky Contra Darwin: Four Episodes 384 3.

2. Darwin Is Dead—Long Live Darwin! 190

Nice Tries 393

3. Function and Specification 195

CHAPTER FOURTEEN

4. Original Sin and the Birth of Meaning 200

The Evolution of Meanings

401

5. The Computer That Learned to Play Checkers 207

6. Artifact Hermeneutics, or Reverse Engineering 212

1. The Quest for Real Meaning 401

7. Stuart Kauffman as Meta-Engineer 220

2. Two Black Boxes 412

10 CONTENTS

3. Blocking the Exits 419

4. Safe Passage to the Future 422

CHAPTER FIFTEEN

The
Emperor's
New Mind,
and Other Fables
428

Preface

1. The Sword in the Stone 428

2. The Library of Toshiba 437

3. The Phantom Quantum-Gravity Computer:

Lessons from Lapland 444

CHAPTER SIXTEEN

On the Origin of Morality

452

1. E Pluribus Unum? 453

2. Friedrich Nietzsche's Just So Stories 461

Darwin's theory of evolution by natural selection has always fascinated me, 3. Some Varieties of Greedy Ethical Reductionism 467

but over the years I have found a surprising variety of thinkers who cannot 4. Sociobiology: Good and Bad, Good and Evil 481

conceal their discomfort with his great idea, ranging from nagging skepticism to outright hostility. I have found not just lay people and religious CHAPTER SEVENTEEN

thinkers, but secular philosophers, psychologists, physicists, and even biol-Redesigning Morality

494

ogists who would prefer, it seems, that Darwin were wrong. This book is about why Darwin's idea is so powerful, and why it promises—not threat-1. Can Ethics Be Naturalized? 494

ens—to put our most cherished visions of life on a new foundation.

2. Judging the Competition 501

A few words about method. This book is largely about science but is not 3. The Moral First Aid Manual 505

itself a work of science. Science is not done by quoting authorities, however eloquent and eminent, and then evaluating their arguments. Scientists do, CHAPTER EIGHTEEN

however, quite properly persist in holding forth, in popular and not-so-The
Future of an Idea

511

popular books and essays, putting forward their interpretations of the work 1. In Praise of Biodiversity 511

in the lab and the field, and trying to influence their fellow scientists. When I quote them, rhetoric and all, I am doing what they are doing: engaging in 2. Universal Acid: Handle with Care 521

persuasion. There is no such thing as a sound Argument from Authority, but authorities can be persuasive, sometimes rightly and sometimes wrongly. I try to sort this all out, and I myself do not understand all the science that is relevant to the theories I discuss, but, then, neither do the scientists (with perhaps a few polymath exceptions). Interdisciplinary work has its risks. I have gone into the details of the various scientific issues far enough, I hope, to let the uninformed reader see just what the issues are, and why I put the interpretation on them that I do, and I have provided plenty of references.

Names with dates refer to full references given in the bibliography at the back of the book. Instead of providing a glossary of the technical terms used, I define them briefly when I first use them, and then often clarify their meaning in later discussion, so there is a very extensive index, which will let you survey all occurrences of any term or idea in the book. Footnotes are for digressions that some but not all readers will appreciate or require.

12 PREFACE

Preface
13

One thing I have tried to do in this book is to make it possible for you to infighting, and whenever I glide swiftly by a controversy, I warn that I am read the scientific literature I cite, by providing a unified vision of the field, doing so, and give the reader references to the opposition. The bibliography along with suggestions about the importance or non-importance of the could easily have been doubled, but I have chosen on the principle that any controversies that rage. Some of the disputes I boldly adjudicate, and others I serious reader needs only one or two entry points into the literature and can leave wide open but place in a framework so that you can see what the issues find die rest from there.

are, and whether it matters—to you—how they come out. I hope you will read this literature, for it is packed with wonderful ideas. Some of the books I cite are among the most difficult books I have ever read. I think of the books In the front of his marvelous new book,
Metaphysical Myths, Mathematical
by Stuart Kauffman and Roger Penrose, for instance, but they are
Practices: The Ontology and Epistemology of the Exact Sciences
(Cam-pedagogical
tours deforce
of highly advanced materials, and they can and bridge: Cambridge University Press, 1994), my colleague Jody Azzouni should be read by anyone who wants to have an informed opinion about the thanks "the philosophy department at Tufts University for providing a near-important issues they raise. Others are less demanding—clear, informative, perfect environment in which to
do
philosophy." I want to second both the well worth some serious effort—and still others are not just easy to read but a thanks and the evaluation. At many universities, philosophy is studied but not great delight—superb examples of Art in the service of Science. Since you done—"philosophy appreciation," one might call it—and at many other are reading this book, you have prqbably already read several of them, so my universities, philosophical research is an arcane activity conducted out of grouping them together here will be recommendation enough: the books by sight of the undergraduates and all but the most advanced postgraduates. At Graham Cairns-Smith, Bill Calvin, Richard Dawkins, Jared Diamond, Manfred Tufts, we
do
philosophy, in the classroom and among our colleagues, and the Eigen, Steve Gould, John Maynard Smith, Steve Pinker, Mark Ridley, and Matt results, I think, show that Azzouni's assessment is correct. Tufts has provided Ridley. No area of science has been better served by its writers than me with excellent students and colleagues, and an ideal setting in which to evolutionary theory.

work with them. In recent years I have taught an undergraduate seminar on Highly technical philosophical arguments of the sort many philosophers Darwin and philosophy, in which most of the ideas in this book were favor are absent here. That is because I have a prior problem to deal with. I hammered out. The penultimate draft was probed, criticized, and polished by have learned that arguments, no matter how watertight, often fall on deaf a particularly strong seminar of graduate and undergraduate students, for ears. I am myself the author of arguments that I consider rigorous and whose help I am grateful: Karen Bailey, Pascal Buckley, John Cabral, Brian unanswerable but that are often not so much rebutted or even dismissed as Cavoto, Tim Chambers, Shiraz Cupala, Jennifer Fox, Angela Giles, Patrick simply ignored. I am not complaining about injustice—we all must ignore Hawley, Dien Ho, Matthew Kessler, Chris Lerner, Kristin McGuire, Michael arguments, and no doubt we all ignore arguments that history will tell us we Ridge, John Roberts, Lee Rosenberg, Stacey Schmidt, Rhett Smith, Laura should have taken seriously. Rather, I want to play a more direct role in Spiliatakou, and Scott Tanona. The seminar was also enriched by frequent changing what is ignorable by whom. I want to get thinkers in other disci-visitors: Marcel Kinsbourne, Bo Dahlbom, David Haig, Cynthia plines to take evolutionary thinking seriously, to show them how they have Schossberger, Jeff McConnell, David Stipp. I also want to thank my been underestimating it, and to show them why they have been listening to colleagues, especially Hugo Bedau, George Smith, and Stephen White, for a the wrong sirens. For this, I have to use more artful methods. I have to tell a variety of valuable suggestions. And I must especially thank Alicia Smith, the story. You don't want to be swayed by a story? Well, I
know
you won't be secretary at the Center for Cognitive Studies, whose virtuoso performance as swayed by a formal argument; you won't even
listen
to a formal argument for a reference-finder, fact-checker, permission-seeker, draft-updater/printer/