Darwin's Dangerous Idea (2 page)

my conclusion, so I start where I have to start.

mailer, and general coordinator of the whole project put wings on my heels.

The story I tell is mostly new, but it also pulls together bits and pieces I have also benefited from detailed comments from those who read most or from a wide assortment of analyses I've written over the last twenty-five all the penultimate-draft chapters: Bo Dahlbom, Richard Dawkins, David years, directed at various controversies and quandaries. Some of these pieces Haig, Doug Hofstadter, Nick Humphrey, Ray Jackendoff, Philip Kitcher, Jus-are incorporated into the book almost whole, with improvements, and others tin Leiber, Ernst Mayr, Jeff McConnell, Steve Pinker, Sue Stafford, and Kim are only alluded to. What I have made visible here is enough of the tip of the Sterelny. As usual, they are not responsible for any errors they failed to iceberg, I hope, to inform and even persuade the newcomer and at least dissuade me from. (And if you can't write a good book about evolution witii challenge my opponents fairly and crisply. I have tried to navigate between the help of this sterling group of editors, you should give up!) the Scylla of glib dismissal and the Charybdis of grindingly detailed Many others answered crucial questions, and clarified my thinking in 14
PREFACE

dozens of conversations: Ron Amundsen, Robert Axelrod, Jonathan Bennett, Robert Brandon, Madeline Caviness, Tim Clutton-Brock, Leda Cosmides, Helena Cronin, Arthur Danto, Mark De Voto, Marc Feldman, Murray Gell-Mann, Peter Godfrey-Smith, Steve Gould, Danny Hillis, John Holland, Alas-tair Houston, David Hoy, Bredo Johnsen, Stu Kauffman, Chris Langton, Dick PART 1

Lewontin, John Maynard Smith, Jim Moore, Roger Penrose, Joanne Phillips, Robert Richards, Mark and Matt (the Ridley conspecifics), Dick Schacht, Jeff Schank, Elliot Sober, John Tooby, Robert Trivers, Peter Van Inwagen, George Williams, David Sloan Wilson, Edward O. Wilson, and BUI Wimsatt.

I want to thank my agent, John Brockman, for steering this big project past STARTING IN THE

many shoals, and helping me see ways of making it a better book. Thanks also go to Terry Zaroff, whose expert copyediting caught many slips and inconsistencies, and clarified and unified the expression of many points. And M

Ilavenil Subbiah, who drew the figures, except for Figures 10.3 and 10.4, IDDLE

which were created by Mark McConnell on a Hewlett-Packard Apollo workstation, using I-dea.

Last and most important: thanks and love to my wife, Susan, for her advice, love, and support.

DANIEL DENNETT

September 1994

Neurath has likened science to a boat which, if we are to rebuild it, we
must rebuild plank by plank while staying afloat in it. The philosopher
and the scientist are in the same boat....

Analyze theory-building how we will, we all must start in die middle.

Our conceptual firsts are middle-sized, middle-distanced objects, and
our introduction to diem and to everything comes midway in the
cultural evolution of die race. In assimilating this cultural fare we are
litde more aware of a distinction between report and invention, substance and style, cues and conceptualization, than we are of a distinction between die proteins and the carbohydrates of our material intake.

Retrospectively we may distinguish the components of theory-building,
as we distinguish the proteins and carbohydrates while subsisting on
diem.

—WILURD VAN ORMAN QUINE I960, pp. 4-6

1. Is NOTHING SACRED?

CHAPTER ONE

Tell Me Why

We used to sing a lot when I was a child, around the campfire at summer camp, at school and Sunday school, or gathered around the piano at home.

One of my favorite songs was "Tell Me Why." (For those whose personal memories don't already embrace this little treasure, the music is provided in the appendix. The simple melody and easy harmony line are surprisingly beautiful.)

Tell me why the stars do shine,

Tell me why the ivy twines,

Tell me why die sky's so blue.

Then I will tell you just why I love you.

Because God made the stars to shine, Because

God made the ivy twine, Because God made

the sky so blue. Because God made you, that's

why I love you.

This straightforward, sentimental declaration still brings a lump to my throat—so sweet, so innocent, so reassuring a vision of life!

And then along comes Darwin and spoils the picnic. Or does he? That is the topic of this book. From the moment of the publication of
Origin of
Species
in 1859, Charles Darwin's fundamental idea has inspired intense reactions ranging from ferocious condemnation to ecstatic allegiance, sometimes tantamount to religious zeal. Darwin's theory has been abused and misrepresented by friend and foe alike. It has been misappropriated to lend scientific respectability to appalling political and social doctrines. It has been pilloried in caricature by opponents, some of whom would have it 18 TELL ME WHY

Is Nothing Sacred?
19

compete in our children's schools with "creation science," a pathetic hodge-irresistible parts. Then—if we were lucky—perhaps the rock-solid scientific podge of pious pseudo-science.1

facts would have no stunning implications about religion, or human nature, Almost no one is indifferent to Darwin, and no one should be. The Dar-or the meaning of life, while the parts of Darwin's idea that get people all winian theory is a scientific theory, and a great one, but that is not all it is.

upset could be put into quarantine as highly controversial extensions of, or The creationists who oppose it so bitterly are right about one thing: Darwin's mere interpretations of, the scientifically irresistible parts. That would be dangerous idea cuts much deeper into the fabric of our most fundamental reassuring.

beliefs than many of its sophisticated apologists have yet admitted, even to But alas, that is just about backwards. There are vigorous controversies themselves.

swirling around in evolutionary theory, but those who feel threatened by The sweet, simple vision of the song, taken literally, is one that most of us Darwinism should not take heart from this fact. Most—if not quite all—of have outgrown, however fondly we may recall it. The kindly God who the controversies concern issues that are "just science"; no matter which side lovingly fashioned each and every one of us ( all creatures great and small) wins, the outcome will not undo the basic Darwinian idea. That idea, which and sprinkled the sky with shining stars for our delight—
that
God is, like is about as secure as any in science, really does have far-reaching Santa Claus, a myth of childhood, not anything a sane, undeluded adult could implications for our vision of what the meaning of life is or could be.

literally believe in.
That
God must either be turned into a symbol for In 1543, Copernicus proposed that the Earth was not the center of the something less concrete or abandoned altogether.

universe but in fact revolved around the Sun. It took over a century for the Not all scientists and philosophers are atheists, and many who are believ-idea to sink in, a gradual and actually rather painless transformation. (The ers declare that their idea of God can live in peaceful coexistence with, or religious reformer Philipp Melanchthon, a collaborator of Martin Luther, even find support from, the Darwinian framework of ideas. Theirs is not an opined that "some Christian prince" should suppress this madman, but aside anthropomorphic Handicrafter God, but still a God worthy of worship in their from a few such salvos, the world was not particularly shaken by Copernicus eyes, capable of giving consolation and meaning to their lives. Others ground himself.) The Copernican Revolution did eventually have its own "shot heard their highest concerns in entirely secular philosophies, views of the meaning round the world": Galileo's
Dialogue Concerning the Two Chief World
of life that stave off despair without the aid of any concept of a Supreme
Systems,
but it was not published until 1632, when the issue was no longer Being—other than the Universe itself. Something
is
sacred to these thinkers, controversial among scientists. Galileo's projectile provoked an infamous but they do not call it God; they call it, perhaps, Life, or Love, or Goodness, response by the Roman Catholic Church, setting up a shock wave whose or Intelligence, or Beauty, or Humanity. What both groups share, in spite of reverberations are only now dying out. But in spite of the drama of that epic the differences in their deepest creeds, is a conviction that life does have confrontation, the idea that our planet is not the center of creation has sat meaning, that goodness matters.

rather lightly in people's minds. Every schoolchild today accepts this as the But can
any
version of this attitude of wonder and purpose be sustained in matter of fact it is, without tears or terror.

the face of Darwinism? From the outset, there have been those who thought In due course, the Darwinian Revolution will come to occupy a similarly they saw Darwin letting the worst possible cat out of the bag: nihilism. They secure and untroubled place in the minds—and hearts—of every educated thought that if Darwin was right, the implication would be that nothing could person on the globe, but today, more than a century after Darwin's death, we be sacred. To put it bluntly, nothing could have any point. Is this just an still have not come to terms with its mind-boggling implications. Unlike the overreaction? What exactly are the implications of Darwin's idea—and, in Copernican Revolution, which did not engage widespread public attention any case, has it been scientifically proven or is it still "just a theory"?

until the scientific details had been largely sorted out, the Darwinian Perhaps, you may think, we could make a useful division: there are the Revolution has had anxious lay spectators and cheerleaders taking sides from parts of Darwin's idea that really are established beyond any reasonable the outset, tugging at the sleeves of the participants and encouraging doubt, and then there are the speculative extensions of the scientifically grandstanding. The scientists themselves have been moved by the same hopes and fears, so it is not surprising that die relatively narrow conflicts among theorists have often been not just blown up out of proportion by their 1. I will not devote any space in this book to cataloguing the deep flaws in creationism, adherents, but seriously distorted in the process. Everybody has seen, dimly, or supporting my peremptory condemnation of it. I take that job to have been admirably that a lot is at stake.

done by Kitcher 1982, Futuyma 1983, Gilkey 1985, and others.

Moreover, although Darwin's own articulation of his theory was monumental, and its powers were immediately recognized by many of the scien-20 TELL ME WHY

Is Nothing Sacred?
21

tists and other thinkers of his day, there really were large gaps in his theory are carefully left unarticulated, displaced from attention by several layers of that have only recently begun to be properly filled in. The biggest gap looks distracting rebuttal and counter-rebuttal. The disputants are forever changing almost comical in retrospect. In all his brilliant musings, Darwin never hit the subject slightly, conveniently keeping the bogeys in the shadows. It is upon the central concept, without which the theory of evolution is hopeless: this misdirection that is mainly responsible for postponing the day when we the concept of a
gene.
Darwin had no proper
unit
of heredity, and so his can all live as comfortably with our new biological perspective as we do with account of the process of natural selection was plagued with entirely reathe astronomical perspective Copernicus gave us.

sonable doubts about whether it would work. Darwin supposed that offspring Whenever Darwinism is the topic, the temperature rises, because more is at would always exhibit a sort of blend or average of their parents' features.

stake than just the empirical facts about how life on Earth evolved, or the Wouldn't such "blending inheritance" always simply average out all differ-correct logic of the theory that accounts for those facts. One of the precious ences, turning everything into uniform gray? How could diversity survive things that is at stake is a vision of what it means to ask, and answer, the such relentless averaging? Darwin recognized the seriousness of this chal-question "Why?" Darwin's new perspective turns several traditional assump-lenge, and neither he nor his many ardent supporters succeeded in responding tions upside down, undermining our standard ideas about what ought to count with a description of a convincing and well-documented mechanism of as satisfying answers to this ancient and inescapable question. Here science heredity that could combine traits of parents while maintaining an underlying and philosophy get completely intertwined. Scientists sometimes deceive and unchanged identity. The idea they needed was right at hand, uncovered themselves into thinking that philosophical ideas are only, at best, ("formulated" would be too strong) by the monk Gregor Mendel and decorations or parasitic commentaries on the hard, objective triumphs of published in a relatively obscure Austrian journal in 1865, but, in the best-science, and that they themselves are immune to the confusions that phi-savored irony in the history of science, it lay there unnoticed until its im-losophers devote their lives to dissolving. But there is no such thing as portance was appreciated (at first dimly) around 1900. Its triumphant philosophy-free science; there is only science whose philosophical baggage establishment at the heart of the "Modern Synthesis" (in effect, the synthesis is taken on board without examination.

of Mendel and Darwin) was eventually made secure in the 1940s, thanks to The Darwinian Revolution is both a scientific and a philosophical revo-the work of Theodosius Dobzhansky, Julian Huxley, Ernst Mayr, and others.

lution, and neither revolution could have occurred without the other. As we It has taken another half-century to iron out most of the wrinkles of that new shall see, it was the philosophical prejudices of the scientists, more than their fabric.