Daniel Dennett's View of Adaptationism

I've prepared a bunch of exam questions for my students and given them out two weeks before the exam. I promised them that I would post some of these questions on my blog to see how you would answer them. I'm hoping that you, dear readers, will show my students that there really is some controversy.

Here's the second question.

Discuss the following statement by Daniel Dennett from his book Darwin’s Dangerous Idea (1995, p. 238). Do you agree or disagree? Pay particular attention to the kind of reasoning required in the field of molecular evolution.

Adaptationist reasoning is not optional, it is the heart and soul of evolutionary biology. Although it may be supplemented, and its flaws repaired, to think of displacing it from its cental position in biology is to imagine not just the downfall of Darwinism but the collapse of modern biochemistry and all the life sciences and medicine. So it is a bit surprising to discover that this is precisely the interpretation that many readers have placed on the most famous and influential critique of adaptationism, Stephen Jay Gould and Richard Lewontin’s oft-cited, oft-reprinted, but massively misread classic, “The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Program” (1979).

My students all have a copy of the Spandrels paper and they should be familiar with it. In case you're not (shame), it seems to me that Lewontin & Gould are advocating a pluralist approach to evolution. They criticize the adaptationist program and really would like to see it disappear. Is Dennett making a distinction between the adaptationist program and adaptationist reasoning? I don't think so because here's what he says on the same page as the quotation above.

The biologists' name for this style of reasoning is adaptationism. It is defined by one of its most eminent critics as the "growing tendency in evolutionary biology to reconstruct the evolutionary events by assuming that all characters are established in evolution by direct natural selection of the most adapted state, that is, the state that is an optimum solution to a problem posed by the environment" (Lewontin 1983). These critics claim that, although adaptationism plays some important role in biology, it is not really all that central or ubiquitous—and, indeed, we should try to balance it with other ways of thinking. I have been showing, however, that it plays a crucial role in the analysis of every biological event at every scale from the creation of the first self-replicating molecule on up. If we gave up adaptationist reasoning, for instance, we would have to give up the best textbook argument for the very occurrence of evolution (I quoted Mark Ridley's version of it on page 136): the widespread existence of homologies, those suspicious similarities of design that are not functionally necessary.

Dennett is a philosopher so he might not be as familiar with modern biochemistry as his statement implies. Can anyone figure out why biochemistry would collapse if we stop attributing everything to adaptation? I wonder how adaptationist thinking helps us understand sequence-based phylogenetic trees and the molecular clock? At the other extreme, how crucial a role does adaptationism play in deciding whether birds are dinosaurs or punctuated equilibria are the dominant pattern in the fossil record?

I'm thinking that it might be a problem grading the answer to this question. Can a student defend Dennett's statement and still get a passing grade?

UPDATE: Dan Dennett Replies.

Let me close, for no particular reason, with a few quotations from one of my personal heroes, Betrand Russell.

A stupid man's report of what a clever man says can never be accurate, because he unconsciously translates what he hears into something he can understand.

I think we ought always to entertain our opinions with some measure of doubt. I shouldn't wish people dogmatically to believe any philosophy, not even mine.

If a man is offered a fact which goes against his instincts, he will scrutinize it closely, and unless the evidence is overwhelming, he will refuse to believe it. If, on the other hand, he is offered something which affords a reason for acting in accordance to his instincts, he will accept it even on the slightest evidence. The origin of myths is explained in this way.

In all affairs it's a healthy thing now and then to hang a question mark on the things you have long taken for granted.

It has been said that man is a rational animal. All my life I have been searching for evidence which could support this.

Passive acceptance of the teacher's wisdom is easy to most boys and girls. It involves no effort of independent thought, and seems rational because the teacher knows more than his pupils; it is moreover the way to win the favour of the teacher unless he is a very exceptional man. Yet the habit of passive acceptance is a disastrous one in later life. It causes man to seek and to accept a leader, and to accept as a leader whoever is established in that position.

Patriots always talk of dying for their country but never of killing for their country.

So far as I can remember, there is not one word in the Gospels in praise of intelligence.

The universe may have a purpose, but nothing we know suggests that, if so, this purpose has any similarity to ours.

The whole problem with the world is that fools and fanatics are always so certain of themselves, but wiser people so full of doubts.

This is one of those views which are so absolutely absurd that only very learned men could possibly adopt them.

This is patently absurd; but whoever wishes to become a philosopher must learn not to be frightened by absurdities.

When one admits that nothing is certain one must, I think, also admit that some things are much more nearly certain than others. It is much more nearly certain that we are assembled here tonight than it is that this or that political party is in the right. Certainly there are degrees of certainty, and one should be very careful to emphasize that fact, because otherwise one is landed in an utter skepticism, and complete skepticism would, of course, be totally barren and completely useless.

Aristotle maintained that women have fewer teeth than men; although he was twice married, it never occurred to him to verify this statement by examining his wives' mouths.

The fact that an opinion has been widely held is no evidence whatever that it is not utterly absurd; indeed in view of the silliness of the majority of mankind, a widespread belief is more likely to be foolish than sensible.

It is undesirable to believe a proposition when there is no ground whatsoever for supposing it is true.

A process which led from the amoeba to man appeared to the philosophers to be obviously a progress though whether the amoeba would agree with this opinion is not known.

Advocates of capitalism are very apt to appeal to the sacred principles of liberty, which are embodied in one maxim: The fortunate must not be restrained in the exercise of tyranny over the unfortunate.

Almost everything that distinguishes the modern world from earlier centuries is attributable to science, which achieved its most spectacular triumphs in the seventeenth century.

I would never die for my beliefs because I might be wrong.

In America everybody is of the opinion that he has no social superiors, since all men are equal, but he does not admit that he has no social inferiors, for, from the time of Jefferson onward, the doctrine that all men are equal applies only upwards, not downwards.

It is possible that mankind is on the threshold of a golden age; but, if so, it will be necessary first to slay the dragon that guards the door, and this dragon is religion.

There is something feeble and a little contemptible about a man who cannot face the perils of life without the help of comfortable myths.

Men are born ignorant, not stupid. They are made stupid by education.

Religion is something left over from the infancy of our intelligence, it will fade away as we adopt reason and science as our guidelines.

Science is what you know, philosophy is what you don't know.

That last one is for John Wilkins.

UPDATE: See Dan Dennett Replies

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