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  More Articles on Evolution

If you're alarmed by Daniel Dennett's vitriolic style, let me reassure you: He's not that mad. (To see the truly splenetic Dennett, check out his response to John Searle in the December 21, 1995 New York Review of Books.) And, looking past the bluff and bluster, it's not hard to find what annoys Dennett: His real targets-Gould, Lewontin and Chomsky-have thoroughly ignored him. Alas, he is reduced to responding to obscure young upstarts-a fact that seems to trouble him to no end given that half his response is bizarrely directed not at me, but at Stephen Jay Gould. As Gould is a big boy and can handle his own fisticuffs, I'll restrict myself to Dennett's critique of my ideas, not Gould's.

Dennett brands my review "hostile," and I suppose it was. There were two reasons. First, I think Dennett's chief claim-that natural selection may explain everything from the value of physical constants to the vagaries of cultural change-is wrong. Second, I think that Dennett all too often misleads and manipulates his readers. Because it's easy to lose sight, in the thicket of his legalistic charges, of the real issues that separate us, let me touch on these two key points before I answer his charges.

Our fundamental disagreement is simple: Dennett sees natural selection everywhere-in cosmology, in the spread of songs, and in the demise of architectural styles. Natural selection is the one Big Idea that explains, if not everything, next to everything. And I think this is silly. Natural selection explains a tremendous amount of biology. And, undoubtedly, it will occasionally explain facts outside of biology.
But I cannot understand the nearly religious zeal that drives Dennett to conclude that
natural selection is the cardinal force governing the ebb and flow of every substance-from quarks to consciousness-in the universe. Indeed I find the notion that natural selection has much to tell us about, say, the origins and fate of political movements downright bizarre. It is, of course, an occupational hazard of the intellectual trade to think that there is some one great "-ism" that explains everything under the sun (take your pick: class struggle, sex, natural selection). But the voice of experience suggests that the world is not so tidy. And, as I'll argue below, the voice of science further suggests that Dennett's attempt to stamp everything from Planck's constant to Plato's Republic with Darwinism is flawed.

As for Dennett's tendency to manipulate readers, I offered two examples: his infamous bait-and-switch (promising revolutions-Consciousness Explained! Universal Acid!-and delivering cabinet shuffles, a trick Searle also picked up on), and his tendency to brow-beat those in the humanities with scientific claims couched in fancy language. So, for instance, if you don't buy his "population memetics" explanation of
cultural change, it's not because the idea is silly. It's because you're a mushy "Darwin-dreader" who's terrified of science. But we needn't look to Dennett's book to find such tactics. His response is loaded with dubious maneuvers. For instance, anyone who doubted Dennett's ability to issue pseudo-scientific bluster should consider my own exhibit A: Dennett's new explanation of what he meant when he said (incorrectly) that evolution by random change is faster than that by natural selection. He now tells us:

I did indeed misspeak (p. 126), but the result was ambiguity, not error. The issue is complicated: it depends on whether you're measuring the (average) speed of departure from a starting point in genetic space, or the speed of attainment of some particular evolutionary product. I meant the former.

Now I've been in the population genetics business for some time and, frankly, I have no idea what Dennett is talking about. And-I can find no polite way of putting this-it's hard to escape the conclusion that Dennett has no idea what he's talking about, either. Even the most charitable interpretation I can come up with is just plain wrong.

But this is minor league stuff compared to exhibit B: Dennett's presentation of yet another exegesis of Gould and Lewontin's spandrels metaphor. Although this is the part of his jihad where he mistook me for Gould, it provides such a good example of Dennett's evasions and obfuscations that it deserves close scrutiny. Here's the chronology:

1) Gould and Lewontin say that spandrels are "necessary architectural by-products of mounting a dome on rounded arches." Although spandrels get decked out with elaborate mosaics, it's silly to think that spandrels were designed in order to show off mosaics: "[T]his would invert the proper path of analysis. The system begins with an architectural constraint."

2) Dennett doesn't buy it. He claims that there are "indefinitely many ways that those spaces could be filled with masonry, all of them about equal in structural soundness." Remarkably, he concludes that Gould and Lewontin have it all backwards-spandrels are there because they're the best way to display your mosaic collection: "The conclusion is inescapable [sic]: the spandrels of San Marco . . . are adaptations, chosen . . . for largely aesthetic reasons. They were designed to have the shape they have precisely in order to provide suitable surfaces for the display of Christian iconography." To prove his point, he sketches a few spandrel-less "alternatives."

3) An engineer, Robert Mark, shows that Dennett is wrong. He slaps Gould and Lewontin on the wrist for their diction (they should have said "pendentive" not "spandrel"), but concludes: "Dennett's critique of the architectural basis of the analogy goes even further astray because he slights the technical rationale of the [pendentives] . . . his treatment of crucial structural elements as a kind of surface decoration that can be altered at will . . . ignores the . . . centuries of construction experience that led to their incorporation." He concludes that, for large structures, pendentives "are necessary structural elements" and that Dennett's alternatives might well collapse.

So what does Professor Dennett
conclude? That Gould and Lewontin were more or less right and he was more or
less wrong? Not by a long shot.
In a breathtaking display of chutzpah, Dennett concludes that, since they're structurally important, spandrels were "a doubly poor choice" for Gould and Lewontin! Heads I win, tails you lose! In case you're confused (and you should be), I urge you to re-read the above quotes, or, better yet, to read Mark's article.

This example shows off all the less savory aspects of Dennett's modus operandi: His intemperate drive to prove his opponents wrong, no matter what the record says (no wonder they ignore him). His ability to duck and weave in such a way that, while admitting an error, he magically emerges victorious and those who were right are found "doubly" wrong. And an ability to pull the whole thing off with such bravura that the reader naturally falls in behind him, certain that Gould, Lewontin, and, yes, H. Allen Orr, were deeply confused about those darned spandrels.

But enough about Dennett's methods. What of the substance of his response? It's worth noting, first of all, that I agree with several of Dennett's pronouncements. I agree that biological evolution is an uncontroversial fact. I agree that natural selection is the most important force driving this evolution. I agree that anyone who claims that adaptive thinking "has been refuted or relegated to a minor role in evolutionary biology" is wrong. Natural selection is alive and well.

But what does this have to do with my review? My charge was not that natural selection is dead, dying, or even collecting a pension. My charge was that Dennett misrepresents biologists' real and legitimate worries about adaptationism. Dennett's response is remarkably silent here. My claim was
simple: Biologists don't get jitters about adaptationism because we fall for some alternative cause of biological "design," but because, sometimes, we're just not sure that a feature is designed (by natural selection, that is).

One cause of our uncertainty is "neutrality"-the possibility that the biological differences we see don't affect fitness much one way or the other. In his response, Dennett tries to justify his failure to tell his readers about the neutral theory. He suggests that neutrality can be ignored since neutral changes are just "typographical change, visible at the molecular level of the genome." This is simply wrong. Neutral changes might well affect the way an organism looks, its "phenotype" (has Dennett confused "neutral" with "silent"?). This was perfectly clear from the examples I gave: e.g., when Dobzhansky wondered if flower color differences in Linanthus are neutral, he was talking about the way an organism looks, not about its DNA.

But all this neutrality talk is misleading. As I made painfully clear, there are other-and surely more important-reasons for doubting we should spin adaptive yarns about every bump and wrinkle on an organism. (Here's one: you just can't optimize a zillion traits at once.) Dennett, in his response, plainly admits the existence of such non-adaptive traits. Which leads us to the big question: If he agrees non-adaptive traits are out there, why does he find biologists' worries about adaptationism a national emergency, calling, one would guess from the tone of his book, for public floggings?

In any case, Dennett completely ignores my biggest worry about adaptationism: Adaptationist culture encourages wild story-telling just where Design is least obvious. The problem is sociology: nobody ever got famous for speculating on why birds have wings ("So they can fly?"). The road to glory instead demands ingenious stories that are far from obvious, and the whole business can degenerate into a display of cleverness. Ironically, Dennett's response provides a superb example of this problem. Now that he's told us it's wrong, consider this hypothesis: Spandrels were "designed to have the shape they have precisely in order to provide suitable surfaces for the display of Christian iconography." This, I submit, is a perfect
example of the peculiar excesses encouraged by adaptationism. If you want to understand why biologists-while loving our natural selection-worry over adaptationism, study this example. Note its features: flatly implausible (a guy hoping to hold up a 42 foot dome is worried about mosaics?), but very cleverly argued. And just wild enough to turn heads. A more sober hypothesis (spandrels are, say, the cheapest way to do the job) would have a far better chance of being right. But, alas, such a hypothesis wouldn't make much of a splash. Exactly the same dynamic occurs in biology with exactly the same result: a big waste of time.

What of Dennett's comments on cultural evolution-memetics? ("Population memetics" is Dennett's attempt to build a Darwinian science that explains cultural change.) Dennett says my main problem with memetics is that we're "very ignorant of how humans hold ideas in their heads. . . So how can we possibly conclude that the process 'must be' Darwinian?" That is, in fact, half of my problem with memetics and, frankly, it's the kinder, gentler half. As I made clear, my other problem is that what we do know about how humans hold ideas in their heads suggests that "memes"-ideas, songs, fashions-aren't anything like genes. And if memes aren't sufficiently gene-like, we have little reason for thinking that "concepts from population genetics transfer quite smoothly" to population memetics, as Dennett hopes.

So does Dennett believe that memes are like genes? He admits: 1) Memes are produced by "directed mutation," while genes are produced by random mutation; 2) exchange between long-isolated cultures has everything to do with cultural evolution, while exchange between long-isolated species can't happen; 3) memes can blend together, while genes don't ; 4) memes show a Lamarckian style of evolution, whereas genes show only Darwinian evolution. By the end of this list, one begins to suspect that the most important feature memes and genes share is the sound of the words. This does not, of course, mean that no sort of theory of cultural change is possible. But it does mean that Dennett's memetics-founded on a strict meme-gene analogy-is in a bad way.

Dennett also claims that I botched my "substrate neutrality" objection to memetics. Dennett's central claim, in his book, is that because natural selection doesn't care what material it works on-because it's "substrate neutral"-it can be lifted from biology and used to explain everything from the origin of the universe to the evolution of musical styles. I pointed out that biological evolution works only because the hereditary substrate behaves in a special way-genes don't blend. If a substrate doesn't behave in this way-if the evolving units blur and blend together-Darwinism may simply not work. So if memes blend, Dennett's got problems.

There are two interesting things about Dennett's answer. First, he concludes that my objection involves "code," not "substrate," problems. It does not, after all, matter that genes are made of DNA and not plastic-selection would work either way. Fine. But so what? My point remains: Some substrates behave in such a way that Darwinism clearly works (particulate), and some don't (blending). If Dennett wants to call this a code problem, I have nothing against this diagnosis. But I suspect that his obstreperous outburst ("It is Orr who has slipped, falling flat on his face," etc.) is intended to make you miss this point: Whatever you call the disease, the patient is still dead. If memes blend, memetics falls flat on its face. The second interesting thing about this blending objection is that I'm not the first to make it. I find this a bit disappointing as I rather liked it, but I now find that Dawkins also noted that memes, unlike genes, blend. As far as I know, Dennett has not assailed Dawkins for recognizing this sad fact.

I did not mean to imply that Dennett blithely ignored criticisms of memetics from biology-he did not. What I did mean to imply was that, by downplaying the severity of these problems, he misled readers about why memetics never caught on. I said: "He would have the naive reader believe that memetics was shot down by soft-headed humanists ('Darwin-dreaders') who panicked when facing the encroachment of science." Is this fair? Here's what Dennett said in his book:

I suggest that the meme's-eye view of what happened to the meme meme is quite obvious: 'humanist' minds have set up a particularly aggressive set of filters against memes coming from 'sociobiology,' and once Dawkins was identified as
a sociobiologist, this almost guaranteed rejection of whatever this
interloper had to say about culture-not for good reasons, but
just in a sort of immunological
rejection.

This is nonsense. There are two reasons why the "meme meme" never caught on, and both are perfectly good: 1) Scientists saw that it's plagued by the problems I listed above and haven't given it a second thought in ten years. 2) Humanists found that the meme perspective didn't do anything for them: Where are the previously baffling patterns in the history of music or of politics that a meme's-eye view suddenly explained? I know of none and Dennett tells us of none. Has Dennett ever wondered why Darwin's ideas-which pulled the rug out from under cherished humanist ideals far more violently than any talk of memes could-caught on, while memetics did not? Even in an age of postmodernist babble the answer is surely obvious: Darwin's ideas worked. They made sense of a staggering number of previously puzzling patterns and gave order to thousands of once disconnected facts. Memetics did-nothing.

Last, a remark or two on Dennett's astonishing claim that the troubles facing memetics are, after all, much like those facing any other science. We biologists, for instance, may never be able to give an "evolutionary account . . . of the nest-building behaviors in birds." I've read this remarkable passage over and over and each time I reach the same depressing conclusion: Dennett really thinks these situations are similar. Apparently, he can't distinguish between a science admitting it faces unsolved problems and a field admitting its problem is that it's not a science. The difference is, of course, profound. For one thing, a field that admits it's no science must give up its absurd claim that it has united cosmology, biology, and culture, indeed "[l]ife and all its glories . . . under a single perspective" of Darwinism. For another, a field that admits it's no science must give up bullying humanists by saying, "But if you weren't so terrified of science, you'd see that. . . ."

For my money, those mushy Darwin-dreaders have far more to say about the pulse of cultural change than does Dennett and his memetics. If you want to understand, say, the rise and fall of fascism, I'd suggest you learn about the International Brigade or Winston Churchill. I'm not sure much is gained by talking loudly of the "war meme" or the "Churchill meme."

Originally published in the October/ November 1996 issue of Boston Review



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