Daniel Dennett is one of my favorite philosophers. Few write with his clarity or liveliness, and the topics to which he turns his attention - evolution, religion, free will, the human mind - fall squarely within my area of interest. His explanations are often brilliantly clever, and his conclusions are ones I can usually agree with. In Darwin's Dangerous Idea, his provocative thesis is that Charles Darwin's idea of modification by natural selection, which he calls "the single best idea anyone has ever had" (p.21), is like a "universal acid" that spreads through every field of science and leaves them all changed in its wake. Before Darwin, Dennett writes, the existence of an irreducible intelligent Mind was believed to be the only way to create anything. Even the arch-skeptic David Hume saw no alternative to this conclusion. But we have learned of another way, and ever since, science has been reverberating with its implications.
However, the downside of Darwin's dangerous idea is that it seems too mechanical, too impersonal, to have given rise to many of the things we value highly - such as religion, or human consciousness, or our moral sense. Therefore, ever since it was first proposed, there have been scientists and philosophers who have attempted to construct levees to hold back this universal acid, to prevent it from reaching their most cherished convictions. In Dennett's terminology, evolution by natural selection is a crane - a powerful but mechanical tool that can be used to build ever greater things, including even larger cranes. The resisters of this idea instead want a skyhook - a magical attachment point, floating free and unbound above the earth, from which their valued principles can be hung. The idea of miraculous creation by God, for example, is a skyhook, as are less mystical ideas that would nevertheless create a boundary past which evolution could not go.
Much of Dennett's book is targeted at those whom, in his view, are skyhook-seekers, engaging in efforts to keep natural selection from reaching what seems most valuable about us. Some modern intellectuals whom he accuses of this sin include Stephen Jay Gould, Noam Chomsky, John Searle and Roger Penrose. Others, such as Stuart Kauffman, espouse positions that at first seem to contradict Darwin's dangerous idea, but that on a closer look can easily be folded into it as a special case.
It is important to note that this book cannot be read in isolation. Dennett's arguments are often rather technical, and cannot be understood without also understanding the position and arguments of the people he attacks. I lack the technical expertise required to tell if all of Dennett's arguments are correct, though it did seem to my inexpert eye that he scores at least a few strong points (to be fair, some of his targets, such as Gould, fought back spiritedly, and I think the ultimate truth incorporates parts of each side's reasoning). I have not reached a firm conclusion regarding Dennett's strong adaptationist viewpoint, but I do think it has much to recommend it. I appreciate that he recognizes the necessity of giving testable evolutionary explanations, rather than unsupported "just-so" stories.
Dennett's ultimate conclusion is that there is nothing to fear - that Darwin's idea is really not so "dangerous" after all, because evolution does not rob our cherished notions of their meaningfulness. Rather, it explains that meaningfulness and shows how such things could have come about in a natural world, as the end result of a process in which cranes build increasingly larger cranes. He offers an array of audacious hypotheses about the origin of language, morality, meaning, religion and culture, all of which are grounded firmly in a Darwinian framework. Not all of these may turn out to be strictly correct (in particular, I accept the often-raised rejoinder that cultural evolution is not quite as Dennett describes it, because memes evolve in a Lamarckian, not Darwinian, sense), but I expect all of them at the very least have stimulated much discussion and will continue to do so, and on the broad points most of them must be largely accurate.
While creationists and others have bemoaned this book as the embodiment of everything they see as evil about Darwinian thinking, an attentive reading will fail to turn up any danger. Dennett firmly and explicitly rejects the favorite strawmen of religious antievolutionists, including nihilism and greedy reductionism (he does advocate a form of non-greedy reductionism, which is as it should be). In some cases, a negative reading can only be derived by taking him blatantly out of context. For example, Phillip Johnson:
Dennett cannot be accused of avoiding the religious liberty issue, or of burying it in tactful circumlocutions. He proposes that theistic religion should continue to exist only in "cultural zoos"... those metaphorical cultural zoos may one day be enclosed by real barbed wire...
...I will pass over the legal issues raised by this program of forced religious conversion because the intellectual issues are even more interesting.
This is an outrageous distortion, even for a creationist such as Johnson. This is what Dennett actually had to say:
Safety demands that religions be put in cages, too - when absolutely necessary. We just can't have forced female circumcision, and the second-class status of women in Roman Catholicism and Mormonism, to say nothing of their status in Islam (p.514).
We preach freedom of religion, but only so far. If your religion advocates slavery, or mutilation of women, or infanticide, or puts a price on Salman Rushdie's head because he has insulted it, then your religion has a feature that cannot be respected. It endangers us all... You are free to preserve or create any religious creed you wish, so long as it does not become a public menace (p.516).
In context, Dennett was clearly advocating a crackdown on religions that advocate violence or violation of human rights, not on "theistic religion" in general, as Johnson deceitfully represents him. This is an absolutely correct and ethical position to take, and if Johnson or any other theist opposes it, they are free to come forward and say so.
Though not as narrowly focused on one idea as Dennett's other books, Darwin's Dangerous Idea is no less interesting, and well worth reading. Those who do, regardless of whether they agree with all of Dennett's conclusions, may well find their thoughts opened up along tracks that had not previously occurred to them.
(Crossposted at Ebon Musings.)