Daniel Dennett opens Darwin’s Dangerous Idea by relating how, as a child, he became intrigued by the idea of acids. He liked to imagine an acid so corrosive that nothing could long contain it; it would eat through steel and concrete and glass. Would it, if left unchecked, eat through the very earth and all we hold dear? This is his metaphor for what he calls Darwin’s dangerous idea. Evolution, Dennett argues, continues to challenge us in our most deeply held assumptions about what it means to be human, and though many have attempted to contain it by denying it entirely (religions) or by placing limits on what it can be said to explain (modern secular liberals), every passing year brings more evidence that how we think, feel and perceive the world and each other can ultimately be understood in Darwinian terms. If this horrifies you, if you think this leaves no room for beauty or ethics and dooms us to barbarism or animal selfishness, this book is of particular relevance to you.
The opening chapters deal largely with the mechanics of evolution, and so will probably not startle anyone who has taken a basic biology course, except that Dennett sheds new light on the process itself by way of mathematics and philosophy. Evolution, he argues, is an algorithmic process, which is to say that the complexity it achieves – stereoscopic vision, for example, or the structure of a bird’s wing – is the result of millions of “inputs” (genetic mutations) that build towards an undefined purpose thanks to one immutable criterion: survival. As a thought experiment, he asks us to consider the odds of winning ten consecutive games of heads-or-tails. The likelihood that any one person achieves such a feat is astoundingly low, but Dennett has some fun with us: now conceive of a tournament bracket in which people compete in games of heads-or-tails, advancing when they win and dropping out when they lose. After ten rounds, there will by definition be a “winner,” someone who has won ten straight games. The strictures of evolution create such a tournament where, given conditions favorable for life, a self-replicating molecule and a great deal of patience, biological complexity can arise.
None of this is controversial to the average Darwinian, except that as our understanding of the process has grown, the scope of Darwin’s dangerous idea has expanded, encroaching on territory that, as it turns out, even the very secular are apt to hold dear. Here he brings to bear a wonderful knowledge of philosophy, examining how the mind-matter dichotomy informed our understanding of our own humanity. Cognition itself was long held to be the exclusive domain of human beings, the primary difference between man and the animals over which he held dominion, but developments in artificial intelligence, made possible by men like Alan Turing, have overturned our notions of what constitutes “thought.” Artificial intelligence is itself no more than an application of algorithms to specific problems, and in its short history it has given us computers capable of beating chess grandmasters – is this “thought”?
Men like Stephen Jay Gould and Noam Chomsky, neither of whom would deny the basic facts of Darwinism, nonetheless come in for scathing critiques from Dennett for their eagerness to explain human complexity by what Dennett terms “sky hooks,” levers appended to the very air. Thus, for example, Chomsky, who inaugurated the evolutionary study of language with his theory of “universal grammar,” has denied that the basic structures of language are implemented via evolution, instead making vague appeals to physics.
Modern liberals, whether they’ve given the issue much conscious thought or not (and it’s almost always not), hold firmly to the view that consciousness and human intelligence, though byproducts of evolution, can more accurately be characterized as a happy accident, of too great a complexity to be explained via natural selection. Whether they know it or not (and, again, it’s almost always not) such a view is no less antithetical to Darwinism than the belief that the complexity of the eye could have arisen by accident.
Dennett, erudite and witty, proves to be a wonderful guide to the challenges Darwinism presents and the history of its slow corrosion through philosophy and science. Best of all, he shows us that there is nothing to fear – and much to gain – by embracing its insights.