Daniel C. Dennett's book, Darwin's Dangerous Idea, is a striking tour de force which synthesizes a great deal of past and current research in order to support the following thesis: All of life's complexity can be attributed, directly or indirectly, to the blind, algorithmic process of evolution via random mutation and natural selection. This idea, according to Dennett, is as dangerous as its critics suspect. It provides a hypothesis which, taken to its extreme, shows that the great miracles of life - including the human brain, the diversity of species, and nature's balance in the biosphere - can be shown to have evolved without any guiding intelligence of any kind.

This is strong stuff.

Dennett, a philosopher of science, writes as an analytical philosopher should - as an interpreter of the results of discoveries across various disciplines in a manner which provides novel insight. On the way, Dennett makes use of illuminating thought experiments, and explains the nuances of the "new Darwinian synthesis", pulling the reader away from many common fallacies:

• He explodes the myth of the "great chain of being", noting that evolution only responds to selection pressure, and is not necessarily moving in a particular direction, good or bad.
• He notes that a Darwinian "adaptationist" perspective does not imply Social Darwinism, eugenics or what he deems "greedy reductionism".
• He explains the logical flaws of "group selection".
• He emphasizes that evolution is a short-term algorithm; adaptations must have short-term benefits to survive. A corollary of this point is that original uses of adaptations may have no correspondence with their ultimate uses, as circumstances and organisms change over time.

Dennett's most provocative point is the idea that evolution is a substrate-neutral algorithm whose operation is not limited to the genome. He attempts to show how the original building blocks of life - enzymes and proteins - were the result of Darwinian processes. He speculates (and this is not science, as far as I can tell) that such mechanistic processes may have even resulted in the physical laws of our universe, which are finely tuned to allow complex matter and, thus, life. Further, he extends the process to the ideas, institutions and cultural artifacts which surround us (borrowing Richard Dawkins' word "meme").

This last point is important, in that he asserts what makes us human, and what makes us distinct from other species, is that we are not merely our own cells and the cells of the various bacteria which live inside or on us. Due to our ability to communicate through language, we are also, in a very important and real sense, made up of the memes which infest our minds. In fact, due to memes such as compulsory education, writing, modern farming techniques and the scientific method, the average person today is, in practical terms, far more intelligent than Pythagoras or Aristotle. In fact, because the changes of culture and technology have allowed us to evolve at such a rapid rate, I differ far more from my great-grandfather than he differed from Plato. (Obviously, Dennett is not saying that culture or science evolve randomly. Rather, he notes that these artifacts are themselves products of a brain that itself evolved from Darwinian processes. Hence, my "direct or indirect" loophole above.)

As I noted earlier, this is hot stuff. Politically-charged and philosophically controversial, the current dialogue regarding Darwin is impassioned precisely because so much of our world view is at stake. Dennett is an unapologetic materialist, atheist, Darwinian adaptationist who takes on opponents with the rigour of a good analytical philosopher. The challenge of this undertaking is enormous because of both the nuance and the sheer scope of these issues which have confounded so many specialists.

This is a tough book to read. It is replete with thought experiments, technical details and jargon that inevitably results from precise philosophy. It helps to have taken a course or two in analytical (that is, non-Continental) philosophy at the undergraduate level. Because I have forgotten most of that stuff, I found myself constantly referring to Wikipedia and to the Stanford Encyclopedia of Philosophy. The sheer density of Dennett's ideas and precision of his prose result in a book which is not the most accessible to the lay reader. However, for those who are willing to expend some effort in trying to penetrate the philosophy and science behind Darwin's hypothesis, this is an excellent starting point.