Dennett, Daniel Clement;
Darwin's Dangerous Idea: Evolution and the Meanings of Life
Simon & Schuster, 1996, 586 pages
ISBN 068482471X, 9780684824710
topics: | philosophy | evolution | brain | sociology
On Sept 11, 1956, at MIT, three papers were presented at a meeting of the Institute for Radio Engineers. One was by Allen Newell and H Simon, "The Logic Theory machine", (foundational in AI) another by George Miller, "The magical number seven, plus or minus two" (foundational in cognitive linguistics), and Noam Chomsky: "Three models for the description of language" (foundational for linguistics). In Herbert Simon's 1969 book, he talks of this occasion and the cordial relations between AI and linguistics. But by 1989 the gulf had widened. - p.385 The Chomsky hierarchy of grammars was closely related to Turing's purely logical investigations of computing processes. When announced, many in the humanities, esp foreign-language departments, were extremely hostile to it. "Chomsky may be prof of linguistics at MIT, and linguistics may be one of the humanities, but Chomsky's work was science, and science was the Enemy-- as every card-carrying humanist knows. Our meddling intellect Misshapes the beauteous forms of things We murder to dissect. - Wordsworth" p.386
Chapter 10, "Bully for Brontosaurus", critiques Stephen Jay Gould's ideas which distort evolutionary theory by undermining adaptationism, gradualism and other evolutionary processes. Chapter 13 investigates the role of language as an interface to a group activity; analyzes behavioural evolution as a possible mechanism that gave rise to language. Section 2 debates the positions of Chomsky ("In the case of such systems as language or wings it is not easy even to imagine a course of selection that might have given rise to them.")
Dennett sees Darwinism as a corrosive acid, capable of dissolving our earlier belief and forcing a reconsideration of much of sociology and philosophy. Although modestly written, this is not a modest book. Dennett argues that, if we understand Darwin's dangerous idea, we are forced to reject or modify much of our current intellectual baggage — for example, the ideas of Stephen Jay Gould, Noam Chomsky, Jerry Fodor, John Searle, E.O. Wilson, and Roger Penrose. Dennett's central thesis is that evolution by natural selection is an algorithmic process. He emphasizes three features of an algorithmic process. First, "substrate neutrality": arithmetic can be performed with pencil and paper, a calculator made of gear wheels or transistors, or even, as was hilariously demonstrated at an open day at my son's school, jets of water. It is the logic that matters, not the material substrate. Second, mindlessness: each step in the process is so simple that it can be carried out by an idiot or a cogwheel. Third, guaranteed results: whatever it is that an algorithm does, it does every time (although, as Dennett emphasizes, an algorithm can incorporate random processes, and so can generate unpredictable results). [Two sources for] Dennett's views of the world. The first is a set of ideas that includes computing science, artificial intelligence, and cognitive science: it is from here that he acquired his conviction that algorithmic processes can generate mind-like activities. The second is the gene's-eye view of evolution pioneered by G.C. Williams and Richard Dawkins. According to this view, evolution is a necessary consequence of the existence of replicating entities; in biology, those entities are genes, but the principle holds for any kind of replicators. I have thought for some time that Dawkins and Williams have made a more fruitful contribution to philosophy than most philosophers, and I am pleased to see this opinion so generously recognized. ... Dennett suggests that criticisms of the neo-Darwinist synthesis come, in the main, from those who are reluctant to believe that they are the product of an algorithmic process. [including Gould]. Stephen Jay Gould occupies a rather curious position, particularly on his side of the Atlantic. Because of the excellence of his essays, he has come to be seen by non-biologists as the preeminent evolutionary theorist. In contrast, the evolutionary biologists with whom I have discussed his work tend to see him as a man whose ideas are so confused as to be hardly worth bothering with, but as one who should not be publicly criticized because he is at least on our side against the creationists. All this would not matter, were it not that he is giving non-biologists a largely false picture of the state of evolutionary theory. There are, Dennett suggests, three main aspects of Gould's thought which reveal a wish to escape from Darwin's algorithmic grip. The first is his critique, with Richard Lewontin, of the "adaptationist paradigm." I have some responsibility for this critique. As organizer of a symposium in London on adaptation, I invited Lewontin, as a well-known critic of naive adaptationist arguments, to contribute. Lewontin, for reasons that, as an exaircraft engineer, I well understand, dislikes flying, and suggested that he write a joint paper with Gould, which Gould would present. The result was the now-famous paper entitled "Spandrels of San Marco." Its thesis is that many structures in the animal world are not adapted for any function, but, like the spandrels of San Marco, are accidental and unselected consequences of something else. Further, they argued, many adaptive explanations are "Just So Stories," unsupported by evidence. Two other Gouldian themes, punctuated equilibria, and the non-repeatability of evolution, can be dealt with more briefly. The tale of punctuated equilibria is an odd one. Its factual basis, commonly reported by paleontologists, is that lineages often change very little for millions of years, and then change rather rapidly. When the idea was first put forward by Gould and Niles Eldredge, it was presented as just what one would expect to see if the orthodox view, that species often arise by rapid evolution in small peripheral populations, is indeed accurate. If only they had left the argument there! Their paper would then have been seen as a useful extension of the picture given in Tempo and Mode in Evolution by George Gaylord Simpson, which was the Darwinian orthodoxy when I was a student. Sometimes, however, Gould appears to be saying that the changes, when they occurred, were not the result of natural selection, but of some other process — genetic revolutions, "hopeful monsters" (large mutational changes), or what you will. Since "sudden" in the fossil record means thousands of generations, there is no reason whatever for supposing any such thing. The non-repeatability of evolution — the idea that if evolution were to happen again from the same starting point, it would not repeat itself — is true, but not new: it is what most scientists have always thought. But what, Dennett asks, is the significance of these various reservations — anti-adaptationism, punctuated equilibria, non-repeatability? The answer, he suggests, is that Gould is trying to escape from an algorithmic explanation of life. Dennett may be right. The natural selection of replicators — essentially, of nucleic acid molecules — may explain the evolution of animals and plants, but what about humans? We, surely, are more than the product of our genes. Indeed we are, admits Dennett, but it does not follow that we are anything other than the products of an algorithmic process. At this point, he embraces Dawkins's notion of a meme. A meme can be anything from the limerick about the young man of Belgrave (mutated in the US, I’m told, to a young fellow called Dave) to the doctrine of the Trinity. A meme is an idea that can lodge in a person's mind, and can be transmitted, in print or by word of mouth, to other minds. In other words, it is a replicator. What is peculiar about humans is that they can hold ideas in their heads, and transmit them to others: they provide an environment in which a new kind of replicator, memes, can evolve. The human mind is another example of a crane. It evolved by natural selection, without need for an intelligent designer. Once evolved, however, it provides a medium in which a new kind of evolution by natural selection can occur, involving a new kind of replicator, the meme. My uneasiness with the notion of memes arises because we do not know the rules whereby they are transmitted. A science of population genetics is possible because the laws of transmission — Mendel's laws — are known. Dennett would agree that no comparable science of memetics is as yet possible. His point is a philosophical rather than a scientific one. We see humans as the joint products of their genes and their memes — indeed, what else could they possibly be?—even if we have no predictive science of meme change. Once a human mind capable of harboring memes evolved, a new kind of evolution, cultural evolution, became possible, more rapid by far than genetic evolution. I [find] Chomsky's views on evolution completely baffling. If the ability to learn a language is innate, it is genetically programmed, and must have evolved. But Chomsky refuses to think about how this might have happened. For example, in 1988 he wrote, "In the case of such systems as language or wings, it is not easy even to imagine a course of selection that might have given rise to them." This is typical of his remarks on evolution. There is, in fact, no difficulty in imagining how wings might have evolved. Language is difficult because it leaves no fossils; it has evolved just once (unlike wings, which have evolved at least four times); and there is an enormous gap between the best that apes, whales, or parrots can do and what almost all humans can do. MODULARITY The most interesting claim made by evolutionary psychologists is that the mind contains specialized modules that evolved to perform particular tasks. This is obviously true of that part of the brain concerned with analyzing visual input, and, if Chomsky is right, it is true of language. It has been proposed that there are also modules concerned, for example, with the detection of cheating and with the identification and classification of living organisms. Of course, even if there are such modules, they cannot be completely isolated. In science, as in other fields, progress often depends on seeing analogies between apparently different processes. For example, my own main contribution has been to see the analogies between human games and the things that spiders, trees, and even viruses do. This would not be possible if the mind consisted of isolated modules. Although he is attracted by the notion of modularity, Dennett warns that the mere fact that humans in different societies behave in similar ways cannot be taken as evidence of genetic determination. People may simply be doing what any intelligent being would do in the circumstances: making a forced move in design space, to use his terminology. A potentially serious challenge to his position is posed by an argument, put forward by Roger Penrose and others, that Gödel's theorem can be used to show that human intelligence cannot be algorithmic. The argument goes as follows — Gödel proved that there exist, within any non-contradictory mathematical system, some true statements that cannot be proved. Yet human mathematicians can intuit the truth of some such statements. Since anything that can be proved can, in principle, be proved algorithmically, it follows that humans can do something that algorithms cannot. Dennett replies that, although there is no algorithm that can prove a given statement to be true, there may well be algorithms that can suggest statements that are very probably true. Humans, perhaps, use algorithms of the latter kind. Their intuited mathematical truths may just be very good guesses. By analogy, a computer programmed to play chess cannot, with certainty, find the best possible move, but it does find very good moves. Dennett's argument on this point should be read with care. I am not sure I have understood it correctly, but I like it, partly because I cannot see what else human intelligence could be, other than algorithmic, and partly, perhaps, because while I am rather good at having mathematical intuitions, I have learned that they are sometimes wrong. - Genes, Memes, & Minds (1995)