Daniel Dennett has a hit list of those he thinks are obstructing the march of evolutionary theory. Aisling Irwin reports

Daniel Dennett, philosopher, is swatting flies. Until now he has been content to potter around building robots that he hopes will develop human consciousness and feel pain. But he finds that the critics are buzzing round him in increasing numbers so he has stopped work to try and obliterate them.

To do so he has written a mega-swatter of a book, called Darwin's Dangerous Idea. It is aimed at one big fly - Stephen Jay Gould, America's most famous evolutionary thinker - and also a lot of medium-sized and little flies. Their shared crime, in Dennett's opinion, is to misunderstand or distort the theory of Darwinian evolution, the notion that living things have evolved by the fittest of each generation surviving to pass their characteristics on to their offspring. Since Dennett makes a lot of appeals to Darwinian theory in his normal work, the repercussion of this crime is that academics are rejecting his, Dennett's, ideas.

At the core of the Darwinian theory used today is the idea that genes code for an organism's characteristics; different organisms, because of their differing characteristics, fare differently in their environments; and so the environment "selects" certain organisms and thus their genes are more prevalent in the gene pool of the next generation.

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Gould, professor of geology at the Museum of Comparative Zoology, Harvard University, is despite his reputation as an evolutionary thinker, uncomfortable with the "fundamental core" of Darwinism, claims Dennett, and is therefore responsible for much of the popular conviction that Darwinism is dead. The linguist Noam Chomsky, the philosopher of mind John Searle and Oxford maths professor Roger Penrose also deserve to be swatted: in their various ways, claims Dennett, they are obstructing the march of evolutionary theory.

But Dennett, director of the Center for Cognitive Studies at Tufts University, Massachusetts, is also in pursuit of the people who place too much emphasis on the role of the gene in explaining human behaviour. On his hit-list are clouds of unnamed sociobiologists, whose goal in life is to explain human organisation and behaviour in terms of evolution and genetics. Many are respectable, some, he says, are not. Sitting in a London garden, on a two-and- half day tour to promote his book, he says: "I'm not going to name them - you won't give me enough space to explain my criticisms properly."

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He is canny, then, about the dust his fly-swatting is kicking up. Let us look at his victims. He chides the first group because they will not speak up when their field is misrepresented by colleagues, usually evolutionary psychologists - whose sin is to claim to have shown that genes explain human behaviour, such as territoriality, when in fact there is an equally good cultural explanation for such behaviour. In the case of territoriality, Dennett says: "It's very likely that it is part of our mammalian (and therefore genetic) heritage but if there wasn't a gene for it I think we would still display territoriality." Therefore caution is required.

Outside academic sociobiology, people seize on genetic ideas in order to diagnose the ills of society: the consequences, from racial IQ theories to eugenics, are known to everyone. Why do people in the field not condemn this, asks Dennett?

"The dangers of popular Darwinism are everywhere," he says. "I think there's a sort of siege mentality that's set in: 'we can't criticise any of our own because we have enough flak from outside'. It's unfortunate but also it's understandable. I've stepped into this role. Since I'm in some sense an outsider I can perhaps undertake this task of criticism a little easier."

On his list of "good" sociobiologists who have "largely eschewed the deeply unpleasant task of pointing out more egregious sins in the work of those who enthusiastically misuse their own good work" Dennett includes the mathematician John Maynard Smith and the zoologist Richard Dawkins.

But Dennett's complaint is not that evolutionary theory in general is being taken too far: it's that it is wrong always to use the gene as the unit of selection. Notions of "survival of the fittest" are often appropriate but it is not always appropriate to use "survival of the fittest gene". Maybe what survives is a unit of culture - or a computer virus. In other words, the important aspect of Darwinian evolution is the process, not the unit. Dennett believes that every area of human endeavour must take evolutionary theory into account. But when assessing the development of human culture, for example, it is probably more useful to harness the explanatory power of "memes" than that of genes.

Memes are discrete ideas, units of cultural transmission, such as the wheel, faith, or a reason to throw yourself off a cliff. Successful memes get passed on, others die out. For example, says Dennett, if Jones acquires a meme that persuades him to jump off a cliff, that Jonesian meme will have lost the carrier who could have spread it to other carriers. Memes like "faith" on the other hand are superbly successful. Memes, invented by Richard Dawkins, are an attractive way of depicting the spread of culture. Sceptics think memes just fill up the diminishing space of ignorance that genetics has not yet reached.

But Dennett receives a steady flow of papers from academics studying memes. He says: "I think memetics is going to play many roles. There's a lot of people out there who are beginning to explore the implications of memes. I think we're going to see something of an oupouring of attempts to expand and apply the concept."

There is not too much evidence to support memes yet, he admits. But he says they will always serve a "bare role": "as a constant reminder that culture is not a skyhook. That you can't impute marvellous properties to agents of culture".

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Cranes and skyhooks are two Dennett devices that help him with his fly- swatting. Cranes are the down-to-earth mechanisms, produced by the slow process of selection by the environment. Skyhooks are a power, such as God, that is an exception to the principle that everything around us is ultimately the result of the mindless, motiveless, process of evolution. Cranes good. Skyhooks bad.

Dennett says that the cranes of Darwinian evolution apply to everything. Darwinism is a "universal acid". It dissolves away biology, ethics, economics, religion. We are compelled to apply it and then pick through the remains to find what is left. Darwinian evolution is a blind, step-by-step process made up of "mindless mechanicity". Evolution happens to memes and computer viruses, not to just genes.

Dennett is hooked on memes because he says they are the only route to a "through and through" Darwinian explanation of the mind. But a refusal to accept memes is a small trouble facing Darwinism compared with the opposition the general theory has stirred up in many academics. In Dennett's view the source of the opposition can be traced back largely to one man - Stephen Jay Gould. He is the enemy within.

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"In my own work over the years," writes Dennett, "I have often appealed to evolutionary considerations, and have almost as often run into a curious current of resistance: my appeals to Darwinian reasoning have been bluntly rejected as discredited, out-of-date science by philosophers, psychologists, linguists, anthropologists and others who have blithely informed me that I have got my biology all wrong - I haven't been doing my homework because Steve Gould has shown that Darwinism isn't in such good shape after all. Indeed it is close to extinction."

Gould is "the boy who cried wolf", says Dennett. He declares each of his new ideas to be a revolutionary overthrowing of orthodox Darwinism. In fact his ideas, at best, add a useful bit to the existing theory.

Dennett claims that the Gould myth is that he is the US's foremost proponent of Darwinian evolutionary theory, but is sadly regularly distorted by the media as an iconoclast. The truth, says Dennett, is that Gould is fundamentally ill at ease with Darwinian theory. Gould's science helps to sharpen Darwinian theory but his rhetoric turns that science into a tool which encourages the sensationalist view that Darwinism is seriously flawed.

"Gould's ultimate target is Darwin's dangerous idea itself; he is opposed to the very idea that evolution is, in the end, just a blind, step-by-step process."

In his book Dennett takes a heavy swipe at each of Gould's most famous ideas, starting with Gould's legendary piece of scientific rhetoric, written with biologist Richard Lewontin, The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme. In this critique, Gould claims the world of evolutionary science is adaptationist-mad, interpreting every feature of an organism as a perfect solution to an environmental problem, ignoring all other explanations. Not so mad, says Dennett, exposing the flaws behind Gould's rhetoric by investigating the architectural history of San Marco, which was Gould's chief rhetorical tool. Gould's critique failed to alter the fact that adaptationist thinking is central to explaining evolutionary theory, says Dennett.

Dennett attacks no one as exhaustively as he attacks Gould. But Chomsky and Searle come close. Their crime has been to resist, in their different ways, the encroachment of Darwinian theory into the mind. Minds, says Dennett, are the result of Darwinian evolution, not, as he says Searle thinks, "original and inexplicable sources of design".

Chomsky pronounced our language ability to be innate, not learned. So far so good, says Dennett: most of the structure that enables us to learn a language as a child is already there in our brains, which is why we pick the language up so quickly. Chomsky's ideas are in fact prime fodder for Darwinian theory. But the sticking point, according to Dennett, is that Chomsky has so far resisted all evolutionary accounts of how language arose.

Chomsky and Gould are also guilty of negligence: they have not done any fly-swatting themselves. Many "amazing objections" to Darwinian theory, says Dennett, can be traced directly to statements by Gould or Chomsky. He says: "I have yet to witness either Gould or Chomsky attempting to correct these howlers when they arise in the heat of battle . . . Both Gould and Chomsky have been vigorous proponents of the view that intellectuals are responsible for the applications and likely misapplications of their own work, so presumably they are at least embarrassed to find themselves cited as the sources of all this nonsense, for they themselves do not hold these views (It is perhaps too much to expect their gratitude to me for doing their dirty work for them)."

Has no one else ever done this dirty work? What about Richard Dawkins in The Blind Watchmaker, the exposition to end all expositions of Darwinian ideas?

Dennett on Dawkins: "In most regards we see just about completely eye to eye. To the point where I've said 'we really must make sure that we talk to other people and don't just egg each other on'. But my work is much more concerned than his is with the genuine pain of those with religious beliefs when they confront what he and I both say they have to give up.".

And so, having followed Dennett through his book we reach religion. What is left, he asks, when you face the fact that nobody designed the world? God is out of the equation; but what remains are meaning, value, ethical systems and centuries of culture inspired by religion.

Can we not just leave the religious to be happy in their so-called delusion? No, says Dennett. Change is necessary. "I acknowledge that this is hurtful and I say, yes, people will suffer. But they have to make whatever accommodation they can to the obligation to educate their children with truth not falsehood. I think there are few sins that are more appalling than deliberately misinforming a defenceless child about the way the world is."

It remains to be seen how the Darwinian world will react to Dennett's book. He's tried to swat a lot of flies. But he's probably stirred up a hornet's nest as well.

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Darwin's Dangerous Idea was published last week, Allen Lane, Pounds 25.