Wednesday, May 09, 2007

Theories of the Mind

Dan Dennett, Steven Pinker and Judith Rich Harris are all promoters of the idea of the primacy of genetics in any scientific explanation of human behaviour. As I said on Monday, I’m with them on that. Whenever my wife or I hear some piece of pop psychology we subject it to the ‘Pinker test’. If it doesn’t give pride of place to genetics then it is probably worthless. This tends to invalidate almost everything you hear about what causes people to behave the way they do. Of course, I see Dennett and co. simply catching up with St Augustine’s work on the inheritability of personality and the impossibility of completely subjugating our desires. Augustine must qualify as one of the greatest psychologists in history and, unlike lost other people of whom it is said, was well ahead of his time (at least in this respect).

Evolutionary psychology is not the only thing that Dennett, Pinker and Rich Harris have in common. A few years back Dennett brought out a book called Consciousness Explained. More recently, Pinker’s How the Mind Works has been almost as influential. Rich Harris’s new book, No Two Alike, ploughs the same furrow.

Their theory is simply stated. The brain has a number of inter-dependent service modules that each do a particular job. The modules are independent enough that if you disable one, the rest of the brain can continue to work. It’ll try a hot fix around the disabled component so that sometimes the conscious mind won’t even notice that something is missing. The modular theory states that consciousness is an epiphenomenon that results from all these modules getting on with their jobs and talking to each other. The modules themselves are in no way controlled by the conscious self. In fact, the conscious self doesn’t do anything very much beyond getting fooled into thinking that it is in charge.

Needless to say, I find this theory rather implausible. But I am more intrigued as to why it enjoys support from the same sorts of people who are also sympathetic to evolutionary psychology. I think it is because the modular mind is highly amenable to an evolutionary explanation. Each module can be explained by a different evolutionary just-so story which keeps things nice and simple. For instance, the speech organ postulated by Noam Chomsky before he turned into a barking mad nut case, can be made the subject of a story that leads from the ability to grunt to the ability to recite Homer in a few easy steps.

There’s another reason why I think that the modular theory is popular and it has to do with how science works when it is successful. Science is usually reductionistic because we lack the tools to analyse complex systems without breaking them up. The brain is the most complex system of all, so splitting it up into manageable chunks would seem a sensible way to go about understanding it. Almost all experiments on the brain have involved prodding it with stimuli and seeing which bits light up. More radically, when particular parts of the brain stop working due to injury or disease, we can examine the effects this has on its overall function. In fact, there are almost no other useful kinds of experiment you can do on the brain. I’m not denying that all this has been fruitful. Just that it hasn’t taken us a single step towards understanding what consciousness is. But it is not surprising that the theories of mind we do have, while generally rather implausible, have been shaped by the experimental limitations of neuroscience and the success of evolutionary theory.

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