Friday, November 28, 2008

Blackburn on Pinker

Looking at Simon Blackburn’s webpage linked to by Humphrey in his post below, I came across this review of Steven Pinker’s The Blank Slate. Regular readers will know that I am a fan of this book and it regularly gets me into trouble. I am pleased to report that Simon Blackburn doesn’t like it at all.

In the review, Blackburn attacks Pinker from several directions. The first is to accuse him of rhetorical trickery. There is no doubt that Pinker’s prose is quite punchy but he also provides plenty of evidence for what he says. The evidence must be the basis of any assault on his ideas. Blackburn also complains that Pinker’s three targets in the book (dualism, the noble savage and the blank slate) are mutually incompatible. This may be true but it is no reason not to attack all three. Besides, holding mutually incompatible ideas in our heads is a typical human trait that Blackburn himself excels at.

But it is with his attacks on behavioural genetics that Blackburn goes well off the rails. He simply doesn’t seem to understand the subject. We get the usual explanation of exactly what heritability means (which you can copy and paste of thousands of internet sites). Yes, having two legs is 100% inherited and 0% heritable, but that is not the traits that we are talking about. Heritability is only meaningful for traits that vary across populations and to point out it is useless in other cases is simply point scoring. If intelligence is 50% heritable (which is almost certainly in the right ballpark), then that means 50% in the variation in intelligence is due to genes. No amount of muddying the waters is going to change this. The bizarre thing is that if Blackburn does not think human intelligence has a sizable heritable portion, then presumably, he also believes that it could not have evolved. If it did not evolve then it must be a miracle, which would make Simon Blackburn a creationist, together with several other stalwarts of the secular left like Johann Hari and David Aaronovitch.

Blackburn then goes on to prove he simply doesn’t understand behavioural genetics at all. In a discussion on the findings by Martin Daly and Margo Wilson that step-fathers are more likely to abuse their partner’s existing offspring than natural fathers are to abuse theirs, he makes a daft comment. Mothers, he says, don’t scowl at their children’s classmates because they are genetic rivals. Well no, because unless the classmates are living with the mother and are someone else’s child, they are not genetic rivals of her own children. And Blackburn makes the wholly irrelevant point that we might also not be so attached to our partner’s existing dogs and sofas. I think he is trying to say that Daly and Wilson’s result might not depend on genes but he provides no evidence for this at all. It’s just an assertion based on intuition which is all the counterarguments to behavioural genetics ever seem to amount to.

Overall, Blackburn’s review, dressed up in his typical too-smug-by-half prose, is a typical example of how wilful misunderstanding of behavioural genetics is an intellectually respectable position. But just because a scientific discovery conflicts with your politics or intuition (or religion for that matter) does not make it false. Blackburn’s distortions of Pinker’s conclusions bear more than a passing similarity to accusations of distortion he migth level at creationists.

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