Last year, there was a slightly embarrassing moment in the race to become Republican nominee for the White House. In answer to the question “do you believe in evolution?”, at least three of the candidates indicated that they did not. Senator John McCain, it must be said, passed the test with flying colours. The question was in fact directed at him and, after a short pause to weigh up his options, he plumped for a straight “yes” – though he then rather spoiled things by saying, “I also believe when I hike the Grand Canyon and see a sunset that the hand of God is there also.” Doubtless with this addendum, he sought to retrieve a few of the votes he had so recklessly thrown away a moment before.

But just when you thought it was safe to go back into the water from which we first emerged over 300 million years ago, along comes the delightful Sarah Palin who appears to be some sort of creationist, or so it is being widely reported in the media. It shouldn’t come as too much of a surprise I suppose; polling regularly reveals over half of Americans to be creationists. But even so, the question has to be asked: how is it that views which are considered crazy amongst intelligent Europeans have come to seem almost normal in the context of American political discourse, particularly that of the right-wing?

I have a somewhat convoluted and highly speculative theory about all of this which borrows heavily from a very important book – perhaps even the most significant book published so far this century. But despite its relevance to political thought, I have yet to see it mentioned in any of the book lists that political types are often asked to draw up as essential reading matter. It wasn’t listed among the favourite books of Chris Huhne or Nick Clegg, nor indeed among those of our leading Lib Dem bloggers (here and here). The book in question is The Blank Slate by Steven Pinker.

Pinker’s book concerns a question that is as old as the hills, and yet in many ways remains central to one’s entire outlook, be it political, philosophical, or moral. The question is: which is the greater determinant of human behaviour – nature or nurture? Yes, that old chestnut! Are we principally fashioned by our genetic inheritance, or are we instead shaped by the environment in which we find ourselves situated? Do we start out in life with a “blank slate” so to speak, or is the slate already covered with writing before we even begin?

The answer, of course, is that there is plenty to be said in support of both of these positions but, once the argument begins, it is astonishing how rapidly tempers flare. For some reason, this stuff is dynamite. Opposing viewpoints are often characterised as being on one extreme or the other. So people like Pinker are “genetic determinists” who believe that our genes control every aspect of our lives, and every decision we make; while Pinker’s opponents are the “out-and-out blank-slaters” who think that every child is born with equal potential, and how we turn out as adults is entirely due to social conditioning. In reality, virtually nobody holds these positions today.

But leaving these caricatures to one side, Pinker’s thesis is that we have, for far too long, erred towards the blank slate end of the philosophical spectrum. I have to say that in general I agree. While I have yet to meet the mythical out-and-out blank-slater, I would nevertheless like to suggest that we are genetically determined to a far greater extent than many people would appear to be comfortable with. The principal opponents of this viewpoint are some on the political left, and the Marxist or feminist academics with whom Pinker seems to have been battling for most of his adult life.

So why all the discomfort?