One of the more curious politican interventions of recent days has been claim that George Osborne thinks Iain Duncan Smith is "thick." I say this is curious not because of the tedious matter of whether Osborne really believes this, but because it's not at all clear that intelligence is a great virtue in politics.

Casual empiricism makes me suspect so. Harold Wilson was brilliant at Oxford, but was a much less successful PM than Thatcher, Blair or Churchill who weren't noted intellectuals. And intelligent men such as Oliver Letwin, Tony Wright and David Willetts (to name but three) haven't had stellar political careers.

One reason for this lies in the nature of politics. Many political problems are either insoluble, or have quite simple solutions which are unsellable (basic income, voluntary jobs guarantee, drug legalization). For the former category intelligence is useless, for the latter unnecessary.

But there's another reason. It's that intelligence (in the narrow sense of IQ or book-learning) can crowd out other virtues. For example:

- If you're so brilliant you can pick things up quickly, you'll not develop the determination and stickability you need to cosy up to dullards, sit through interminable meetings or plough through red boxes.

- Intellectuals want to say something interesting. And this leads them into "gaffes". Keith Joseph's flirtation with eugenics is the most notorious British example of this, but Larry Summers has made a career of it.

- Intellectuals are, very often, out of touch; they might well therefore lack the political antennae which tells them what'll sell and what won't.

- Intelligence can lead to one of two possible drawbacks. Sometimes, it can breed indecisiveness, which might have been Wilson's problem; being able to see both sides of a problem can rule out clear and decisive leadership. At other times, it might lead to overconfidence and hubris. The poll tax, remember, was the idea of intelligent people.

But here's the thing. All this doesn't just apply to politics. I suspect it's true of many other careers.Miriam Gensowski has estimated (pdf) that, among high-IQ people, the link between IQ and earnings is not significant; it's conscientiousness and social skills that matter more. Beyond a certain level, then, intelligence doesn't matter. And even across a wider ability spectrum (except perhaps at the very low end) it matters less (pdf) than many believe (pdf).

Personally speaking, all this is consistent with introspection. I suspect that if I had a higher IQ (and I have no idea what my IQ is), my life wouldn't have been much different - and if it had been, I might well have been poorer rather than richer. If I'd had better social skills, ambition or a capacity to tolerate boredom, however, I might well have been more "successful". I know it's dangerous to generalize from personal experience (especially mine!) but mightn't this be more widely the case?

Another thing: for Christ's sake, don't claim that IDS's advocacy of workfare and benefit caps shows he's thick. The idea that people would agree with us if only they were more intelligent owes more to self-love than to serious thought.