What is the hottest new idea in Conservative circles? I don’t know. By which I do not mean that I have no knowledge of it. I mean instead that the hottest idea in Conservative circles is not knowing things.

That sounded better in my head before I typed it. I think I’d better explain.

On Monday this week David Cameron was fishing for mackerel, on Tuesday his prey was swans. Black swans to be exact. On returning from a little light angling on holiday, the Conservative leader met Nassim Nicholas Taleb, author of Fooled by Randomness and the bestselling volume The Black Swan.

It is common for rising politicians to associate themselves with rising intellectual stars. And the choice is always illuminating. Margaret Thatcher, for instance, was not a libertarian, but her interest in free-market economists such as Milton Friedman spoke eloquently of her outlook.

So what does Cameron’s association with Taleb tell you about his Tories? Well, first of all, oddly enough, it tells you that Cameron’s is not likely to be a Government dominated by intellectual gurus. There was a meeting of minds with Taleb, but to call him the Tory Svengali would be a preposterous elevation of his political (as opposed to his intellectual) status. Nor does Taleb belong to a recognisable school. So this dalliance is nothing like the intense love affair between Margaret Thatcher and the free-market economists.

The second thing it tells you is something about Cameron himself.

After Taleb spoke there were various misinterpretations of what he had said. We were told, for instance, that “Cameron’s guru” was a “flat earther” who didn’t believe in climate change. Here’s what he actually said. He said that he didn’t know whether man-made climate change was a looming disaster. The distinction is important.

Taleb’s argument is that the world is shaped by high-impact events of a low probability. We impose order on our thinking mainly by wrongly ignoring the possibility of these events. He provides the example of turkeys. In the run-up to Christmas they develop a theory. Human beings are benevolent, feeding them generously every day. Then just before the holiday itself, the turkey is forced to rethink its position.

His background being finance, Taleb concentrates on banking. Long before the recent crash, he was giving warning that bankers were counting their financial strategies a success only because they were ignoring the possibility of a huge financial disaster somewhere in the near distance. He suggests that in a single event in 1983, banks lost cumulatively every penny they had ever made. And he urges banks and governments to lower their debt so as to cope with an unknowable future fiasco. His argument on climate change is simply that we should prepare for it, even if we don’t know for certain that it is happening.

This emphasis on not knowing, on doubt, on scepticism, on caution is the new Conservative hot button. But also its oldest theme. And Cameron’s interest in it confirms that his conservatism is of a much more traditional stamp than any of his immediate predecessors.

daniel.finkelstein@thetimes.co.uk

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