Foxes and Hedgehogs

April 2, 2009

Before I had even heard of this particular distinction, my Russian Literature professor pointed out that Dostoevsky was a Hedgehog, while Tolstoy was a Fox. According to her (and, apparently, Isaiah Berlin), “the Fox knows many small things, but the Hedgehog knows one big thing.” I was never entirely clear on what the big thing was that Dostoevsky knew, but then again, I rarely understood what my professor was saying.

More recently, I was tipped off to the work of Phil Tetlock, who tries to bring some analysis to the realm of expert prediction by political scientists. And very interesting work it is, though depressing if you’re a hedgehog (as I am).

Tetlock describes Hedgehogs as being convinced about one big idea, be it Libertarianism, Anarchism, Marxism, Environmentalism, or any other -ism you can name. As a result, they tend to make very confident predictions, “X will happen but Y will not happen.” And, quite often, their predictions turn out to be wrong. Tetlock cites, as an example, his finding that when a Hedgehog says that something will happen with a probability of 1 (i.e. they cannot imagine a universe in which it does not happen), it happens about 78% of the time.

Much better at predictions are the Foxes, who tend to make much less certain pronouncements than the Hedgehogs and are less convinced that the world is explainable by one big theory. Their real skill, according to Tetlock, is in taking the best parts of Hedgehog ideas and incorporating them into a more nuanced worldview. One interesting example he gives is that many experts believed Gorbechev was not a true liberalizer, because Russian politicians were intelligent and monolithic, and they would have known that liberalization meant the end of the Soviet Union. Others thought liberalization was real but that the foundations of the USSR were strong.

The Hedgehog advantage is that they are usually out in front when it comes to bold predictions, like the dissolution of the Soviet Union, that do come true. Imagining big changes is not really the Fox’s game. The problem, of course, is that this means Hedgehog make a lot of bold predictions, like the dissolution of Canada, that turn out to be wrong.

To tie in with current events a bit, this is part of why I was so surprised by the Jon Stewart/ Jim Cramer affair. Vanguard’s John Bogle demonstrated thirty years ago that when it comes to investing, expert money managers can’t beat simple index funds. This result has been known for some time; Tetlock extends it to other areas. So if you’re seriously watching CNBC for investment advice, you’re likely making a mistake.

One thing I should point out, which I found interesting, is that even though expert Hedgehogs and Foxes have a hard time beating what Tetlock calls “simple statistical models,” such as extrapolation of a trend or “no change,” they do much better than a control group of non-experts. This reminds me of Robin Hanson’s point that if you think that economists, in general, don’t know very much, you are right, but if you want to talk to people who really don’t know very much, talk to people who have no knowledge of economics.

What you should take away from Tetlock’s work is that the world is much more probabilistic and less deterministic than you think it is, and that anyone who claims to be utterly certain that some event is going to occur is very likely wrong. If you subscribe to one big theory, you’re not going to make very good predictions, but there’s not a whole lot you can do about it.

This post was pretty scattered; I was just trying to summarize a podcast I listened to. A probably better summary can be found here. And if you look around just at bit you should be able to download the podcast as well.


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