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“You find serious overconfidence by hedgehogs,” Mr. Tetlock said. “With a rigid, self-justifying style of thinking, combined with a lot of content knowledge, combined with trying to see far in the future — well, you are more likely to go off a cliff.

“On the other hand, a key factor underlying superior fox performance was that they were more modest about what they could predict. The longer you try to see into the future, the more advantageous it is to be modest. I think they also derive some befits by being more self-critical and aware of alternative possibilities.”

The most common problem with forecasts like the Global Trends report, Mr. Horowitz said, is that they fall into a hedgehog-style trap of treating current conventional wisdom as a blueprint for the long-term future. For example, extrapolating from the late 1990s economic boom, the 2001 Global Trends report predicted that the global economy of 2015 would “return to the high levels of growth reached in the 1960s and early 1970s.”

“The most natural thing to do intellectually is look at the present,” Mr. Horowitz said. “What is going on now is going on for a reason, and therefore it is most likely to continue. There’s nothing wrong with that. To do better is difficult. It requires both being more aware of your own biases and being forced out of your intellectual comfort zone.”

The future of forecasting?

Mr. Horowitz and Mr. Tetlock are involved in an ongoing, multi-year project funded by the Intelligence Advanced Research Projects Activities Agency (IARPA) that is attempting to create better metrics for evaluating analyst accuracy.

Encompassing studies at a half-dozen universities and involving thousands of forecasters making predictions on hundreds of questions — Who will win the upcoming election in Ghana? Will Iran test a nuclear weapon by the end of the year? — the research aims to help participants recognize biases, avoid common errors and make better predictions in the future, lessons that can then be applied to American intelligence gathering.

One of the most important lessons, Mr. Tetlock said, is learning to avoid something he calls “accountability ping-pong” — that is, overreacting to errant prediction by abstaining from predictions going forward.

“We’re making progress in that direction,” he said. “Our forecasters are gradually becoming better calibrated. How far can they can go? Nobody knows for sure.”

Spoken like a fox.