STREET DOGS

THE philosopher Isaiah Berlin famously divided thinkers into two categories: the hedgehog and the fox. Hedgehogs, argued Berlin, see the world through the prism of a single overriding idea, whereas foxes dart hither and thither, gathering inspiration from the widest variety of experiences and sources.

Philip Tetlock, professor of psychology at the University of Pennsylvania, conducted a 20-year study in which 284 experts were asked to make 28,000 predictions about the future. What he found was that they were only slightly more accurate than chance, and worse than basic computer algorithms. Forecasters with the biggest media profiles were especially bad. The study also compared the records of “foxes” and “hedgehogs”.

“The most important factor was not how much education or experience the experts had but how they thought,” Tetlock argues. “The better forecasters were like Berlin’s foxes: self-critical, eclectic thinkers who were willing to update their beliefs when faced with contrary evidence, were doubtful of grand schemes and modest about their predictive ability. The less successful forecasters were like hedgehogs: they tended to have one big, beautiful idea they loved to stretch, sometimes to breaking point.”

But while Tetlock believed you were likely to be better off listening to “humble, self-critical experts who shy away from bold pronouncements and are more likely to use words such as ‘however’ and ‘perhaps’, instead of ‘moreover’ and ‘all the more so’.” He recognised foxes are “a tougher sell to CNBC”. Hedgehogs “tend to be more articulate and very persuasive as to why their idea explained everything. Consequently, the media love hedgehogs.”

Michel Pireu — e-mail: pireum@streetdogs.co.za