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Noah Smith

Black Swans, Frankenfoods and Disaster Fairy Tales

Nassim Taleb, who wrote "The Black Swan," and several co-authors of a recent research paper overstate the likelihood that genetically modified crops pose an inordinate risk.
You can never be too safe.

You can never be too safe.

Photographer: Sion Touhig/Getty Images

The 17th-century French mathematician Blaise Pascal had what he thought was a great reason to believe in God -- it’s all about expected utility. If you believe in God and God turns out not to be real, it’s not so bad. But if you deny God and it turns out that God does exist, you get sent to Hell for all eternity. Even if the chance that God exists is infinitesimally small, the downside is so huge that you would be a fool not to believe.

Nassim Taleb, author of "The Black Swan" and other books, believes that there are other such wagers around. The idea of “black swans” combines the concept of tail events -- things that are so rare that you can’t estimate their frequency from past data -- with the concept of special cause, the idea that the future won’t necessarily look like the past. Normal risk management doesn’t work if you can’t use the past as a quantitative guide to the future. So to combat the threat of black swans, Taleb and his co-authors on a recent working paper suggest that we adopt the “precautionary principle” -- a close cousin to the strategy used by Pascal: