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Big Short’ author says we’re not truthful when we add up the numbers

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Chuck Twardy

Three and a half stars

The Undoing Project: A Friendship That Changed Our Minds By Michael Lewis, $29.

Cable pundits and data-miners woke up November 9 wondering how they could have missed what they saw coming at them. Michael Lewis could have told them: The mind sees what it wants.

Lewis has made a career narrating the stories of mavericks who shame experts—investors who foresaw the mortgage-market collapse in The Big Short, a general manager who calculated the value of overlooked baseball players in Moneyball. As he explains in his latest book, The Undoing Project, it was after the publication of Moneyball that he started hearing about the work of two Israeli psychologists who had demonstrated that even data devotees sometimes submit to intrinsic biases.

Before getting into the biographies of Daniel Kahneman and Amos Tversky, Lewis tells about Daryl Morey, data-driven general manager of the NBA’s Houston Rockets, who found that his interpretation of data about players could be skewed by forms of mental prejudice—the Moneyball caveat. It turned out that Kahneman and Tversky had been trying to warn the world about the various foibles of the human mind in the 1970s.

Each arrived at Hebrew University by different paths. Kahneman, as a Holocaust survivor, was troubled that so many European Jews perished because they did not appreciate the unique menace of Hitler, and this might have fed Kahneman’s tendency to doubt his own brilliance. Tversky, by contrast, was supremely confident in his genius. The diffident Kahneman and gregarious Tversky collaborated in groundbreaking research that has led to positive changes, even in government.

Their first discovery, described in a paper titled “Belief in the Law of Small Numbers,” was that, as Lewis puts it, “Even statisticians tended to leap to conclusions from inconclusively small amounts of evidence.” Working at the Oregon Research Institute in Eugene, the pair went on to show that the mind often gauges evidence by recourse to stereotypes and similarities. And they found, again in Lewis’ words, “not just that people don’t know what they don’t know, but that they don’t bother to factor their ignorance into their judgments.”

So, do we no longer trust experts? Both the presidential election and its winner might lead us in that direction. But Lewis’ genial narration of Kahneman and Tversky’s lives and influence points elsewhere. Their work was not about distrusting our intellect; rather, it warns us to be more careful. We need to account better for the sway of bias over our minds.

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