Thinking, Fast and Slow

Thinking, Fast and Slow

It is 1955, and a young Israeli psychologist named Daniel Kahneman is trying to figure out why some soldiers fail leadership training and others do not. His job is to send recruits through leaderless group challenges -- moving heavy beams, crossing obstacles, solving tactical problems as a team -- and then predict which ones will become good officers. He and his colleagues watch a recruit take charge of the beam, notice how he handles setbacks, observe whether the others follow him naturally. Then they score him and write a prediction.

The predictions turn out to be useless. Kahneman later checks them against actual officer school performance. The correlation is near zero. The scores his team produces with such confidence tell almost nothing about who will succeed. The recruits are strangers; the observations last a few hours; the social dynamics shift with every new exercise. And yet Kahneman and his colleagues sit down after each session and write their predictions with the quiet certainty of men who believe they have seen something real.

He calls this the "illusion of validity." It does not go away when you learn it exists. Years later, after a Nobel Prize, after decades of research, Kahneman says that he still makes these errors. He still feels the pull of a compelling story, still jumps to conclusions that are not justified by the evidence. His book -- published in 2011, fifty-six years after that military training ground -- is an attempt to explain why. Not to cure us of our thinking errors, but to help us recognize when we are making them.

Thinking, Fast and Slow is one of the most important books written about the human mind. It is also one of the most honest. Kahneman does not position himself above the material. He is not selling you a system for becoming a perfectly rational thinker. He is telling you, clearly and with some sadness, that you are not one -- and neither is he.