The Undoing Project: A Friendship That Changed Our Minds by Michael Lewis Norton, 362 pp., $28.95

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We are living in an age in which the behavioral sciences have become inescapable. The findings of social psychology and behavioral economics are being employed to determine the news we read, the products we buy, the cultural and intellectual spheres we inhabit, and the human networks, online and in real life, of which we are a part. Aspects of human societies that were formerly guided by habit and tradition, or spontaneity and whim, are now increasingly the intended or unintended consequences of decisions made on the basis of scientific theories of the human mind and human well-being.

The behavioral techniques that are being employed by governments and private corporations do not appeal to our reason; they do not seek to persuade us consciously with information and argument. Rather, these techniques change behavior by appealing to our nonrational motivations, our emotional triggers and unconscious biases. If psychologists could possess a systematic understanding of these nonrational motivations they would have the power to influence the smallest aspects of our lives and the largest aspects of our societies.

Michael Lewis’s The Undoing Project seems destined to be the most popular celebration of this ongoing endeavor to understand and correct human behavior. It recounts the complex friendship and remarkable intellectual partnership of Daniel Kahneman and Amos Tversky, the psychologists whose work has provided the foundation for the new behavioral science. It was their findings that first suggested we might understand human irrationality in a systematic way. When our thinking errs, they claimed, it does so predictably. Kahneman tells us that thanks to the various counterintuitive findings—drawn from surveys—that he and Tversky made together, “we now understand the marvels as well as the flaws of intuitive thought.”

Kahneman presented their new model of the mind to the general reader in Thinking, Fast and Slow (2011), where he characterized the human mind as the interrelated operation of two systems of thought: System One, which is fast and automatic, including instincts, emotions, innate skills shared with animals, as well as learned associations and skills; and System Two, which is slow and deliberative and allows us to correct for the errors made by System One.

Lewis’s tale of this intellectual revolution begins in 1955 with the twenty-one-year-old Kahneman devising personality tests for the Israeli army and discovering that optimal accuracy could be attained by devising tests that removed, as far as possible, the gut feelings of the tester. The testers were employing “System One” intuitions that skewed their judgment and could be avoided if tests were devised and implemented in ways that disallowed any role for individual judgment and bias. This is an especially captivating episode for Lewis, since his best-selling book, Moneyball (2003), told the analogous tale of Billy Beane, general manager of the Oakland Athletics baseball team, who used new forms of…