**“Brilliant. . . . Lewis has given us a spectacular account of two great men who faced up to uncertainty and the limits of human reason.” —William Easterly, *Wall Street Journal*** Forty years ago, Israeli psychologists Daniel Kahneman and Amos Tversky wrote a series of breathtakingly original papers that invented the field of behavioral economics. One of the greatest partnerships in the history of science, Kahneman and Tversky’s extraordinary friendship incited a revolution in Big Data studies, advanced evidence-based medicine, led to a new approach to government regulation, and made much of Michael Lewis’s own work possible. In *The Undoing Project,* Lewis shows how their Nobel Prize–winning theory of the mind altered our perception of reality.