While introducing his new book, journalist Michael Lewis makes an unusual and gracious concession. After describing his 2003 best-seller "Moneyball," Lewis writes, "My book wasn't original. It was simply an illustration of ideas that have been floating around for decades and had yet to be fully appreciated by, among others, me." He thinks those ideas—many of which classify the systematic biases in human cognition—originated in the collaborative work of two Israeli psychologists, Daniel Kahneman and Amos Tversky.
In "The Undoing Project: A Friendship That Changed Our Minds," Lewis narrates the long friendship of Kahneman and Tversky and explains some of their most influential ideas. Half of the book is largely redundant; Kahneman himself wrote an excellent 2011 popular book, "Thinking, Fast and Slow." Lewis skillfully highlights the wide-reaching implications of some of these ideas, but much of what makes his new book original is his deep reporting on the personalities and biographies of the two psychologists.
Both men lived interesting and dramatic lives. As a young boy, Kahneman lived with his family in a chicken coop in France to avoid detection by the Nazis during World War II. They fled to Palestine after the war, and by the mid-1950s, when he was only 21 years old, Kahneman designed a psychological test for the Israeli army so successful that it is still used today. His essential insight was to use data to diminish the role that intuitive, often wildly inaccurate assessments played in the evaluation. It's not hyperbolic to say that this practice has transformed vast sectors of the modern world: from medicine to law, finance to athletics, the gut feelings of human experts have been supplemented and in many cases supplanted by the predictive power of algorithmic modeling.
Born in Israel, Tversky was in many ways the temperamental opposite of Kahneman. Brash and argumentative and extremely self-confident, Tversky enjoyed leaping from planes and proving to others that they were wrong. Kahneman disliked athletics and generally suspected that his own ideas were wrong. They began collaborating in Israel in the 1960s, and they spent years in intense, animated conversation. They even wrote together, sitting side-by-side in front of a single typewriter. Kahneman compared the emotional intensity of the relationship to that of a marriage, and Lewis' account suggests that, if anything, that is an understatement.
From their conversation and research emerged many ideas that are now central to psychology and economics: the availability bias, the anchoring bias, hindsight bias, the endowment effect, framing and many others. One way to understand these biases is as the mental equivalents of optical illusions. Just as the eye is easily tricked into misperceiving lines of equal length as unequal, human minds are also susceptible to a range of errors. We tend to overvalue what we already possess only because we possess it (endowment), to overestimate the probability that things would turn out the way they have (hindsight), to allow initial information to have a disproportionate impact upon our decisions (anchoring) and to overestimate the frequency of items we happen to be able to summon to mind easily (availability).
Those and other findings are interesting and useful, but to present them as epochal discoveries in intellectual history is misleading. The impulse to form a systematic classification of human mental frailties is at least as old as Aristotle's Sophistical Refutations—an early treatise that analyzes types of persuasive fallacies used by ancient Sophists. Plato and Socrates were also keenly aware that human judgments of dilemmas vary based on the language used to describe them and the implied alternatives to various options—what in today's jargon we would call "framing effects." To determine through psychology experiments the precise nature and extent of certain cognitive susceptibilities is a valuable continuation of a long philosophical tradition, but it is a refinement, not a revelation.
Lewis' tone, however, is often quite worshipful. In a presumably unintentional demonstration of the hindsight bias, he lingers on details and episodes from both men's past that seem to prefigure future greatness. He approvingly quotes someone comparing Tversky to Einstein, and he presents as profundities truths about memory and perception that novelists and their readers have known for centuries. With typical grandiosity, Lewis describes one of Kahneman's research projects like this: "He wanted, in short, to discover the rules of the imagination." His depiction of the men as brilliant iconoclasts depends on a certain blindness to intellectual history.
While he praises the positive applications of their findings in areas such as medicine and government policy, he neglects to consider the sinister ramifications of "choice architecture" as deployed by corporations or tyrannical governments. Corporate and political misinformation campaigns already exploit the frailties of human cognition; in the wrong hands, the principles of behavioral economics are a how-to guide for more effective manipulation. Lewis overstates both the intellectual significance of their research and its power to do good.
Though Lewis seems not to share it, Kahneman's own assessment is ultimately the most persuasive: "I am not a genius. Neither is Tversky. Together we are exceptional."