The bestselling author combines biography with recent intellectual history in a saga about the influential Israeli psychologist team of Daniel Kahneman and Amos Tversky. Tversky died in 1996, before Lewis (Flash Boys: A Wall Street Revolt, 2014, etc.) even recognized his name. But Kahneman is still living, and Lewis spent lots of time with him studying his theories of how the human mind works while making decisions ranging from product purchasing decisions to choosing a marriage partner. Lewis' fascination with Tversky and Kahneman began with a reference in a review of his bestseller Moneyball, a book that explained how the Oakland Athletics organization overhauled its decision-making processes in order to sign the best athletes possible on a limited budget. The review praised Lewis for explaining how most baseball executives had been choosing players using irrational criteria. The review also emphasized that the author seemed unaware that the techniques were grounded in the decades-old research of Tversky and Kahneman. That research demonstrated the irrationalities of the human brain and recommended how such irrational thinking could be minimized. By the time Lewis approached Kahneman, the potential book subject had won the Nobel Memorial Prize in Economic Sciences, despite identifying as a psychologist. However, he had not yet completed his bestselling book Thinking, Fast and Slow (2011), so Lewis would be chronicling an individual nearly unknown outside academia. The result is largely successful. As always, Lewis' writing style is engaging and mostly irresistible. The opening chapter is slightly disorienting because it never mentions the book's subjects; instead, the author chronicles the journey of a professional basketball executive hoping to construct a systematic method of choosing players. However, after Lewis eases into the main subjects, he ably captures their outsized personalities, explaining how they came to collaborate and how that collaboration slowly frayed. Kahneman and Tversky approached their personal lives and their research in extremely divergent manners. At times, Lewis' details about the unlikely coupling overwhelm the larger narrative, but that is a minor complaint in another solid book from this gifted author.