The Undoing Project

Michael Lewis's argument unfolds through the story of two Israeli psychologists whose collaboration, and eventual falling out, reshaped how economics, medicine, and everyday decision-making are understood. Daniel Kahneman and Amos Tversky discovered that people don't reason about probability and risk the way classical economic theory assumed; instead, they rely on mental shortcuts, heuristics, that work well enough most of the time but produce systematic, predictable errors in specific, identifiable situations. Their joint research, conducted largely through an intense back-and-forth process of arguing, testing, and rewriting each other's ideas, established that these errors weren't random noise but consistent patterns built into how human minds process uncertainty.

This matters because their work, later recognized with a Nobel Prize in Economics awarded to Kahneman after Tversky's early death, undercut a foundational assumption behind much of twentieth-century economic theory: that people generally make rational, self-interested decisions when given adequate information. Lewis uses the arc of the two men's friendship, its remarkable productivity and its painful dissolution, as a lens on both the psychology of judgment and the psychology of collaboration itself.

Who should read it

Readers interested in behavioral economics, decision-making, or the psychology of collaboration, along with anyone who enjoyed Kahneman's own Thinking, Fast and Slow and wants the human story behind the research. It also appeals to readers drawn to stories of brilliant, complicated partnerships and how they form and fracture.

About the author

Michael Lewis is an American author and journalist known for narrative nonfiction books on finance, sports, and decision-making, including Moneyball, The Big Short, and Liar's Poker.