The Undoing Project

A Friendship That Changed How We Think About Thinking

Daniel Kahneman and Amos Tversky met at Hebrew University in Jerusalem in 1969 and began a collaboration that would, over the next decade, produce some of the most cited papers in social science history. The Undoing Project is Lewis’s account of that partnership — how it started, how it worked, and how it eventually became something both men struggled to contain.

The book began, Lewis explains in the prologue, as a response to criticism that Moneyball had missed what was most interesting about the A’s success: the work of Kahneman and Tversky had shown decades earlier that expert judgment was systematically biased in the ways Oakland’s scouts demonstrated. Lewis decided to tell the story of the people whose research explained his earlier book.

Kahneman and Tversky

The two men were temperamentally opposite. Kahneman was self-doubting, prone to depression, and meticulous about uncertainty. Tversky was supremely confident, charismatic, and fast. Together they were unusually productive — their collaboration created a kind of intellectual environment where each man was better than either was alone.

Lewis traces their major joint discoveries: the representativeness heuristic, the availability heuristic, anchoring, and above all prospect theory — the observation that people value losses and gains asymmetrically, with losses typically weighted roughly twice as heavily as equivalent gains. This single insight demolished the classical economic assumption that rational actors respond symmetrically to equivalent outcomes.

The Human Cost of a Great Partnership

What makes The Undoing Project distinctive among accounts of their work is Lewis’s attention to the friendship’s texture and eventual strain. As their work became famous and prizes accumulated, questions arose about credit and precedence. Tversky, more extroverted and quotable, received more of the public recognition. Kahneman, who had often pushed Tversky toward the questions, felt the imbalance acutely.

The final chapters, set during Tversky’s fatal illness, are genuinely moving. Lewis handles the professional jealousy, the love, and the grief with a restraint that makes them more affecting.

Why Read This Over Thinking, Fast and Slow

Kahneman’s own book is a comprehensive account of the research program. The Undoing Project is a different kind of document — a story about how ideas come into being, what the people behind them were actually like, and what it costs to do genuinely original work. For many readers, Lewis’s version is the more human and therefore more durable account.

Our rating: 4.3/5 — A brilliant account of one of the great intellectual collaborations in modern science, with emotional depth that makes the ideas genuinely unforgettable.

The Friendship That Changed Our Understanding of the Mind

The Undoing Project is Michael Lewis’s engaging account of the remarkable collaboration and friendship between the psychologists Daniel Kahneman and Amos Tversky, whose work transformed our understanding of how the human mind makes decisions. Lewis tells the story of these two very different men, their intense intellectual partnership, and the groundbreaking research they conducted together, which revealed the systematic errors and biases that shape human judgment. By focusing on the human relationship behind the science, Lewis brings to life one of the most important intellectual collaborations of the twentieth century.

The Science of Judgment

The book illuminates the revolutionary research of Kahneman and Tversky, which demonstrated that human judgment and decision-making are subject to predictable biases and errors, departing systematically from the rational ideal assumed by traditional economics. Their work on heuristics, biases, and the quirks of human reasoning laid the foundations for behavioral economics and reshaped fields from psychology to medicine to public policy. Lewis explains these ideas accessibly, conveying their significance and their surprising implications for how we understand the mind and its limitations.

A Story of Friendship and Collaboration

What distinguishes the book is its focus on the deeply human story of the relationship between the two men. Lewis explores their contrasting personalities, the extraordinary creative chemistry of their partnership, the joys and eventual strains of their collaboration, and the profound bond and its complications between them. This attention to the human dimension, the friendship, the personalities, the emotional realities behind the science, gives the book its narrative warmth and power, transforming an account of intellectual history into a moving human story.

Lewis’s Narrative Gift

As in his other acclaimed books, Lewis brings his considerable narrative gifts to bear, finding the compelling human drama within a complex intellectual subject and rendering it with clarity, momentum, and emotional engagement. He has a talent for making difficult ideas accessible and for building his nonfiction around vivid, fascinating characters, and The Undoing Project exemplifies these strengths. His storytelling makes the science and the relationship equally compelling, drawing readers into both the ideas and the lives of the men who developed them.

A Rewarding Exploration

The Undoing Project offers a rewarding exploration of one of the most important developments in the modern understanding of the human mind, made accessible and engaging through Lewis’s storytelling and his focus on the people involved. It serves as an excellent introduction to the ideas of behavioral economics and the psychology of judgment, complementing Kahneman’s own influential work, while telling a genuinely moving story of friendship and collaboration. For readers interested in psychology, decision-making, or simply a well-told story of two remarkable minds, the book is an illuminating and absorbing read. By telling the human story behind a scientific revolution, Lewis makes the origins of behavioral economics not only comprehensible but genuinely moving, and the book stands among his most rewarding work.