Thinking, Fast and Slow (2011), written by Nobel Laureate Daniel Kahneman, examines how people exercise judgment and make decisions. It draws from Kahneman’s long career—particularly his collaboration with fellow psychologist Amos Tversky beginning in 1969—identifying the mechanisms, biases, and perspectives that constitute human decision-making. Its 38 chapters provide detailed information affecting disciplines ranging from mathematics to law. The book was named one of the best books of 2011 by The New York Times and The Wall Street Journal, and it has sold more than 2 million copies worldwide.

Plot Summary

Kahneman presents the human mind when making decisions through three types of lenses, each represented by one or more parts of the book. The first and third lenses rely on partially opposed, partially collaborative “characters” that Kahneman crafts to represent facets of the human mind. In Part 1, he discusses the two systems of thinking, System 1 and System 2. These systems of thinking include the “fast” thinking, intuitive System 1, which governs most decisions most of the time, and the “slow” thinking System 2, which comes into play for careful evaluation, such as one might use to solve a complicated math problem. In Part 5, Kahneman discusses two “selves,” which can be understood as an experiencing self that lives in the moment and a remembering self that is more evaluative and draws on the memory’s storage of past experiences.

In between these two presentations of the mind as divided, Kahneman discusses a vast array of complex psychological processes that constitute how people actually—and often illogically—make decisions. Parts 2, 3, and 4 tour the heuristics, biases, illusions, and aspects of human thinking that frequently lead to illogical decisions and other errors. Part 4 reviews much of Kahneman’s work with Amos Tversky in developing prospect theory, which showed the errors of then-dominant economic theory. This work, which incorporates psychological insights into the study of decision-making, has since blossomed into behavioral economics and influenced a range of other disciplines as well as public policy.

In some instances, Kahneman and Tversky were the first to reveal certain biases or illusions, and in other instances they built on the findings of others. Broadly speaking, though, no one has done more to illuminate the mechanisms underlying consistent errors in human judgment, which is necessary to taking any corrective action.

Kahneman discusses, to some degree, the policy developments related to the concepts he helped to pioneer. He also provides an overview of the evolving concept of human well-being, research in which he has also participated robustly. Throughout the book, Kahneman offers practical insights that will help people make better decisions, avoid being misled, and focus energy where it can make the most difference in one’s life.