This evaluation of the sources of illogical decisions explores the reasons why irrational thought often overcomes level-headed practices, offering insight into the structural patterns that cause people to make the same mistakes repeatedly. In a series of illuminating, often surprising experiments, the author, a MIT behavioral economist, refutes the common assumption that we behave in fundamentally rational ways. Blending everyday experience withgroundbreaking research, he explains how expectations, emotions, social norms, and other invisible, seemingly illogical forces skew our reasoning abilities. Not only do we make astonishingly simple mistakes every day, but we make the same types of mistakes, he discovers. We consistently overpay, underestimate, and procrastinate. We fail to understand the profound effects of our emotions on what we want, and we overvalue what we already own. Yet these misguided behaviors are neither random nor senseless. They are systematic and predictable, making us predictably irrational. From drinking coffee to losing weight, from buying a car to choosing a romantic partner, he explains how to break through these systematic patterns of thought to make better decisions. This book offers ways to change the way we interact with the world one small decision at a time.