Judgment pervades human experience. “Is it worth it?” “Would he be a good father to my children?” “Is our case strong enough to go to court?” “Is our left flank adequately protected?” How – and how well – do people make such judgments? It is to these questions that this book is devoted.

This book addresses these questions by presenting a number of contributions – some preexisting, some new – to the understanding of everyday judgment. Each of these contributions is connected to what has been called the heuristics and biases approach to the study of judgment under uncertainty. Indeed, this book is intended as an update or successor to the influential 1982 book on the subject by Kahneman, Slovic, and Tversky, Judgment under Uncertainty: Heuristics and Biases. Much has happened in the field of judgment since that book appeared, and in this work we attempt to capture many of the most important contributions and developments.

The core idea of the heuristics and biases program is that judgment under uncertainty is often based on a limited number of simplifying heuristics rather than more formal and extensive algorithmic processing. These heuristics typically yield accurate judgments but can give rise to systematic error. Kahneman and Tversky originally identified three such general purpose heuristics – availability, representativeness, and anchoring and adjustment. This book accordingly begins with twelve chapters dealing with more recent research on these heuristics.