Expert Political Judgement — How Good is it? How Can we Know?

The intelligence failures surrounding the invasion of Iraq dramatically illustrate the necessity of developing standards for evaluating expert opinion. This book fills that need. Here, Philip E. Tetlock explores what constitutes good judgment in predicting future events, and looks at why experts are often wrong in their forecasts.

Tetlock first discusses arguments about whether the world is too complex for people to find the tools to understand political phenomena, let alone predict the future. He evaluates predictions from experts in different fields, comparing them to predictions by well-informed laity or those based on simple extrapolation from current trends. He goes on to analyze which styles of thinking are more successful in forecasting. Classifying thinking styles using Isaiah Berlin's prototypes of the fox and the hedgehog, Tetlock contends that the fox--the thinker who knows many little things, draws from an eclectic array of traditions, and is better able to improvise in response to changing events--is more successful in predicting the future than the hedgehog, who knows one big thing, toils devotedly within one tradition, and imposes formulaic solutions on ill-defined problems. He notes a perversely inverse relationship between the best scientific indicators of good judgement and the qualities that the media most prizes in pundits--the single-minded determination required to prevail in ideological combat.

Clearly written and impeccably researched, the book fills a huge void in the literature on evaluating expert opinion. It will appeal across many academic disciplines as well as to corporations seeking to develop standards for judging expert decision-making.

"This book is a landmark in both content and style of argument. It is a major advance in our understanding of expert judgment in the vitally important and almost impossible task of political and strategic forecasting. Tetlock also offers a unique example of even-handed social science. This may be the first book I have seen in which the arguments and objections of opponents are presented with as much care as the author's own position."--Daniel Kahneman, Princeton University, recipient of the 2002 Nobel Prize in economic sciences

"This book is a major contribution to our thinking about political judgment. Philip Tetlock formulates coding rules by which to categorize the observations of individuals, and arrives at several interesting hypotheses. He lays out the many strategies that experts use to avoid learning from surprising real-world events."--Deborah W. Larson, University of California, Los Angeles

"This is a marvelous book--fascinating and important. It provides a stimulating and often profound discussion, not only of what sort of people tend to be better predictors than others, but of what we mean by good judgment and the nature of objectivity. It examines the tensions between holding to beliefs that have served us well and responding rapidly to new information. Unusual in its breadth and reach, the subtlety and sophistication of its analysis, and the fair-mindedness of the alternative perspectives it provides, it is a must-read for all those interested in how political judgments are formed."--Robert Jervis, Columbia University

"This book is just what one would expect from America's most influential political psychologist: Intelligent, important, and closely argued. Both science and policy are brilliantly illuminated by Tetlock's fascinating arguments."--Daniel Gilbert, Harvard University