How Good Is It? How Can We Know?
Philip E. Tetlock
Winner of the 2006 Woodrow Wilson Foundation Award, American Political Science Association
Winner of the 2006 Grawemeyer Award for Ideas Improving World Order
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.
"It is the somewhat gratifying lesson of Philip Tetlock's new book. that people who make prediction their business--people who appear as experts on television, get quoted in newspaper articles, advise governments and businesses, and participate in punditry roundtables--are no better than the rest of us. When they're wrong, they're rarely held accountable, and they rarely admit it, either. It
would be nice if there were fewer partisans on television disguised as "analysts" and "experts". But the best lesson of Tetlock's book may be the one that he seems most reluctant to draw: Think for yourself."--Louis Menand, The New Yorker
"The definitive work on this question. Tetlock systematically collected a vast number of individual forecasts about political and economic events, made by recognised experts over a period of more than 20 years. He showed that these forecasts were not very much better than making predictions by chance, and also that experts performed only slightly better than the average person who was casually informed about the subject in hand."--Gavyn Davies, Financial Times
"Before anyone turns an ear to the panels of pundits, they might do well to obtain a copy of Phillip Tetlock's new book Expert Political Judgment: How Good Is It? How Can We Know? The Berkeley psychiatrist has apparently made a 20-year study of predictions by the sorts who appear as experts on TV and get quoted in newspapers and found that they are no better than the rest of us at prognostication."--Jim Coyle, Toronto Star
"Tetlock uses science and policy to brilliantly explore what constitutes good judgment in predicting future events and to examine why experts are often wrong in their forecasts."--Choice
Table of Contents:
Chapter 1: Quantifying the Unquantifiable 1
Chapter 2: The Ego-deflating Challenge of Radical Skepticism 25
Chapter 3: Knowing the Limits of One's Knowledge: Foxes Have Better Calibration and Discrimination Scores than Hedgehogs 67
Chapter 4: Honoring Reputational Bets: Foxes Are Better Bayesians than Hedgehogs 121
Chapter 5: Contemplating Counterfactuals: Foxes Are More Willing than Hedgehogs to Entertain Self-subversive Scenarios 144
Chapter 6: The Hedgehogs Strike Back 164
Chapter 7: Are We Open-minded Enough to Acknowledge the Limits of Open-mindedness? 189
Chapter 8: Exploring the Limits on Objectivity and Accountability 216
Methodological Appendix 239
Technical Appendix: Phillip Rescober and Philip E. Tetlock 273
Another Princeton book authored or coauthored by Philip E. Tetlock: