Expert Political Judgment: How Good Is It? How Can We Know? (英語) ペーパーバック – 2017/8/29
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Since its original publication, Expert Political Judgment by New York Times bestselling author Philip Tetlock has established itself as a contemporary classic in the literature on evaluating expert opinion.
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. Now with a new preface in which Tetlock discusses the latest research in the field, the book explores what constitutes good judgment in predicting future events and looks at why experts are often wrong in their forecasts.
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
Philip Tetlock has just produced a study which suggests we should view expertise in political forecasting--by academics or intelligence analysts, independent pundits, journalists or institutional specialists--with the same skepticism that the well-informed now apply to stockmarket forecasting. . . . It is the scientific spirit with which he tackled his project that is the most notable thing about his book, but the findings of his inquiry are important and, for both reasons, everyone seriously concerned with forecasting, political risk, strategic analysis and public policy debate would do well to read the book.---Paul Monk, Australian Financial Review
Mr. Tetlock's analysis is about political judgment but equally relevant to economic and commercial assessments.---John Kay, Financial Times
Why do most political experts prove to be wrong most of time? For an answer, you might want to browse through a very fascinating study by Philip Tetlock . . . who in Expert Political Judgment contends that there is no direct correlation between the intelligence and knowledge of the political expert and the quality of his or her forecasts. If you want to know whether this or that pundit is making a correct prediction, don't ask yourself what he or she is thinking--but how he or she is thinking.---Leon Hadar, Business Times
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
[This] book . . . Marshals powerful evidence to make [its] case. Expert Political Judgment . . . Summarizes the results of a truly amazing research project. . . . The question that screams out from the data is why the world keeps believing that "experts" exist at all.---Geoffrey Colvin, Fortune
Phillip E. Tetlock does a remarkable job . . . applying the high-end statistical and methodological tools of social science to the alchemistic world of the political prognosticator. The result is a fascinating blend of science and storytelling, in the the best sense of both words.---William D. Crano, PsysCRITIQUES
"It is the somewhat gratifying lesson of Philip Tetlock's new book ... that people who make prediction their business ... are no better than the rest of us."--Louis Menand, New Yorker"The definitive work on this question." --Gavyn Davies, Financial Times
"[This] book ... marshals powerful evidence to make [its] case.Expert Political Judgment... summarizes the results of a truly amazing research project.... The question that screams out from the data is why the world keeps believing that 'experts' exist at all."--Geoffrey Colvin, Fortune
His first critical conclusion is that, in forecasting complex political events, "we could do as well by tossing coins as by consulting experts". This is based on a massive set of surveys of expert opinion that were compared to outcomes in the real world over many years. The task was enormously complex to set up; defining an experiment in the social sciences presents the problems that constantly arise in making judgements in these sciences (what does one measure, and how? How can bias be measured and eliminated? etc. etc.) Much of the book is devoted to the problems in constructing the study, and how they were resolved.
His second key conclusion is that, while that may be true of experts as an undifferentiated group, some experts do significantly better than other experts. This does not reflect the level of expertise involved, nor does it reflect political orientation. Rather, it reflects the way the experts think. Poorer performers tend to be what Tetlock characterizes as "hedgehogs" -- people who apply theoretical frameworks, who stick with a line of argument, and who believe strongly in their own forecasts. The better performers tend to be what he calls "foxes" -- those with an eclectic approach, who examine many hypotheses, and who are more inclined to think probabilistically, by grading the likelihood of their forecasts.
But, as he notes, the forecasters who get the most media exposure tend to be the hedgehogs, those with a strong point of view that can be clearly expressed. This makes all the sense in the world; someone with a clear cut and compelling story is much more fun to listen to (and much more memorable than) someone who presents a range of possible outcomes (as a former many-handed economist, I know this all too well).
What does that mean for those of us who use forecasts? We use them in making political decisions, personal financial decisions, and investment decisions. This book tells us that WHAT THE EXPERTS SAY IS NOT LIKELY TO ADD MUCH TO THE QUALITY OF YOUR OWN DECISION MAKING. And that says be careful how much you pay for expert advice, and how much you rely on it. That of course applies to experts in the social sciences, NOT to experts in the hard (aka real) sciences. Generally, it is a good idea to regard your doctor as a real expert.
Because it makes it impossible to avoid these conclusions, I gave this book five stars; this is very important stuff. I would not have given it five stars for the way in which it is written. For me, it read as if it had been written for other academics, rather than for the general reader. This is hard to avoid, but some other works in the field do manage -- for example, "Thinking Fast and Slow". Don't skip the book because it is not exactly an enjoyable read, however: its merit far outweighs its manner.
Secondly, Tetlock demonstrates that experts who know something about a number of related topics (foxes) predict better than experts who know a great deal about one thing (hedgehogs). Generalist knowledge adds to accuracy.
Tetlock's survey of this research is clear, crisp, and compelling. His work has direct application to world affairs. For example he is presenting his findings to a conference of Intelligence Community leaders next week (Jan 2007) at the invitation of the Director of National Intelligence.
"Expert Political Judgment" is recommended to anyone who depends on political experts, which is pretty much all of us. Tetlock helps the non-experts to know more about what the experts know, how they know it, and how much good it does them in making predictions.