托福阅读：群体智慧成了陈词滥调

　　那么，“群体的智慧”这一说法又是如何产生的呢?它表达的其实是一种数学特性，即对同一变量的许多独立判断的平均值比个人自己判断的预期错误率要低。这就是詹姆斯?苏罗维奇(JamesSurowecki)在他那本广为传阅的同名书《群体的智慧》(wisdom ofcrowds)中所援引那个例子的背景。苏罗维奇援引的是著名数学家弗朗西斯?高尔顿(FrancisGalton)对一场猜测一头公牛重量比赛的观察(实际上，高尔顿关注的是中位数而非平均估值，但这里忽略这一技术细节)，从而提出了群体有智慧的观点。

　　It is entirely rational to adopt the common opinion on a subject aboutwhich one knows little; Ibelieve the earth is round because that is the balanceof informed opinion, and would amillennium ago have believed it to be flat, forthe same reason. But the number of practicalsituations in which this statisticalproperty is useful is severely limited. It is usually better todirect one’sefforts at reducing the error of estimates rather than increasing the numberoferroneous estimates. That is why we prefer to entrust the navigation of aplane to a skilledpilot instead of using the average of the opinions of thepassengers.

　　在一个自己不甚了解的问题上接受公认的看法是完全明智的;我相信地球是圆的，因为这一结论是主流权威观点，而出于同样的原因，1000年前的人们曾经相信它是平的。但能让这种统计特性能发挥作用的现实情形是非常有限的。通常情况下，更好的办法是去努力减少估计中的错误，而非增加错误估计的数量。这就是为什么我们更愿意将开飞机的任务托付给熟练的飞行员，而不是综合采纳大多数乘客的意见。

　　The wisdom of crowds becomes a pathology when the estimates of the membersof the crowdcease to be independent of each other, and this is likely when thecrowd is large, ill-informed,or both. It is in the nature of a crowd to turn onanyone who dissents from what is already theaverage opinion. This is equallytrue on the streets of revolutionary Paris, the squares ofPyongyang, and theterraces of Chelsea Football Club.