【英语生活】别信“预言家”

This is the time when pundits make predictions about what will happen in 2009 – after a year of shocking and unanticipated economic events. The Queen, visiting the London School of Economics, wondered why the credit crisis and its evolution were not predicted. Here, Ma'am, is the outline of one loyal subject's answer. You will appreciate, I am sure, that economic prediction is hard. National economies, financial markets and businesses are complex, dynamic, non-linear systems. Your economy contains many people and many agents, and there are many interactions between them. Your Royal Society rightly commemorates the successes of the natural sciences. Many of these successes have been achieved because the problems of physics often involve objects large enough to be studied individually – the motion of the earth, for example. Or components small enough to be subject to statistical regularities – we can never predict the behaviour of an individual molecule or electron, but there are so many molecules and electrons that for most purposes it does not matter. Many of the phenomena we deal with in economics and business fall in between – the units of analysis are individualistic but also too numerous for their idiosyncrasies to be individually understood.

Economic systems are also dynamic. Dynamic in the sense that they evolve – which makes the mathematics harder. But also dynamic in the sense that the structural relationships constantly change. Some economists – perhaps a majority in your former American colonies – believe there is a deep underlying structure from which laws of economic behaviour that are universal in time and space can be deduced. I think that search is a wild goose chase and that the best we can do is to identify empirical regularities that
apply to particular contexts. Whoever is right, it is evident more work needs to be done in understanding the relationships.

But the killer is that dynamic complexity interacts with non-linearity. If that statement sounds like an extract from a monologue by Gordon Brown, UK prime minister, recall the (false) story that your predecessor, Richard III, lost the crown at Bosworth Field for want of a nail in the shoe of his horse. The point is that small differences in initial conditions can have dramatic differences in ultimate outcomes. The problem is often expressed through the metaphor of the butterfly which, by flapping its wings on one side of the world, sets in train a chain of consequences that results in a tornado many thousands of miles away.

The nature of such complex, dynamic, non-linear systems is that we may be able to say a lot about their general properties, while being unable to make specific predictions. You will recognise this characteristic in the work of your Meteorological Office, which can tell you fairly reliably when spring will follow summer, or how much cooler or warmer it will be when you visit far-flung outposts, but which can never predict what the weather will be more than a few days ahead, or even with certainty what it will be like tomorrow.

Such limitations on our knowledge lead to a further problem. Although people endlessly ask for predictions, they rarely really want the answers. It was only late – too late – in life that I realised that when people said, “We really want you to challenge our ideas,” they mostly did not. They wanted instead to be congratulated on their wisdom. Similarly, when they ask,
“What is going to happen?” they seek reaffirmation and reassurance rather than insight into the future.

The market for clairvoyance has existed through history and is satisfied by messages based on hope and ambiguity. The market for economic prediction is similar. Successful proponents are distinguished by their television manner rather than the accuracy of their forecasts.

I learnt during the new economy bubble that people preferred to be told they were right than to be told what would happen. Only when I
quit business and academe to write, and did not have to placate clients or potential benefactors, could I openly say that the conventional wisdom was in error.

Most people in the financial world enjoy no such freedom. I believed that I would win kudos for my contrarian view when the bubble burst. But people who had not wished to be told they were talking nonsense before the bubble burst did not wish to be told they had been talking nonsense after the bubble burst either. Indeed they did not recall that they had been talking nonsense. Either they had known that it was a bubble all the time or they had been victims of events that could not have been predicted. Frequently the same individual would make both claims. And the same people would make the same false assertions when the credit bubble burst.

Shakespeare, traducing Richard III with the connivance of the first Queen Elizabeth, understood better than anyone that a good story is more compelling than the search for truth. The American political scientist, Philip Tetlock, has studied the prognostications of pundits over several decades. He finds that the better known the forecaster, the less accurate the forecast. Business people, politicians and journalists value clarity and certainty of view more highly than acknowledgement of the uncertainty of a complex world. But it is mostly people who appreciate that complexity who have worthwhile things to say about the future.

And that is where you have a role, Ma'am. The foolish sovereign rewards the courtiers who tell her what she wants to hear; the wise sovereign bestows her gratitude on those who struggle, however vainly, to reach the truth. I respectfully hope you will bear that in mind when you graciously bestow your new year honours.

John Kay's new book, The Long and the Short of It, is published on January 20

在经历一年令人震惊和意外的经济事件之后，现在轮到预言家们对将在2009年发生的事做出预测了。英国女王在访问伦敦政治经济学院(LSE)时，对于没人预料到信贷危机及其发展表示纳闷。夫人，下面是我这位忠诚子民给出的答案纲要。我相信您会认识到，经济预测是很难的。国民经济、金融市场和企业是复杂、动态和非线性的体系。经济是由许多普通人和许多代理人组成的，他们之间存在着大量互动。皇家学会(Royal Society)恰如其分的代表着自然科学的成就。许多成就之所以能够取得，是因为物理学问题所涉及的对象往往大到足以对其进行个体研究，例如地球的运动；或者这个对象的成分小到足以受统计学规律的支配——我们永远无法预测单个分子或电子的行为，但组成这个对象的分子和电子是如此之多，以至于对大多数课题而言，单个分子或电子的行为并不重要。而我们所研究的许多经济学和商学现象正好介于两者之间——分析的单位是个体的，但其数目过多，以至于无法理解每一个个体的特性。

经济体系还是动态的。这里的动态是就其演化而言的，这使数学表述难上加难。这里的动态还指其结构关系的不断变化。一些经济学家（也许多数在您的前美洲殖民地）认为，经济体系存在一个深层次的结构，从这一结构可得出超越时空的普世经济行为法则。我认为，搜寻这一结构的努力是白费力气；我们能够尽力而为的，是找出适用于特定环境的经验性规律。无论谁正确，我们都需要在理解结构关系上做更多的工作。

但致命的一点是，这个动态的复杂结构体又与非线性过程存在互动。如果这话听起来像是英国首相戈登•布朗(Gordon Brown)的一段独白，那么就回想一下谣传的、关于您的前任理查德三世(Richard III)的典故吧——他因自己战马的马掌缺少一枚掌钉而在博斯沃思原野(Bosworth Field)丢掉了皇冠。这个故事的要点在于，初始条件的微小不同，可以导致最终结果出现巨大差异。这个问题往往是通过蝴蝶的比喻来表述的——蝴蝶在世界一角扇动翅膀会产生一连串的后果，最终导致数千英里之外出现龙卷风。

经济体系这一复杂、动态和非线性的本质，使得我们或许能够大谈特谈其一般特性，却无法给出具体的预测。您会发现，气象局的工作同样具备这个特点。它可以相当有把握地告诉您，春夏交替是在什么时节，或者在您访问遥远的海外属地时，告诉您当地会比伦敦凉爽或温暖多少。但是，它永远无法预测出未来数天之后的天气如何，甚至无法确定无疑的预测出明天的天气。

这类知识上的局限还带来一个问题。尽管人们无休止的要求给出各种预测，但他们很少真的想知道答案。在人生历程中，我很晚（太晚）才意识到：当人们说“我们真希望你挑战我们的看法”时，多数情况下其实他们并不这么想。他们想要的，是人们对他们的智慧表示赞许。同样，当他们问“会发生什么？”时，他们是在寻求对自身看法的肯定与支持，而不是对未来的洞悉。

预言的市场由来已久，其消费者对基于希望与模棱两可的预言感到满足。经济预测的市场与此类似，预测者的成功，在更大程度上取决于于其在电视上的风采，而非其预测的准确性。

我在“新经济”泡沫期间认识到：人们宁愿被告知自己正确，也不愿被告知会发生什么。只有当我退出商界和学术界从事写作、而不必安抚客户或潜在的捐助人时，我才可以公开表示，传统智慧误入了歧途。

大部分金融界人士享受不到这样的自由。我曾相信，当泡沫破裂的时候，我会因为我的逆向操作观点而赢得荣誉。但那些在泡沫破裂前不希望被告知自己在胡说的人，在泡沫破裂后，也不企盼别人告诉他这个事实。实际上，他们已经想不起来他们一直在胡说。要么他们一直就知道这是泡沫，要么他们是不可预测事件的受害者。往往，同一个人会声称上述两种情形都发生在自己身上。当信贷泡沫破裂的时候，这些人也会做出相同的不实声明。

在伊丽莎白女王一世的默许下中伤理查德三世的莎士比亚比任何人都清楚，一个好故事比寻找真相更能打动人。美国政治学者菲利普•泰洛克(Philip Tetlock)研究预言家的各种预测已有数十载。他发现，预言家越出名，其预测就越不准确。较之承认复杂世界的不确定性，商人、政界人士和新闻记者更看重观点的清晰和确定性。但往往正是那些重视复杂性的人对于未来的说法更有价值。

而这就是您该发挥作用的地方，夫人。愚蠢的君主奖赏那些擅长奉承的朝臣；英明的君主则感激那些（无论怎样徒劳）都努力寻求真理的人。我恭敬地希望您在优雅地颁发新年荣誉的时候，会把这点记在心里。

约翰•凯的新书《金融投资学入门指导》(The Long and the Short of It)将于1月20日出版

译者/汪洋、董琴