谨记经济学的“自我实现属性”
纽约大学斯特恩商学院(Stern School of Business)经济学家约翰•J•霍顿(John J Horton)最近发表的一篇博客文章说，使用亚马逊(Amazon)的土耳其机器人(Mechanical Turk)服务的潜在雇主的开价是每小时1.38美元。这一薪资水平不止是低，其数字本身也很奇怪。为什么是1.38美元?霍顿猜测这一数字来自7年前他联名发表的一篇论文，该论文报告称，在土耳其机器人开展的试验中，1.38美元是保留工资的中位数。所谓保留工资，是指低于该水平个人就不会接受相关工作的工资水平。
He suggests this is an example of “performativity” in economics. This term originates in linguistic philosophy, where it refers to statements whose very utterance is the action referred to: “I name this ship the QE2” or “I promise I’ll do the washing up.”
他指出这是经济学中“操演性”(performativity)的一个例子。“操演性”这个名词源自语言哲学，是指那种说出来本身就完成了所指动作的陈述：“我将这条船命名为QE2”，或者“我发誓我会清洗的”。
Some sociologists have applied the concept to economic theory. One of the most notable examples is the Black-Scholes-Merton model of option pricing. Professor Donald Mackenzie, of University of Edinburgh, argued that before the publication of the model, no market for options was possible as nobody was sure how to price these instruments. Once there was an agreed pricing model, the market sprang into existence.
部分社会学者将这一概念用到了经济学理论中。其中一个最引人注目的例子就是有关期权定价的布莱克-斯科尔斯-默顿(Black-Scholes-Merton)模型。爱丁堡大学(University of Edinburgh)教授唐纳德•麦肯兹(Donald MacKenzie)曾指出，在该模型发表之前，由于没人能确定如何为期权定价，期权市场根本不可能存在。一旦存在了人人认可的定价模型，市场就突然存在了。
It only takes a bit of reflection to see that a lot of economics concerns self-fulfilling (or self-averting) phenomena. An economy can go into recession when enough people think it will, for instance. But while accepting that expectations are important, many economists would regard the idea that the way they think about the world changes the world as fanciful. They see themselves rather as careful observers of empirical facts.
只需要略微思考一下，就可以发现许多经济学涉及自我实现(或自我避免)的现象。比如，当足够多的人认为一个经济体会陷入衰退时，这个经济体就可能陷入衰退。不过，尽管许多经济学家承认预期很重要，但对于经济学家对世界的看法会改变世界这种想法，他们却认为是一种幻想。他们宁愿将自己视为对经验事实的小心观察者。
I have never been so sure. And, as it happened, Prof Horton’s post about an old paper affecting wages was not the only recent example of financial performativity. The other was the horrifying attack on the Borussia Dortmund bus, seemingly carried out to make a profit on put options on the football club’s share price.
对于这种现象，我从未像现在这样确信，而且，事实上，霍顿教授有关旧论文影响薪资水平的帖子，并不是近期金融操演性的唯一例子。另一个例子是对多特蒙德俱乐部(Borussia Dortmund)大巴的可怕袭击，其目的似乎是为了利用对该足球俱乐部股价的看跌期权盈利。
Attempts to rig financial market prices long predate economics. Yet, though real world effects are often a byproduct of financial trades, there is something highly disturbing about this attempt to change reality to bring about a particular market outcome, rather than attempting manipulation by, say, spreading rumours.
在经济学出现很久以前，就有人企图操纵金融市场价格。然而，尽管对真实世界的影响往往是金融交易的副产品，但这种试图改变现实来实现特定市场结果、而不是试图通过比如说扩散谣言来操纵市场的做法，也非常令人担忧。
All the blame lies with the criminal, not with economics. The moral opprobrium in the MTurk case lies with the employer offering a pittance. But it is important for economists to understand that they are players in the world they analyse, uncomfortable as it makes them to go down this self-referential rabbit hole. In fact, the very conceptual framework — that there is a self-contained domain called “the economy’” that is measured by statistics such as gross domestic product and the unemployment rate — affects behaviour in ways that bring about exactly what is described. After all, we do have an economy.
所有谴责都落到了犯罪分子身上，没有落到经济学身上。土耳其机器人一例中的道德谴责落到了开价低廉的雇主身上。然而，对经济学家来说重要的是，要明白他们是其所分析世界的参与者——尽管这会让他们因陷入自我引述的循环而很不舒服。事实上，那种认为存在一个由国内生产总值(GDP)和失业率等统计数字衡量的名为“经济体”的独立世界的概念框架，恰恰通过影响人们的行为，催生了其所描述的东西。结果，我们就确实有了“经济体”这个东西。
However, there could have been alternative realities. Suppose instead of the GDP statistics defining the economy in terms of the market value of specified activities during certain periods there had been an alternative conceptual framework based on measuring the value of assets (including natural assets) in terms of how much it would cost to replace or restore them. There would have been less measured GDP growth and we would have a cleaner and greener society.
然而，另外一种现实原本也可能是存在的。想象一下，不采用以特定时期特定活动的市场价值定义经济体的GDP统计，而采用一种替代性的概念框架，其基础是以重置或恢复资产(包括自然资产)的成本来衡量资产的价值。这种框架下统计出的GDP增速会低一些，我们会拥有更清洁、更环保的社会。
It is not obvious which is better for human welfare, but the outcome we have reflects the framework of economic statistics and their underpinning theory. Statistics can make some things invisible by omission: unpaid work in the home is one example; another — until recently — has been distribution in terms of households’ position on the income ladder or income distribution region of the country. households’ position on the income ladder or income distribution in different regions of the country.
至于哪一种方式对人类的福祉更有利，并不是显而易见的。不过，我们所得到的结果，反映了经济统计的架构、以及它们背后的支撑理论。统计可以通过省略的办法隐匿某些事物：在家中完成的没有酬劳的工作就是个例子;另一个直至最近都被忽略的例子，是家庭收入在收入阶梯中的分布情况，或一国收入的地区分布情况。
Critics of economics also hone in on the central role markets play in the discipline, arguing that this emphasis has marketised more and more of society. Michael Sandel’s bestselling What Money Can’t Buy is an eloquent statement of this critique. The argument conflates the use of processes of exchange to attain certain outcomes — including the market design strand of economics, used for example in Al Roth’s kidney exchange — with specific models of the market, whether option pricing or the idea that companies maximise shareholder value, or the claim that executives need incentive pay. Alternative models would lead to different conclusions and realities.
经济学的批评者也把火力集中到了市场在经济学中的中心地位上，称经济学对市场的这种强调把社会中越来越多的领域市场化了。迈克尔•桑德尔(Michael Sandel)的畅销书《金钱无法买到的东西》(What Money Can’t Buy)就是这种批评的一份雄辩声明。他们的论证，把通过交换过程实现特定结果(包括经济学中的市场设计理论，该理论运用的一个例子，是阿尔•罗斯(Al Roth)有关换肾的研究)，与特定的市场模型(不论是期权定价模型、企业最大化股东价值的理念、还是高管需要激励性薪酬的说法)混为一谈。而换用不同的模型，可能会导致不同的结论和现实。
Still, the popularity of the anti-market mood demonstrated in large votes in many countries for candidates who claim they will turn back the tide is something we economists need to note and respond to. An answer that consists only in saying, “We are right, but need to do a better job of educating the public,” will not wash. For a start, we need to become more reflective about what happens when we send our models and measurements out into the world.
不过，在许多国家中，声称会逆转市场化潮流的候选人得到大量选票，这反映出反市场情绪的流行，这是我们经济学家需要注意和回应的现象。只说一句“我们是对的，我们只是需要更好地教育公众”，是不会令人信服的。作为开始，我们需要更充分考虑到把我们的模型或指标向世界推广时会发生什么。
Diane Coyle is a professor of economics at the University of Manchester
黛安娜•科伊尔(Diane Coyle)是曼彻斯特大学(University of Manchester)经济学教授
