Why economists should be more like plumbers［堵漏人员］

经济学家到底是干什么的？

What kind of economist should I be when I grow up? The opening weeks of the year have brought an embarrassment of answers. 长大以后，我应该成为什么样的经济学家？在今年伊始的几周时间里，人们对这一问题的回答令人尴尬。

Andrew Haldane, chief economist of the Bank of England, won headlines for comparing economists to weather forecasters. Alas, it was not a flattering comparison: Haldane mentioned Michael Fish’s infamous October 1987 forecast on primetime British TV, which offhandedly reassured viewers that there wouldn’t be a hurricane so “don’t worry”. The warning was followed by a severe storm that killed 18 people in the UK and four in France. 英国央行(BoE)首席经济学家安德鲁•霍尔丹(Andrew Haldane)因将经济学家比作天气预报员而登上新闻头条。唉，这不是一个恭维经济学家的对比：霍尔丹提到了1987年10月迈克尔•菲什(Michael Fish)在英国电视台黄金时间做出的声名狼藉的预测，他不假思索让观众放心，不会有什么飓风，因此“不必担忧”。之后，一场暴风雨导致英国18人、法国4人死亡。

But if economists are like weather forecasters, the lesson is that they should keep trying. Meteorologists have a difficult job yet they do it well — partly with the help of half-a-million weather measurements a day and powerful supercomputer simulations. Perhaps economic forecasting should emulate that approach. For now, many serious economists think that economic forecasting is for fools and charlatans, and that real economists have a different job entirely. 但如果经济学家真的像天气预报员，那么教训是，他们应该继续努力预测。气象学家的工作不好干，但他们干得很好——这在一定程度上得益于每天50万次天气测量和强大的超级计算机模拟。或许经济预测也应该效仿这种方法。就目前而言，许多严肃经济学家认为，只有傻子和骗子才会进行经济预测，真正的经济学家的工作完全不同。

What, then, is that job? Beatrice Cherrier, a historian of economic thought, points out that economists have long looked for an appealing metaphor. In the 19th century, economics was part science, part moral philosophy and part art. Later, economists liked to compare themselves to physicists, borrowing the jargon, the methodology and the mathematics of physics. With the discipline inspiring awe after the splitting of the atom, it must have been tempting for economists to seek the same quality of insight — not to mention the prestige and the funding. 那么经济学家的工作到底是什么？经济思想史家贝亚特丽斯•谢里耶(Beatrice Cherrier)指出，经济学家长期以来一直在为这个问题寻找一种理想的比喻。在19世纪，经济学一部分是科学、一部分是伦理学，还有一部分是人文科学。后来，经济学家喜欢自比为物理学家，借用了物理学的行话、方法论和数学。随着原子分裂后物理学成为一门令人敬畏的学科，经济学家必定也想要寻求同样质量的洞见，更别提声望和资金了。

Whether economics has really been strengthened by ideas from physics remains a matter of controversy. Some critics say that economists should embrace ideas from psychology. Others simply argue that economists have copied the wrong kind of physics and, if they used more up-to-date technical tools, they’d achieve better results. 经济学是否真的因借鉴物理学观念而变得更强依然存在争议。一些评论人士称，经济学家应该拥抱心理学观念。其他人干脆说，经济学家借用了不适当的物理学理论，而如果他们使用更现代的技术工具，他们就会取得更好的结果。

An alternative view is that economics should be a practical, problem-solving discipline. The most famous proposal along these lines is a throwaway remark from John Maynard Keynes, who looked forward to the day when economists would be “humble, competent people on a level with dentists”. 还有一种观点是，经济学应该是解决问题的实践型学科。按照这个逻辑，最著名的提议是约翰•梅纳德•凯恩斯(John Maynard Keynes)随口说的一句话：期待有那么一天，经济学家将是“像牙医那样的谦卑、能干的人”。

Humility and competence sound good to me — and dentistry seems an appealing model in other ways. Dentists don’t forecast how much tooth decay you might suffer［很生动但是段位略高不建议学］over the next decade; they tell you to floss and to lay off the fizzy drinks. Dentists know that their job is not forecasting but preventing or solving problems. 对我来说，谦卑和能干听起来还不错，而且从其他方面来说牙科似乎也是个不错的榜样。牙医不会预测今后十年里你可能有多少龋齿问题［注］；他们告诉你要用牙线，而且别喝碳酸饮料。牙医知道，他们的工作不是预测，而是预防或解决问题。

MTI百科：龋病俗称虫牙、蛀牙，是细菌性疾病，可以继发牙髓炎和根尖周炎，甚至能引起牙槽骨和颌骨炎症。

But Tony Greenham, a programme director at the RSA, recently declared that Keynes was quite wrong. Dentistry is built on objective science, says Greenham, but economics is not: economic analysis should involve clashing schools of thought, debating ideas in front of a public who must then make their choices at the ballot box. Greenham has a point, of course. Economics will never be a hard science, so there must always be room for debate. And most economic policy decisions produce winners and losers, each with a right to be heard. 但英国皇家文艺学会(RSA)的项目总监托尼•格里纳姆(Tony Greenham)最近宣称，凯恩斯完全错了。他说，牙医建立在客观科学基础之上，但经济学不是：经济分析应该包含打破思想流派，在随后必须投票做出选择的公众面前辩论观点。格里纳姆当然有一定道理。经济学永远不会成为硬科学［注］，因此始终存在辩论的空间。大多数经济决策会产生赢家和输家，每一方都有权发出自己的声音。

硬科学Hard science释义是自然科学与技术科学交叉的统称，内容是数学、物理学、化学、天文学等。 它主要是应用本学科系统的理论和方法去研究具体的“有形”课题为主的以解决理论与实践紧密结合的各种问题。相对的，社会科学属于软科学。

Still, if dentistry offers a practical, evidence-based approach to solving problems, I’m not sure that Greenham is wise to warn economists away from that goal unless there really is no hope. 然而，如果牙科提供了一种具有实际操作性的循证方法来解决问题，我不确定格里纳姆建议经济学家不要采用这种方法是否明智——除非真的没有任何希望。

Several leading economists have argued that economics should have a more practical bent. Al Roth, Nobel laureate in economics, says that economists should be like engineers. Roth has designed systems for matching students to schools and kidney donors to recipients, and his argument is that when designing such a system it’s not enough to get the broad outlines right — as a physicist or an economic theorist might — but the details too.数位领先经济学家都说，经济学应该更贴近实践。诺贝尔经济学奖获得者阿尔•罗斯(Al Roth)表示，经济学家应该像工程师一样。罗斯设计了让学生与学校、以及肾脏捐献者与接受者相匹配的体系。他的观点是，在设计此类体系的时候，仅勾画出框架还不够——对物理学家或经济理论家而言做到这样或许就够了——还需要把细节填充完整。

Meanwhile Esther Duflo — too young for a Nobel but hugely celebrated in the profession — recently gave the prestigious Ely Lecture in Chicago. She argued that economists should act like plumbers, or at least that, “some of us should do some of it some of the time.” 与此同时，埃丝特•迪弗洛(Esther Duflo)最近在芝加哥发表了享有盛名的“埃利演讲”(Ely Lecture)。迪弗洛虽然过于年轻而没有获得诺贝尔奖，但在经济学界很受看重。她认为，经济学家应该像管道工那样工作，或者至少“我们中应该有一些人花部分时间做部分那样的工作”。

For Duflo, plumbing is even more practical than engineering: not only must the plumber install the system, she must observe and tinker with it as leaks and blockages become apparent. Issues that weigh heavily in theory may be trivial in practice, and vice versa.对迪弗洛来说，管道工的工作比工程还要实际：管道工不仅必须安装系统，而且还必须随时观察，在出现明显泄露和堵塞的时候进行修补和疏通。在理论上有重大意义的问题可能在实践中微不足道，反之亦然。

So perhaps I should be a meteorologist, or dentist, or engineer, or plumber — or, as others might advise, psychologist, epidemiologist, historian, anthropologist or data scientist? Of course, the wonderful and frustrating thing about economics is that each of these approaches — and others — has something to offer as we try to comprehend the dizzying interactions of the economy all around us. No wonder economics is so much fun — and so hard to do well. 因此或许我应该是气象学家、牙医、工程师或者是管道工——或者像其他人建议的那样，应该是心理学家、流行病学家、历史学家、人类学家或者数据科学家？当然，关于经济学美妙又讨厌的事情是，当我们努力理解身边令人目眩的经济互动的时候，所有这些方法（以及其他方法）都能提供一些启发。难怪经济学如此有趣，又如此难做好。

As I pondered all this career advice, I couldn’t help but think of Bill Phillips. Phillips was born in 1914 to a New Zealand farming family. He learnt engineering via correspondence course, and was a gold miner, crocodile hunter and war hero. He studied sociology but became an economics professor at the London School of Economics. He produced perhaps the most-cited macroeconomic paper ever written, describing the “Phillips curve”. He learnt several languages and, later in life, was fascinated both by complex dynamic systems and by the economy of China. He also built the first computer model of the British economy. It was a hydraulic computer — a system of equations, crafted in plumbing.在我考虑所有这些职业建议的时候，我不禁想起了比尔•菲利普斯(Bill Phillips)。菲利普斯1914年出生于新西兰一个农民家庭。他通过函授学习了工程学，挖过金矿，捕过鳄鱼，还是战争英雄。他研究了社会学，但后来在伦敦政治经济学院(LSE)当了经济学教授。他撰写了或许是有史以来被引用最广的宏观经济论文，文章描述了“菲利普斯曲线”。他学了多种语言，后来又痴迷上复杂的动态系统和中国经济。他还创建了首个展现英国经济的计算机模型。那是一台液压计算机——一个利用管道工程设计的平衡系统。

Now that’s an economist.这才是真正的经济学家。