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经济学家怎么会错得这么厉害？


Eugene Chen [译]



I.
MISTAKING BEAUTY FOR TRUTH

一、真相之上的华丽错误



It’s hard to believe now, but not long ago economists were congratulating themselves over the success of their field. Those successes — or so they believed — were both theoretical and practical, leading to a golden era for the profession. On the theoretical side, they thought that they had resolved their internal disputes. Thus, in a 2008 paper titled “The State of Macro” (that is, macroeconomics, the study of big-picture issues like recessions), Olivier Blanchard of M.I.T., now the chief economist at the International Monetary Fund, declared that “the state of macro is good.” The battles of yesteryear, he said, were over, and there had been a “broad convergence of vision.” And in the real world, economists believed they had things under control: the “central problem of depression-prevention has been solved,” declared Robert Lucas of the University of Chicago in his 2003 presidential address to the American Economic Association. In 2004, Ben Bernanke, a former Princeton professor who is now the chairman of the Federal Reserve Board, celebrated the Great Moderation in economic performance over the previous two decades, which he attributed in part to improved economic policy making.
现在说起来真叫人难以置信，但就是不久前，经济学家们还在为他们领域里取得的成就自行庆功摆好。这些成就——或者他们自己认为的成就——既有理论上的， 也有实践上的，把经济学这个行当带进一个黄金时期。在理论方面，经济学家们认为他们已经摆平了内部的争纷。因此，在2008年一篇题为“宏观现状”的论文里，（宏观指的是宏观经济学，一门研究诸如经济衰退之类大尺度画面问题的学问），麻省理工学院教授、现为国际货币基金组织首席经济学家布兰查德宣称：“宏观现状良好。” 他还说，昔日的论战已经休兵。 经济学家们“观点普遍趋同。”在现实世界中，经济学家则认为他们已经对各种事情有把握控制。“防范经济萧条的核心问题，已告解决，” 芝加哥大学教授卢卡斯在美国经济协会2003年度会长报告中如此宣布。2004年，前普林斯顿大学教授、现联邦储备委员会主席伯南克，大举庆祝前此20年 国家在经济表现上的大平稳，他把这个成就部分地归功于经济决策的进步。
Last year, everything came apart.
去年，凡此一切均分崩离析了。
Few economists saw our current crisis coming, but this predictive failure was the least of the field’s problems. More important was the profession’s blindness to the very possibility of catastrophic failures in a market economy. During the golden years, financial economists came to believe that markets were inherently stable — indeed, that stocks and other assets were always priced just right. There was nothing in the prevailing models suggesting the possibility of the kind of collapse that happened last year. Meanwhile, macroeconomists were divided in their views. But the main division was between those who insisted that free-market economies never go astray and those who believed that economies may stray now and then but that any major deviations from the path of prosperity could and would be corrected by the all-powerful Fed. Neither side was prepared to cope with an economy that went off the rails despite the Fed’s best efforts.
很少有几个经济学家预见到当前危机的降临，不过， 这个预测失败还算不上是该领域的什么大问题。更重要的问题是该学科对市场经济有可能发生灾难性失灵一事带有盲点。在志得意满的黄金岁月里，金融经济学家开始相信市场的内在稳定性——相信股票和其他资产的定价在实际上都是对头的。在流行的各种模型中， 竟然没有一个对去年发生的那种经济崩溃的可能性有任何暗示。不过，宏观经济学家的观点还是有分歧的。主要的分野只是这样的两派：一派坚持自由市场经济不会迷途，另一派则相信尽管经济时有可能偏离，但一旦违背繁荣之路发生重大偏离，全能的美联储都能也都会加以纠正。任何一方都对“联储已然尽力，而经济依然脱轨”之经济现象毫无准备。
（待续）

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关键词：保罗·克鲁格曼 克鲁格曼 经济学家 鲁格曼 经济学 profession themselves practical 经济学家 克鲁格曼

And in the wake of the crisis, the fault lines in the economics profession have yawned wider than ever. Lucas says the Obama administration’s stimulus plans are “schlock economics,” and his Chicago colleague John Cochrane says they’re based on discredited “fairy tales.” In response, Brad DeLong of the University of California, Berkeley, writes of the “intellectual collapse” of the Chicago School, and I myself have written that comments from Chicago economists are the product of a Dark Age of macroeconomics in which hard-won knowledge has been forgotten.

经济危机发生后，经济学界的裂痕之宽则比以往任何时候都要大了。卢卡斯说，奥巴马政府的刺激经济计划是一种“水货经济学”，他的芝加哥大学同事柯克兰也说，刺激经济计划的理论基础是一个已被驳得体无完肤的“童话”。对此加以回应，同时也对芝加哥学派的理论崩溃加以述评，不但我自己而且加州大学伯克利分校德隆教授都写道：芝加哥学派经济学家的意见是宏观经济学愚昧黑暗世纪的产物，我们辛苦学来的知识全被置诸脑后。

What happened to the economics profession? And where does it go from here?

经济学界出了什么事？经济学界由此又将向何处而去？

As I see it, the economics profession went astray because economists, as a group, mistook beauty, clad in impressive-looking mathematics, for truth. Until the Great Depression, most economists clung to a vision of capitalism as a perfect or nearly perfect system. That vision wasn’t sustainable in the face of mass unemployment, but as memories of the Depression faded, economists fell back in love with the old, idealized vision of an economy in which rational individuals interact in perfect markets, this time gussied up with fancy equations. The renewed romance with the idealized market was, to be sure, partly a response to shifting political winds, partly a response to financial incentives. But while sabbaticals at the Hoover Institution and job opportunities on Wall Street are nothing to sneeze at, the central cause of the profession’s failure was the desire for an all-encompassing, intellectually elegant approach that also gave economists a chance to show off their mathematical prowess.

以我观之，经济学界所以误入歧途，是因为经济学家整体言之，常把披着精妙数学外衣的美丽误当作真理。直到大萧条之前，大多数经济学家还死死抱着资本主义就是一个完美或近乎完美制度的观点。这一观点，面对大规模失业，自然无以为系。 但是， 随着对经济大萧条的记忆日益淡漠，经济学家又重温旧爱， 投怀送抱进那个古老的、理想的经济观；把经济参与者都看作是理性人在完美的市场里互动，不过这回， 这一切都穿起了精美的方程式做的华丽衣裳。 诚然， 这一场对理想市场的旧恋重燃，部分是因政治风向的转变所做的回应， 部分也是因金钱激励的存在所做的回应。但是，尽管在胡佛研究所作休假年的研究，或是在华尔街找到就业的机会都是不容小觑的良机，这个行当失败的中心原因乃是那种苦苦追求一条无所不包的、思维上优雅的、并能给经济学家机会以炫耀数学才能的研究路径。

Unfortunately, this romanticized and sanitized vision of the economy led most economists to ignore all the things that can go wrong. They turned a blind eye to the limitations of human rationality that often lead to bubbles and busts; to the problems of institutions that run amok; to the imperfections of markets — especially financial markets — that can cause the economy’s operating system to undergo sudden, unpredictable crashes; and to the dangers created when regulators don’t believe in regulation.

遗憾的是，这个浪漫化了的和消毒净化了的经济观导致了大多数经济学家忽略所有可能出错的事情。他们对很多东西视而不见，诸如：经常引起泡沫发生和破灭的有 限人类理性、因失控而胡为的机构问题、市场的不完善——特别是金融市场的不完善——可以导致经济的操作系统发生突然的、难以预料的崩溃，以及监管者自身不相信监管所产生的危险。

（待续）

It’s much harder to say where the economics profession goes from here. But what’s almost certain is that economists will have to learn to live with messiness. That is, they will have to acknowledge the importance of irrational and often unpredictable behavior, face up to the often idiosyncratic imperfections of markets and accept that an elegant economic “theory of everything” is a long way off. In practical terms, this will translate into more cautious policy advice — and a reduced willingness to dismantle economic safeguards in the faith that markets will solve all problems.

要说经济学界由此会向何处而去，就要更难一些了。 但几乎可以肯定的是，经济学家们将不得不学会与杂乱不纯共处同生。也就是说，他们将不得不承认无理性的且往往不可预知的行为的重要性，不得不正视各种市场独特的不完善之处，并接受一个优雅的“万物经济理论”还有很长的路要走的事实。在实践方面，以上这个认识就将变成更加谨慎的政策建议——不再因相信市场万能而随意拆除各种经济保障。

II. FROM SMITH TO KEYNES AND BACK

二、从斯密到凯恩斯又从凯恩斯到斯密

The birth of economics as a discipline is usually credited to Adam Smith, who published “The Wealth of Nations” in 1776. Over the next 160 years an extensive body of economic theory was developed, whose central message was: Trust the market. Yes, economists admitted that there were cases in which markets might fail, of which the most important was the case of “externalities” — costs that people impose on others without paying the price, like traffic congestion or pollution. But the basic presumption of “neoclassical” economics (named after the late-19th-century theorists who elaborated on the concepts of their “classical” predecessors) was that we should have faith in the market system.

经济学作为一门学科的诞生通常归功于亚当斯密，他在1776年出版了“国富论”。在随后的160年里，经济理 论得到长足的发展， 但这许多汗牛充栋的理论只有一个中心思想：相信市场。诚然，经济学家承认，在某些情形里， 市场可能会失效。 其中最重要的是“外部性”的情形——也就是， 某些人不付出代价就强加在别人头上的费用，比如交通堵塞或环境污染。但“新古典主义”经济学（其名来自19世纪晚期的理论家， 他们对其“古典主义”的前辈的各种概念加以进一步的阐述）的基本预设就是，我们应该对市场体系有信心。


This faith was, however, shattered by the Great Depression. Actually, even in the face of total collapse some economists insisted that whatever happens in a market economy must be right: “Depressions are not simply evils,” declared Joseph Schumpeter in 1934 — 1934! They are, he added, “forms of something which has to be done.” But many, and eventually most, economists turned to the insights of John Maynard Keynes for both an explanation of what had happened and a solution to future depressions.

但是， 这种信心，为大萧条所击碎。事实上，尽管面临市场完全崩溃， 还有一些经济学家坚持认为，市场经济中无论发生什么，都一定是对的：“萧条不仅仅就是邪恶，”熊彼特在1934年如此宣称！他接着又说：萧条也是 “某些必行之事的形式。”但是许多、而且最终是大多数的经济学家，都转而向凯恩斯的洞见寻求对刚刚发生过的事情的解释理由，也寻求对未来可能发生的萧条的解决之道。

Keynes did not, despite what you may have heard, want the government to run the economy. He described his analysis in his 1936 masterwork, “The General Theory of Employment, Interest and Money,” as “moderately conservative in its implications.” He wanted to fix capitalism, not replace it. But he did challenge the notion that free-market economies can function without a minder, expressing particular contempt for financial markets, which he viewed as being dominated by short-term speculation with little regard for fundamentals. And he called for active government intervention — printing more money and, if necessary, spending heavily on public works — to fight unemployment during slumps.

不论你听到的传言如何，凯恩斯并不要政府操纵经济的运行。他在介绍自己在1936年的杰作——“就业，利息和货币通论”——一书中所做的分析，将其描述为“蕴旨意涵温和保守”。他想纠正资本主义，而不是取代资本主义。但他的确是在挑战自由市场经济无人照管也可正常发挥功能这个观念。他对金融市场 特别蔑视，认为该市场被短期投机支配，几乎不考虑基本面。为了减少经济下降期发生的失业，他呼吁政府要积极干预——多印钞票，如有必要，还要花费大量开支于公共工程。

（待续）

It’s important to understand that Keynes did much more than make bold assertions. “The General Theory” is a work of profound, deep analysis — analysis that persuaded the best young economists of the day. Yet the story of economics over the past half century is, to a large degree, the story of a retreat from Keynesianism and a return to neoclassicism. The neoclassical revival was initially led by Milton Friedman of the University of Chicago, who asserted as early as 1953 that neoclassical economics works well enough as a description of the way the economy actually functions to be “both extremely fruitful and deserving of much confidence.” But what about depressions?

很重要是要明白，凯恩斯除了以上大胆断言之外，所做远远不止这些。 “通论”是一深邃，精到的分析之作。此作让当年那些最优秀的年轻经济学家由衷佩服。然而，在过去半个世纪里的经济学史，在很大程度上，就是一个从凯恩斯主义撤退和对新古典主义回归的经济学 史。新古典主义复兴最初是由芝加哥大学的弗里德曼领导的，他早在1953年就主张新古典经济学作为经济实际运行方式的描述已经是够好了，因此新古典经济学 “不但极其富有成果而且也值得大量的信任。”但对于萧条又怎么说呢？

Friedman’s counterattack against Keynes began with the doctrine known as monetarism. Monetarists didn’t disagree in principle with the idea that a market economy needs deliberate stabilization. “We are all Keynesians now,” Friedman once said, although he later claimed he was quoted out of context. Monetarists asserted, however, that a very limited, circumscribed form of government intervention — namely, instructing central banks to keep the nation’s money supply, the sum of cash in circulation and bank deposits, growing on a steady path — is all that’s required to prevent depressions. Famously, Friedman and his collaborator, Anna Schwartz, argued that if the Federal Reserve had done its job properly, the Great Depression would not have happened. Later, Friedman made a compelling case against any deliberate effort by government to push unemployment below its “natural” level (currently thought to be about 4.8 percent in the United States): excessively expansionary policies, he predicted, would lead to a combination of inflation and high unemployment — a prediction that was borne out by the stagflation of the 1970s, which greatly advanced the credibility of the anti-Keynesian movement.

弗里德曼对凯恩斯反击以货币主义论开始。货币主义者并不从原则上反对市场经济需要审慎的稳定措施的观念。 “我们现在都是凯恩斯主义者了，”弗里德曼曾经说过，尽管他后来声称，他是被人断章取义了。 但是， 货币主义者力主说，只要靠一种程度非常有限的、不超出某种范围的政府干预形式——亦即政府指示央行保持国家的货币供给，也就是流通中的现金和银行存款之总 和，使之处于平稳增长的路径之上——那么这就足以防止衰退。弗里德曼和他的合作者施瓦茨曾说过，设若联储会把自己的工作做好，大萧条本不会发生，两人声名 并因此鹊起。后来，弗里德曼还提出令人信服的理由反对政府采取任何刻意的举措将失业率压到“自然”失业率水平（美国目前该率被认为是在4.8%左右）之 下：他预言，过度扩张的政策，将导致通货膨胀和高失业率联翩而至——这个预言后来为1970s发生的滞胀所证实，这也给反凯恩斯主义运动带来了极大的信 誉。

（待续）

Eventually, however, the anti-Keynesian counterrevolution went far beyond Friedman’s position, which came to seem relatively moderate compared with what his successors were saying. Among financial economists, Keynes’s disparaging vision of financial markets as a “casino” was replaced by “efficient market” theory, which asserted that financial markets always get asset prices right given the available information. Meanwhile, many macroeconomists completely rejected Keynes’s framework for understanding economic slumps. Some returned to the view of Schumpeter and other apologists for the Great Depression, viewing recessions as a good thing, part of the economy’s adjustment to change. And even those not willing to go that far argued that any attempt to fight an economic slump would do more harm than good.

不过，后来反凯恩斯主义的反革命终于远远超越了弗里德曼的立场，跟他的后继者的主张相比，弗里德曼的立场似乎温和了许多。在金融经济学家中 间， 凯恩斯将金融市场贬损为“赌场”的观点， 已被“有效市场”理论取代， 这个理论主张，给定所有可能获得的信息，金融市场资产定价总是对的。与此同时，许多宏观经济学家完全拒绝用凯恩斯的框架来理解经济低迷。有的甚至还回到了熊彼特以及其他大萧条辩护士的观点，认为衰退是一件好事，是经济对改变所做调整的一部分。即使那些不愿意走如此极端的人也认为，任何对抗经济衰退的企图都 会弊大于利。

Not all macroeconomists were willing to go down this road: many became self-described New Keynesians, who continued to believe in an active role for the government. Yet even they mostly accepted the notion that investors and consumers are rational and that markets generally get it right.

不是所有的宏观经济学家都愿意走上这条路：许多人成了自我标榜的新凯恩斯主义者，他们坚持相信政府应起积极的作用。但是， 即使是他们， 也大多接受了这样的观念：投资者和消费者都是理性的，市场在一般情况下都能办好事情。



Of course, there were exceptions to these trends: a few economists challenged the assumption of rational behavior, questioned the belief that financial markets can be trusted and pointed to the long history of financial crises that had devastating economic consequences. But they were swimming against the tide, unable to make much headway against a pervasive and, in retrospect, foolish complacency.

当然，对于这些趋势也存在例外情形：有少部分经济学家起而挑战理性行为假设，质疑对金融市场值得信任的信念，指出金融危机带来破坏性经济后果的长期历史。但是，他们是在逆流而泳，无甚进展，因为他们所对抗的是一种普遍的，现在看起来也是愚蠢的，自满自大。

（待续　）　

III. PANGLOSSIAN FINANCE

三、潘格罗斯眼里的（译者：潘格罗斯——一个不可救药的盲目乐观主义者）的金融市场

In the 1930s, financial markets, for obvious reasons, didn’t get much respect. Keynes compared them to “those newspaper competitions in which the competitors have to pick out the six prettiest faces from a hundred photographs, the prize being awarded to the competitor whose choice most nearly corresponds to the average preferences of the competitors as a whole; so that each competitor has to pick, not those faces which he himself finds prettiest, but those that he thinks likeliest to catch the fancy of the other competitors.”

在1930s，金融市场，由于显而易见的原因，没有得到多少尊 重。凯恩斯把金融市场比作“报纸上举行的某种比赛。 比赛的规则是参赛者必须从一百张相片中挑出六张最漂亮的脸孔， 但是大奖将被授予这样的参赛者， 他选的脸孔，最最贴近参赛者全体挑选的平均脸孔；因此，每一个参赛者在挑选时，都不应挑选那些他自己认为最漂亮的脸孔， 而应挑选那些他认为最可能讨其他参赛者喜欢的脸孔。”

And Keynes considered it a very bad idea to let such markets, in which speculators spent their time chasing one another’s tails, dictate important business decisions: “When the capital development of a country becomes a by-product of the activities of a casino, the job is likely to be ill-done.”


凯恩斯认为，让这样的市场——其中的投机者们花时间就是为了相互之间追逐彼此的尾巴——规定重要的商业决策，是一个非常糟糕的主意。 “当一个国家的资本发展沦为一个赌场活动的副产品，这个工作大有可能搞砸。”




By 1970 or so, however, the study of financial markets seemed to have been taken over by Voltaire’s Dr. Pangloss, who insisted that we live in the best of all possible worlds. Discussion of investor irrationality, of bubbles, of destructive speculation had virtually disappeared from academic discourse. The field was dominated by the “efficient-market hypothesis,” promulgated by Eugene Fama of the University of Chicago, which claims that financial markets price assets precisely at their intrinsic worth given all publicly available information. (The price of a company’s stock, for example, always accurately reflects the company’s value given the information available on the company’s earnings, its business prospects and so on.) And by the 1980s, finance economists, notably Michael Jensen of the Harvard Business School, were arguing that because financial markets always get prices right, the best thing corporate chieftains can do, not just for themselves but for the sake of the economy, is to maximize their stock prices. In other words, finance economists believed that we should put the capital development of the nation in the hands of what Keynes had called a “casino.”

可是， 到了1970年左右，金融市场的研究似乎都移交给了伏尔泰笔下的潘格洛斯博士，他坚称我们已经生活在最好的一个可能的世界里了。对投资者非理性的讨论、对泡沫的讨论、对破坏性投机的讨论，几乎都从学术话语中消失。支配学术领域的是“有效市场假说”，由芝加哥大学法玛提出。这个假说声称，金融市场， 在给定所有公开信息的条件下，正是以资产的内在价值给其资产定价。（例如，一家公司的股票价格，在给定所有可获得的诸如公司收益、企业前景等资料的条件下，始终准确地反映公司的价值。）到了1980s， 金融经济学家们，特别是哈佛商学院的詹森，争辩说，由于金融市场总是正确定价，公司头目可以做的最好的事情，不仅对其本人而言，也是为了整个经济，就是最大地推高其股票价格。换句话说，金融经济学家认为，我们应该把国家的资本发展， 交让给被凯恩斯称为“赌场”的手中。



It’s hard to argue that this transformation in the profession was driven by events. True, the memory of 1929 was gradually receding, but there continued to be bull markets, with widespread tales of speculative excess, followed by bear markets. In 1973-4, for example, stocks lost 48 percent of their value. And the 1987 stock crash, in which the Dow plunged nearly 23 percent in a day for no clear reason, should have raised at least a few doubts about market rationality.

这个行当里的上述转型， 要说是因发生的各种事件得以驱动， 这点很难加以论证。 诚然，1929年的记忆已逐渐消逝，但牛市仍在继续发生，随后有关投机过度的流言则开始四处传播，接着就发生熊市。例如，1973-4，股票失去了其价值 的48%。而1987年的股灾，让道琼斯指数，几乎没有明显的原因，在一天内下跌23%。 凡此种种，总应该对市场理性提出几点疑问才对。




These events, however, which Keynes would have considered evidence of the unreliability of markets, did little to blunt the force of a beautiful idea. The theoretical model that finance economists developed by assuming that every investor rationally balances risk against reward — the so-called Capital Asset Pricing Model, or CAPM (pronounced cap-em) — is wonderfully elegant. And if you accept its premises it’s also extremely useful. CAPM not only tells you how to choose your portfolio — even more important from the financial industry’s point of view, it tells you how to put a price on financial derivatives, claims on claims. The elegance and apparent usefulness of the new theory led to a string of Nobel prizes for its creators, and many of the theory’s adepts also received more mundane rewards: Armed with their new models and formidable math skills — the more arcane uses of CAPM require physicist-level computations — mild-mannered business-school professors could and did become Wall Street rocket scientists, earning Wall Street paychecks.

可 是，这些事件，换了凯恩斯一定会视之为市场不可靠的证据，却对一个美丽观念所具的力量几乎毫发无伤。这个观念就是金融经济学家靠着假设每个投资者都在理性 地平衡回报和风险，并以此推导出的一个理论模型——即所谓的资本资产定价模型CAPM（发音为capem）——它是如此精妙优雅。它也是极其的有用， 假定你已经接受模型的前提。CAPM模型不仅告诉你应如何选择投资组合， ——从金融业的角度来看，尤其更重要的是，它告诉你如何对——建立在索取权基础之上的索取权——金融衍生产品进行定价。这个新理论的优雅性和表面上的有用性，给它的创造者带来了一系列诺贝尔奖，而该理论的许多行家里手们，也获得了更为世俗化的回报：一些温文尔雅的商学院教授以簇新的模型和令人敬畏的数学技 能来做武装——因为CAPM较深奥的应用要求物理学家水平的计算——可能而且的确摇身一变成了华尔街的火箭科学家，拿起华尔街水平的薪水。

（待续）

To be fair, finance theorists didn’t accept the efficient-market hypothesis merely because it was elegant, convenient and lucrative. They also produced a great deal of statistical evidence, which at first seemed strongly supportive. But this evidence was of an oddly limited form. Finance economists rarely asked the seemingly obvious (though not easily answered) question of whether asset prices made sense given real-world fundamentals like earnings. Instead, they asked only whether asset prices made sense given other asset prices. Larry Summers, now the top economic adviser in the Obama administration, once mocked finance professors with a parable about “ketchup economists” who “have shown that two-quart bottles of ketchup invariably sell for exactly twice as much as one-quart bottles of ketchup,” and conclude from this that the ketchup market is perfectly efficient.

公平地说，金融理论家接受有效市场假说并非仅仅因为它既优雅、方便，又可生财进宝。他们也提出过许许多多的统计证据，起初似乎都强烈支持该假说。但是，这 样的证据都带有一个奇怪的有限形式。金融经济学家很少提问看似明显（实却难答）的问题：给定现实世界的基本面比如说收益，某资产价格是否合理。相反，他们只提问这样的问题： 给定其他资产价格，某资产价格是否合理。萨默斯，现为奥巴马政府头号经济顾问，曾经用一个“番茄酱经济学家”的比喻， 嘲讽过金融学教授。这位番茄酱经济学家“证明了两夸脱瓶装的番茄酱所卖之价刚好两倍于一夸脱瓶装的番茄酱”，因此得出结论说，番茄酱市场是完全有效市场。

But neither this mockery nor more polite critiques from economists like Robert Shiller of Yale had much effect. Finance theorists continued to believe that their models were essentially right, and so did many people making real-world decisions. Not least among these was Alan Greenspan, who was then the Fed chairman and a long-time supporter of financial deregulation whose rejection of calls to rein in subprime lending or address the ever-inflating housing bubble rested in large part on the belief that modern financial economics had everything under control. There was a telling moment in 2005, at a conference held to honor Greenspan’s tenure at the Fed. One brave attendee, Raghuram Rajan (of the University of Chicago, surprisingly), presented a paper warning that the financial system was taking on potentially dangerous levels of risk. He was mocked by almost all present — including, by the way, Larry Summers, who dismissed his warnings as “misguided.”

不过， 无论是这种嘲弄，还是耶鲁大学经济学家席勒比较客气的批评， 都没起什么大作用。金融理论家继续相信，他们的模型基本上是正确的，许多进行现实世界决策的人士也这样相信。其中一个很重要的人就是格林斯潘，时任美联储主席， 也是对放松金融管制的长期支持者。他之所以拒而不闻人们要求控制次贷的呼声以及要求回应日益膨胀的房地产泡沫的呼声，有很大一部分是因为他相信现代金融经济学已可掌控一切。 2005年，在一个为表彰格林斯潘在美联储的长期任职而举行的会议上， 有一个令人难忘的时刻。一位勇敢的与会者拉詹（出身芝加哥大学，令人惊诧），提出了一篇论文警告说，金融体系当时所持风险水平已经具有潜在危险。他被在场几乎所有的人嘲讽——包 括， 顺便说一下，萨默斯，他也将这个警告当作是“被误导”而拒绝考虑。



By October of last year, however, Greenspan was admitting that he was in a state of “shocked disbelief,” because “the whole intellectual edifice” had “collapsed.” Since this collapse of the intellectual edifice was also a collapse of real-world markets, the result was a severe recession — the worst, by many measures, since the Great Depression. What should policy makers do? Unfortunately, macroeconomics, which should have been providing clear guidance about how to address the slumping economy, was in its own state of disarray.

不过， 到了去年10月，格林斯潘承认说，他处于“极度震惊难以置信”的状态，因为“整个智理大厦”已经“崩溃。由于这个智理大厦的崩溃也是真实世界里市场的崩 溃，其结果就是严重的经济衰退——这是自从大萧条以来，以多种方法测定，最最严重的一次。政策制定者应该怎么做？遗憾的是，宏观经济学，本应提供明确的指导，以回应经济下滑，其本身却陷入混乱状态。

（完）　

谢谢楼主！！！

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