【英语财经】应鼓励经济学家打赌 A good economic bet

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2014-6-26 06:26

小艾摘要: Two economists disagree about the state of the economy. That’s not terribly surprising; you can insert your own joke here. Refreshingly, they’ve decided to put money on the table: instead of spoutin ...
A good economic bet
Two economists disagree about the state of the economy. That’s not terribly surprising; you can insert your own joke here. Refreshingly, they’ve decided to put money on the table: instead of spouting hot air, they have made a bet. Bravo. More public intellectuals should follow suit.

Jonathan Portes is director of a UK think-tank, the National Institute for Economic and Social Research. Andrew Lilico runs Europe Economics, a consulting firm. Portes thinks that there’s plenty of spare capacity in the British economy, and that even as economic growth picks up, inflation will remain modest. Lilico disagrees. The men have staked £1,000 – inflation-adjusted, naturally.

The bet says (roughly) that once economic growth tops 2 per cent in the UK, inflation will exceed 5 per cent within 18 months. Economic growth has indeed picked up, so the bet is on and the clock is ticking. By October 2015 we should have a winner.

There is a long-running debate about whether this sort of wager is to be welcomed. Alex Tabarrok, an economics professor at George Mason University, is all in favour. “A bet is a tax on bull****,” he wrote after statistical journalist Nate Silver offered a wager on the results of the 2012 presidential election, with profits to go to charity. The New York Times public editor, Margaret Sullivan, disagreed. Silver was writing for the newspaper back then, and Sullivan declared it was “inappropriate” for journalists to be publicly wagering that their opinions were well founded.

Who’s right? Sullivan’s main argument against Silver’s wager was that it created the “appearance” of a conflict of interest. Albeit indirectly, Silver stood to profit from a victory for the Democratic Party, if only by avoiding having to make a charitable donation. Suddenly he was no longer disinterested. This is a shallow foundation for the case against public wagers.

And there are strong counter-arguments. Pundits who make wagers may look grubby but at least they are accepting a cost for failure. A more subtle advantage is that betting encourages forecasts that are specific and quantifiable.

This matters, because too many forecasts are both vague and consequence-free. A pundit can shoot his mouth off about what will happen in the future and nobody much cares. If the forecast should happen to come true, the pundit can revisit his words and claim to have predicted the financial crisis, the fall of the Berlin Wall or whatever. What’s more, many forecasts are hazy enough, especially on timing, to make them impossible to falsify.

Making a wager helps correct both these problems. A forecast that is specific enough to bet on is also specific enough to come true, or to fail. And for any wager, there is at least one person with an incentive to keep track of what happened.

The most famous bet about economics is that between Paul Ehrlich, ecologist, doomsayer and author of the massive 1968 bestseller The Population Bomb, and Julian Simon, an economist most famous because he persuaded Ehrlich to bet with him. Ehrlich believed that overpopulation would cause disaster and widespread scarcity. Billions would die, developed countries would disintegrate, India was beyond saving. Simon thought that people would find substitutes for scarce resources and that things would be fine.

The bet, however, needed to revolve around something specific. It was that the price of five metals would rise between 1980 and 1990 as scarcity continued to bite. Instead prices fell, dramatically. Ehrlich lost the bet. In some ways, this story shows the value of the wager. Because the bet was specific, we now know that Ehrlich was wrong and Simon, who died in 1998, was right.

Yet the tale of the Ehrlich-Simon bet is not entirely reassuring. The very fact that the bet was so specific means that long after Simon won, the argument continues to rage about whose worldview was truly correct. I have never met an environmentalist who was convinced by Simon’s victory that technology will save the world. And I have encountered many conservatives who seem to believe that because Paul Ehrlich was wrong about the price of metals in the 1980s, all environmentalists are wrong about everything.

Paul Sabin, a historian who wrote a book about the bet, argues that the affair brought more heat than light. He reports that Ehrlich took his loss with poor grace, sending Simon a cheque with no cover note. And Ehrlich seems unrepentant. In a recent interview with NPR’s Planet Money show, he said of the late Simon, “It’s hard to be more wrong… he knew absolutely nothing about anything important.”

This pigheadedness is disheartening but unsurprising. Perhaps the wager pushed each side into stubborn tribalism and encouraged a reductive view of complex affairs.

Yet on balance, the world needs more wagers between pundits. The alternative is intolerable: a world full of confident forecasts that nobody ever bothers to verify. The betting man must be thoughtful and specific or his wallet will suffer the consequences. We should all be quicker to ask ourselves before we open our mouths: would I be willing to bet on this?

Tim Harford’s new book, “The Undercover Economist Strikes Back”, is out in paperback on July 3


乔纳森?波特斯(Jonathan Portes)是英国智库机构国家经济社会研究院(National Institute for Economic and Social Research, NIESR)的院长。安德鲁?里利可(Andrew Lilico)则是咨询公司Europe Economics的负责人。波特斯认为,英国经济具备足够规模的闲置产能,即便经济增长提速,通货膨胀也仍将维持较为温和的水平。里利可则持相反观点。两人打赌的赌注是1000英镑——这自然是经过通胀调整之后的金额。


关于这类赌博是否应当得到鼓励,存在持续多时的争议。乔治梅森大学(George Mason University)的经济学教授亚历克斯?塔巴罗克(Alex Tabarrok)对此举双手赞成。此前统计新闻记者纳特?西尔弗(Nate Silver)就2012年美国总统选举的结果公开打赌,并计划把所有打赌收益捐献给慈善组织。塔巴罗克写道:“打赌相当于是对吹牛征税”。《纽约时报》(New York Times)公共事务编辑玛格丽塔?沙利文(Margaret Sullivan)不赞同打赌的做法。西尔弗当时是《纽约时报》的撰稿人。沙利文声称,记者公开打赌保证自己的观点具有充分依据,这种做法是“不合适”的。





经济学领域最著名的赌局发生在保罗?埃利希(Paul Ehrlich)和朱利安?西蒙(Julian Simon)之间。前者是是生态学家、末世预言者以及1968年超级畅销书《人口爆炸》(The Population Bomb)的作者。后者是一位经济学家,出名主要是因为他说服了埃利希跟自己打赌。埃利希认为,人口过多将导致灾难和大范围的物资紧缺。数十亿人可能死亡,发达国家或发生分裂,印度则将无药可救。西蒙则认为,人们能够找到稀缺资源的替代品,万事安好。



历史学家保罗?萨宾(Paul Sabin)曾就埃利希和西蒙打赌一事写了一本书。他指出,这一事件引发的争议比其所带来的启示更多。据他描述,埃利希面对自己的失败表现得很没风度,他给西蒙寄了一张没有附带面函(cover note)的支票。但埃利希对自己的观点似乎并不后悔。他在近期接受美国全国公共广播电台(NPR)的《金钱星球》(Planet Money)栏目采访时提到了已经去世的西蒙,并表示:“很难犯下比这更大的错误……他对任何重要的事物都一无所知。”



本文作者蒂姆?哈福德(Tim Harford)的新书《卧底经济学家反击战》(The Undercover Economist Strikes Back)将于7月3日发行平装本。


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