经济学人下载:六大经济学原理:新凯恩斯主义(2)

Inflation has behaved strangely over the past decade.
在过去的十年中，通胀表现得很陌生。

The recession that followed the financial crisis of 2007-08 sent American unemployment soaring to 10%.
2007-08年金融危机之后的衰退曾令美国的失业率升至10%。

But underlying inflation fell below 1% only briefly—nothing like the fall that models predicted.
但是，基础通胀仅短暂地跌到过1%以下——无一类似于模型预测的那种下跌。

Because the only way economists can estimate the natural rate is by watching how inflation and unemployment move in reality, they assumed that the natural rate had risen (an estimate in 2013 by Robert Gordon, of Northwestern University, put it at 6.5%).
由于经济学家能够估算自然比率的唯一方式就是观察通胀和失业如何现实中波动，因而，他们假定自然比率上升了(由西北大学的罗伯特·戈登在2013年提出的一种估算将其设定为6.5%)。

Yet as labour markets have tightened—unemployment was 4.3% in July—inflation has remained quiescent.
然而，尽管劳动力市场收紧了——失业率在今年4月为4.3%——通胀仍旧波澜不惊。

Estimates of the natural rate have been revised back down.
自然比率的估算又被调低了回来。

Such volatility in estimates of the natural rate limits its usefulness to policymakers.
自然比率估算的这种波动使得它对决策者的有用性大打折扣。

Some argue that the wrong data are being used, because the unemployment rate excludes those who have stopped looking for work.
有人指出，错误的数据正被使用中。因为失业率排除了那些停止寻找工作的人。

Others say that the short-term Phillips curve has flattened as inflation expectations have become ever more firmly anchored.
其他人认为，短期的菲利普斯曲线已经随着通胀预期变得愈发稳固地锚定不动而走平了。

The question is: how long will they remain so?
现在的问题是：它们会维持这样多久？

So long as low unemployment fails to generate enough inflation, central banks will face pressure to keep applying stimulus.
只要低失业率没能产生足够的通胀，央行就将面对保持运用刺激的压力。

Their officials worry that if inflation suddenly surges, they might lose their hard-won credibility and end up back in 1980, having to create a recession to get inflation back down again.
央行官员担心，如果通胀骤然飙升，他们可能失去来之不易的信誉，最后的结果是退回到1980年，不得不制造一次衰退以便让通胀再次回落。

This recent experience has led some to doubt the very existence of the natural rate of unemployment.
最近的经历让有些人对失业的自然比率的真实存在产生了怀疑。

But to reject the natural rate entirely, you would need to believe one of two things.
但是，要想彻底否定自然比率，就必需相信两件事中的一件。

Either central banks cannot influence the rate of unemployment even in the short term, or they can peg unemployment as low as they like—zero, even—without sparking inflation.
央行要么不能在短期内影响失业率，要么能够在不激起通胀的情况下，把失业率固定在与他们所喜欢的位置一样低——甚至是0——的位置。

Neither claim is credible.
这两种观点，没有一个是可信的。

The natural rate of unemployment surely exists.
失业的自然比率的确存在。

Whether it is knowable is another matter.
它是否可知另当别论。