I cannot recall a moment when the gap between what markets expect the US Federal Reserve to do and what the Fed itself has forecast it will do has been as large. Markets predict that the Fed will raise rates only to 1.6 per cent by the end of 2017; the Federal Open Market Committee’s average forecast is 3.5 per cent.
我想不起曾有哪一个时刻，市场预期美联储会做的事跟美联储自己预计要做的事差异如此巨大。市场预计美联储到2017年底会将利率提高到1.6%，而联邦公开市场委员会(FOMC)的平均预计值为3.5%。
Such a divergence raises the risk of volatility and poses a communications challenge for the Fed. More important, it raises the question of what should guide future policy.
这种认知差异会带来市场波动风险，也让美联储在向市场传递信息方面遇到挑战。更重要的是，它引发了应以什么来指导未来政策的问题。

Especially after Friday’s very strong employment report, there can be no doubt that cyclical conditions are normalising. The unemployment rate now is at its postwar average level, and continues to fall. Job openings are above their historic average. Other indicators such as the insured unemployment rate suggest a normal or rapidly normalising economy. All of this taken in isolation would suggest that interest rates should not remain at zero much longer.
特别是最近强劲的就业报告出炉之后，周期性状况正在恢复正常这一点已不再有疑问。眼下失业率处于战后平均水平，并在继续下降。职位空缺数量超过历史平均值。参保失业率(IUR)等其他指标显示，经济已回归正轨、或正迅速回归正轨。只从这些来看，说明零利率不应维持太长时间了。
On the other hand, the available inflation data suggests little cause for concern. The core consumer price index has averaged 1.1 per cent over the past six months; if housing costs were stripped out it would be zero. Wages actually fell in December and over the past year employment costs have risen 2.25 per cent which, in conjunction with productivity growth of only 1 per cent, suggests inflation of below 2 per cent. Perhaps most troubling: market indications suggest inflation is more likely to fall than rise .
另一方面，现有通胀数据表明没有什么可担心的。核心消费价格指数(CPI)过去6个月的均值为1.1%，如果剔除住房成本，则核心CPI为0。去年12月工资实际上下跌了；过去一年的雇佣成本上涨了2.25%，而生产率仅增长了1%，这意味着通胀率不到2%。最令人不安的或许是：各项市场指标显示通胀率降低的可能性大于升高的可能性。
The Fed has rightly made clear that its decisions will be data dependent. The further key point is that it should allow the flow of information on inflation rather than on real economic activity to determine its timing in adjusting interest rates. And it should not raise rates until there is clear evidence that inflation, and inflation expectations, are in danger of exceeding its 2 per cent target. Here are four important reasons why.
美联储明确表示有关调息的决定将取决于数据，这是对的。更关键的一点是，它应根据有关通胀、而不是实体经济活动的数据决定何时调息，并且不应在有明确证据显示通胀、以及通胀预期有可能超过2%目标值之前升息。这么说有四个重要理由：
First, real wages for most workers have been stagnant. Median family incomes are down by 4.5 per cent over the past five years and the economy is about $1.5tn — or $20,000 for the average family of four — below pre-recession estimates of its 2015 potential.
首先，大多数劳动者的实际工资一直停滞不前。过去5年家庭收入中值下降了4.5%，目前的经济规模比衰退前预测的2015年潜在经济规模低出约1.5万亿美元，相当于每个家庭（按平均每家4口人计算）低于预测值2万美元。
In such circumstances efforts to reduce demand and growth require a compelling justification. Yet the idea that below normal unemployment will necessarily lead to accelerating inflation as suggested by the so called Phillips curve is very uncertain. Contrary to such predictions, inflation did not decelerate by much even a few years ago when unemployment was in the range of 10 per cent. Nor was there much evidence of accelerating inflation in the 1990s when the unemployment rate fell below 4 per cent.
在这种情况下，若要采取降低需求和抑制增长的措施，需有充分理由。然而，所谓的菲利普斯曲线(Phillips curve)所描绘的情形——低于通常水平的失业率肯定会导致通胀加速上升——存在极大不确定性。与菲利普斯曲线预测的情形相反，就在几年前，当失业率达到10%水平的时候，通胀也并没有降多少，而上世纪90年代，失业率降至4%以下时，也没有多少证据显示通胀升高。
Second, if inflation were to accelerate a bit this would be a good thing. It is now running and is expected to run below the Fed target. Prices are about 4 per cent below where they would have been if 2 per cent inflation had been maintained since 2007. So there is a case for some inflation above 2 per cent to catch up to the Fed’s price level target path. They may also be a case for inflation a little bit above 2 per cent for the next few years to allow real interest rates low enough to promote recovery when the next recession comes.
其次，假如通胀真的略有升高，那是件好事。眼下通胀率低于美联储目标值，并且预计未来将继续低于目标值。假如通胀自2007年至今一直维持2%，那么物价水平将比现在高4%左右。因此，让通胀升至略高于2%是有理由的，这样可以让物价水平追赶美联储的目标物价水平。考虑到目前的物价水平低于目标水平，让通胀在未来几年维持在略高于2%还能够让实际利率变得足够低，以便在下一次衰退到来时为推动复苏提供空间。
Third, a plane that accelerates too rapidly as it takes off may cause passengers discomfort while a plane that accelerates too slowly may crash at the end of the runway. Historical experience is that inflation accelerates only slowly so the costs of an overshoot on inflation are small and reversible with standard tightening policies. In contrast, aborting recovery and risking a further slowing of inflation is potentially catastrophic — as Japan’s experience demonstrates. So in a world where economic forecasts are highly uncertain, prudence in avoiding the largest risks counsels in favour of Fed restraint in raising rates.
第三，飞机起飞时加速太快会让乘客感到不适，但起飞太慢，飞机可能会坠毁在跑道上。历史经验显示，通胀升高速度并不快，因此通胀超标的成本很小，并且可通过实施常规紧缩政策来补救。相反，让复苏中断、冒让通胀进一步放缓的风险却可能造成灾难性后果——如日本的经验所示。因此，在这个经济预测高度不确定的世界里，出于避免最大风险的审慎考虑，美联储应谨慎对待升息。
Fourth, the US has never been more intertwined with the global economy. Higher interest rates and the stronger dollar they would bring would mean greater debt burdens for debtor countries, a growing US trade deficit that damages manufacturing, and growing protectionist pressures.
第四，美国与全球经济的联系从未像现在这样紧密。更高的利率、以及高息带来的更强势美元，意味着债务国的债务负担将变得更重，美国贸易赤字会增加（不利于制造业），贸易保护主义压力也会增强。
There is already a danger given all the problems in Europe, Japan and emerging markets that safe haven flows will drive the dollar up to the point where the US economy could be significantly slowed. Raising rates without evidence of rising inflation could dramatically increase real rates and exacerbate these risks.
鉴于欧洲、日本和新兴市场的种种问题，目前已经存在这样的风险：因资金流入避险货币，导致美元币值升高到可能使美国经济显著放缓的地步。在没有证据显示通胀升高的情况下升息，可能使实际利率大幅上升，加剧上述风险。
None of this is to say that rates should never be raised or that inflation indicators might not justify a rate increase before long. It is to say that the Fed could inject much needed confidence in the economy today and minimise future risks by announcing and following a strategy of not raising rates until it sees the whites of inflation’s eyes.
这些并不意味着我们应无限期推迟升息，也不意味着通胀指标不可能在短期内变得支持升息，而只是说，通过宣布和遵循这样一种策略——“在没有看到通胀的确凿证据之前不升息”，美联储可使人们对经济重拾信心（这是当前非常需要的），并最大程度地减小未来的风险。
The writer is Charles W Eliot university professor at Harvard and a former US Treasury secretary
本文作者为哈佛大学(Harvard)查尔斯•W•艾略特大学教授(Charles W Eliot University Professor)，曾任美国财政部长