“长期停滞论”过时了？

A year ago, Lawrence Summers’ perceptive warnings about the possibility of secular stagnation in the world economy were dominating global markets. China, Japan and the Eurozone were in deflation, and the US was being dragged into the mess by the rising dollar. Global recession risks were elevated, and commodity prices continued to fall. Fixed investment had slumped. Productivity growth and demographic growth looked to be increasingly anemic everywhere.

一年前，劳伦斯•萨默斯(Lawrence Summers)有关世界经济可能陷入长期停滞的有洞察力的警告主导着全球市场。那时，中国、日本和欧元区都处于通缩状态，而美元升值把美国也拖入这个乱局。全球经济衰退风险升高了，大宗商品价格持续下跌。固定投资大幅减少。在全球各地，生产率增长和人口增长似乎越来越疲弱。

Estimates of the equilibrium real interest rate in many economies were being marked down. It seemed possible that the world economy would fall into a “Japanese trap”, in which nominal interest rates would be permanently stuck at the zero lower bound, and would therefore not be able to fall enough to stimulate economic activity.

许多经济体的均衡实际利率的预测值开始被调低。世界经济看来有可能陷入“日本陷阱”——名义利率将永远停留在底部为零的极低区间，因此没有进一步下调以刺激经济活动的空间。

Just when the sky seemed to be at its darkest, the outlook suddenly began to improve. Global reflation replaced secular stagnation as the theme that dominated investor psychology, especially after Donald Trump’s election in November. Why has secular stagnation lost its mass appeal, and has it disappeared forever? Was it all a case of crying wolf?

就在局势似乎最糟糕之际，前景突然开始改善。全球再通胀取代了长期停滞，成为主宰投资者心理的主题，特别是在去年11月唐纳德•特朗普(Donald Trump)胜选之后。为什么长期停滞失去了大众吸引力，它永远消失了吗?当初有关它的说法是“狼来了”故事重演吗?

Lawrence Summers has always made it clear that in his mind secular stagnation was a hypothesis, not a proven reality, especially in the US. He and others have argued that the combination of very low global GDP growth, alongside falling real interest rates, could be caused by two factors: (i) inadequate global demand, stemming from low business investment, high savings rates in Asia, wide disparity in income distribution and rising risk aversion; and (ii) inadequate global supply, stemming from falling productivity growth, and slowing growth in the labour force.

萨默斯始终明确表示，长期停滞只是他心里的一种假设，而非已被证明的现实，尤其是在美国。他和其他人辩称，全球GDP增长非常低，加上实际利率下降，这一组合可能是由两个因素造成的：(1)企业投资水平低、亚洲储蓄率高、收入分配不均严重和避险情绪升高导致的全球需求不足;以及(2)生产率增长减速和劳动力总数增长放缓带来的全球供应不足。

With fears of deflation on the increase until early in 2016, it seemed that the weakness in demand was the more powerful force, although there was plenty of evidence of slowing growth in supply as well. Since inadequate demand growth seemed to be the main problem, and since the efficacy of monetary stimulus was being widely questioned, those economists who believed in secular stagnation frequently argued that fiscal stimulus was needed to rectify the problem.

在2016年初之前，人们对通缩的担心日益加剧;有鉴于此，需求疲软似乎是更为强大的力量，尽管也有大量证据表明供应增长在放缓。由于需求增长乏力似乎是主要问题，由于货币刺激的效果受到广泛质疑，那些相信长期停滞的经济学家经常主张，需要财政刺激来纠正这个问题。

What has happened since to change the market’s level of concern about secular stagnation? The flow of incoming economic data has clearly changed a lot, as shown in our monthly update of the Fulcrum nowcast models, attached here.

后来发生的什么事情改变了市场对长期停滞的担忧?陆续发布的经济数据显然发生了很大变化，正如本文随附的每月更新的支点(Fulcrum)短时预测模型所显示的那样。

Global activity growth has rebounded sharply, and recession risks have plummeted. Growth in real output is now running at higher levels than anything seen since the temporary rebound from the financial crash in 2009/10. Importantly, recent data suggest that the growth rate of fixed investment is beginning to recover, which is a body blow to one of the central tenets of the secular stagnation school, though much of this may simply be due the end of the slump in the commodity sector.

全球活动增长已大幅反弹，经济衰退风险已直线下降。目前实际产出的增速高于自金融危机之后2009/10年短暂反弹以来的任何时候。重要的是，近期数据似乎表明，固定投资的增幅开始回升——这对“长期停滞论”的核心依据之一构成了沉重打击——尽管这一局面在很大程度上可能只是因为大宗商品行业低迷的结束。

This recovery in real activity has not yet led to any rebound in long run underlying growth, according to the models. There has been no improvement in the growth of the labour force, and little rise in labour productivity growth, in the advanced economies in the last year. It therefore seems reasonable to conclude that the vast majority of the rise in real output growth has been due to improving aggregate demand, not aggregate supply.

模型预测显示，实际经济活动的复苏还没有带来长期潜在增长率的任何反弹。去年，在发达经济体中，劳动力增长并未出现起色，生产率也几乎未见上升。因此，我们似乎有理由得出这样的结论：实际产出增长的加快在很大程度上来源于总需求(而非总供给)的改善。

The conclusion that global data have improved because of demand factors is also supported by the rise in inflation expectations that has occurred in all the main economies in the past 12 months. The increases in US and UK inflation expectations are not surprising, since both of these economies are operating very close to full employment. But the increases in Japan and the Eurozone are more impressive. These were the two economies that seemed to be completely stuck in secular stagnation due to excess capacity a year ago. Now, they seem to be escaping.

有关全球数据的改善缘于需求因素的结论，还得到过去12个月所有主要经济体通胀预期上升的支持。美国和英国通胀预期上升并不奇怪，因为这两个经济体目前都非常接近充分就业，但日本和欧元区的通胀预期上扬更令人印象深刻。这两个经济体一年前还貌似因产能过剩而深陷长期停滞，而现在它们似乎在摆脱停滞。

Up to a point, these escapes seem to be due to the success of macro-economic policies that were aimed to correct secular stagnation. The Fed postponed its plan to raise interest rates, so US short rates are about 75 basis points below the levels threatened a year ago. The Bank of Japan introduced a 10 basis points ceiling on 10 year government bond yields, an initiative that has appeared more successful than some of its earlier efforts to stimulate the economy. The ECB maintained and extended its programme of quantitative easing, and this has succeeded in normalising monetary conditions throughout the euro area.

在某种程度上，摆脱停滞似乎应该归因于旨在纠正长期停滞的宏观经济政策取得成功。美联储(Fed)推迟了加息计划，所以美国短期利率比一年前威胁要达到的水平低了约75个基点。日本央行(Bank of Japan)对10年期政府债券收益率提出10个基点的上限，这一举措似乎比该行早前一些经济刺激措施更加成功。欧洲央行(ECB)维持并延长了量化宽松计划，此举成功地让整个欧元区的货币状况正常化。

On fiscal policy, the changes were not huge, but they were definitely in the direction of expansion. According to the IMF, the stance of fiscal policy in the advanced economies in 2016 was 0.7 percent of GDP more stimulatory than planned a year ago. Furthermore, the election of Donald Trump greatly increased expectations of future easing in US fiscal policy, boosting business and household optimism about growth prospects.

财政政策方面的变化并不巨大，但肯定是向着扩张的方向改变。据国际货币基金组织(IMF)估算，2016年发达经济体的财政政策姿态比一年前规划的水平更具刺激效果，两者之差相当于GDP的0.7%。此外，唐纳德•特朗普当选大大增加了人们对于未来美国放宽财政政策的预期，促进了企业和家庭对增长前景的乐观情绪。

All this suggests that stimulatory macro-economic policy may finally be working and that the secular stagnation scare might now be over. But that is probably too optimistic. Although there has been a cyclical improvement in demand in the advanced economies, there is no reason yet to believe that the supply side of the global economy is performing any better than it was a year ago. The secular speed limit on growth in the advanced economies is still much lower than it was in earlier decades. This speed limit has yet to be seriously tested but that may happen soon in the US and the UK.

所有这些都似乎表明，刺激性的宏观经济政策可能终于起了作用，长期停滞恐慌现在或许已经结束。但这么想很可能太乐观了。虽然发达经济体的需求出现周期性改善，但没有理由认为全球经济供给侧的表现比一年前有任何提高。发达经济体增长速度的长期限制仍远低于几十年前。这一速度限制尚未经过严格测试，但可能很快就会在美国和英国经受测试。

In any case, the recent spurt in growth in the advanced economies may turn out to be another false dawn, rather than the achievement of “escape velocity”. Even if escape velocity is achieved, and proves sustainable, it would need to prove that it can be maintained in the face of the policy tightening that would surely follow.

无论如何，发达经济体近期的快速增长可能是又一个虚假的黎明，而不是达到了“逃逸速度”。即使达到了逃逸速度，而且被证明是可持续的，也还需要证明在面对肯定会接踵而来的政策收紧时，可以维持这一速度。

Last week, the President of the San Fancisco Fed, John Williams, released a paper on the decline in the equilibrium real interest rate in the US (r*), the concept that has been at the heart of the secular stagnation debate. This paper concluded that low r-star is a global phenomenon, is likely to be very persistent, and is not confined only to safe assets.

上周，旧金山联邦储备银行(San Francisco Fed)行长约翰•威廉斯(John Williams)就美国均衡实际利率下降发表了论文，这个概念处于长期停滞辩论的核心。这篇文章的结论是，均衡实际利率较低是一个全球现象，可能会非常持久，而且不仅限于安全资产。

In other words, a cyclical recovery in demand, especially if confined mainly to the US, is unlikely to banish the problem of secular stagnation for very long.

换句话说，需求的周期性复苏(特别是如果主要限于美国)，不太可能长久地消除长期停滞问题。

Gavyn Davies is a macroeconomist who is now chairman of Fulcrum Asset Management and co-founder of Prisma Capital Partners. He was the head of the global economics department at Goldman Sachs from 1987-2001, and was chairman of the BBC from 2001-2004.

加文•戴维斯(Gavyn Davies)是一位宏观经济学家，现任支点资产管理公司(Fulcrum Asset Management)董事长，他还是Prisma Capital Partners联合创始人。他于1987年至2001年在高盛(Goldman Sachs)全球经济部门担任负责人，2001年至2004年在英国广播公司(BBC)担任董事长。