【英语社会】不要被“萌芽”论误导

Those with short memories have forgotten that “green shoots” became notorious in the UK when Norman Lamont, then British chancellor of the exchequer, proclaimed the beginning of the end of the 1990-92 recession. Lord Lamont later argued that he was not all that wrong in the light of subsequent statistics. We need not enter this historical debate. The point is that his political opponents and many in the financial markets did not believe him and used “green shoots” as an ironic taunt. Yet the same people, or their successors, now talk about green shoots with a straight face, oblivious of historic connotations.

There are many reasons for not going to town on present talk. The clearest is the stock cycle which first magnifies and then damps the underlying output movement. Another is that much of the discussion emanates from the financial markets, especially equities and commodities. This is not to deny that stock market movements can initiate as well as signal changes in the wider economy. The problem is their inherent volatility. The US economist Paul Samuelson once remarked that Wall Street predicted eight of the last five recessions; the same might be said of recoveries.

World output cannot go on falling at turn-of-the-year rates without the international economy winding down. Jean-Claude Trichet, president of the European Central Bank, has said that output is now falling “at a decreasing rate”. It is highly likely that we will have before long a quarter or two of stable output – probably first in the US and last in the eurozone, with the UK in between. The interesting question is where we go from there.

The accompanying chart makes no predictions but illustrates some alternative scenarios, which have different policy implications. The steadily rising line shows an underlying growth trend normally taken to be somewhere between 2 and 3½ per cent a year in advanced industrial countries. It does not, of course, show what the economy is physically capable of, for example under the stress of wartime pressures. It shows rather what can be sustainably achieved under normal conditions. The curved line first falling below it and then rising above it is the kind of business cycle behind most official macroeconomic models. On this view booms and slumps are fluctuations around a given trend and any monetary or fiscal stimulus in the downturn must be reversed in the upturn, for example by a budget surplus or a monetary slowdown.

The point marked “green shoots” shows a resting place where we might soon be. The lower dotted line illustrates how we can lapse from there into a double dip recession. Even a treble dip one is possible, as for instance in the 1930s, when the US upswing following the New Deal was terminated by a premature monetary and fiscal tightening in 1937. Now, orthodox policymakers, such as those in Germany, may be relying too much on exports to rising emerging world markets to prevent it happening again. The middle dotted line is there just as a warning that continuing growth of any kind cannot be taken for granted and that external shocks or policy mistakes can induce long-term stagnation.

The most interesting of the lines is the top dotted one, which I have labelled, perhaps tendentiously, “growth recession”. It takes seriously the conclusion of Christopher Dow, the late British economist, that “major recessions” lead not merely to a downward dip in output below trend but to a downward displacement in the trend itself. The UK Treasury in its 2009 Budget has assumed, with many cautions and qualifications, a one-off downward displacement in the level of trend gross domestic product of 5 per cent of GDP, after which growth can resume at a trend rate of about 2¾ per cent a year. Everything depends, however, on the reasons for this downward shift. The Treasury cites factors such as a reduction in the capital to output ratio as a result of higher risk premiums in capital markets, and the likely reduction in the size of the UK financial sector, which has shown above average productivity growth.

John Maynard Keynes suggested a different approach in his 1936 General Theory. He remarked: “I doubt if we have had any recent [peacetime] experience of a boom so strong that it led to full employment.” He saw a long-term state in which the propensity to save outran the propensity to invest, thus making full employment impossible without major policy changes. He never quite faced up to the challenge of making budget deficits respectable; but he envisaged a combination of backdoor measures to encourage public and private investment, plus fiscal redistribution to the less well off and permanently low interest rates to encourage consumption. This is the opposite of the belt-tightening measures called for by the economic bien pensants.

I am not arguing that Keynes's vision applies to the very long term, when we will have to cope with unfavourable demographic pressures. But it could apply for quite a few years. We should not rush too soon to base policy on an assumption that trend output has shifted downwards.

那些记性不好的人已经忘记，当时任英国财务大臣诺曼•拉蒙特(Norman Lamont)宣称1990年至1992年间的经济衰退显示出结束的征兆时，“萌芽”一词在英国变得声名狼藉。后来拉蒙特辩称，根据其后的统计数据，他错得也不是那么离谱。我们不必参与这场历史上的争论。关键是拉蒙特的政治对手以及金融市场中的许多人不相信他，并把“萌芽”当成了讽刺他的把柄。不过，同样是这些人（或他们的继任者），眼下却一本正经地谈论着“萌芽”，忘掉了这个词在历史上的含义。

我们不应太起劲地谈论复苏萌芽，这有着诸多原因。其中最明显的是起初放大、随后又抑制了潜在产出活动的库存周期。另一个原因在于，大多数有关萌芽的言论都来自于金融市场，尤其是股市和大宗商品市场。这不是否认股市变动可以造成并显示更广泛经济中的变化。问题在于它们内在的波动性。美国经济学家保罗•萨缪尔森(Paul Samuelson)曾经说过，在过去的5次衰退中，华尔街预言到了8次。此言或许同样适用于复苏。

如果全球经济没有放缓，全球产出就不可能一直以岁末年初时的速度下降。欧洲央行行长让-克劳德•特里谢(Jean-Claude Trichet)曾表示，目前产出下降正“逐渐减速”。很可能出现的情况是，用不了多久，我们将看到一两个季度产出稳定的情景——或许从美国开头，在欧元区收尾，英国则夹在中间。人们感兴趣的是：随后我们将走向何方？

文中的图表没有给出预测，但列举了一些其他情景，它们可能具有不同的政策意味。稳定上升线显示的是一种潜在增长趋势，在发达工业国家，增长率通常为每年2%至3.5%。当然，它并没有显示经济实际的增长潜力——比如在战时压力的紧迫状况下，而只是在正常情况下可持续实现的增长。那条曲线先是降至稳定上升线之下，随后又上升至其上，它就是大多数官方宏观经济模型背后的那种商业周期。从这种观点看，繁荣和衰退就是围绕着一种给定趋势的波动，同时，低迷时期的任何货币或财政刺激，都必须在上升时期予以逆转——比如说通过预算盈余或货币供应减速等手段。

标着“萌芽”的那个点代表着整理平台，我们或许很快就会到达那里。下面的虚线表明，我们可能怎么背离那里，陷入双底型衰退。甚至还有可能出现“三底”衰退，上世纪30年代就是个例子，当时在罗斯福新政(New Deal)后出现的经济复苏，由于1937年过早实施的货币和财政紧缩措施而夭折。目前，正统的政策制定者——如德国的领导人——或许过于依赖向不断增长的新兴市场的出口，以避免上述情景重演。中间的那条虚线只是一种警告：即对任何形式的持续增长都不能想当然，外部冲击或政策失误都可能导致长期的滞涨。

这些线条中最有趣的是上面的那条虚线，我将其标记为“增长型衰退”（这或许带有成见）。这种说法认真参考了已故英国经济学家克里斯托弗•道(Christopher Dow)的结论，即“大衰退”不仅仅会导致产出向下跌破趋势线，还会造成趋势线本身向下位移。英国财政部在2009年预算报告中假设——这种假设非常谨慎，并附有许多限制条件——国内生产总值(GDP)年增长5%的趋势线，出现一次性的向下位移，之后恢复一种年均2.75%左右的增长。不过，一切都取决于造成这种下行变化的原因。英国财政部提到的理由包括：资本市场风险溢价水平上升导致的资本/产出比下降，英国金融部门的规模可能缩减，该部门的生产率增长一直高于平均水平。

约翰•梅纳德•凯恩斯(John Maynard Keynes)在1936年发表的《通论》(General Theory)中，提出了一种不同的方法。他写道：“我怀疑，我们最近是否有过（和平时期的）强劲繁荣经历，其繁荣程度足以实现充分就业。”他发现了一种储蓄倾向超过投资倾向的长期情形，正因如此，如果没有重大政策变化，就不可能实现充分就业。他从未真正勇敢面对过让预算赤字受人尊重的挑战；但他构想了一套鼓励公共及私人投资的秘密举措，同时向穷人进行财政再分配，并长期施行低利率政策，以鼓励消费。这与经济正统派人士所呼吁的强制性节约措施背道而驰。

我并不是说凯恩斯的观点在很长时期内都适用，届时我们将不得不应对不利的人口压力。但它或许在多年内都适用。我们不应过于匆忙地将政策建立在趋势产出已向下位移的假设基础上。

译者/君悦