作者 尼尔•弗格森 2013年1月25日 The Financial Times.jpg)
在经济学中没有哪个问题像汇率这样易于受到政治上错误表述的影响。近日的事实正是对这一观点的又一个完美证明。
上周二，由于日本新任首相安倍晋三(Shinzo Abe)的压力，日本央行(BoJ)投票决定将通胀目标从1%上调到2%，并要“尽早”达成这一目标。为此，日本央行将在一年后开始每个月购买数额为13万亿日元（合1400亿美元）以短期国债为主的资产。
日本这一举措引发了一轮警告，称有可能会立即导致“货币战争”
。率先发难的是俄罗斯央行第一副主席阿列克谢•乌卢卡耶夫(Alexei Ulyukayev)，紧随其后的是德国央行(Bundesbank)行长延斯•魏德曼(Jens Weidmann)和韩国财政部长朴宰完(Bahk Jae-wan)。魏德曼暗指日本央行的举动是一次“惊人的违规行为”，代表着“央行独立性的终结”。对此日本人迅速做出回应。日本经济财政大臣甘利明(Akira Amari)回击说：“德国是出口受益于欧元区固定汇率制度最多的国家，他没资格做出这种批评。”
当然在达沃斯(Davos)众人并没因为这事大打出手——这也不太可能发生，不过还是让我们从历史的角度来探讨一下这件事。先考虑如下四个事实。
首先，回到上世纪30年代，很明显谁发动了货币战争。在大萧条(the Depression)之前，多数国家都实行金本位，也就是货币与黄金的兑换率固定。1931年9月英国脱离金本位时引发了一波竞争性贬值的热潮。正如经济学家巴里•埃森格林(Barry Eichengreen)指出的那样，脱离金本位是从大萧条走向复苏的第一个必要步骤。英镑采取浮动汇率不仅令英国出口商品更廉价，更重要的是它使得英国央行(BoE)能够采取关注国内需求的货币政策。
然而，如今我们生活在法定货币时代，汇率多数是浮动的。1971年8月份，当理查德•尼克松(Richard Nixon)终止美元与黄金的自由兑换之时，金本位的最后遗迹也被扫除干净。从这点来说，2013年一个国家指责另一个国家发动货币战争是荒谬的。实际上这场战争已经进行了逾40年，它是所有人对所有人的战争（ it is a war of all against all）。
其次，我们应思考日本的形势有多么严峻。这个国家自上世纪80年代末以来一直处于近乎停滞的状态。以日元计的日本名义国内生产总值(GDP)仍然与20年前的水平差不多。日本的公共债务处于极高的、难以为继的水平。日本的人口状况是世界上最糟的。因此，别再为难他们了。
第三，日本央行的措施根本算不上革命性。日本央行行长白川方明(Masaaki Shirakawa)2013年没有提出新的资产购买计划，2014年的资产购买计划净影响也将有限，因为计划购买的大部分资产都将是即将到期的短期债券。2014年资产购买净增额将仅为10万亿日元，相当于日本GDP的2%左右。
比较一下美联储(Fed)的政策。自金融危机开始以来，美联储的政策一直比日本央行的极端。上上周，美联储的资产负债表规模首次超过了3万亿美元。如果美联储在2013年剩余的时间里继续以每个月850亿美元的速度购买资产，它的长期资产将进一步增加1万亿美元，相当于美国GDP的6%至7%。这还只是今年的数字，不包括明年的。
第四点（也是最重要的一点），政客和公众往往关注名义汇率短期变动，这可能制造很大响动，但却没有多少效果。诚然，日元对美元的名义汇率自去年9月以来显著走弱。那时，1美元仅能兑换77日元。如今，1美元可兑换90多日元。但回想上世纪90年代初，1美元还可兑换158日元，另外除1995年一段短暂的时期之外，1美元只能兑换不到90日元的日子自2010年中期才开始，那么如今日元这17%的贬值似乎也没什么大不了的。
无论如何，单单一种货币的名义汇率实际上并不十分重要。国际清算银行(BIS)编制的各种实际汇率要重要得多，这些汇率的编制考虑了与一国进行贸易的所有不同经济体，尤其关键的是，还考虑了相对价格的变化。
考虑这些因素，日本的情形就迥然不同了。自上世纪90年代以来，通缩效应已经使日元的实际有效汇率走弱。从1994年至2007年年中，日元实际有效汇率下跌幅度超过三分之一。但随着全球金融危机的爆发，日本不得不把之前所获的竞争力优势部分拱手让出。从2007年8月至2011年10月，日元实际有效汇率累计升幅27%。日本近来的政策只是部分逆转了这一趋势。
根据国际清算银行的数据，韩国和英国一直是过去5年半时间里动作最大的货币斗士（自2007年8月以来，韩元和英镑分别实际贬值了19%和17%）。因此，韩国人成为了上周的虚伪奖得主。至于英国人，难怪乎英国首相戴维•卡梅伦(David Cameron)把欧洲货币联盟的危机视为一个巨大的政治机会。有些聪明的保守党成员反对英国加入欧元区，卡梅伦正是其中之一。此外，正因为英国央行一直实施宽松货币政策，才缓解了卡梅伦政府实施紧缩政策的痛苦。
过去的两周里，卡梅伦收获了许多称号，唯独没有“货币斗士”。但他入住唐宁街10号以来所推行政策的部分内容就是悄悄地让英镑贬值。英国央行行长默文•金爵士(Sir Mervyn King)向来乐于助人。他的继任者马克•卡尼(Mark Carney)更是如此。
天真的评论人士认为，卡梅伦承诺在下一次大选之后举行是否退出欧盟的全民公决，是一种鲁莽的举动。其实，这不但具有政治意义，也有经济意义，因为它是英镑悄悄贬值策略的一部分。我要给日本提个醒：汇率战的胜利属于采取秘密行动的人。
本文作者是哈佛大学(Harvard)劳伦斯•A•蒂什(Laurence A. Tisch)历史学教授，著有《大退化》(The Great Degeneration)。
Few issues in economics are more susceptible to political misrepresentation than exchange rates. The past few days have provided another perfect illustration of this point.
On Tuesday, in response to pressure from Shinzo Abe, the country’s new prime minister, the Bank of Japan voted to increase its inflation target from 1 per cent to 2 per cent and to hit that target “at the earliest possible date”. To that end, starting a year from now, the BoJ will buy Y13tn ($140bn) of mostly short-term government debt each month.
The Japanese move triggered a flurry of warnings of an imminent “currency war”. Alexei Ulyukayev, first deputy chairman of Russia’s central bank, led the charge, closely followed by Jens Weidmann, Bundesbank president, and Bahk Jae-wan, South Korea’s finance minister.
Mr Weidmann referred darkly to “alarming infringements” and an “end to central bank autonomy”. The Japanese were not slow to respond. “Germany is the country whose exports have benefited most from the euro area’s fixed exchange rate system,” shot back Akira Amari, the country’s economy minister. “He’s not in a position to criticise.”
Before the beer glasses start flying in Davos (fat chance), let’s put this in historical perspective. Consider four things.
Back in the 1930s, it was obvious who was waging a currency war. Before the Depression, most countries had been on the gold standard, which had fixed exchange rates in terms of the yellow metal. When Britain abandoned gold in September 1931, it unleashed a wave of competitive devaluations. As economist Barry Eichengreen argues, going off gold was the essential first step towards recovery in the Depression. Floating the pound not only cheapened British exports; more importantly, it allowed the Bank of England to pursue a monetary policy focused on domestic needs. Lower interest rates helped generate recovery via the housing market.
Today, however, we live in a world of fiat money and mostly floating rates. The last vestige of the gold standard was swept away in August 1971, when Richard Nixon suspended the convertibility of the dollar into gold. For one country to accuse another of waging a currency war in 2013 is therefore absurd. The war has been going on for more than 40 years and it is a war of all against all.
Secondly, we should reflect on just how dire things are in Japan. The country has been in a near stationary state since the end of the 1980s. Nominal gross domestic product in yen terms is about where it was 20 years ago. Its public debt is unsustainably large. Japan’s demographics are the world’s worst. So give them a break.
Thirdly, the BoJ’s move is hardly revolutionary. Governor Masaaki Shirakawa offered no new asset purchases in 2013 and the net impact of the purchases promised for 2014 will be limited since most of the money will be used to buy short-term debt close to maturity. The net increase in asset purchases for 2014 will be only Y10tn, equivalent to about 2 per cent of GDP.
Compare that with the policy of the US Federal Reserve, which has consistently been more aggressive than its Japanese counterpart since the beginning of the financial crisis. Last week the Fed’s balance sheet exceeded $3tn for the first time ever. If the Fed keeps buying assets at the current pace of $85bn a month for the rest of 2013, it will accumulate another trillion in long-term assets: between 6 and 7 per cent of GDP. And that’s this year, not next.
Fourthly, and most importantly, the tendency of politicians and the public to focus on short-term movements in nominal exchange rates generates much more heat than light. True, Japan’s nominal rate in terms of the dollar has weakened markedly since September. Back then, a dollar was worth just Y77. Today it’s above Y90. But that 17 per cent depreciation looks less impressive when you remember that the dollar was worth Y158 back in early 1990 and apart from a brief period in 1995 it has traded below Y90 only since the summer of 2010.
In any case, it’s not a single nominal exchange rate that really matters. The Bank for International Settlements calculates far more meaningful real effective exchange rates, which take into account all the different economies with which a country trades and, crucially, changes in relative prices.
Put in these terms, Japan’s story looks very different. Since the early 1990s, the effects of deflation have weakened the real effective exchange rate. Between 1994 and the summer of 2007, this rate declined by more than a third. But with the onset of the global financial crisis, Japan had to give back some of its gains in competitiveness. Between August 2007 and October 2011 the real effective exchange rate strengthened by 27 per cent. Recent Japanese policy has only partly reversed that.
On the basis of the Bis data, the most aggressive currency warriors of the past 5½ years have been South Korea (a 19 per cent real effective depreciation since August 2007) and the UK (minus 17 per cent). So the Koreans win this week’s prize for hypocrisy. As for the Brits, small wonder Prime Minister David Cameron regards the crisis of the European Monetary Union as a huge political opportunity. He was one of those wise Conservatives who opposed British membership of the euro. And it has been the BoE’s easy monetary policy that has eased the pain of his government’s austerity.
Mr Cameron has been called many things in the past week but not “currency warrior”. Yet part of the plan since he entered Number 10 has been discreetly to weaken the pound. Sir Mervyn King, BoE governor, has been obliging. Mark Carney, his successor, will be even more so.
Naive commentators have portrayed Mr Cameron’s promise of an “in-out” referendum on EU membership after the next general election as reckless. But it not only makes political sense. It also makes economic sense as part of a covert devaluation strategy. Memo to Tokyo: victory in currency wars goes to the stealthy.
The writer is Laurence A. Tisch professor of history at Harvard and author of ‘The Great Degeneration’
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