◎ 聂 丹

　　在当今主要工业化国家的货币间汇率实行浮动的国际货币体系下，许多发展中国家、新兴工业化国家和地区及小型开放的发达国家仍倾向于将其货币钉住在某种主要工业化国家的货币上：有些国家通过特殊的制度安排――货币局安排、双边、多边汇率协议即货币联盟保证其钉住汇率制是"不可调整"的，有些宣称其汇率制度是管理浮动的国家或者在某一时期对于其汇率水平有明确的承诺（如人民币不贬值），或者事实上保持其汇率水平的稳定，当然这些汇率水平并不一定能保证长期固定不变，因此这些汇率安排都被作者视为可调整的钉住，包括如港元汇率这样的"不可调整"的汇率安排，事实上市场参与者也认为它存在着调整的可能性，只不过其调整的政治成本较大而已，否则就不会出现1998年的投机冲击。当今世界唯有单一货币如欧元最接近但也并非不可调整的钉住，因为欧元也并没有消除成员国退出即调整汇率的可能性，只不过是这样作的政治成本更加增大了而已。
　　为什么钉住汇率制这样有市场？因为它的实现汇率稳定从而促进贸易与投资的微观经济收益对于对上这几类国家确实很有吸引力，但为什么持久的钉住汇率这样少见？――自20世纪80年代以来， 国际社会已发生了1982年拉美债务危机、1994年墨西哥金融危机、1992年欧洲汇率机制危机、1997年东南亚金融危机及1998年巴西金融危机――因为一方面钉住汇率安排也有成本－－在一定的条件下妨碍了决策者更为看重的其他政策目标如产出、价格稳定、改善贸易收支以减少外债负担等的实现，使得决策者为实现这些目标而调整钉住汇率，这是主动型的货币危机；另一方面，在资本自由流动的情况下，钉住汇率的维持是市场参与者与政府（货币当局）对于本币的供求平衡的结果，如果市场参与者对本币的供给即对外汇的需求超过政府对外汇的供给能力即外汇储备，则钉住汇率就将崩溃，而市场参与者对外汇的需求主要来源于其基于对本、外币资产的收益率的比较而调整其资产组合的行为，这种收益率的比较首先取决于对本币汇率的预期――人们不相信有哪个钉住汇率如政府所承诺的那样是"不可调整"的，因而对汇率的预期亦非静态的――如果预期钉住汇率将贬值，就将发动投机冲击，使政府或者因外汇储备的耗尽而被迫放弃、令本币浮动，或提高利率以补偿本币资产预期收益率的降低、从而危害到实质经济的产出稳定，而产出稳定也许是政府更为看重的目标，因此钉住汇率将被放弃，这是投机者的贬值预期"自促成"的货币危机。
　　本论文在肯定钉住汇率对于以上这几类国家的微观经济收益的前提下探讨如何管理这种折衷的汇率制度――在哪些情况下"钉住"比"调整"的收益更大从而应维持钉住？在哪些情况下应调整初始的钉住汇率水平，实行一个新的、更
加贬值或升值了的钉住汇率，或退出钉住汇率制度而转向浮动？当需要维持时，应对宏观经济施加怎样的约束？或者说宏观经济的供给与需求发生怎样的变化时钉住汇率将难以为继（具体内容参见下面的内容概要）？既然有许多国家尚无条件实行浮动汇率、仍希望借助于钉住汇率实现汇率的稳定，因此，研究钉住汇率的管理――钉住与调整就是有实用价值和理论意义的，这就是本论文选题的意义。
本论文的创新之处在于：
　　第一、系统地研究了钉住汇率的问题，而此前国内经济学界对钉住汇率的系统性研究为数甚少（至少作者在大量检阅文献时尚未发现研究钉住汇率的中、英文专著）；
　　第二、吸收了1990年以后国际货币经济学新出现的带有实证色彩的中长期实际汇率的决定理论，从宏观经济内外平衡的角度探讨了工业化和长期经济增长过程中钉住汇率的维持与调整的问题，将标准的宏观经济分析与经济增长理论结合起来，这就增强了汇率理论对于现实问题如拉美、东亚的货币与金融危机（货币危机在本论文中被处理成钉住汇率的被迫调整）的解释力。这一点对于发展中国家尤其实用，因为发展中国家包括所谓的新兴工业化国家（地区）或新兴市场国家（地区）的潜在总供给即充分就业时的产出水平是不断变化的，而在标准的宏观经济学分析只是在假定潜在总供给不变的前提下分析由总需求的波动而引起的经济周期波动，显然，单单用标准的宏观经济分析难以解释成功的工业化中钉住汇率的稳定与不成功的工业化中钉住汇率的不稳定；
　　第三、为了分析的方便，作者区分了宏观经济的平衡与均衡，创立了与宏观经济平衡相对应的"自然实际汇率"的概念，并对IMF经济学家斯旺于1963年提出的、后来常被用于分析宏观经济内外平衡问题的一个图表――作者称之为斯旺图表加以改造，区分了供给曲线与需求曲线，这样，本论文的几乎所有结论都可被用这张图表表现出来，因而取得了分析方法上的统一性。
　　下面简要总结一下钉住汇率在什么情况下会被维持或调整。
　　一、经济扩张期
　　钉住汇率的崩溃来自国内的原因总是国产品的供给持续地小于需求――或者是需求持续地超过供给即正的需求冲击，或者是供给能力下降即负的供给冲击。前者包括：1、政府在经济已充分就业的情况下为了刺激经济而实行赤字财政政策，导致经常帐户恶化，引起克鲁格曼（Krugman）1979年模型式的政府在外汇储备枯竭后被迫放弃钉住汇率的国际收支危机的情形；2、经常帐户恶化表明外债增加，有凯恩斯主义倾向的政府可能会主动贬值希望以此来实现实际贬值，但如果价格呈粘性，则在充分就业条件下，名义贬值的效果终将为通货膨胀所侵蚀；3、在惯性通货膨胀环境中私人部门居高不下的通货膨胀预期将迫使政府进行贬值，这是商品市场上的"自促成"的贬值；4、政府在治理惯性通胀时要让私人部门相信其反通胀的决心，可引入一种钉住汇率，将其作为反通胀的货币政策的"名义锚"。后者包括：1、在负的供给冲击下的举债消费使得经常帐户恶化，当外资不再流入时钉住汇率就难以为继，这就是1982年拉美债务危机的情形；2、银行的存在使得负的供给冲击首先表现为银行呆坏账的上升，银行通常不愿用其资本金冲减，而是举借外债以保证向存款人支付，当银行即将破产时，政府通常会履行最后贷款人职能，而这将造成财政赤字，并通过克鲁格曼式的投机冲击的方式危胁到钉住汇率的稳定；3、发展中国家在引进外资实现工业化的过程中将面临着初期外债增长、经常帐户恶化、实际汇率升值，如果投资项目最终不能产生出口创汇能力，一旦外资不再流入，该国将被迫偿还外债本息，就可能造成钉住汇率的贬值。
　　二、 经济收缩期
　　假定经济的初始状态是内外平衡或衰退而非经济过热，在以下一些情形中初始钉住汇率将受到危胁：1、锚币国家的利率水平提高将迫使本币利率也要提高才可以维持钉住汇率，而这将造成衰退，因此政府可能会主动贬值，如1992年欧洲汇率机制危机；2、锚币相对于其他主要工业化国家的货币升值将使本币的实际有效汇率升值；出口竞争国货币相对于本币贬值将通过出口品的需求交叉价格弹性的作用使本国的出口需求减少，这两种情形都可能使本币发生主动贬值或自促成的贬值，这就是1997年的人民币汇率情形；3、治理惯性通货膨胀时可能会出现滞胀局面――私人部门不肯调低其通胀预期，因而名义工资、产品价格即通胀率也降不下来，一个办法是使通胀预期下降到负值，这就是通货紧缩、萧条，显然其所付出的产出代价太大了；另一种方法即名义贬值、使实际汇率迅速贬值，这样可使产出结构发生转换――生产出口品比生产非贸易品更有利可图、从而使非贸易品部门因需求减少而失业的生产资源转移到出口品部门，达到充分就业，也可使支出结构发生转换――使本国居民和外国居民将支出更多地用在本国产品上从而改善经常帐户，使经济走出衰退；4、1997后人民币不贬值使其实际有效汇率升值，对出口造成的打击结合其他一些体制性因素共同构成了较严重的负的总需求冲击，甚至使经济陷入了"流动性陷阱"之中，解决此问题可用名义贬值的方法，它可使人民币实际有效汇率贬值，从而扩张总需求；5、不成功的工业化使钉住汇率下的实际汇率高估，如果引发货币危机，就会使本币过度贬值、资本外流、内需萎缩，此时既需保持"软货币"以利于出口增长，又需保持低利率以实行扩张性政策，在资本自由流动的情况下这是不可得兼的，只有实行资本管制，才可缓解衰退，这可谓正统经济学所反对的"异端"调整计划，马来西亚在1998年曾用过此方法。

　

◎ Dan NIE

　　Under the current floating exchange rate system, many developing countries、emerging markets、small developed countries still intend to peg their currencies : some of them use currency board arrangement or multiple exchange-rate arrangements －that is , monetary union to insure their exchange-rate pegs being 'unadjustable', some of them declare their exchange-rate is managed floating, but promise their exchange-rate being fixed during certain period(for example, the' not-devalued' RMB exchange-rate)，or have kept their exchange-rates being fixed actually. Of course , there have not being a long lived、not being adjusted peg in history, so that all the declared 'un-adjustable 'pegs are actually adjustable in the author's opinion－including the'un-adjustable'Hong Kong dollar's exchange-rate, what different is their adjusting will induce more political costs.
　　Why the pegs are so popular? Because they can keep the exchange-rates fixed so as to promote international trades and investments, this is the micro-economic benefit that pegged exchange-rate regime produces, which is desirable to those countries. But why long-lived pegs are so rare? －from the 80' s of the last century, there happed so many currency crises in the world, for example ,the 80's Latin American debt crises、the 1992 European Monetary System crisis、the 1994 Mexico's crisis、the 1997 Asian crisis and the 1998 Brazil crisis－Because on one hand, the peg has cost－it obstructs the government or the currency authority to fulfil some more important policy goals , for example, to promote the national yield、to keep the price stable、to improve the current account and to decrease the foreign debt, etc., so that the government will adjust the original peg on his own initiative; on the other hand, under the incomplete capital movement(like China), the peg's maintaining and adjusting depends on the supply and demand of the foreign exchange between the market participants and the government, if the demand surpasses the supple, then the peg will collapse. The demand of the foreign exchanges depends on the market participants're-arrangement of their portfolio according to the expected earnings between the foreign assets and the local assets, which depends on the expected local currency's exchange-rate－people never believe the government's promise on the exchange-rate, that is , the expectation is not static－if they anticipate the pegged exchange-rate will devalue, then they will attack the local currency, and the government will have to give up the original peg when they used up their foreign exchange reserves , or the government will make the interest rate rises to defend the peg, and this will hurt the real economy, so that the government will give up the original peg, this is the'self-fulfilling'currency crisis.
　　This paper discussed how to manage the eclectic regime－under what circumstance pegging will induce more benefit compared to adjusting? Under what circumstance the original peg should be adjusted to a new peg, or the country should exit from the adjustable exchange-rate regime and shift to the managed floating regime? when adjustment is needed, what restraints the macro-economy should bear？or what kind of change of the supple and demand in the macro-economy can damage the peg?
　　What is new in the dissertation is as following:
　　It analyzed the pegged exchange rates systematically for the first time, and this sort of systematic research on the subject is rare before (at least the author did not find one when searching for the reference materials ) .
　　It absorbed the determination theory for the real exchange rates of the medium and long term emerged in international monetary economics after 1990 to analyze the peg's adjusting and maintaining during the industrialization and long-term economic development while combining standard macro-economic analysis with economic development theory , so enhanced exchange rate theory's explaining power to several problems such as the Latin-American and the East-Asia's financial crises(financial crisis was regarded as the compelled adjustment of the peg).This is especially useful to developing countries, for potential aggregate supply in these countries(including so-called emerging markets) are varying , but the standard macro-economic analysis simply suppose that the potential aggregate supply remains unchanged, in this circumstance it analyzes the economic fluctuant caused by that of the aggregate demand, apparently, it is difficult to explain the peg's stability in successful industrialization and it's instability in unsuccessful industrialization with standard macro-economic method alone .
　　3.The author distinguished the balance of the macro-economy and it's equilibrium, and employed the IMF economist --Swan's diagram(He developed it in 1963 and thereafter it is used to analyze the inner-and-outside equilibrium problem frequently ), almost all the conclusions in the dissertation can be described in the diagram, so gives the dissertation consensus for it's analysis method.

　　The following is a summary of under what circumstances the peg could be maintained or be adjusted.
1、During the economic expansion period
The collapse of a peg is always because the supply of domestic goods is short than their demand persistently--this can be a positive demand attack which means the demand is long than supply, or a adverse supply attack which means the supply is decreasing. The former consists of the following circumstances:
The government creates fiscal deficits to stimulate the economy under full-employment , so brings the deterioration of the current account, and leads to balances of payments crisis when the government is forced to abandon the peg because its foreign exchange is depleted, and this is what the Paul Krugman 1979 model says;.
　　b. The deterioration of current account means the increase of foreign debt, the Kenneyse 's like government may devalue its currency , expecting this would make the real exchange rate devalue, but if the prices are sticky, the effect of nominal devaluation will be eroded by inflation under full-employment.
Under the chronic inflation circumstance, the high level of inflation expectation in the private agents may force the government to devalue, and this is the self-fulfilling devaluation in the goods market.
The government want the private agents to believe its resolution to fight the inflation, so it can introduce a peg as a nominal anchor for the anti-inflation.
　　The latter consists of the following circumstances:
　　Consumption via borrowing from abroad under adverse supply attack will make the current account worsen, when foreign capital has no longer moved in , the peg will not sustain., this is what happened in the Latin American debt crisis in 1982.
　　The existence of banks make adverse supply attack appear to be bad loans increasing , the banks, however, usually are reluctant to write them off by their capital, instead , they borrow from abroad to pay the depositors, when the banks go bankruptcy, the government usually will act as the lender of last resort, and this will end up with fiscal deficit, and throw threat to the peg through Paul Krugman's model's speculation attack.
　　When developing countries undertake industrilization via foreign capital, the foreign debt increase , the current account turn to bad, the real exchange rate appreciate initially, if the projects invested cannot earn foreign exchange through export in the end , once the foreign capital no longer move in , the m country will have to pay the capital and interest for foreigners, and this could make the local currency depreciate.
　　2. During the economic contraction period
　　Suppose the economy is equilibrium in its inside and outside sectors, or is in recession, not overheating, under the following circumstances the peg will be treatened.
The interest rate in the anchor -currency country rise and make the pegged country to rise its interest rate in order to maintain the peg, but this will cause recession, so the government may devalue, just like what happened in the European Currency Mechanism crisis in 1992.
　　The anchor currency appreciate relative to the other major industry countries will make the local currency's real effective exchange rate appreciate, besides this, the currencies of the export competitors depreciate relative to the local currency will decrease the local exports through the cross-demand price elasticity , both these circumstances may make the local currency depreciate , just like the RMB 's case in China in 1997.
　　Stagflation may appear when curing the chronic inflation--the private agents are reluctant to decrease their expected inflation rate, so the nominal wages and products price cannot decrease likewise. One method is to make the expected inflation rate to decrease to below zero, in fact this is deflation and recession, apparently, its production cost is too big. Another way is nominal depreciation to make the real depreciation, this can shift the production structure -- make the local residents and the foreign ones to spend more on home products so that improve the current account condition, and to make the economy throw away the recession.
　　That the RMB did not depreciate after 1997 make its real effective exchange rate appreciate, its adverse effect on exports combined with other institutional factors became a severe aggregate demand attack, and it even make the economy to fall in a ' liquidity trap '. The resolution is nominal devaluation, it can make RMB's real effective exchange rate depreciate, so as to stimulate the aggregate demand .
　　Unsuccessful industrilization make the real exchange rate overvalued under the initial peg, if it causes currency crisis, it will make the local currency overdepreciate, the capital will move out of the country, the inner demand will deminish. At this time it is necessary to maintain the soft currency to stimulate the export, and to maintain the low interest rate to conduct expansive policy, but with the capital move freely, it is impossible to achieve both, only the use of capital control can resolve recession, and this is what the main economics call 'heretical plan ', and it has been used in 1998 in Malaysia.

　　作者简介：聂丹，1970年生，女，华东师范大学2000届博士研究生，师从潘英丽教授，主要从事国际金融汇率研究。现在华东师范大学金融学系工作。

（责任编辑：王苏娜）