自由匯率制度的政策效果與隔絕功能

MACROECONOMIC POLICIES AND INSULATION PROPERTIES UNDER THE FREE EXCHANGE RATE SYSTEM

本文將Chen（1973）自由匯率制度（即允許居民持有外幣的浮動匯率制度）的兩國模型簡約為小國的分析架構，藉此研究總體政策（包括財政政策和貨幣政策）及國外干擾對小型開放經濟產出與實質匯率的影響，並據以探討自由匯率制度的貨幣自主性、隔絕功能及其與通貨替代的關係。我們的分析發現：通貨替代程度、國外通貨膨脹率的大小、以及國外通貨需求的成本彈性等模型的結構參數，是影響本國政策效果、貨幣自主性與隔絕功能的判定因素。當國外通貨膨脹率恰為某一定值（從而貿易條件的變化對經常帳沒有影響），或兩種通貨獨立無關，則無論兩種通貨的替代彈性是大或小，本國皆具有貨幣自主性；在其他情況下，自由匯率制度下貨幣政策效果的大小，要看兩種通貨究竟是毛替代或毛補充而定，並非如Miles（1978）所謂：單憑通貨替代彈性的高低即可決定貨幣自主性的強弱。

This paper reduces Chen’s (1973) two-country, two-money model to the conventional small-economy with currency substitution model to investigate the effects of macroeconomic policies and foreign inflation under the free exchange rate system (i.e., flexible exchange rates without restrictions on holding outer currencies). It has been shown that the relative magnitude among the currency substitution elasticity, the cost (interest) elasticity of holding currency, the foreign monetary growth rate, and trade elasticities determine critically the steady-state values and dynamic properties of real exchange rates. Given other relevant parameters, the relative value of the currency substitution elasticity to the currency cost (interest) elasticity rather than the absolute value of the currency substitution elasticity, in turn, is crucial in influencing the monetary independence and the insulation effect of the free exchange rate system. The results differ significantly from Miles’s (1978) argument that “the degree to which inflation will be transmitted between the countries will of course be proportional to the degree of substitution between currencies.”