A Theory of International Currencies and its Microfoundation

在这个项目中，我们构建了一个国际货币模型。更具体地说，它提出了一种两国模式，两种货币相互竞争。存在一种均衡，即两种通货膨胀率不同的货币作为交换媒介流通，尽管没有一种货币被强制用于交易。政策游戏也在考虑之列，即两国政府同时控制并承诺税率，甚至通胀率。除其他因素外，将通胀率设定在名义利率为零水平的弗里德曼规则并不会因为货币竞争而发生。此外，它还表明，货币疲软的国家可能会因为向外国敞开大门而变得更糟。这与贸易理论的一个主要发现相反，即贸易通常会提高国家的福利。在这个项目的实施过程中，研究者对货币流通作为一种规范的方面越来越感兴趣。一种货币之所以流通，是因为接受它的人认为它以后会被其他人接受。人们接受金钱是因为其他人做同样的事情，这一事实是社会规范的特征。与社会规范有关的问题非常广泛，不可能在几年内完成。但是，我希望，如果我们更好地理解货币作为社会规范的问题，就能对国际货币问题有一个新的认识。

In this project, a model of international currencies is constructed. More specifically, it presents a two-country model in which two currencies compete with each other. There exists an equilibrium in which the two currencies with different rate of inflation circulate as media of exchange despite that neither currency is forced to be used for transaction. Policy games, in which the two governments simultaneously control and commit to tax rates and, possibly inflation rates, are also considered. Among other things, the Friedman rule of setting inflation rate at the level of zero nominal interest rate does not occur because of currency competition. Also, it is shown that the country with weak currency may be worse off by opening its door to a foreign country. This is contrary to one of major findings in trade theory that trade usually improves the welfare of the country.In carrying out this project, the researcher became more and more interested in the aspect of currency circulation as a norm. A currency is circulated since people who accept it think it will be accepted by someone else later on. This fact that people accept money because other do the same thing is the very feature of social norms. Issues related to social norms are very broad, and it cannot be done within a few years. However, I hope that a new light will be shed on the issue of international currencies if we understand better about currencies as social norms.