Sovereign Debt and Political Economy

为什么主权国家要偿还债务？政治经济约束对国际金融市场有何影响？为什么国家会违约，它们应该在什么时候违约？这些都是国际金融中最基本和最重要的问题，影响着政策制定者、国际金融机构、超国家机构和整个国家。然而，经济学家对这些问题中的任何一个都没有令人信服的答案，因此无法分析改革对国际金融体系的福利影响等重要问题。目前的项目开发和测试了一种易于处理的主权债务偿还模式，该模式为其中几个问题提供了答案。该模型生成了一组新颖的经验预测，可用于福利分析。该项目的第一部分表明，在政治经济模型中产生超支的相同经济力量，可以保证一个小型开放经济体偿还其主权义务，即使在没有直接制裁的情况下也是如此。这个模型内生地产生了一个不平凡的借款上限，并将一国的债务能力与几个经验上相关的变量联系在一起，例如国内经济面临的冲击的大小、政党或地区的数量、国内代理人的贴现率和国际利率。该模型提供了几个与政治制度、国内机构和一个经济体的借款数量有关的新的经验预测。该项目生成了一组重复交互的代理节省的显式模型。因此，基本模式的适用范围超出了所关注的特殊情况：参与国际金融市场的国家的情况。例如，该模型可能有助于解释家庭储蓄行为、公共产品条款和资源提取问题，从而赋予其更广泛的影响。一旦模型求解，就可以生成比较静态的结果，并检验隐含的经验预测。最后，该模型可用于研究国际金融体系和某些与进入该体系相关的国内机构的变化对福利的影响。该项目旨在回答是什么让各国不会拖欠外债的问题。到目前为止，现代量化文献绕过了这个问题，并假设存在违约的外生成本。然而，这种外生成本的性质一直很难通过经验来识别和量化。通过将政治经济学考量引入到一个相当标准的模型中，该项目建立了一个丰富的模型，在该模型中，债务得到均衡偿还，违约后的特殊惩罚形式在所有违约中一直很普遍：违约国家被排除在再次借款之外。

Why do sovereign countries pay their debt? How do political-economy constraints affect international financial markets? Why do countries default and when should they? These are among the most basic and important questions in International Finance, affecting policy makers, international financial institutions, supra-national institutions and entire countries. However, economists do not have convincing answers to any of these questions, and hence important issues like the welfare effects of reforms to the international financial system cannot be analyzed. The current project develops and tests a tractable model of sovereign debt repayment that provides answers to several of these questions. The model generates a novel set of empirical predictions, and it can be used for welfare analysis. The first part of the project shows that the same economic forces that generate overspending in a political-economy model, can guarantee that a small open economy repays its sovereign obligations, even in the absence of direct sanctions. This model endogenously generates a non-trivial borrowing limit and ties the debt capacity of a country to several empirically relevant variables, such as the size of the shocks faced by the domestic economy, the number of political parties or regions, the discount rate of the domestic agents, and the international interest rate. The model provides several novel empirical predictions relating to the political system, domestic institutions and the amount of borrowing in an economy. The project generates an explicit model of savings by a group of agents that interact repeatedly. Hence, the applicability of the basic model extends beyond the particular case in focus: that of countries participating in the international financial market. For example, the model could be useful in explaining household savings behavior, public good provisions, and resource extraction problems, thereby giving it broader impacts.Once the model has been solved, comparative-static results can be generated and the implied empirical predictions tested. Finally, the model can be used to study the welfare effects of changes in the international financial system and in certain domestic institutions that are relevant for access to that system. This project aims to answer the questions of what keeps countries from defaulting on their external obligations. The modern quantitative literature has so far by-passed this question and assumed the existence of an exogenous cost of defaulting. However, the nature of this exogenous cost has been difficult to identify and quantify empirically. By introducing political economy considerations into a fairly standard model, this project develops a rich set up where debt is repaid in equilibrium and where the particular form of punishment after default is the one that has been prevalent among all defaults: countries when defaulting are excluded from borrowing again.