经济增长模型中的公共资本

PUBLIC CAPITAL IN GROWTH MODELS

关于公共资本与经济增长关系的理论研究在近二十年来取得了长足进步。本文提供了一个一般性分析框架,将公共资本与经济增长领域的众多研究成果统一在该框架中进行了系统梳理,从而清晰呈现了其理论发展脉络。首先,本文在基本模型中探究了该领域内学者普遍关心的核心问题,这些问题包括增长率最大化与社会福利最大化公共投资规则以及最优与均衡转移路径等。然后,通过逐个放宽基本模型的假设,本文考察了主要结论在扩展模型中是否依然成立。具体而言,本文分别在公共资本具有拥挤性而非纯公共产品性质,公共资本折旧率内生决定而非外生给定,公共投资同时以流量与存量形式而非仅以存量形式影响私人生产以及存在多级政府而非仅一级政府的假设下,对模型结论进行了检验。本文探讨了这些更反映现实的假定对结论产生的不同影响,并进而指出该领域所面临的挑战与未来可能的发展方向。

The theoretical literature on the link between public capital and economic growth has boomed in recent years.By providing a general framework this paper unifies the work of the various econo-mistsin this area to show how the theory develops.First in a basic model it explores the fundamental ques-tions that the researchers mostly care about,including the growth-and welfare-maximizing fiscal rules and the optimal and equilibrium transition paths.Then in extended models it relaxes the assumptions of the basic model,one by one,to see if the core results still hold.That is,we test the results when public cap-ital is congested rather than non-rival,its deprecation is endogenous rather than exogenous,both the flow and the stock of public investment rather than the stock alone affect private production,and public invest-ment is carried out by two levels of governments rather than only one.Finally after presenting a compari-son of the results for the various assumptions,this paper further discusses several challenges to the theory development and then proposes three possible directions for future research.