Overlapping generations: the first jubilee
Overlapping generations: the first jubilee
复制标题
世代重叠：第一个禧年
DOI：
10.1257/jep.22.4.115
复制
发表时间：
2008
期刊：
影响因子：
--
通讯作者：
P. Weil
中科院分区：
文献类型：
--
作者：
P. Weil
保罗·萨缪尔森（1958）的世代重叠模型已经50岁了。很少有如此简单的模式如此有影响力。这份报纸尽管年代已久，但仍然令人惊叹。从毫无争议的观察“我们生活在一个新一代总是沿着而来的世界”出发，萨缪尔森建立了一个模型，这个模型违反了第一基本福利定理的信条，50年后我们仍然在向大学生灌输这一信条。根据萨缪尔森的观点，在最好的市场经济中，一切都不一定是好的：在世代重叠的情况下，即使没有扭曲和市场失灵等通常的怀疑，竞争性均衡也不一定是帕累托有效的。最糟糕的是，第一福利定理在世代重叠模型中的失败发生在一个框架中，在许多方面，这个框架比同步和有限存在的代理人世界更合理和现实，而这个定理通常是在这个框架中证明的。就像莫纳丽莎神秘的微笑一样，世代重叠模型的神秘福利属性在很大程度上是其流行的原因--沿着的还有它在过去半个世纪里阐明的许多经济问题。我把它作为我在这篇庆祝性论文中的简要介绍，在简短地阐述了确定性下的世代重叠模型的主要结果之后，解释了为什么世代重叠模型的福利性质与经典的阿罗-德布鲁框架有如此大的不同，并以一种故意非线性的方式回顾了萨缪尔森的欺骗性简单模型的一些引人注目的应用和扩展。
Paul Samuelson's (1958) overlapping generations model has turned 50. Seldom has so simple a model been so influential. The paper, in spite of its ripe age, still elicits wonder. Starting from the uncontroversial observation that "we live in a world where new generations are always coming along," Samuelson built a model that violates the credo of the first fundamental welfare theorem with which we still inculcate undergraduates 50 years later. According to Samuelson, all is not necessarily well in the best of market economies: with overlapping generations, even absent the usual suspects such as distortions and market failures, a competitive equilibrium need not be Pareto efficient. Worst of all, this failure of the first welfare theorem in an overlapping generations model occurs in a framework that is, in many ways, more plausible and realistic than the world of agents living synchronous and finite existences in which the theorem is usually proved. Like Mona Lisa's enigmatic smile, the mysterious welfare properties of the overlapping generations model are, to a significant extent, responsible for its popularity -- along with the many economic issues it has illuminated in the last half-century. I take it as my brief in this celebratory paper to provide, after a short exposition of the main results of the overlapping generations model under certainty, an explanation of why the welfare properties of the overlapping generations model differ so much from the canonical Arrow-Debreu framework and to review, in a deliberately nonencyclopedic mode, a few striking applications and extensions of Samuelson's deceptively straightforward model.