两种制度下公共资源长期耗用之比较

丁和张维迎对“公共地悲剧”的论述，是以参与耗用公共资源的人数不变为假定的。但是，有些资源即使在长期中也无法改变其公共资源的属性，这使得耗用这类资源的人数在长期中会发生变化。只要有超额利润，就会有更多的人参与耗用该资源；反之，则会有人退出。通过构建数学模型，探讨了长期中两种不同的制度安排（个体理性与集体理性）下，人们耗用这种无进入壁垒公共资源的均衡情况的差异。结果显示，集体理性可以使该资源的耗用速度减慢，但是会导致生产效率低下、社会福利减少；而个体理性下资源的消耗速度更快，但可以达到提高生产效率、增加社会福利的效果。进一步认为，解决资源短缺问题，制度只能是权宜之计，技术才是根本出路。

COMPARISON OF EXPLOITATION OF PUBLIC RESOURCES IN THE LONG RUN UNDER TWO DIFFERENTI NSTITUTIONS

Hardin and Zhang's arguments about the tragedy of the commons are based on the hypothesis that the number of the participants entering into the commons is fixed.But actually it may be variable in the long run because some resources are always public resources even in a long time.And more people will participate in exploiting these resources if there are extra profits,and vice versa.By building mathematic models,we discussed the different results under the following two different institutions,i.e.individual rationality(IR)and collective rationality(CR),in the long run about the exploitation of this kind of public resources without entrance barriers in this paper.The conclusions are that CR will lead to production inefficiency and less welfare while slowing down the exploiting speed and that IR will get an opposite result.This paper further argues that institutional measures can only be used as a makeshift in dealing with the problem of resource shortage and that the ultimate solution is technical measures.