本文从三个和尚没水喝的故事为切入点,挖掘了故事背后蕴藏的公共物品、外部性及产权界定等耐人寻味的问题。公共物品的非竞争性和非排他性,使得它成为了滋生“不劳而获”心理的土壤。于是,在公共物品提供的便利下,越来越多的人在扮演着或是努力去扮演“搭便车者”的角色,他们在没有付费的情况下却享受了服务,也即,享受到了别人带来的正外部性。当然,经济中还存在着负的外部性,即一个人在追求自己利益的同时,损害了他人的利益。然而,不论是正的还是负的外部性,都会使资源配置效率受损,难以实现帕累托优化配置。尽管通过产权界定等手段,可以规范外部性,是外部成本内在化,从而克服市场失灵的缺陷,实现资源的优化配置。但不容忽视的是,产权界定过程中还会产生诸如交易成本,谈判双方信息不对称,难以达成协议等问题。这种种原因,都产生了市场缺陷无力克服的无奈,寻求社会福利最大化的道路,还有一个很艰辛的过程。 This article starts with the story of three monks who did not drink plenty of water and excavated the thought-provoking question of public goods hidden behind the story, externalities and property rights. The noncompetitive and non-excludable nature of public goods makes it a fertile ground for “nothing”. As a result, more and more people are playing or trying to play the role of “free-rider” with the convenience of providing public goods. They enjoy the service without paying, that is, enjoying To the positive externalities brought by others. Of course, there is still a negative external economy in the economy, that is, a person in the pursuit of his own interests, while undermining the interests of others. However, whether positive or negative externality, will make resource allocation efficiency is impaired, it is difficult to achieve Pareto optimal configuration. Although through the definition of property rights and other means, we can regulate the externalities, internalize the external costs, so as to overcome the shortcomings of the market failure and realize the optimal allocation of resources. However, it should not be overlooked that issues such as transaction costs, asymmetric information between the two negotiators, and difficulties in reaching agreements will also arise in the process of property right definition. All these kinds of reasons have given rise to the helplessness of market imperfections and the pursuit of the maximization of social welfare. There is also a very difficult process.