曼昆-经济学原理 10
Summary of Chapter 10 – Externalities
关键词：
externality: 外部效应
social cost: 社会成本
Coase theorem: 科斯定理
The equilibrium of demand and supply fails to maximize the total benefit to society as a whole when there are negative externalities. In this case, governments can respond by trying to influence the behavior of buyers and sellers to protect the interests of bystanders.
Negative externalities lead markets to produce a larger quantity than is socially desirable. Positive externalities lead markets to produce a smaller quantity than is socially desirable. To remedy the problem, the government can internalize the externality by taxing goods that have negative externalities and subsidizing goods that have positive externalities.
Government action is not always needed to solve the problem of externalities. Sometimes the problem of externalities can be solved with moral codes and social sanctions. According to the Coase theorem, the private economic actors can solve the problem of externalities among themselves. Whatever the initial distribution of rights, the interested parties can always reach a bargin in which everyone is better off and the outcome is efficient.
When the private solutions do not work, the government can respond in one of two ways, which are command-and-control pollicies (eg. regulation )and market-based policies (eg. corrective taxes, subsidies and tradable pollution permits).