外部性引起市场失灵的机理与条件分析

The mechanism and conditions of market failure caused by externality

外部性一直是经济学界争论的焦点,是经济学中最难琢磨的概念之一.本文通过刻画经济系统和区分消费外部性与生产外部性,然后引入外部影响函数,对外部性的内涵进行界定,对外部性引起市场失灵的作用机理和条件进行分析,取得了两个重要发现:非本质外部性和本质外部性.非本质外部性不影响市场效率,只有本质外部性才会通过影响消费偏好或生产技术来使市场失灵.这两个发现改善了庇古的断言:“如果经济中存在外部性,市场就要失灵”.根据这两个发现,本文进一步通过区分内部替代率和外部替代率,提出了矫正外部性影响的措施建议.

Externality is one of the most elusive concepts and has always been the focus of debate in economics.This paper is designed to analyze the mechanism and conditions for externality to make the market fail.We described accurately an economic system and defined the connotation of externality by designing external action functions.Through dividing externalities into two categories,consumption or production externality,the mechanism and conditions are excavated for externalities to cause market failure.On this basis we found that whether the externality causes market failure is depend on if it is intrinsic.An intrinsic externality will change consumer′s preference or producer′s technique.So the Pigou′s assertion is revised,which said that the market will fail if there is an externality in an economy.Furthermore,the external action can be rectified by making the internal and external rate of substitution equal.