10externalities.ppt

4 THE ECONOMICS OF THE PUBLIC SECTOR Copyright ? 2004 South-Western 警告:假设的作用 Warning: Assumptions ?为了得出市场有效率的结论,我们作出了一些关于市场如何运行的假设。 To conclude that markets are efficient, we made several assumptions about how markets work. ?当这些假设不成立的时候,关于市场均衡有效率的结论可能就不成立了。 When these assumptions do not hold, our conclusion that the market equilibrium is efficient may no longer be true. ?两个重要的假设 Two important assumptions ?市场是完全竞争的,即不存在市场势力。 Markets are petitive. (No Market power) ?市场结果只与买者和卖者相关,即无外部性。 The e in a market matters only to the buyers and sellers in that market. (No externalities) Copyright ? 2004 South-Western Copyright ? 2004 South-Western Copyright ? 2004 South-Western Copyright ? 2004 South-Western Copyright ? 2004 South-Western 灯泡的不同遭遇?夜晚大街上处处流光溢彩。可许多居民区的楼道内却黑咕隆咚,晚上都不敢下楼出门, 很多小区都存在这样的情况。?“黑楼道”为何难消除?怎么总没人来换灯泡呢? ?如果你家洗手间的灯泡坏了,你肯定会马上买新灯泡换上。?同样是灯泡,但楼道上的灯泡与你家洗手间的灯泡却有不同的遭遇。?为什么? Copyright ? 2004 South-Western 10 10 Externalities 外部性 Copyright ? 2004 South-Western 学****目的?外部性是什么? ?外部性为什么会使市场无效率? ?为什么有些时候私人无法解决外部性问题? ?解决外部性的政府政策有哪些? Copyright ? 2004 South-Western ? Recall: Adam Smith ’ s of the marketplace leads self-interested buyers and sellers in a market to maximize the total benefit that society can derive from a market. 回忆: 亚当斯密的市场的“看不见的手”能够引导在市场中追求自身利益最大化的买者和卖者,结果是整个社会的福利达到最大 But market failures can still happen.