(b) Pollution Permits
Price of Pollution Supply of pollution permits
P
Demand for pollution rights 0 2. . . . which, together with the demand curve, determines the price of pollution. Q Quantity of Pollution 1. Pollution permits set the quantity of pollution . . .
• 科斯定理 Coase Theorem：只要所有权是明 确的，而且交易成本 Transaction costs为零 ，则不管所有权的最初配置状态如何，都可 以达到资源的有效配置。
• 交易成本 Transaction costs： 各方在协议与遵 守协议过程中所发生的成本； • 科斯定理下的最优配置并非是唯一的，而是根 据初始产权不同可以相异。
• 污染许可证的交易
• 例如：假设两个造纸厂每天各排出污物3吨，甲厂消除 第一、第二吨污物的边际成本分别为3000元、4000元， 而在乙厂，这些边际成本是5000元、6000元。
Copyright © 2004 South-Western
Figure 4 The Equivalence of Pigovian Taxes and Pollution Permits
Copyright © 2004 South-Western
Copyright © 2004 South-Western
负的外部性
• • • • 吸烟 夜半歌声 小区养狗的问题 汽车（交通拥挤、因此车祸、污染环境）
Copyright © 2004 South-Western
正的外部性
• • • • 教育 免疫针 技术创新 历史建筑的修复
Copyright © 2004 South-Western
(a) Pigovian Tax
Price of Pollution
Hale Waihona Puke P 1. A Pigovian tax sets the price of pollution . . . 0 Q 2. . . . which, together with the demand curve, determines the quantity of pollution.
Figure 2 Pollution and the Social Optimum
Price of Aluminum
Social cost
Cost of pollution
Supply (private cost)
Optimum
Equilibrium
Demand (private value) 0 QOPTIMUM QMARKET Quantity of Aluminum
4
公共部门经济学
外部性
10
Copyright©2004 South-Western
外部性与市场失灵
• 市场失灵的原因
• 外部性 • 垄断 • 不完全信息
Copyright © 2004 South-Western
外部性与市场无效率
• 外部性 externality ：一个人的行为对其他人 产生影响，但并不因此而承担损失或收益。
Copyright © 2004 South-Western
科斯定理的讨论
• 养狗的问题 • 校车应如何走高架
Copyright © 2004 South-Western
解决外部性的公共政策
• 管制——限定污染量 • 庇古税 Pigovian taxes 和补贴
• 用市场的方式分配污染权 • 提供了降低污染的激励
Copyright © 2004 South-Western
Figure 3 Education and the Social Optimum
Price of Education
Supply (private cost)
Demand (private value)
0 QMARKET
Social value
QOPTIMUM
Quantity of Education
Copyright © 2004 South-Western
外部性的私人解决办法
• • • • 道德规范和社会约束 慈善事业 外部性行为的内部化 市场交易——谈判和协议
Copyright © 2004 South-Western
科斯定理 ——市场行为解决外部性的有效性
Figure 1 The Market for Aluminum
Price of Aluminum
Supply (private cost)
Equilibrium
Demand (private value)
0
QMARKET
Quantity of Aluminum
Copyright © 2004 South-Western
Pigovian tax
Demand for pollution rights Quantity of Pollution
Copyright © 2004 South-Western
Figure 4 The Equivalence of Pigovian Taxes and Pollution Permits