曼昆经济学 Chap_10.ppt

Externalities Chapter 10 LEARNING OBJECTIVES: By the end of this chapter, students should understand: what an externality is. why externalities can make market outcomes inefficient. how people can sometimes solve the problem of externalities on their own. why private solutions to externalities sometimes do not work. the various government policies aimed at solving the problem of externalities. Market Efficiency - Market Failures Recall that: Adam Smith’s “invisible hand” of the marketplace leads self-interested buyers and sellers in a market to maximize the total benefit that society can derive from a market. Market Failures: Externalities When a market outcome affects parties other than the buyers and sellers in the market, side-effects are created called externalities. Externalities cause markets to be inefficient, and thus fail to maximize total surplus. An externality arises... . . . when a person engages in an activity that influences the well-being of a bystander and yet neither pays nor receives any compensation for that effect. Market Failures: Externalities When the impact on the bystander is adverse, the externality is called a negative externality. When the impact on the bystander is beneficial, the externality is called a positive externality. Examples of Negative Externalities Automobile exhaust Cigarette smoking Barking dogs (loud pets) Loud stereos in an apartment building Examples of Positive Externalities Immunizations Restored historic buildings Research into new technologies The Market for Aluminum... The Market for Aluminum and Welfare Economics The quantity produced and consumed in the market equilibrium is efficient in the sense that it maximizes the sum of producer and consumer surplus. The Market for Aluminum and Welfare Economics If the aluminum factories emit pollution (a negative externality), then the cost to society of producing aluminum is larger than the cost to aluminum producers. The Market for Aluminum and Welfare Economics Fo