中级微观经济学——理论与应用（第10版）（经济学经典教材·双语教学用书） 教学课件 ppt 作者 尼克尔森等 著 0324319681_67680

1、Chapter 18, 2006 Thomson Learning/South-Western,Externalities and Public Goods,2,Defining Externalities,An externality is the effect of one partys economic activities on another party that is not taken into account by the price system. Externalities can occur between any two economic actors. Externalities can be beneficial or harmful.,3,Externalities between Firms,One of the most famous beneficial externalities between firms involves one firm producing honey and the other producing apples. Bees

2、feed on apple blossoms, which increases the production of honey, and Bees pollinate apple crops, which increases the production of apples.,4,Externalities,Firms can generate air, water, and other types of pollution when producing products. Alternatively, auto pollution, graffiti, and noise are some externalities imposed by people on firms. When people do things that harm others, like playing their radios loudly, or help, like shoveling their sidewalk, they can impose externalities on other peopl

3、e.,5,Reciprocal Nature of Externalities,In dealing with externalities it is important to recognize that both parties are needed for an externality to exist. If the eyeglass producer was not located near the charcoal factory, there would be no externality. If another person was not around, no one would be bothered when someone plays their radio loudly.,6,Externalities and Allocational Efficiency,The presence of externalities can cause a market to operate inefficiently. In the previous example an

4、externality affected the production of eyeglasses. The firm producing charcoal did not take into account the negative effect its production had on the production of eyeglasses.,7,Social Costs,Social costs are the costs of production that include both input costs and costs of the externalities that production may cause. In the previous example, by not recognizing the externality in its production, the charcoal firm produced too much. Society would be better-off by reallocating resources away from

5、 charcoal production and toward the production of other goods.,8,A Graphical Demonstration,Assume the charcoal producer is a price taker so that its demand curve is horizontal, as shown in Figure 18-1. The firm maximizes profits, given the prevailing market price, by producing q* where price(P*) equals marginal cost(MC). Due to the externality, however, the social marginal cost (MCS) exceeds MC.,9,MCS,MC,E,P*,Charcoal per week,0,q*,Price, costs of charcoal,FIGURE 18-1: An Externality in Charcoal

6、 Production Causes an Inefficient Allocation of Resources,10,A Graphical Demonstration,The cost of the externality is shown by the vertical distance between MSC and MC. At q* the social marginal cost exceeds what people are willing to pay for the charcoal, P*. Resources are misallocated and production should be reduced to q where MSC equals P*. The reduced total social costs (area ABq*q) exceed the reduced total spending (area AEq*q).,11,MCS,MC,E,B,A,C,P*,Charcoal per week,0,q,q*,Price, costs of

7、 charcoal,FIGURE 18-1: An Externality in Charcoal Production Causes an Inefficient Allocation of Resources,12,Property Rights,Property rights are the legal specification of who owns a good and the trades the owner is allowed to make with it. Common property is property that may be used by anyone without cost. Private property is property that is owned by specific people who may prevent others from using it.,13,Costless Bargaining and Competitive Markets,Considering the charcoal-eyeglass external

8、ity, suppose property rights were defined so as to give sole rights to use the air to one of the firms. The firms were then free to bargain over how the air might be used. If bargaining is costless the two parties might arrive at q on their own.,14,Ownership by the Polluting Firm,If the charcoal firm owns the land, it must add these ownership costs to its total costs. The costs of polluting the air are what someone else is willing to pay for this resource (clean air) in its best alternative use.

9、 The eyeglass company would be willing to pay the an amount equal to the external cost the charcoal company is imposing.,15,Ownership by the Polluting Firm,The charcoal companys marginal cost will be MSC, and it will produce q. The charcoal company will sell the remaining air use rights to the eyeglass maker for a fee of some amount between AEC (the lost profits of producing q rather than q*) and ABEC (the maximum amount the eyeglass maker would be willing to pay to avoid having the charcoal producer increase production to q*.,16,Ownership by the Injured Firm,If the eyeglass maker owns the air, the charcoal firm will offer a payment to use the air associated with output level q. The eyeglass owner will not sell rights to pollute beyond this because the price that the charcoal maker would be willing to pay (P* - MC) falls short of the cost of this additional pollution (MCS - MC). The socially optimal charcoal output, q, is produced in this case as well.,17,T

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