1、博弈论与实验经济学28/10/05Chapter 10 Why Environmental Problems Are Easy to Arise, Hard to FixSummary10.1 Introduction10.2 The Fishermens Dilemma (The Genesis of the Problem)10.3 The Original Prisoners Dilemma (With Its Spillover to the Remedy) 10.3.1 The District Attorneys Incentives and the Larger Society1
2、0.4 The Woburn Toxics Case (A Case Study) 10.4.1 The Harm 10.4.2 Deciding on a Lawsuit 10.4.3 The Plaintiffs Tasks 10.4.4 The Strategies 10.4.5 Preparations 10.4.6 The Trial10.5 Negligence and Strict Liability 10.5.1 Unforseeability 10.5.2 Strict Liability 10.5.3 The Link between Strict Liability an
3、d Briers Scoring Rule10.6 Summary Analytic Question Discussion Questions10.7 Appendix: A Brief History of the Concept of ExternalityFigures and TablesFigure 10.1 Fishermens DilemmaFigure 10.2 The Original Prisoners DilemmaFigure 10.3 Externality in Tort LawFigure 10.4 ExternalityFigure 10.5 Schlicht
4、manns Probability AssessmentFigure 10.6 The Preponderance of the Evidence as a Legal StandardFigure 10.7 The Earliest Date of Contamination, by a Preponderance of the EvidenceTable 10.1 Profit, Depending on x and Possible Liability of $600xFigure 10.8 The Firms Probabilities and Decision Consequence
5、sFigure 10.9 The Parabola of Expected ProfitFigure 10.10 The Chemical Firms Decision FunctionTable 10.2 The Brier Scoring RuleFigure 10.11 The Weather Forecasters Decision FunctionFigure 10.12 The Chemical Firms Decision Function for the Less Toxic ChemicalChapter 10 Why Environmental Problems Are E
6、asy to Arise, Hard to FixIf men were angels, no government would be necessary.-James Madison (The Federalist, Feb. 6, 1788)The water had never tasted right, it never looked right, and it never smelled right.-Anne Anderson (cited from A Civil Action, p. 21.The truth? Truth is at the bottom of a botto
7、mless pit.-Jerome Facher (cited from A Civil Action, p. 340.10.1 Introduction A theme in our inquiry so far is that the combination of individual self-interest and externality is a primary source of environmental problems. Both the genesis and the effects of externalities are further shaped by the c
8、onflicting interests among different people, uncertainty, and difficulties of valuation so common in environmental problems. Individual self interest of course does not always lead to externalities and environmental problems. We saw in Chapter 6 an example of a well-functioning market without extern
9、alities and environmental problems (and then we saw in Chapter 7 a market failure with externalities and environmental problems). In this chapter we begin with a classic example of self interest and externality, and then shift our focus to attempts of remedy. We will find that the same characteristi
10、cs that lead to environmental problems in the first place make them hard to remedy in the second place.10.2 The Fishermens Dilemma (The Genesis of the Problem) We begin with a particularly simple example of a fishery. Consider the example of two fishermen, A and B, and Figure 10.1 below. If both A a
11、nd B fish a little, both get a large catch (the upper left rectangle). The low level of fishing effort of both A and B avoids over-fishing, allowing for the fish to reproduce effectively, leading to large harvests for both fishermen. If both A and B fish a lot, both get a small catch (lower right).
12、The intensive fishing leads to over-fishing, depleting the fisherys productivity and causing a small harvest for both fishermen. In the externality each fisherman harms the other by depleting the resource base. If A fishes a lot and B fishes a little, A gets an extra large catch and B gets an extra
13、small one (upper right). The fishery is a little depleted. A gets an extra large catch because A fishes a lot in the only partially depleted fishery; B gets an extra small catch because B fishes a little in the partially depleted fishery. If B fishes a lot and A fishes a little, B gets an extra larg
14、e catch and A gets an extra small catch (lower left). The fishery is a little depleted. B gets an extra large catch because B fishes a lot in the only partially depleted fishery; A gets an extra small catch because A fishes a little in the partially depleted fishery.Figure 10.1 If A and B could coop
15、erate and coordinate, the obvious thing to do is for both to fish a little. But in our example, communication is hard and the fishermen dont cooperate. Perhaps they speak different languages or come from different continents, as is the case in many of the worlds fisheries. When each fisherman does t
16、he best he can for himself there is an incentive for each person to fish a lot, even though doing so leads to a bad social outcome. Heres the way the incentive works. Fisherman A reasons: “Suppose B fishes a little. Then if I fish a little I get a large catch (upper left). But if I fish a lot I get
17、an extra large catch (upper right). So when B fishes a little I am better off fishing a lot. “Suppose B fishes a lot. Then if I fish a little I get an extra small catch (lower left). If I fish a lot I get a small catch (lower right). So when B fishes a lot I am better off fishing a lot. “Whatever B
18、does, I am better off fishing a lot. I guess I will fish a lot.” B reasons in a similar way, and together they end up depleting the resource and hurting themselves. A has a dominant strategy of fishing a lot because fishing a lot is his best strategy no matter what B does. B also has a dominant stra
19、tegy of fishing a lot because fishing a lot is his best strategy no matter what A does. The strategy pair (A fishes a lot, B fishes a lot) is called an equilibrium in dominant strategies. The equilibrium predicts that both fishermen will end up with a small catch, when they could both have a large c
20、atch. In summary, the example says that “self-interest in the presence of externalities can lead to inefficiency,” in this case the inefficiency of over-fishing. Its the same idea as in Gordons fishery problem, but with a simpler model. You may have recognized the example is a prisoners dilemma, app
21、lied to an environmental problem. In its various versions, the prisoners dilemma has intrigued game theorists and economists for the last half-century because it so directly illustrates the idea that what is good for the individual can be bad for society (the society of the two fishermen end up with
22、 the inefficient, depleted fishery). In this way the prisoners dilemma parallels the hawk-dove game, which illustrates the idea that what is good for the individual fitness of an individual bird can be harmful to the species as a whole. And just as the hawk-dove game is an elegantly simple model tha
23、t helped change the way biologists think about evolution, the prisoners dilemma is an elegantly simple model that helped change the way economists think about environmental problems. Maynard Smiths hawk-dove game provides a simple and clear alternative to the older view that adaptations benefiting i
24、ndividuals automatically benefit the species (Chapter 3). In a parallel way the prisoners dilemma provides a simple and clear alternative to the older view of Adam Smiths invisible hand automatically leads individual interest to the public interest (Chapter 6). The fishermens dilemma, our environmen
25、tal version of the prisoners dilemma, by being simple, is stylized and much is left out. Narrow self-interest is not the only motivator. If A were to fish a lot and B to fish a little, wouldnt there be moral pressure on A to conserve and not injure the fishery and B? There are of course other-direct
26、ed values of cooperation, reciprocity, and altruism, which we will study in the next chapter. But with many of the worlds fisheries in decline, these values are often insufficient to overcome self-interest in the presence of externalities. James Madison, an architect of the U.S. Constitution and fou
27、rth President, put the matter, “If men were angels, no government would be necessary.” Since Madison thought government was necessary, his obvious inference is that men arent angels. But if men arent angels, does the prisoners dilemma, simple and stylized as it is, have anything to say about the dif
28、ficulties of non-angels in fashioning remedies in government agencies? To address this question, we go back to the original version of the prisoners dilemma.10.3 The Original Prisoners Dilemma (With Its Spillover to the Remedy) There is a story (probably incorrect) that scholarly interest in the pri
29、soners dilemma began when a pioneer game theorist was sitting in a barber shop. While cutting his customers hair, the barber made conversation by asking his customer what game theory was. The theorist gave a few words of explanation, and the barber responded by asking “have you heard this one?” “The
30、re are two prisoners A and B, just caught and suspects for a crime (Figure 10.2). There is some evidence but possibly not enough to get a conviction in court. The district attorney in charge of the case puts the prisoners into separate cells where they cannot communicate with each other. The distric
31、t attorney goes to the cell holding A and tells him: “If you (A) know what is good for you and you cooperate with me by pleading guilty, things will go well for you. How much better depends on B. If B also cooperates, I will seek a reasonable sentence for the crime, 6 years for each of you (lower ri
32、ght). If B remains silent, I will throw the book at him, but I will reward you with an extra light sentence of just a year (upper right).Figure 10.2 “If you (A) dont cooperate with me, things will go hard for you. Just how hard depends on what B does. If B testifies against you, and you keep silent, I will use his evidence to put you in prison for 10 years (lower left). If he keeps silent, I still have enough evidence to put you in prison for 2 years (upper left). If you refuse to cooperate with me I will t
