《政治经济学经典导读 Comparative Political Economy》课程教学资源（阅读资料）The Evolution of Cooperation

The Problem ofCooperation we will invite acquaintances for dinner if they never invite us over in return.An executive in an organization does favors for another executive in order to get favors in ex- change.A journalist who has received a leaked news story gives favorable coverage to the source in the hope that further leaks will be forthcoming.A business firm in an industry with only one other major company charges high prices with the expectation that the other firm will also maintain high prices-to their mutual advantage and at the expense of the consumer. For me,a typical case of the emergence of cooperation is the development of patterns of behavior in a legislative body such as the United States Senate.Each senator has an incentive to appear effective to his or her constituents,even at the expense of conflicting with other senators who are trying to appear effective to their constituents.But this is hardly a situation of completely opposing interests,a zero- sum game.On the contrary,there are many opportunities for mutually rewarding activities by two senators.These mutually rewarding actions have led to the creation of an elaborate set of norms,or folkways,in the Senate.Among the most important of these is the norm of reciprocity-a folkway which involves helping out a colleague and get- ting repaid in kind.It includes vote trading but extends to so many types of mutually rewarding behavior that "it is not an exaggeration to say that reciprocity is a way of life in the Senate"(Matthews 1960,p.100;see also Mayhew 1975). Washington was not always like this.Early observers saw the members of the Washington community as quite unscrupulous,unreliable,and characterized by "falsehood. deceit,treachery"(Smith 1906,p.190).In the 1980s the practice of reciprocity is well established.Even the signifi- 5

The Problem of Cooperation we will invite acquaintances for dinner if they never invite us over in return. An executive in an organization does favors for another executive in order to get favors in ex￾change. A journalist who has received a leaked news story gives favorable coverage to the source in the hope that further leaks will be forthcoming. A business firm in an industry with only one other major company charges high prices with the expectation that the other firm will also maintain high prices—to their mutual advantage and at the expense of the consumer. For me, a typical case of the emergence of cooperation is the development of patterns of behavior in a legislative body such as the United States Senate. Each senator has an incentive to appear effective to his or her constituents, even at the expense of conflicting with other senators who are trying to appear effective to their constituents. But this is hardly a situation of completely opposing interests, a zero￾sum game. On the contrary, there are many opportunities for mutually rewarding activities by two senators. These mutually rewarding actions have led to the creation of an elaborate set of norms, or folkways, in the Senate. Among the most important of these is the norm of reciprocity—a folkway which involves helping out a colleague and get￾ting repaid in kind. It includes vote trading but extends to so many types of mutually rewarding behavior that "it is not an exaggeration to say that reciprocity is a way of life in the Senate" (Matthews 1960, p. 100; see also Mayhew 1975). Washington was not always like this. Early observers saw the members of the Washington community as quite unscrupulous, unreliable, and characterized by "falsehood, deceit, treachery" (Smith 1906, p. 190). In the 1980s the practice of reciprocity is well established. Even the signifi- 5

Introduction cant changes in the Senate over the last two decades,tend- ing toward more decentralization,more openness,and more equal distribution of power,have come without abat- ing the folkway of reciprocity (Ornstein,Peabody,and Rhode 1977).As will be seen,it is not necessary to assume that senators are more honest,more generous,or more public-spirited than in earlier years to explain how cooper- ation based on reciprocity has emerged or proved stable. The emergence of cooperation can be explained as a conse- quence of individual senators pursuing their own interests. The approach of this book is to investigate how individ- uals pursuing their own interests will act,followed by an analysis of what effects this will have for the system as a whole.Put another way,the approach is to make some assumptions about individual motives and then deduce con- sequences for the behavior of the entire system (Schelling 1978).The case of the U.S.Senate is a good example,but the same style of reasoning can be applied to other settings. The object of this enterprise is to develop a theory of cooperation that can be used to discover what is necessary for cooperation to emerge.By understanding the condi- tions that allow it to emerge,appropriate actions can be taken to foster the development of cooperation in a specific setting. The Cooperation Theory that is presented in this book is based upon an investigation of individuals who pursue their own self-interest without the aid of a central authority to force them to cooperate with each other.The reason for assuming self-interest is that it allows an examination of the difficult case in which cooperation is not completely based upon a concern for others or upon the welfare of the group as a whole.It must,however,be stressed that this assumption is actually much less restrictive than it appears. 6

Introduction cant changes in the Senate over the last two decades, tend￾ing toward more decentralization, more openness, and more equal distribution of power, have come without abat￾ing the folkway of reciprocity (Ornstein, Peabody, and Rhode 1977). As will be seen, it is not necessary to assume that senators are more honest, more generous, or more public-spirited than in earlier years to explain how cooper￾ation based on reciprocity has emerged or proved stable. The emergence of cooperation can be explained as a conse￾quence of individual senators pursuing their own interests. The approach of this book is to investigate how individ￾uals pursuing their own interests will act, followed by an analysis of what effects this will have for the system as a whole. Put another way, the approach is to make some assumptions about individual motives and then deduce con￾sequences for the behavior of the entire system (Schelling 1978). The case of the U.S. Senate is a good example, but the same style of reasoning can be applied to other settings. The object of this enterprise is to develop a theory of cooperation that can be used to discover what is necessary for cooperation to emerge. By understanding the condi￾tions that allow it to emerge, appropriate actions can be taken to foster the development of cooperation in a specific setting. The Cooperation Theory that is presented in this book is based upon an investigation of individuals who pursue their own self-interest without the aid of a central authority to force them to cooperate with each other. The reason for assuming self-interest is that it allows an examination of the difficult case in which cooperation is not completely based upon a concern for others or upon the welfare of the group as a whole. It must, however, be stressed that this assumption is actually much less restrictive than it appears. 6

The Problem ofCooperation If a sister is concerned for the welfare of her brother,the sister's self-interest can be thought of as including (among many other things)this concern for the welfare of her brother.But this does not necessarily eliminate all potential for conflict between sister and brother.Likewise a nation may act in part out of regard for the interests of its friends, but this regard does not mean that even friendly countries are always able to cooperate for their mutual benefit.So the assumption of self-interest is really just an assumption that concern for others does not completely solve the problem of when to cooperate with them and when not to. A good example of the fundamental problem of coopera- tion is the case where two industrial nations have erected trade barriers to each other's exports.Because ofthe mutual advantages of free trade,both countries would be better off if these barriers were eliminated.But ifeither country were to unilaterally eliminate its barriers,it would find itself fac- ing terms of trade that hurt its own economy.In fact, whatever one country does,the other country is better off retaining its own trade barriers.Therefore,the problem is that each country has an incentive to retain trade barriers, leading to a worse outcome than would have been possible had both countries cooperated with each other. This basic problem occurs when the pursuit of self-inter- est by each leads to a poor outcome for all.To make head- way in understanding the vast array of specific situations which have this property,a way is needed to represent what is common to these situations without becoming bogged down in the details unique to each.Fortunately, there is such a representation available:the famous Prison- er's Dilemma game.2 In the Prisoner's Dilemma game,there are two players. Each has two choices,namely cooperate or defect.Each 7

The Problem of Cooperation If a sister is concerned for the welfare of her brother, the sister's self-interest can be thought of as including (among many other things) this concern for the welfare of her brother. But this does not necessarily eliminate all potential for conflict between sister and brother. Likewise a nation may act in part out of regard for the interests of its friends, but this regard does not mean that even friendly countries are always able to cooperate for their mutual benefit. So the assumption of self-interest is really just an assumption that concern for others does not completely solve the problem of when to cooperate with them and when not to. A good example of the fundamental problem of coopera￾tion is the case where two industrial nations have erected trade barriers to each other's exports. Because of the mutual advantages of free trade, both countries would be better off if these barriers were eliminated. But if either country were to unilaterally eliminate its barriers, it would find itself fac￾ing terms of trade that hurt its own economy. In fact, whatever one country does, the other country is better off retaining its own trade barriers. Therefore, the problem is that each country has an incentive to retain trade barriers, leading to a worse outcome than would have been possible had both countries cooperated with each other. This basic problem occurs when the pursuit of self-inter￾est by each leads to a poor outcome for all. To make head￾way in understanding the vast array of specific situations which have this property, a way is needed to represent what is common to these situations without becoming bogged down in the details unique to each. Fortunately, there is such a representation available: the famous Prison￾er's Dilemma game.2 In the Prisoner's Dilemma game, there are two players. Each has two choices, namely cooperate or defect. Each 7

Introduction must make the choice without knowing what the other will do.No matter what the other does,defection yields a higher payoff than cooperation.The dilemma is that if both defect,both do worse than if both had cooperated. This simple game will provide the basis for the entire anal- ysis used in this book. The way the game works is shown in figure 1.One player chooses a row,either cooperating or defecting.The other player simultaneously chooses a column,either coop- erating or defecting.Together,these choices result in one of the four possible outcomes shown in that matrix.If both players cooperate,both do fairly well.Both get R,the re- wardfor mutual cooperation.In the concrete illustration of figure 1 the reward is 3 points.This number might,for example,be a payoff in dollars that each player gets for that outcome.Ifone player cooperates but the other defects,the defecting player gets the temptation to defect,while the coop- erating player gets the sucker'spayoff.In the example,these are 5 points and 0 points respectively.If both defect,both get I point,the punishment for mutual defection. What should you do in such a game?Suppose you are the row player,and you think the column player will coop- FIGURE 1 The Prisoner's Dilemma Column Player Cooperate Defect Cooperate R=3,R=3 S=0,T=5 Reward for Sucker's payoff,and Row mutual cooperation temptation to defect Player Defect 7T=5,S=0 P=1,P=1 Temptation to defect Punishment for and sucker's payoff mutual defection NOTE:The payoffs to the row chooser are listed first. 8

Introduction must make the choice without knowing what the other will do. No matter what the other does, defection yields a higher payoff than cooperation. The dilemma is that if both defect, both do worse than if both had cooperated. This simple game will provide the basis for the entire anal￾ysis used in this book. The way the game works is shown in figure 1. One player chooses a row, either cooperating or defecting. The other player simultaneously chooses a column, either coop￾erating or defecting. Together, these choices result in one of the four possible outcomes shown in that matrix. If both players cooperate, both do fairly well. Both get R, the re￾ward for mutual cooperation. In the concrete illustration of figure 1 the reward is 3 points. This number might, for example, be a payoff in dollars that each player gets for that outcome. If one player cooperates but the other defects, the defecting player gets the temptation to defect, while the coop￾erating player gets the sucker's payoff. In the example, these are 5 points and 0 points respectively. If both defect, both get 1 point, the punishment for mutual defection. What should you do in such a game? Suppose you are the row player, and you think the column player will coop￾FIGURE 1 The Prisoner's Dilemma Row Player Cooperate Defect Column Player Cooperate R=3, R=3 Reward for mutual cooperation T=5, S=0 Temptation to defect and sucker's payoff Defect S=0, T=5 Sucker's payoff, and temptation to defect P=1, P=1 Punishment for mutual defection NOTE: The payoffs to the row chooser are listed first. 8

The Problem ofCooperation erate.This means that you will get one of the two out- comes in the first column of figure 1.You have a choice. You can cooperate as well,getting the 3 points of the re- ward for mutual cooperation.Or you can defect,getting the 5 points of the temptation payoff.So it pays to defect if you think the other player will cooperate.But now suppose that you think the other player will defect.Now you are in the second column of figure 1,and you have a choice be- tween cooperating,which would make you a sucker and give you 0 points,and defecting,which would result in, mutual punishment giving you 1 point.So it pays to defect if you think the other player will defect.This means that it is better to defect if you think the other player will cooper- ate,and it is better to defect if you think the other player will defect.So no matter what the other player does,it pays for you to defect. So far,so good.But the same logic holds for the other player too.Therefore,the other player should defect no matter what you are expected to do.So you should both defect.But then you both get 1 point which is worse than the 3 points of the reward that you both could have gotten had you both cooperated.Individual rationality leads to a worse outcome for both than is possible.Hence the dilemma. The Prisoner's Dilemma is simply an abstract formula- tion of some very common and very interesting situations in which what is best for each person individually leads to mutual defection,whereas everyone would have been bet- ter off with mutual cooperation.The definition of Prison- er's Dilemma requires that several relationships hold among the four different potential outcomes.The first re- lationship specifies the order of the four payoffs.The best a player can do is get T,the temptation to defect when the 9

The Problem of Cooperation erate. This means that you will get one of the two out￾comes in the first column of figure 1. You have a choice. You can cooperate as well, getting the 3 points of the re￾ward for mutual cooperation. Or you can defect, getting the 5 points of the temptation payoff. So it pays to defect if you think the other player will cooperate. But now suppose that you think the other player will defect. Now you are in the second column of figure 1, and you have a choice be￾tween cooperating, which would make you a sucker and give you 0 points, and defecting, which would result in, mutual punishment giving you 1 point. So it pays to defect if you think the other player will defect. This means that it is better to defect if you think the other player will cooper￾ate, and it is better to defect if you think the other player will defect. So no matter what the other player does, it pays for you to defect. So far, so good. But the same logic holds for the other player too. Therefore, the other player should defect no matter what you are expected to do. So you should both defect. But then you both get 1 point which is worse than the 3 points of the reward that you both could have gotten had you both cooperated. Individual rationality leads to a worse outcome for both than is possible. Hence the dilemma. The Prisoner's Dilemma is simply an abstract formula￾tion of some very common and very interesting situations in which what is best for each person individually leads to mutual defection, whereas everyone would have been bet￾ter off with mutual cooperation. The definition of Prison￾er's Dilemma requires that several relationships hold among the four different potential outcomes. The first re￾lationship specifies the order of the four payoffs. The best a player can do is get T, the temptation to defect when the 9