Prisoner's dilemmas and other forms of commitment problems abound in economic transactions. Being known not to have strictly self-interested preferences can be extremely useful for solving these problems. In order for such preferences to be advantageous, others must be able to discern that one has them. If preferences could be observed without cost or uncertainty, there would be only cooperative people in the world. But because costs and uncertainty are an inherent part of the process, there will virtually always be an ecological niche for at least some of the opportunistic people assumed in conventional self-interest models. The chapter has also illustrated that the predominance of one group or mode of behaviour can be highly sensitive to the structure of rewards in the payoff matrix. The two main points of this chapter are: (1) the self-interest model, which assumes that everyone behaves opportunistically, is destined to make important errors in predicting actual behaviour; and (2) people who are concerned about the interests of others need not suffer on that account, even in purely material terms. Because others can recognize the kind of people they are, opportunities will be open to them that would not be open to the opportunist. | 
2002 McGraw-Hill Higher Education