The paper first summarizes the author's decision-theoretical model of moral behavior, in order to compare the moral implications of the act-utilitarian and of the rule-utilitarian versions of utilitarian theory. This model is then applied to three voting examples. It is argued that the moral behavior of act-utilitarian individuals will have the nature of a noncooperative game, played in the extensive mode, and involving action-byaction maximization of social utility by each player, In contrast, the moral behavior of rule-utilitarian individuals will have the nature of a cooperative game, played in the normal mode, and involving a firm commitment by each player to a specific moral strategy (viz. to the strategy selected by the rule-utilitarian choice criterion) -even it" some individual actions prescribed by this strategy, when considered in isolation, should fail to maximize social utility.
The most important advantage that rule utilitarianism as an ethical theory has over act utilitarianism lies in its ability to give full recognition to the moral and social importance of individual rights and personal obligations. It is easy to verify that action-byaction maximization of social utility, as required by act utilitarianism, would destroy these rights and obligations. In contrast, rule utilitarianism can fully recognize the moral validity of these rights and obligations precisely because of its commitment to an overall moral strategy, independent of action-by-action social-utility maximization.
The paper ends with a discussion of the voter's paradox problem. The conventional theory of rational behavior cannot avoid the paradoxical conclusion that, in any large electorate, voting is always an irrational activity because one's own individual vote is extremely unlikely to make any difference to the outcome of any election. But it can be shown that, by using the principles of rule-utilitarian theory, this paradox can easily be resolved and that, in actual fact, voting, even in large electorates, may be perfectly rational action. More generally, the example of rule utilitarianism shows what an important role the concept of a rational commitment can play in the analysis of rational behavior.
1. Introduction
In earlier publications (Harsanyi, 1953(Harsanyi, , 1955(Harsanyi, , 1977a(Harsanyi, , b, 1978a, b, c), b, c), I have argued that the modern theory of rational behavioras developed by economists (as well as by decision theorists and game theorists)-can make important contributions to our understanding of the nature of morality. Now I would like to carry this argument a little further and discuss the Theory and Decision 12 (1980) 115-133.