A longstanding tradition in the social sciences contrasts instrumental rationality and social norms as alternative ways of explaining action. Rational choice theory defines action as the outcome of a practical inference that takes preferences and beliefs as premises. An explanation in terms of norms depicts a socialized actor whose behavior is not outcome oriented, since when acting in accordance with a norm one does not engage in a rational calculation nor does one pay very much attention to the consequences. Attempts at bridging the gap have either tried to establish that social norms are rational, in the sense of being efficient means to achieve individual or social welfare, or that it is rational to conform to norms, thus reducing compliance to utility maximization. The first reductionist strategy makes a typical post hoc, ergo propter hoc fallacy, since the mere presence of a social norm does not justify inferring that it is there to accomplish some social function. Besides, it does not account for the fact that many social norms are inefficient, as in the case of discriminatory norms against women and blacks, or are so rigid as to prevent the fine-tuning that would be necessary to successfully accommodate new cases. Even if a norm is a means to achieve a social end, such as cooperation, retribution, or fairness, usually it is not the sole means. Many social norms are underdetermined with respect to the collective objectives they may serve, nor can they be ordered according to a criterion of greater or lesser efficiency in meeting these goals. Such an ordering would be feasible only if it were possible to show that one norm among others is the best means to attain a given social objective. Often, though, the objectives themselves are defined by means of some norm. Consider as an example norms of revenge; until not long ago, a Sicilian man who "dishonored" another man's daughter or sister had to make amends for the wrong by marrying the woman or pay for his rashness with his own life. The objective was to restore the family's lost