Rationality, Morality, and Exit

The morality and rationality issue is explored from an Axelrod-type perspective; that is, it is discussed in terms of recurrent-prisoner's-dilemma-type games and behavioral strategies or programs for playing them. We argue that intuitive notions of rationality and morality can be shown to be mutually compatible if two assumptions are made: (1) that morality is specified as a general behavioral disposition or program whose rationality is to be determined in comparison to alternative behavioral programs and (2) that the recurrent game is specified as a prisoner's dilemma game with an exit option. The results of a simulation experiment are presented, showing that a “moral program” (specified as one that never defects, but exits in response to an opponents defection) is successful in competition with a variety of alternative programs, including Tit for Tat.