Decision makers are usually not hermits and do not function in isolation from others. They are usually influenced by the opinions (i.e., preferences) of other decision makers, and their problem is one of how to select a course of action, not only for themselves, but for the community. If each individual were to possess a notion of rationality for the group as well as a notion of rationality for itself, it might be in a position to improve its behavior.

Group rationality, however, is not a logical consequence of rationality based on individual self-interest. Under substantive rationality, where maximization of individual satisfaction is the operative notion, group behavior is not usually optimized by optimizing each individual's behavior, as is done in conventional game theory. Unfortunately, those who put their final confidence in exclusive self-interest may ultimately function disjunctively, and perhaps illogically, when participating in collective decisions.

The point of departure for conventional game theory is games of pure conflict, with the prototype being constant-sum games, where one player's loss is another player's gain. For a constant-sum game, any notion of group-interest is vacuous; individual self-interest is the only appropriate motive.