Structural satisfaction in simple games

A fundamental maxim for any theory of social behavior is that knowledge of the theory should not cause behavior that contradicts the theory's assertions. Although this maxim consistently has been heeded in the theory of noncooperative games, it largely has been ignored in solution theory for cooperative games. Solution theory, the central concern of this paper, seeks to identify a subset of the feasible outcomes of a cooperative game that are ‘stable’ results of competition among participants, each of whom attempts to bring about an outcome he favors, rather than to prescribe ‘fair’ outcomes that accord with a standard of equity. We show that learning by participants about the solution theory can cause the outcomes identified as stable by certain solution concepts to become unstable, and discover that an important distinction in this regard is whether the solution concept requires each element of the solution set to defend itself against alternatives rather than relying on other elements for its defense. Finally, we develop a concept of ‘solid’ solutions which have a special claim for stability.The unifying theme of this paper concerns the sense in which certain outcomes of a cooperative game may be regarded as stable, and the extent to which this stability requires that the players are ignorant of the theory. Although the issues raised here have implications for the theory of cooperative games in general, Section 1 establishes the focus of the analysis on collective decision games. Section 2 develops some general perspectives on solution theory which are used in Sections 3 and 4 to evaluate the Condorcet solution, the core, the robust proposals set, von Neumann- Morgenstern solutions and competitive solutions. Section 5 presents the concept of a solid solution and relates this idea to the solution concepts reviewed earlier. We demonstrate that in general a solution concept has a strong claim to stability only if it is solid. Finally, Section 6 concludes by indicating that the basic argument also can be applied to Aumann and Maschler's bargaining sets and, more generally, to solution theory for any cooperative game.