WHEN IS UNIVERSAL CONTRIBUTION BEST FOR THE GROUP - CHARACTERIZING OPTIMALITY IN THE PRISONERS-DILEMMA

Social scientists from a variety of disciplines have long been captiva ted by the simplicity and elegance of the two-person, binary choice pr isoners' dilemma (2 x 2 PD). Over the years, the domain of the researc h has been extended and applied to events that are neither two person nor binary. We use a defining characteristic of the 2 x 2 PD to identi fy situations under which full levels of contribution are suboptimal. We propose, on the basis of that characteristic, an extended definitio n and categorization of prisoners' dilemmas to n-person and nonbinary situations. The new distinction is shown to point to differing normati ve and strategic imperatives for the different categories of games.