ABSTRACT
Georg Simmel's reflections on the ‘quantitative conditioning of the group’ mark the beginning of a sociological tradition of thought that emphasizes the constitutively triadic structure of sociation against theories of the social based on binary models of intersubjectivity. The dyad of ego and alter thus establishes intersubjectivity, but society only begins with three. Two people can love and quarrel, they can cooperate and exchange, but without a third party there would be neither family nor market nor law nor other institutions. Figures of the third, however, are also the ones who challenge the social order again and again. Based on Simmel's remarks on the third party as well as on game-theoretical studies on coalition formation in triads, the chapter elaborates the role of third instances for the foundation and preservation, but also for the destabilization of social institutions.
