Voting for voters: The unanimity case

We present a simplified model of the evolution of a society which is regulated by a formal unanimity voting procedure. We examine several protocols, which depend on whether admission or expulsion are permissible, and on the order with which they are implemented. Conditions which ensure the existence of pure-strategy perfect equilibrium profiles for some voting protocols, and counter examples for the existence of such profiles in other protocols are presented. Finally, we prove that, if the agents insist on perfect equilibrium strategy profiles in a one-stage play, the original founders would prefer a protocol in which expulsion precedes admission to protocols in which either admission precedes expulsion, or the two are treated simultaneously. The paper concludes with an overview and a discussion on the results and suggestions for further research.