In this paper, we study how the pro-social impact due to the vigilance by other individuals is conditioned by both environmental and evolutionary effects. To this aim, we consider a known model where agents play a Prisoner’s Dilemma Game (PDG) among themselves and the pay-off matrix of an...

In this paper we argue that authorities aid cooperation by means ofdirect coordination or the enforcement of re-commitment devices suchas contract laws.Credible threats of violence allow this role. In alocal interaction model, an authority forms if mutually connected individuals with sufficient...

We show that for many classes of symmetric two-player games, the simple decision rule 'imitate-if-better' can hardly be beaten by any strategy. We provide necessary and sufficient conditions for imitation to be unbeatable in the sense that there is no strategy that can exploit imitation as a...