Public goods that benefit everyone are often threatened by defectors that exploit others, typically undermining cooperation and leading to a collapse of the public good. One way to stabilise these public goods is to allow the punishment of defectors. Usually, models are restricted such that only cooperators can punish defectors. If everyone can punish everyone instead, the public good may collapse. Focusing on such more general strategy sets seems a superior and more fair way to model evolutionary dynamics — otherwise, only those behaviours that are to be explained by the model are included in the first place. However, given appropriate assumptions cooperation can prevail in the face of antisocial peer punishment. Also pool punishment, where individuals outsource punishment to an institution, is stable towards such an extension to anti-social institutions.
Prof. Dr. Arne Traulsen is Director and Scientific Member at the Max Planck Institute for Evolutionary Biology in Plön.