Evolving intergroup cooperation

This paper examines the problem of inter-group cooperation using an agent-based model. Within a single, small group, reputation can be used to promote cooperation. However, reputation fails across groups when the members of the groups cannot identify each other individually. Two mechanisms have been proposed in the literature to foster inter-group cooperation: collective sanctions and in-group policing. I use an agent-based model in an evolutionary environment to determine the effectiveness of these two mechanisms. Examining them separately, I find in-group policing results in high-levels of inter-group cooperation while collective sanctions do not. When employed concurrently, collective sanctions do nothing to enhance the effectiveness of the in-group policing mechanism and may impede its functioning.