We analyse interethnic cooperation in an infinitely repeated prisoner’s dilemma when members of one group are unable to target punishment towards individual defectors from the other group. We first show that indiscriminate outgroup punishment may sustain cooperation in this setting. Our main...

It has been argued that accountability is a public good that only citizens can provide. Governments can put institutions in place that allow citizens to hold public servants to account, but citizens must participate in those institutions if accountability is to be achieved. Thus, citizens face a...

We analyze an experimental public goods game in which group members can endogenously determine whether they want to supplement a standard voluntary contribution mechanism with the possibility of rewarding or punishing other group members. We find a large and positive effect of endogenous...

We study the stability of voluntary cooperation in response to varying rates at which a group grows. Using a laboratory public-good game with voluntary contributions and economies of scale, we construct a situation in which expanding a group's size yields potential efficiency gains, but only if...

Previous research shows that collective action to avoid a catastrophic threshold, such as a climate "tipping point", is unaffected by uncertainty about the impact of crossing the threshold but that collective action collapses if the location of the threshold is uncertain. Theory suggests that...

A large number of individuals are randomly matched into groups, where each group plays a finite symmetric game. Individuals breed true. The expected number of surviving offspring depends on own material payoff, but may also, due to cooperative breeding and/or reproductive competition, depend on...

We consider how group size affects the private provision of a public good with non-refundable binary contributions. A fixed amount of the good is provided if and only if the number of contributors reaches an exogenous threshold. The threshold, the group size, and the identical, non-refundable...

This paper studies the effect of endogenous group formation on the outcome in two types of coordination games with multiple Pareto-ranked equilibria. Endogenous group formation means that in each period players are free to choose among two or more groups within which they want to play the...