The Evolution of Collective Action

A public good is produced if and only if a team of m or more volunteers contribute to it. An equilibrium-selection problem leads to the questions: will collective action succeed? If so, who will participate in the team? The paper studies the evolution of collective action: as part of a strategy-revision process, updating players choose quantal responses to existing play. With symmetric players, success depends upon the cost of contribution, the benefit from provision, and the critical team-size m; the relative variability of costs and benefits, and their correlation, are also critical. When players differ, successful teams consist of either the most efficient contributors, or those with the most idiosyncratic preferences. The addition of a single bad apple (for instance, an individual whose costs are particularly variable) to a population in which a successful team operates may result in destabilisation: over time, the bad apple might supplant an existing contributor, prompting a collapse.