THE ROLE OF NETWORKS IN COLLECTIVE ACTION WITH COSTLY COMMUNICATION.

Individuals frequently contribute their resources voluntarily to provide public goods. This paper models the manner in which the linkage between members in a community influences the likelihood of such actions through spontaneous activism in networks. The model I use abstracts from the issue of free-riding behavior by means of small deviations from standard preferences. Instead, it concentrates on the communication aspect of provision through collective action. The solution concept is Nash equilibrium. I find that the likelihood of efficient provision of a discrete public good in random social networks increases very rapidly for parameter values where the network experiences a phase transition and large-scale decentralized activism becomes feasible. As a result, the model shows that successful coordination may be more readily achieved the larger the population is, provided its members are sufficiently connected. In contrast with previous results in the literature, this results holds even as the size of the population increases without bound, and it is consistent with the existence of largescale activism in large populations.