Speaker: Christopher Costello

Title: "The supernatural and the commons"

with B. Kelsey Jack and Tamatoa Bambridge

Abstract
We examine whether beliefs in supernatural punishment can coordinate resource extraction in the commons. Traditional small-scale religious belief systems around the world often include restrictions on the use of natural resources, such as fish, forests and specific species, that result in supernatural punishment if violated. Motivated by specific regularities documented in the anthropological literature, and by the Ra ̄hui of Polynesian cultures in particular, we introduce beliefs about supernatural punishment into a standard commons model for which the tragedy of the commons is the no-regulation equilibrium. Here, players form beliefs about whether they will be pun- ished, for example via sickness or misfortune, for violating extraction norms, even when their extraction is private information. We show that sufficiently strong beliefs can sustain fully cooperative behavior even in the complete absence of formal rules, monitoring, or punishment. We then introduce the possibility of learning about the supernatural, where agents can violate norms and learn (albeit noisily) about true supernatural punishment. Even in this setting, certain belief structures can sustain cooperation indefinitely. Comparative statics reveal the features of a belief system under which cooperation is sustained or unravels. We develop a new database of tradi- tional belief systems around the world, providing empirical support for our theoretical predictions.