Title: Testing Coleman's social-norm enforcement mechanism
Description: Since Durkheim, sociologists have believed that dense network structures lead to fewer norm violations. Coleman (1990) proposed one mechanism generating this relationship and argued that dense networks provide an opportunity structure to reward those who punish norm violators, leading to more frequent punishment and in turn fewer norm violations. Despite ubiquitous scholarly references to Coleman's theory, little empirical work has directly tested it in large-scale natural settings with longitudinal data. We undertake such a test using records of norm violations during the editing process on Wikipedia, the largest user-generated on-line encyclopedia. These data allow us to track all three elements required to test Coleman's mechanism: norm violations, punishments for such violations and rewards for those who punish violations. The results are broadly consistent with Coleman's mechanism.