Throughout human history, informal sanctions by peers were ubiquitous and played a key role in the enforcement of social norms and the provision of public goods. However, a considerable body of evidence suggests that informal peer sanctions cause large collateral damage and efficiency costs....

Throughout human history, informal sanctions played a key role in the enforcement of social norms and the provision of public goods. However, a considerable body of evidence suggests that informal peer sanctions often cause large efficiency costs. This raises the question whether alternative...

This paper investigates the driving forces behind informal sanctions in cooperation games and the extent to which theories of fairness and reciprocity capture these forces. We find that cooperators' punishment is almost exclusively targeted towards the defectors but the latter also impose a...