Tolerant moral judgment drives evolution of collective action

In public goods games, the benefit of collective action is shared among all participants, and this creates strong incentives to defect. Theoretical studies and economic experiments predict that without enforcement mechanisms, cooperation in public goods games should collapse. But human societies have repeatedly resolved collective action dilemmas through social norms and institutions. Humans condition their social behavior on the moral reputations of other individuals, and the reputations themselves reflect their past behavior. Here I show how Indirect Reciprocity mechanisms based on group reputations and group-level norms can evolve to promote collective action in public goods games. Individual reputations reflect moral judgments of social behavior within groups, according to the prevailing social norm. Only three norms previously studied as part of Indirect Reciprocity in pairwise games can sustain public goods investments, and their performance depends on how tolerant individuals are to occasional antisocial behavior within groups. When members of the society have predominantly tolerant moral views towards groups, only the norm that abstains from judgment in morally ambiguous interactions (known as ``Staying'') can sustain collective action.