Polarize, Catalyze, Stabilize: How a minority of norm internalizers amplify group selection and punishment

TL;DR

This paper explores how a minority of norm internalizers can promote and stabilize cooperation in groups, even with limited observation and punishment, by polarizing and catalyzing cooperative behavior among others.

Contribution

It demonstrates that norm internalization, even when rare, can significantly enhance cooperation by influencing others, without requiring internalizers to be numerous or highly cooperative.

Findings

Norm internalizers can increase overall cooperation despite being a minority.

They influence others through polarization, catalysis, and stabilization of cooperative behavior.

High cooperation levels are achieved without internalizers dominating the population.

Abstract

Many mechanisms behind the evolution of cooperation, such as reciprocity, indirect reciprocity, and altruistic punishment, require group knowledge of individual actions. But what keeps people cooperating when no one is looking? Conformist norm internalization, the tendency to abide by the behavior of the majority of the group, even when it is individually harmful, could be the answer. In this paper, we analyze a world where (1) there is group selection and punishment by indirect reciprocity but (2) many actions (half) go unobserved, and therefore unpunished. Can norm internalization fill this "observation gap" and lead to high levels of cooperation, even when agents may in principle cooperate only when likely to be caught and punished? Specifically, we seek to understand whether adding norm internalization to the strategy space in a public goods game can lead to higher levels of cooperation when both norm internalization and cooperation start out rare. We found the answer to be positive, but, interestingly, not because norm internalizers end up making up a substantial fraction of the population, nor because they cooperate much more than other agent types. Instead, norm internalizers, by polarizing, catalyzing, and stabilizing cooperation, can increase levels of cooperation of other agent types, while only making up a minority of the population themselves.