Competitions between prosocial exclusions and punishments in finite populations

TL;DR

This study compares prosocial exclusion and punishment strategies in finite populations, revealing that exclusion generally outperforms punishment in promoting cooperation, with the effectiveness depending on the presence of second-order sanctions.

Contribution

It provides a comprehensive analysis of the competitive dynamics between exclusion and punishment strategies, highlighting the conditions under which each strategy is most effective.

Findings

Pool exclusion outperforms pool punishment in all scenarios.

Peer exclusion surpasses pool exclusion unless second-order exclusion is present.

Exclusion strategies are generally more effective than punishment in resolving social dilemmas.

Abstract

Prosocial punishment has been proved to be a powerful mean to promote cooperation. Recent studies have found that social exclusion, which indeed can be regarded as a kind of punishment, can also support cooperation. However, if prosocial punishment and exclusion are both present, it is still unclear which strategy is more advantageous to curb free-riders. Here we first study the direct competition between different types of punishment and exclusion. We find that pool (peer) exclusion can always outperform pool (peer) punishment both in the optional and in the compulsory public goods game, no matter whether second-order sanctioning is considered or not. Furthermore, peer exclusion does better than pool exclusion both in the optional and in the compulsory game, but the situation is reversed in the presence of second-order exclusion. Finally, we extend the competition among all possible sanctioning strategies and find that peer exclusion can outperform all other strategies in the absence of second-order exclusion and punishment, while pool exclusion prevails when second-order sanctioning is possible. Our results demonstrate that exclusion is a more powerful strategy than punishment for the resolution of social dilemmas.