The dual role of constructive agents in public goods games: limited alone, amplifying cooperation with destructive agents

Résumé : Recent studies have revealed a paradoxical phenomenon in public goods games, wherein destructive agents, harming both cooperators and defectors, can unexpectedly bolster cooperation. Building upon this intriguing premise, our paper introduces a novel concept: constructive agents, which confer additional benefits to both cooperators and defectors. We investigate the impact of these agents on cooperation dynamics within the framework of public goods games. Employing replicator dynamics, we find that unlike destructive agents, the mere presence of constructive agents does not significantly alter the defective equilibrium. However, when the benefits from constructive agents are outweighed by the damage inflicted by destructive agents, the coexistence of both agent types can amplify the ability of destructive agents to sustain cooperation. This occurs through the facilitation of a coexistence pattern involving cooperators, defectors, constructive agents, and destructive agents via cyclic dominance. Conversely, if the benefits from constructive agents surpass the harm caused by destructive agents, the presence of constructive agents nullifies the ability of destructive agents to foster cooperation. Our results highlights the nuanced dual role of constructive agents in shaping cooperation dynamics, emphasizing the necessity of carefully assessing incentive balances in evolutionary game theory.