Simple Records Support Robust Indirect Reciprocity

TL;DR

This paper introduces a new simple record-based model of indirect reciprocity that supports robust social cooperation in coordination-dominated dilemmas, highlighting the importance of strategic complementarity.

Contribution

It proposes a decentralized record mechanism based solely on individuals' own past behavior, enhancing robustness of cooperation models.

Findings

Simple records support cooperation under strategic complementarity.

Robust cooperation is not achievable in strategic substitutability scenarios.

The model exhibits strong stability properties in suitable social dilemmas.

Abstract

Indirect reciprocity is a foundational mechanism of human cooperation. Existing models of indirect reciprocity fail to robustly support social cooperation: image scoring models fail to provide robust incentives, while social standing models are not informationally robust. Here we provide a new model of indirect reciprocity based on simple, decentralized records: each individual's record depends on their own past behavior alone, and not on their partners' past behavior or their partners' partners' past behavior. When social dilemmas exhibit a coordination motive (or strategic complementarity), tolerant trigger strategies based on simple records can robustly support positive social cooperation and exhibit strong stability properties. In the opposite case of strategic substitutability, positive social cooperation cannot be robustly supported. Thus, the strength of short-run coordination motives in social dilemmas determines the prospects for robust long-run cooperation.