Coevolution of Reciprocity and Trust
Technical Report, pp.1-45, 2026
- Publication Type: Other Publication / Technical Report
- Publication Date: 2026
- Page Numbers: pp.1-45
- Open Archive Collection: AVESIS Open Access Collection
- Galatasaray University Affiliated: Yes
Abstract
This paper provides an analytical model to study the co-evolution of trust and trustworthiness in a game-theoretic framework. Trust reflects an agent’s belief that other agents cooperate in a two-stage prisoner’s dilemma game. Altruist agents receive a utility from their opponents’ payoffs, while selfish agents do not consider other players. We also model the third type of agents using Cox et al.’s (2016) concept of vulnerability-responsiveness. A second-mover vulnerability-responsive agent feels responsible for a first-mover agent who cooperated; therefore, she cooperates if her opponent cooperated. However, she does not cooperate if her opponent does not. Then, we use agent-based modeling to test our analytical solutions. We find a very complex relationship between trust and trustworthiness. An increase in trust creates a suitable environment for malicious agents. Hence, a cyclic relationship may emerge.