Moral Sentiments in the Iterated Prisoner's Dilemma and in Multi-Agent Systems

We present a simulation of a society of agents where some of them have moral sentiments towards the agents that belong to the same social group, using the Iterated Prisoner's Dilemma as a metaphor for the social interactions. Besides the well-understood phenomenon of short-sighted, self-interested agents performing well in the short-term but ruining their chances of such performance in the long run in a world of reciprocators, the results suggest that, where some agents are more generous than that, these agents have a positive impact on the social group to which they belong, without compromising too much their individual performance (i.e., the group performance improves). The inspiration for this project comes from a discussion on Moral Sentiments by M.Ridley. We describe various simulations where conditions and parameters over determined dimensions were arranged to account for di erent types and compositions of societies. Further, we indicate several lessons that arise from the analysis of the results and comparison of the diferent experiments. We also relate this work to our previous anthropological approach to the adaptation of migrant agents, and argue that allowing agents to possess suitably-chosen emotions can have a decisive impact on Multi-Agent Systems. This implies that some common notions of agent autonomy (and related concepts) should be reexamined.