Morality and Equality from Rationality Alone - A repeated game approach of contractarianism

This paper highlights the role that equality and reciprocity play in preserving peace and cooperation among individuals with conflicting interests. Following the contractarian tradition, I model a mutually beneficial interaction as a prisoner's dilemma and using repeated game theory, I show that a mutually beneficial joint venture may be undertaken only if the final distribution of incomes is sufficiently egalitarian. From a pre-moral context, the model allows to derive endogenous bounds on the income of each individual that reproduce Moehler (2018)'s weak universalisation principle. Contrasting with the well-known equity-efficiency trade-off, the model also produces an equity-efficiency complementarity.