Abstract

This paper revisits the classical use of Nash bargaining to model the social contract by addressing the two central objections of John Rawls: the influence of threat advantage and the multiplicity of bargaining solutions. We introduce an innovative framework that applies an optimific moral rule, termed Pure Strategy Deontarianism (PSD), to the Nash Bargaining Game. PSD is a synthesis of Kantian deontology and utilitarian altruism. By applying PSD to the Nash bargaining game, we demonstrate how rational agents can normatively select maximal disagreement points as rights, thereby equalizing bargaining power and aligning with Rawls’ first principle of justice. Furthermore, we derive the Kantian solution (KS) for surplus division from PSD, and prove that KS satisfies five key axioms of fairness - symmetry, Pareto optimality, scale invariance, strong monotonicity, and contraction consistency. We argue that KS is an ideal solution, since it does not always lie in the feasible set and so serves as an ideal benchmark that practical approximations like the Nash Bargaining Solution can approach. This synthesis not only offers a robust theoretical resolution to Rawls’ objections but also provides a structured methodology for integrating moral considerations into game-theoretic models of justice.