Nash Equilibrium and International Law
A new wave of realists argues that international law loses its normative force because states that ‘follow’ international law are merely participants in a Prisoner’s Dilemma seeking to achieve self-interested outcomes. Such claims are not just vastly exaggerated; they misunderstand the significance of game theory. Properly conceived, international law is a Nash Equilibrium – a focal point for states as they make rational decisions regarding strategy. In domains where international law has the greatest purchase, the preferred strategy is reciprocal compliance with international norms. This strategy is consistent with the normativity of law and morality, both of which are characterized by self-interested actors who accept reciprocal constraints to generate Nash Equilibria and, ultimately, a stable social contract. These agents – ‘constrained maximizers’, as the philosopher David Gauthier calls them – accept constraints in order to achieve cooperative benefits. This article concludes that it is also rational for states to comply with these constraints: agents evaluate competing plans and strategies, select the best course of action, and then stick to their decision, rather than obsessively re-evaluating their chosen strategy. A state that defects when the opportunity arises may reduce its overall payoff as compared to a state that selects and adheres to a strategy of constrained maximization.