Exit Rights, Free Movement Alliances, and Game-Theoretic War Deterrence: A Formal Model of Conflict Prevention through Institutional Design

This paper presents a formal game-theoretic model in which states are prohibited from blocking citizen emigration during wartime, and members of a free movement alliance grant each other unconditional exit and entry rights. Philosophically, the model formalizes and extends Immanuel Kant (1795) Third Definitive Article of Perpetual Peace from a peacetime principle to a wartime deterrence institution. We derive Nash equilibria for war and peace, showing that open exit rights during wartime reduce war incentives by endogenizing population loss (brain drain) as a cost of aggression. The model identifies a selectorate boundary condition, suggesting the mechanism is most effective for democracies and hybrid regimes.