The Stability Imperative: Why Human Societies Prohibit Infidelity

Why do human societies almost universally prohibit infidelity? This paper proposes an answer grounded in relational dynamics and stability theory rather than morality or evolutionary psychology alone. Using the framework of Relational Emergence Systems (RES) and the Landau-Stuart equation for phase transitions, I argue that infidelity prohibitions emerge as stability-maintenance mechanisms in small-scale human communities constrained by Dunbar's number (approximately 150 individuals). In such communities, pair-bond disruption creates cascading relational perturbations that can destabilize the entire social field. The prohibition against infidelity is not primarily about controlling sexuality but about maintaining the relational coherence necessary for community survival. When the stability parameter β approaches critical thresholds, societies develop norms that suppress high-variance behaviors threatening social coherence. This analysis explains cross-cultural universality, variation in enforcement intensity, and the apparent weakening of infidelity norms in modern large-scale societies where relational perturbations are more easily absorbed.