If the realist tradition has underappreciated the formalizable quality of Thucydides’ scientific investigations, neorealist teachers and writers have generally failed to see the normative and dramatical features of Thucydides’ political science, each an expression of his dialectical epistemology and ontology. Nicholas Rescher’s partial formalization of dialectics as a controversy-oriented approach to knowledge cumulation and Kenneth Burke’s dramaturgical approach to textual understanding are both shown to fit Thucydides’ argumentation in the Melian dialogue. Thus argumentation produces new knowledge about the inner determinants of Athenian imperialism; simultaneously it dramatically reveals the constituting practical rationale of Athenian actions to be unjust. Once Thucydides’ determining essences of power politics are properly uncovered, their false eternal, mathematical necessity can be appropriately criticized. A case is thus suggested for a neoclassical polimetrics more fundamentally grounded in political argumentation about practical choices in particular contexts than in ahistorical laws, inductive statistics or deductive mathematics.