Abstract

This article posits that Renaissance humanism is a foundational antecedent to both Realist and Liberal traditions in international relations and international law, clarifying the enduring tension between state power and normative obligation. By reorienting political thought around human reason, secular authority, and historical consciousness, humanist thinkers reshaped the epistemic and normative foundations of political and legal order. Realism and Liberalism thus emerge not as purely modern paradigms but as divergent trajectories within a shared humanist genealogy that continues to shape debates on power, sovereignty, rights, and legal duty. Contrary to accounts situating the origins of modern international law in the 16th and 17th centuries, particularly the Peace of Westphalia, this article shows that earlier intellectual developments anticipated tensions between power and normative constraint. Drawing on Thucydides’ 5th century BCE account of the Peloponnesian War and its reception in Renaissance humanism, it traces themes of moral responsibility, empirical reasoning, civic virtue, and principled judgment alongside reflections on competition, fear, and strategic calculation. These strands prefigure liberal commitments to law, accountability, and human dignity, and realist insights into power, interest, and prudence. The analysis then extends to contemporary power politics. The 2026 United States intervention in Venezuela illustrates the enduring interplay between ethical reasoning and coercive strategy. Doctrinal analysis identifies violations of the prohibition on the use of force, non-intervention, and sovereign equality, yet cannot fully explain why such breaches occur or how they are justified. Integrating international relations theory with legal analysis highlights the continuing value of humanist philosophy in evaluating state conduct and for illuminating the persistent tension between moral obligation and strategic necessity in international law.