Thucydides, International Law, and International Anarchy

Abstract

Ancient Greek city-states existed in a world that was essentially bereft of international law. This lack of international law had profound effects on international relations. The anarchic environment encouraged the development of heavily militarized and diplomatically aggressive societies. The prevalence of such societies, combined with the absence of any overarching authority over them, made wars between polities common. Faced with a conflict of interest with another polity, every government independently decided what constituted justice for itself, and—in the absence of international law--all governments had to be ready to use violence or the threat of violence to enforce that view of justice. Hellenic intellectuals—most famously Thucydides, but including Aristotle and Demosthenes--reacted to the anarchy by hypothesizing that interstate relations were determined above all by relations of power. Thucydides expressed this view of power-politics in international life most clearly in what is called the Melian Dialogue (Thuc. 5.84-116). This essay also emphasizes Thucydides’ analysis of the outbreak of the Peloponnesian War (1.23), and underlines the nature of what he considered “the truest cause” (1.23.6) of that devastating conflict, demonstrating that the shift in the balance of power (ibid.) expressed itself in the specific “quarrels and disputes” of 1.23.5, so that there is no contradiction between the two Thucydidean explanations.