Morgenthau is usually believed to be a modernist theorist of international relations. His Realism is taken to present a scientific pattern of human political behavior. Yet Morgenthau himself was a critic of “scientific” models for the explanation and prediction of human behavior. This article, in line with the body of work that criticizes the usual understanding of Morgenthau, shows how his thought was influenced by thinkers whose ideas were in some significant respects against the modern naturalist philosophy of social science. His philosophical anthropology, his ontology with its emphasis on the complex and contingent nature of international life, his criticism of Behavioralism in IR, his hermeneutic approach to knowledge, and the way in which he saw the role of ethics in international life would all suggest that he was far from being a modernist thinker and that, at the same time, he avoided the extremities of postmodernism.