There isn’t, to my knowledge, any attempt at recovering this genetic link between political theology and IR theory, and this is what my current work is trying to address. There are, here and there, some treatments of Schmitt’s influence on IR scholars (I think in particular of Martti Koskenniemi’s wonderful book on the history of international law, or William Scheuerman’s Carl Schmitt: The End of Law), besides a couple of articles or studies about the renewed cultural currency of Christianity in postwar academic debates. But a systematic analysis is missing.

Regarding Morgenthau, Jonathan has a point: a Jewish émigré scholar, Morgenthau may at first sight appear as an exception in the cenacle of Christian realists that promoted the development of a theory of international relations in the 1950s. But what matters here is not so much his Jewish identity – largely ascribed to him from outside, in a period of intense anti-Semitism – than his peculiar intellectual trajectory. On the Weimar political and cultural scene, a critic of liberalism who was not attracted to Marxism – and Morgenthau was definitely not – tended to side with the more conservative and anti-liberal forces. It is hard to ignore Morgenthau’s early intellectual proximity with Carl Schmitt. In retrospect, the extent of this hidden dialogue is stunning, as it ranges from Morgenthau’s direct influence on the definition of the political in the third edition of The Concept of the Political (a definition cut and pasted from Morgenthau’s thesis without any other form of acknowledgements than a private letter), to his critique of international law, framed in explicit reference to Schmitt and ominously published in 1933, or more generally the “decisionist” view of statesmanship that pervades Morgenthau’s later writings. This could be written off as a post facto intellectual reconstruction of course, was it not for the way Morgenthau was perceived by his like-minded IR colleagues in the United States. It is very telling that his work was explicitly regarded – and praised – as “political theology” by his disciple Kenneth Thompson, himself a self-avowed Christian realist. As late as 1979, Morgenthau still posited the existence of a universal “moral order,” adding that, in his view, “it is impossible to postulate a plausible moral code without a theological foundation.” The role of Schmitt as a contemporary mediator with the tradition of counterrevolutionary Catholicism and more generally with political theology should not be understated either, as the early proponents of IR theory often conceive explicitly the new discipline as a reaction against the tradition of Enlightenment rationalism and its blind faith in progress and human perfectibility that had inspired the peace movement and the hopes placed in international law.

One other question for you: As a Jewish émigré scholar, Morgenthau seems on the face of things to represent a possible exception to the “Christian realist” identity of the group you discuss. What do you think?