In recent years, a number of IR theorists have argued in favor of a “practice turn” for the study of international politics. According to this line of thought, a more direct focus on international practices can reinvigorate the study of world politics by resolving prevalent dichotomies in the field and by suggesting new avenues of research. In this paper, I turn a skeptical eye on this new and important line of research, and I claim that as it currently exists practice theory does not possess the conceptual or theoretical tools to capture the idea of political legitimacy in world politics. Political legitimacy is a central theoretical construct in modern IR scholarship, providing theorists with an important means to conceptually represent the relationship between moral ideas and stable political institutions. I claim that the idea of political legitimacy poses a significant conceptual problem for the practice turn in IR theory: on most accounts, legitimacy seems to be an eminently mentalistic phenomenon, largely dependent upon conscious mental acts of moral judgment rather than embodied social practices or skills. In order to capture the idea of political legitimacy, practice theory is in serious need of refinement, and in this paper I develop a strategy for overcoming this important theoretical impasse. In particular, I argue that practice theorists need to develop a better understanding of the relationship between the mentalistic aspects of social judgment that are the essence of legitimacy and embodied social practices that form the conceptual centerpiece of practice theory. I argue that they can do this by re-conceptualizing legitimacy as a social process that involves thinking through practice. On this view, the internal mental process of formulating and expressing moral judgments is bound up with embodied social practices; although moral judgments are reducible to individual mental states, they are brought forth into the political sphere through embodied processes of deliberating with others. To show how this practice-theoretic re-conceptualization of legitimacy can increase our knowledge of international politics, I analyze the diplomatic processes that led to the creation of the International Criminal Court in 1998. I focus on how the various modes and types of diplomatic practices that were used in the pre-Rome Statute negotiations influenced the types of moral judgments that diplomats made in deliberating publicly with each other. Not only does this paper promise to show how practice theorists can capture the idea of international legitimacy, but in addition it promises to shed light on how variations in international diplomatic practice affect the use of moral judgments in political deliberation.
