In this article I will explore the paradoxical relationship between anarchism and realism in International Relations (IR) theory. I will do this in an oblique way by uncovering an uncomfortable complicity shared by that existentialist and heretical realist, Carl Schmitt, with his ideological archenemies the anarchists. In their diametrically opposed positions on the state, both Schmitt and the anarchists reveal the absolutism of the state in the sovereign moment of exception, and its reliance on a figure of anarchy which at the same time destabilises it, blurring the division between inside and outside and opening up a genuinely revolutionary moment. Here the notion of anarchy is used to deconstruct realism, while at the same time suggesting a move beyond anarchism itself towards a post-foundationalist anarchism or 'postanarchism'. Anarchy reveals the contingency and inconsistency of hegemonic identities in IR, as well as the autonomy of the political which is vital to understanding contemporary movements of resistance to statism and capitalism.