This article examines Habermas’s critique of Schmitt’s Großraum (large space) theory in light of Kant’s concept of perpetual peace. Habermas accepts Kant’s idea of perpetual peace and revises it into a theory of world order suited to contemporary contexts and endowed with a cosmopolitan dimension. In his view, Schmitt’s Großraum theory, as a conception of world order, attempted to preserve plurality and resist a unipolar universal order; thus, his theory stands in direct opposition to Kant’s cosmopolitan position. In addition, Habermas points out that although both Schmitt’s Großraum theory and Kant’s idea of peace reject hegemonic unilateralism, the former, because of its categorical rejection of universal moral values, may be used in contemporary contexts to justify discourses opposing human rights and democracy in the context of the “clash of civilizations”.