Robert W. Cox's dictum that ‘(t)heory is for someone and for some purpose’ (emphasis in the original) is said to be the most-quoted line in International Relations (IR) theory. Yet whilst this spurred a revolution in critical thinking in IR, it echoed a far older conception of Critical Theory advanced by Max Horkheimer in the 1930s that claimed there is ‘no theory of society … that does not contain political motivations'. Both sentiments emphasize the relation between knowledge and human interests, and yet both formulate two distinct—though allied—ways of approaching ‘critical’ theorizing. In order to understand the similarities and differences in their approaches, this paper draws out three loci of difference between Cox and Horkheimer regarding the question of emancipation: (i) the epistemological relation between ‘critical’ and ‘Problem-Solving’ (Cox) or ‘Traditional Theory’ (Horkheimer); (ii) the emphasis placed on transformation and historical process; and (iii) the importance of intersubjectivity in how each approach emancipation. It is argued that by actively combining critical (dialectical) approaches across the social sciences, broadening human agency through civilizational dialogue, and retaining a commitment to emancipatory (and visionary) political futures based on human association, that Critical International Theory can maintain ongoing relevance in IR.