The main goal of this paper is to offer a reading of Reinhart Koselleck's work as an ally of critical theory. My contention is that, despite customary accusations of Koselleck being an anti-Enlightenment historian detrimental to social criticism and emancipatory politics, his investigations on the semantic fabric of modern society may actually expand our resources for the critique of domination. In order to make this argument plausible, I reconstruct some antinomies that are at the basis of Koselleck's work (state/society, language/reality, experience/expectation) and discuss their critical potential. This analysis shows that, rather than a rejection of the spirit of critique, Koselleck contributes to the temporalization of the practice of critique as such: namely, a clarification of the contradictions and potentials of a reflexive practice imbued in the struggle between the need to comprehend the world as it is and the right to experiment with other forms of life.