Debates in and around Critical Theory during the past three to four decades highlighted the need to take a new look at its classical foundations. Developments in both continental and analytic philosophy, for instance the linguistic and pragmatic turns, which recast the question of knowledge in the mould of language and action in keeping with transformations in social life, made available a new philosophical basis. This prompted a clarification of the subterranean connection between Critical Theory and pragmatism, which in turn led to an elaboration of this relation. Charles S. Peirce emerged here as the central figure, the ‘American Kant’, who kept alive enough potential contact points to allow a fruitful articulation of Critical Theory and pragmatism. From here the attention then shifted towards Critical Theory’s own classical tradition in which questions were raised about the taken-for-granted understanding of these roots. Most immediately, the focus fell on the left-Hegelians, the first generation after Hegel, among whom the towering figure of Marx remained in his dominant position but was now joined by two others from the same generation who had not often been recognized as belonging to this same tradition, namely Peirce and Kierkegaard. By the mid1980s, this debate about the Hegelian left, the most characteristic heritage of Critical Theory, forced the discussants to take yet a further step back in order to re-investigate the question of the relation between Kant and Hegel as well as the relation of Critical Theory to Kant and Hegel. Like the linguistic and pragmatic turns, like the relation with pragmatism and like the status of the left-Hegelian heritage, the question of the theoretical sense of the relation between and to Kant and Hegel has remained a matter of reflection, debate and elaboration into the twenty-first century.