We could describe the history of the most interesting currents of post-Hegelian philosophy as a movement towards detranscendentalizing the knowing subject, in one version or another. But we would not include Hegel in that movement in spite of the fact that nobody did more to set the stage for it. Hegel was the first to put the transcendental subject back into context and to situate reason in social space and historical time. [Wilhelm von] Humboldt [176-1835], [Charles Sanders] Peirce [1839–1914], [Wilhelm] Dilthey [1833–191], [John] Dewey [1859-1952], [Ernst] Cassirer [1874-1945], and [Martin] Heidegger [1889–1976] are among those post-Kantian philosophers who were or, if we think of [Ludwig] Wittgenstein [1889-1951], could have been influenced by Hegel in their attempts to treat language, practice and historical forms of life as dimensions of the symbolic embodiment of reason. In his Jena period, Hegel did in fact introduce language, work and symbolic interaction as media through which the human mind is formed and transformed. Considering Hegel’s notion of spirit, it is difficult to understand why we are hesitant to describe Hegel as a protagonist of detranscendentalization. One might suppose, perhaps, that his rationalism separates him from the following generations. But though linguistic philosophy, pragmatism, and historicism undermined the status of a noumenal subject beyond space and time, they do not necessarily lead to the kind of contextualism that has given rise to the familiar debates concerning the ethnocentricity or incommensurability of rationality standards. [my emphasis; links added]Habermas writes further about Hegel's situating of reason in history:
The choice of the term ‘Geist’ [for "Spirit"] reminds us of the origin and rise of the ‘Geisteswissenschaften’ after 1800. Though the great works of the founding fathers – of Leopold Ranke [1795-1886], Jakob and Wilhelm Grimm [1785-1863 and 1786-1859, respectively], Carl von Savigny [1779-1861] and the others had not yet been published, a new historical consciousness and a philosophy of historicism already formed a background for the emerging disciplines that would revolutionize the classical concept of the humanities in the course of Hegel’s life-time. They were already manifest in the earlier works of Justus Möser [1720-1794], Gottfried Herder [1744-1803] and Johann Georg Hamann [1730–1788], of Friedrich Schleiermacher [1768-1834], Wilhelm v. Humboldt, and Friedrich Schlegel [1772–1829]. With this historical mode of thought, three dimensions gained philosophical significance for the first time: (a) the historicity of the human mind, (b) the objectivity of symbolic forms and (c) the individuality of actors and their historical contexts. [my emphasis in bold; links added]Habermas is the best-known figure of what came to be known as the "second generation" of the Frankfurt School, who framed their perspective as "critical theory."
Their philosophical approach is heavily rooted in the classical German philosophical tradition, of whom Kant and Hegel were the leading figures.
Axel Honneth, a "third generation" Frankfurt School thinker and, as head of the Insitute for Social Research, the formal head of the "Frankfurt School," said in an interview in 1993 ("Critical Theory in Germany Today: An Interview with Axel Honneth," Radical Philosophy 65:1993), "in all the productive approaches of Critical Theory: it's always an ongoing tension between Kant and Hegel. I would say that the most productive element - one of the most productive elements of the Critical Theory tradition - is to be unable to decide which side you are on here." (my emphasis)