Herbert Marcuse, answered from the texts and cited to the page.
The 1928-1932 essays attempted to ground historical materialism in Heideggerian categories — historicity as the temporal structure of human existence, concrete philosophy as the demand that thought be situated in the historical moment of its production, the radical act as the existential ground of revolutionary praxis.1 The synthesis was philosophically productive. Hegel's Ontology and the Theory of Historicity (1932) read the Science of Logic through Heidegger to recover the dialectic as a movement of historicity in Being itself, not as the formal-logical exercise the neo-Kantian reception had reduced it to.
The discovery of Marx's Economic and Philosophical Manuscripts of 1844 in 1932 displaced Heidegger as the philosophical lodestar — "New Sources on the Foundation of Historical Materialism" (1932) is the announcement of the Hegelian-humanist Marx the Frankfurt Institute would develop.2 The break with Heidegger came in 1933 over Nazism. The 1947 letter to Heidegger — written from Washington after the war, holding him to account for the rectoral address and his failure to publicly disavow National Socialism after 1945 — formalized the break that the philosophical work had already begun.3
Heidegger's politics did not retroactively invalidate the philosophical work the early synthesis had done. What survived into the later work — the Great Refusal contains elements of the radical act; the late aesthetic dimension preserves the categories of concreteness and historicity the early essays developed — was always Marxism's own resource that the Heideggerian apparatus had helped articulate, not a covert Heideggerianism.4
At the same time that he was writing essays synthesizing Marxism and phenomenology, Marcuse The text stressed the importance of the categories of life and history in Hegel and contributed to the revival of interest in Hegel that was taking place in Europe. In 1932, as the Nazis came to power, the situation in Freiburg became precarious for Marcuse.Introduction: Herbert Marcuse and the Vicissitudes of Critical Theory, pp. 3–4
Perhaps this provisional review of the Manuscripts will suffice to show the inadequacy of the familiar thesis that Marx developed by moving from providing a philosophical to providing an economic basis for his theory.Heideggerian Marxism, p. 87
The Hegel-Marx question is not explicitly addressed, although I hope that this interpretation will throw some new light on this connection. Neither does this work contain a critical discussion of Heidegger nor is it intended to do so.Hegel's Ontology and the Theory of Historicity, pp. xii–xiii
Rather, Marx goes back to the problems at the root of Hegel's philosophy (which originally determined his method), independently appropriates their real content, and thinks the philosophy through to a further stage.Heideggerian Marxism, pp. 87–88
The standing question is whether the early synthesis should be read as the legitimate philosophical formation of a Marxist whose break with Heidegger over Nazism was clean (Kellner's reading; the Wolin / Abromeit defense in publishing the 2005 anthology), or as a philosophically compromised period that the move to the Frankfurt Institute in 1933 decisively superseded (the older Anglophone reading that treated Reason and Revolution as the first "mature" work). The contested ground in the contemporary scholarship is whether Richard Wolin's Politics of Being line — which holds that Heidegger's 1933 turn raises hard questions about anyone who continued to draw on his philosophy after 1933 — applies to a Marcuse who in fact broke with Heidegger over precisely the politics Wolin foregrounds. The position is the modal- philosophical reading: the early work stands as Marcuse's own, acknowledged as part of the corpus, with the political break formalized and held to.