Grünberg came to Marxism through law, economic history and the socialist debates of Vienna. Historian Rolf Wiggershaus describes his legal studies there under Lorenz von Stein and Anton Menger. The two teachers offered different answers to social inequality. Stein favored reform within capitalism; Menger, a socialist lawyer, challenged private property. Grünberg later studied with economic historian Georg Friedrich Knapp, whose work helped shape his research on the end of peasant dependence in Central Europe.[2] (pp. 21–22)
That training made changes in property and social relations subjects of historical inquiry. It does not by itself establish when Grünberg accepted Marxism. In his own 1924 address [1], he said that he had once doubted the materialist conception of history, the account that gives economic and social relations a central role in historical change. He said later developments had persuaded him to give up those doubts. He did not identify a single event or book as the turning point in that passage.[1] (p. 9)
By 1910 he was editing a journal on the history of socialism and the labor movement. Wiggershaus places that work alongside his teaching and socialist education in Vienna. This was the background he brought to Frankfurt: a legal and historical scholar with a Marxist research commitment, rather than a political position acquired through his appointment to the new Institute .[2] (pp. 22–23)
When Carl Grünberg inaugurated Frankfurt's Institute for Social Research on June 22, 1924, he made its intellectual orientation explicit. He identified himself with Marxism and expected a transition from capitalism to socialism. He proposed to use the Marxist research method in the Institute's work. This was a declaration by its first director, made in a university address, rather than evidence that a socialist transformation had occurred.[1] (p. 9)
Grünberg distinguished his scholarly program from party politics. He treated Marxism as a way to investigate economic and social life and its historical changes. Material interests and social relations belonged at the center of that inquiry. His address therefore provides an original statement of what the Institute's initial Marxist identity meant, before Horkheimer 's later program and the American exile.[1] (pp. 10–11)
His commitment also placed obligations on research. He rejected the claim that investigators could begin without assumptions, but insisted that they subject their starting points to criticism. If empirical inquiry contradicted them, they had to change. He proposed research into the labor movement in its political, trade-union and other forms, its opponents, social policy, and both socialist and nonsocialist theories. The library would collect materials across those fields.[1] (pp. 12–13)
The organization was intended to protect sustained inquiry. Grünberg gave research priority over professional instruction and insisted on strong authority for the director. Within that framework, he defended the freedom of scholarly collaborators and warned against training students merely to repeat a teacher's conclusions. These commitments describe the institution he proposed. Establishing how they worked in practice requires administrative records and the research itself.[1] (pp. 4–7, 14–15)
For the exile story, Grünberg belongs in the account of the Institute's origins. His address explains the first program that later directors inherited and changed. It supplies no evidence of his own work in America, of American recipients adopting the program, or of a single unchanging doctrine running from Frankfurt in 1924 through the Institute's later publications.