With Karl Mannheim, Arnold Hauser and Ervin Szabó he was also involved in the Budapest Free School of Humanities, founded by Lukács.
A December 1915 lecture on historical materialism to the Hungarian Philosophical Society criticized economic determinism.
[2] In December 1918 he joined the Hungarian Communist Party and was appointed as editor of Vörös Újság (The Red Journal).
[5] In 1923 he lectured, alongside Lukacs, at the Marxist Work Week, out of which later grew the Institute for Social Research.
A Fellow of the Soviet Academy of Sciences, he worked with Eugen Varga, Stalin's economic advisor.