concerning "socialism in one country", was not a "mechanist" per se, but was seen as an ally.) The mechanists (A.K. Timiryasev, Axelrod, Skvortsov-Stepanov...), came mostly from scientific backgrounds, claimed that Marxist philosophy found its basis in a causal explanation of Nature. They upheld a positivist interpretation of Marxism which asserted that Marxist philosophy had to follow the natural sciences. Stepanov thus wrote an article flatly titled "The Dialectical Understanding of Nature is the Mechanistic Understanding". To the contrary, "dialecticians", whose background was Hegelian, insisted that dialectics could not be reduced to simple mechanism. Basing themselves mainly on Engels' Anti-Dühring and Dialectics of Nature, they maintained that the laws of dialectics could be found in nature. Taking support from the theory of relativity and quantum mechanics, they responded that the mechanists' conception of nature was too restricted and narrow. Deborin, who had been a student of Georgi Plekhanov, the "father of Russian Marxism", also disagreed with the mechanicists concerning the place of Baruch Spinoza. The latter maintained that he was an idealist metaphysician, while Deborin, following Plekhanov, saw Spinoza as a materialist and a dialectician. Mechanism was finally condemned as undermining dialectical materialism and for vulgar evolutionism at the 1929 meeting of the Second All-Union Conference of Marxist–Leninist Scientific Institutions. Two years later, Stalin settled by fiat the debate between the mechanist and the dialectician tendencies by issuing a decree which identified dialectical materialism as the philosophical basis of Marxism–Leninism. Henceforth, the possibilities for philosophical research independent of official dogmatics virtually vanished, while lysenkoism was enforced in the scientific fields (in 1948, genetics were declared a "bourgeois pseudoscience"). However, this debate between "mechanists" and "dialecticians" would retain importance long after the 1920s. Otherwise, David Riazanov was named director of the Marx-Engels Institute, which he had founded, in 1920. He then created the MEGA (Marx-Engels-Gesamt-Ausgabe), which was supposed to edit Marx and Engels' complete works. He also published other authors, such as Diderot, Feuerbach or Hegel. Riazanov was however excluded from any political functions in 1921 for defending trade unions' autonomy. During the Fifth Comintern Congress, Grigory Zinoviev condemned for "revisionism" the works of Georg Lukács, History and Class Consciousness (1923) and of Karl Korsch, Marxism and Philosophy. History and Class Consciousness was disavowed by its author, who made his self-criticism for political reasons (he thought that, for a revolutionary, being part of the party was the priority). It became however a