For "many Marxian libertarian socialists, the political bankruptcy of socialist orthodoxy necessitated a theoretical break. This break took a number of forms. The Bordigists and the SPGB championed a super-Marxian intransigence in theoretical matters. Other socialists made a return 'behind Marx' to the anti-positivist programme of German idealism. Libertarian socialism has frequently linked its anti-authoritarian political aspirations with this theoretical differentiation from orthodoxy. [...] Karl Korsch [...] remained a libertarian socialist for a large part of his life and because of the persistent urge towards theoretical openness in his work. Korsch rejected the eternal and static, and he was obsessed by the essential role of practice in a theory's truth. For Korsch, no theory could escape history, not even Marxism. In this vein, Korsch even credited the stimulus for Marx's "Capital" to the movement of the oppressed classes".