Marxism and philosophy
The philosopher Étienne Balibar wrote in 1996 that "there is no Marxist philosophy and there never will be; on the other hand, Marx is more important for philosophy than ever before." So even the existence of Marxist philosophy is debatable (the answer may depend on what is meant by "philosophy," a complicated question in itself). Balibar's remark is intended to explain the significance of the final line of Karl Marx's 11 Theses on Feuerbach (1845), which can be read as an epitaph for philosophy: "The philosophers have only interpreted the world, in various ways; the point is to change it".
If this claim (which Marx originally intended as a criticism of German Idealism and the more moderate Young Hegelians) is still more or less the case in the 21st century, as many Marxists would claim, then Marxist theory is in fact the practical continuation of the philosophical tradition, while much of philosophy is still politically irrelevant. Many critics , both philosophers outside Marxism and some Marxist philosophers, feel that this is too quick a dismissal of the post-Marxian philosophical tradition.
Much sophisticated and important thought has taken place after the writing of Marx and Engels; much or perhaps even all of it has been influenced, subtly or overtly, by Marxism. Simply dismissing all philosophy as sophistry might condemn Marxism to a simplistic empiricism or economism, crippling it in practice and making it comically simplistic at the level of theory.
Nonetheless, the force of Marx's opposition to Hegelian idealism and to any "philosophy" divorced from political practice remains powerful even to a contemporary reader. Marxist and Marx-influenced 20th century theory, such as (to name a few random examples) the critical theory of the Frankfurt School, the political writing of Antonio Gramsci, and the neo-Marxism of Fredric Jameson, must take Marx's condemnation of philosophy into account, but many such thinkers also feel a strong need to remedy the perceived theoretical problems with orthodox Marxism.
Such problems might include a too-simple economic determinism, an untenable theory of ideology as "false consciousness," or a simplistic model of state power rather than hegemony. So Marxist philosophy must continue to take account of advances in the theory of politics developed after Marx, but it must also be wary of a descent into theoreticism or the temptations of idealism.
Étienne Balibar claimed that if one philosopher could be called a "Marxist philosopher", that one would doubtlessly be Louis Althusser:
Althusser proposed a 'new definition' of philosophy as "class struggle in theory"... marxism had proper signification (and original "problematic") only insofar as it was the theory of the tendency towards communism, and in view of its realization. The criteria of acceptation or rejectal of a 'marxist' proposition was always the same, whether it was presented as 'epistemological' or as 'philosophical': it was in the act of rendering intelligible a communist policy, or not." (Ecrits pour Althusser, 1991, p.98).
However, "Althusser never ceased to put in question the images of communism that Marxist theory and ideology carried on: but he did it in the name of communism itself." Althusser thus criticized the evolutionist image which made of communism an ultimate stage of history, as well as the apocalyptic images which made it a "society of transparence", "without contradiction" nor ideology. Balibar observes that, in the end, Althusser enjoined the most sober definition of communism, exposed by Marx in The German Ideology: Communism is "not a state of the future, but the real movement which destroys the existing state of being.".