<<Marxism... Is it a political commitment, an ethical affiliation, a methodological relation, all of them but to what extent? >>
I am coming more and more to the view that the most important issue for Marxism is Ethics. I think theory of knowledge is vital, but it is not knowledge which is really revolutionary. Marx took the development of the bourgeoisie's theory of knowledge to a new height, but it was not in that that lay his revolutionary essence. If we remain at the level of Marx's theory of knowledge (materialism, dialectics, critique of political economy, etc.) we do no more than take bourgeois science forward, even if to a point they can't take it themselves! To go beyond is to be able to live differently, and that it not just a uestion of the nature of knowledge and its limits.
<<discourse. Here I am primarily using it in the Foucauldian sense, discourses creating their own regimes of truth, ...>>
In Ilyenkov's 5th essay <http://home.mira.net/~andy/essay5.htm> he points out what Hegel had done with the subject matter of logic:
"when Hegel formulated a programme for the critical transformation of logic as a science, he posed the task of bringing it ... into correspondence with its real object, i.e. with real thought, with its real universal forms and laws.
"The last-named do not exist in thought simply or even so much as schemas and rules of conscious thinking, but rather as universal schemas of objective thinking that are realised not so much as a subjective psychic act as the productive process that created science, technique and morality. "
I see this as a key to what made Hegel's Logic so powerful.
Now, in the late 19th century, before the rise of "structuralism", we had natural scientists insisting on "sensations" as the subject matter of their science and rejecting concepts indicating something "beyond sensation" and this was what was behind Lenin's famous 1908 polemic. Natural science overcame this one-sidedness and science progressed courtesy of all sorts of so-called metaphysical concepts, though much more self-critically than before.
It seems to me that in "post-strucuralism" we have a kind of "return to the old at a higher level" (if you'll excuse the term!). The writers (especially now the historians and social people) dissolve the structures deemed to be "beyond" the text and want to make the subject matter of their science(s) just the text.
This is probably an exaggeration of anything most of them would actually say. Nevertheless, the constant talk of "text" and "discourse" seems to carry with it the same rejection of what Hegel would have called "real thought" and what Marx may have called "the totality of social relations" or "practical activity".
I have to say I think that Foucault has something. He is FORCING us to be more precise. But if power rests on nothing but "discourse" and "text" we are in deep shit.