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. [Andy]
I think you misunderstand what post-structuralism [Derrida in particular] is all about.
There is an important question at issue here which I think it would be good to clarify.
In several of your posts, [there's one in particular but I can't find it on my new computer] you talk as if materialism involves the view that there is an objective world and it is this objective world that science studies. Is this your position ? Is there such a thing as 'objective' knowledge of an objective [that is one existing independently of us] world?
One of Derrida's main arguments, one he takes directly from Heidegger, is directed against precisely this idea. In his words, the idea that there is something beyond the text is in fact itself a text.
I think he is absolutely correct in this and I also think this was Marx's view.
Whether the planet would still be here if all us humans disappeared tomorrow is I suppose one question that could be debated. However this is NOT an issue that any philosopher has ever wasted more than two minutes on and quite rightly so - it is NOT this question that separates classical materialism from classical idealism. All the debates in philosophy, including the more recent contributions of post-structuralists, have nothing whatsoever to do with the question of whether there is or is not, in 'reality', an 'objective' world out there, somewhere.
The real question, and it is one of Heidegger's major contributions to have posed this question starkly, is - what follows when human beings adopt the attitude that there is an objective world that can be studied by a subject removed from this world, the attitude that characterises Modernity and which is expressed above all in the philosophy of Descartes? What kind of relationship do we take up towards the world when we remove ourselves from it in this way and see it as an 'object' of study?
For the point is that there is no 'objective' world devoid of us - we are beings IN this world. Therefore to see the world as objective is in fact to take up certain stance towards this world, our world, it is to 'be in the world' IN A CERTAIN WAY, or as Derrida would put it - it is a text. For Heidegger this leads directly to viewing the world as a 'standing reserve' of raw material ready for us to put to use for our 'subjective' ends, the ends of beings who as subjects stand opposed to the objectivity of the world. Heidegger's goal was to demolish the rootless 'subjectivity' or nihilism that for him is a direct consequence of the 'objectivity' of the scientific world view, of Modernity.
Surely Marx's approach is the same. To view society 'objectively' and study it through the science of political economy is in fact an expression of our alienation from this society. This alienation may well be an objective fact, and is indeed so, but this defines precisely the problem that needs to be overcome through revolution. Like Heidegger, Marx can be understood in terms of the need to overcome the opposition between subject and object that defines the scientific method. I think Marx and Heidegger are at their closest in this comment by Marx,
'Natural science will lose its abstractly material - or rather its idealistic - tendency, and will become the basis of human science...Natural science will in time incorporate into itself the science of man, just as the science of man will incorporate into itself natural science ; there will be ONE science'. [MECW Vol 3 quoted in Cyril's book]
ONE science - the science of beings 'in the world', not of beings estranged from it.
To ask if there is a world beyond the one we live in, an 'objective' world in this sense, is a similar question to asking is there such a thing as a society beyond the people who make it up. That such a question is even possible is surely the point to be taken on board. In other words the question is not whether there is an objective world, but rather how is it that such a question could even arise ? What does the existence of this question as a question tell us about us, about the way we live as the 'beings in the world' we are.
There is no 'objective' world, nothing beyond the text. There is however our world, the one we are engaged in, the one that is our text. This is Derrida's point.