How do Foucault, Butler, and other Post-moderns differ with these materialist principles ?
^^^ Let me suggest a third level of materialist determination, derived from the dialectic between the Marxists and the structuralists/post-moderns, et. al.
The superstructure is _determined_ when it is changed. It is changed only rarely, in revolutions. Revolutions are rare, by definition; in "punctuations". Most of the time of history, society is in convention or "equilibrium", not revolution. In conventional times, it is the superstructure of ideas that determines individual peoples' conduct. There is determination by ideas, ideology. Thought determines the actions by "beings".
Only when practice of ideas comes into such crisis as to create a system changing contradiction in the system of ideas ( the cultural "grammar" in Levi-Straussian structural anthropology) does a revolution arise.
This system and convention changing crisis and contradiction between practice and ideas is what Marx describes in his famous passage below.
"At a certain stage of their development, the material productive forces of society come in conflict with the existing relations of production, or — what is but a legal expression for the same thing — with the property relations within which they have been at work hitherto. From forms of development of the productive forces these relations turn into their fetters.
Then begins an epoch of social revolution. With the change of the economic foundation the entire immense superstructure is more or less rapidly transformed. In considering such transformations a distinction should always be made between the material transformation of the economic conditions of production, which can be determined with the precision of natural science, and the legal, political, religious, aesthetic or philosophic — in short, ideological forms in which men become conscious of this conflict and fight it out. Just as our opinion of an individual is not based on what he thinks of himself, so can we not judge of such a period of transformation by its own consciousness; on the contrary, this consciousness must be explained rather from the contradictions of material life, from the existing conflict between the social productive forces and the relations of production. "
Preface of A Contribution to the Critique of Political Economy
http://www.marxists.org/archive/marx/works/1859/critique-pol-economy/preface-abs.htm
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