An enormously fruitful suggestion from Hilary Putnam’s recent Jewish Philosophy as a Guide to Life (Indiana UP, 2008). Discussing I And Thou, Putnam says that
There is nothing outside the text. If the previous sentence is in a text then it refers only to an element of that particular text; it establishes nothing whatever about truth-assertions as such. So too for Foucault. If truth indeed is power then is that an assertion of a truth? If so it is not true but only an exercise of domination. But if it is true then at least one truth-assertion stands outside relations of power; namely, that one; and if one why not more?
Perhaps, though, what Putnam suggests about Buber is true also of Derrida and Foucault. They are not describing how truth-assertions operate. They are exhorting their readers to think of them that way.