Latour, Kristeva, Derrida, Baudrillard, etc

[CountArach]

Hmm, I'm not exactly sure. It might be that he means to say that outside of discourse, nothing real exists in the world, but I might be confusing him with someone else here.

I belive this is the crux of it, or at least Post-Structuralism in general (that is to say, the same philosophy that most of the above authors are generally accepted to be founding members of).

Does he go further(ie making claims about the meaning of actual knowledge, not just terms) than that, like Latour does? And if he does, what is your opinion of the validity of such thought?

That's really something much more associated with Foucault and Epistemiology than Derrida though my knowledge of Derrida is much more limited. Derrida was more linguistically focussed where Foucault's thought was founded on a discussion of knowledge (and the methods for 'discovering' it) as a discursively-created thing with no intrinsic value.