One of the many problems at the heart of philosophy is the lack of any requirement for logical consistency. Another problem is the lack of empiricism. One can fairly say, therefore, that philosophy - in all its forms - is largely a pre-scientific attempt to answer questions that can only be answered by an entirely different approach. Thus, philosophy (with a very few exceptions) is a waste of everyone's time. The post-structuralists (Lacan, Derrida, Barthes, et al) found themselves in a position where they could generate income and attention by spouting pseudo-philosophical babble, and naturally they took full advantage of the opportunity. No doubt many enjoyable hours were spent filling the impressionable heads of graduate student with empty assertions, and no doubt a not-inconsiderable number of opportunities were thereby generated for teacher-student mating events. But from the perspective of history, nothing was achieved and this is not surprising: we now live in a world in which real things can be accomplished through empiricism, whereas in the entire history of philosophy not a single material output has been produced. At best, half-digested notions have helped the unscrupulous and cynical dress up their primary motivations, but that's hardly an accomplishment of which to be proud.