A scientist once complained to me that “the purpose of teaching philosophy is only to reproduce the discipline”. Except perhaps this is precisely the point.
Assumed, of course, in that statement is the implication that philosophy does not “progress”—we still read Aristotle after a couple millennia, whereas a discipline such a science doesn’t bother with such charming antiquarianism. Instead of re-hashing all the old arguments about how to define “progress”, there is perhaps an easier answer: the task of contemporary philosophy—insofar as it is not a discipline—is the construction of meta-conceptual field.
This indicates a division in the practice of philosophy. As a discipline (or, better: as an institution), philosophy is constituted at the nexus of the various histories, material institutions, languages, and political conditions that have resulted in what is the equivalent of a literary canon or, roughly, what Foucault would call a “discourse” and Bourdieu would call a “field”. This is, essentially, the “ideological apparatus” of philosophy (I’d prefer to call it the “ideology” of philosophy except that one should not confuse these structures with any particular content of philosophy).
On the other hand, we used to say that philosophy is that discipline that is self-reflective. The trouble with this formulation—other than apparently drawing students with a predilection for “existential brooding” to philosophy departments—is that in being reflective, if it is successful, philosophy can no longer be a discipline. This practice must constitute an exception to the conceptual field.