I don’t believe that there is "a specifically philosophical writing", a sole philosophical writing whose purity is always the same and out of reach of all sorts of contaminations. And first of all for this overwhelming reason: philosophy is spoken and written in a natural language, not in an absolutely formalizable and universal language. That said, within this natural language and its uses, certain modes have been forcibly imposed (and there is a relation of force) as philosophical. The modes are multiple, conflictual, inseparable from the philosophical content itself and from its "theses". A philosophical debate is also a combat in view of imposing discursive modes, demonstrative procedures, rhetorical and pedagogical techniques. Each time philosophy has been opposed, it was also, although not only, by contesting the properly, authentically philosophical character of the other’s discourse.
Jacques Derrida, "Is There A Philosophical Language?". In: Points . . . Interviews, 1974-1994