The article analyses Habermas' interpretation of Foucault in the Philosophical Discourse of Modernity and argues that the former misunderstands the Foucaultian project of genealogy fundamentally. While Habermas assumes that Foucault aims at a strictly scientific approach to the writing of history it can be shown that Foucaultian genealogy is strongly characterised by rhetorical aspects, creating a hybrid model of critique that stands in between science and literature. The essay goes on arguing that this misreading can be explained with reference to Habermas' reconstruction of Nietzsche's philosophy in the Philosophical Discourse. On the basis of this clarification the article analyses what a Habermasian position vis-à-vis genealogy including the rhetorical element would look like. Making use of Habermas' remarks on Derrida in the Philosophical Discourse the essay concludes that, counter-intuitively, a rhetorically understood genealogy has to be considered a valid philosophical approach even on Habermas' own terms..