Françoise Dastur on Heidegger's problem with dialectic.
Although he saw in Platonic dialectic ‘a genuine philosophical embarrassment’, Heidegger himself always considered the recourse to dialectic as an evasion (Ausweg), a manner of avoiding what is in question, since gathering into a greater unity contradictions that have been fully accentuated in advance leaves unquestioned the opposed terms in themselves and the status of their relation. This is why Heidegger seeks to display prudence (Vorsicht) when engaging in the question of the relation of being and time. It is this absence of precipitation and uncriticised presuppositions that leads him to posit Ereignis ‘neither as something opposite us nor as something all-encompassing’ and thus to view in it neither an object nor an all-embracing absolute, since ‘Ereignis neither is, nor is Ereignis there’ for ‘to say the one or to say the other is equally a distortion of the matter, just as if we wanted to derive the source from the river’. Perhaps it is not by chance that the image recurring here is precisely the Heraclitian, Hölderlinian and Husserlian image of the river and its source, and perhaps we ought to see in dialectics, when it is no longer an embarrassment (Verlegenheit) but rather an evasion (Ausweg), just such a perversion of the matter (Verkehrung des Sachuerhalts) leading to the anachronism with which the process of becoming is reconstructed on the basis of its result. Nevertheless, such a mimetic reconstruction is in no way the last word of an impossible phenomenology but instead that against which a ‘phenomenology of the inapparent’ can be constituted.