What I intend to demonstrate in this paper is that Heidegger pretends to immunize his philosophy from any possibility of refutation. The thesis that I argue is that precisely because the ontological cannot be corroborated by the empirical realm and, on the other hand, does not provide a foundation for what he considers the a priori, the German philosopher shields his philosophy from any kind of reply: the ontological cannot be corroborated by beings and, at the same time, it can (...) only be reached by a “leap”. The question is: on what is the a priori founded? how to establish the validity or legitimacy of a horizon? There seems to be no answer. (shrink)