112     Plank Three: Being and Disclosing, Part I

We will never get an answer to the question ‘What possibilizes that which possibilizes everything?’ Even to ask that question is a fool’s errand insofar as it traps us in a petitio principii, a begging of the question— in this case, not realizing that we are already wrapped up from the outset in what we are attempting to find. […T]hus, to seek the ultimate basis for intelligibility already presupposes the ultimate basis of intelligibility and thus is caught in circular reasoning. Everything is knowable except the reason why everything is knowable.48

But it is not obvious why this self-presupposing, stated generally, is a problem. If the ultimate basis of being intelligible (Dasein as disclosing, worlding, third-plank unconcealing) is presupposed by the quest to find it, then why does it follow that the quest is doomed? That aiming to understand the ground of x presupposes the ground of x is either a harmless circularity or a bland triviality. It is blandly trivial if the point is that the quest to find the ground of x presupposes that x obtains and possesses a ground. This is an ordinary condition of seeking a ground rather than a question-begging move. It is harmlessly circular if what is presupposed is not the fact of x and its ground but instead some grasp of it on the part of the seeker. This is merely the fact that ‘[e]very seeking gets guided beforehand by what is sought’ (SZ: 5)—which, as Heidegger argues, is simply a feature of hermeneutic understanding and not a vicious circularity (SZ: 8).

The problem with presupposing itself as a chooser is not that Dasein posits or assumes the ground that it seeks but that Dasein is attempting to precede itself. No one can precede their own birth! This is why Dasein cannot choose itself. And yet, at the same time, it must choose itself—not only in becoming authentic by choosing to make up for not choosing (SZ: 268), but also in standing at its own ground. The call of conscience calls a case of Dasein to explicitly and authentically take over the self-grounding structure of Dasein itself, as ‘being-the-[null-]basis-of-a-nullity’ (SZ: 283, original italicised):

48 Sheehan, Making Sense of Heidegger, 228.

Steven Galt Crowell - Normativity and Phenomenology in Husserl and Heidegger