The "principle of reason" as a "supreme principle" seems to preclude from the very outset anything like a problem of ground. Yet is the "principle of reason" an assertion about ground as such? As a supreme principle, does it reveal at all the essence of ground? The usual,11 abbreviated version of the principle states: nihil en sine ratione, nothing is without reason.b Transcribing it positively, this states: omne ens habet rationem, every being has a reason. The principle makes an assertion about beings, and does so with regard to something like "ground."c Yet what constitutes the essence of ground is not determined in this principle. It is presupposed for this principle as a self-evident "idea." However, the "supreme" principle of reason makes use of the unclarified essence of ground in yet another way; for the specific character of principle belonging to this principle as a "grounding" principle, the character of principle belonging to this principium grande (Leibniz) can after all be delimited originarily only with regard to the essence of ground.
The "principle of reason" is thus worthy of question both in the way it is posed and in terms of the "content" it posits, if the essence of ground is indeed now able to become a problem over and above some indeterminate general "idea."d
Even though the principle of reason sheds no immediate light on ground as such, it can nevertheless serve as a point of departure for characterizing the problem of ground. The principle is indeed subject to many kinds of interpretation and appraisal, quite irrespective of those points worthy of question that we have indicated. Yet for our present purposes it seems
a First edition, 1929: The approach in terms of the truth of beyng is undertaken here still entirely within the framework of traditional metaphysics and in a straightforward retrieval corresponding to the truth of beings, the unconcealment of beings, and the unveiledness pertaining to beingness. Beingness as ἰδέα is itself unveiledness. Here one path toward overcoming "ontology" as such is broached (cf. Part III), but the overcoming is not accomplished or constructed in an originary manner from our of what has been attained.
b First edition, 1 929: Wherever and whenever there are beyings [Seyendes], there there is ground; thus, there is grounding wherever there is beyng. What is the essence of beyng, such that grounding belongs to it; what does grounding mean here; how is this "belonging" to be understood, and how does it change in accordance with the particular way of being? (Cf. Part III.) Where does the necessity lie for grounding? In abyss of ground and in non-ground. And where is this? In Da-sein.
c First edition, 1929: Here there lies a specific interpretation of beyng: (1) being asserted (being true); (2) being produced from (what something is made of, φύσις); (3) (1 and 2) presence - constant.
d First edition, 1929: This "idea" of ground is nm only universally accepted in an indeterminate manner, but behind this indeterminacy there lies the determinacy of a quite limited provenance. Λόγος - (ratio) - ὑποκείμενον as οὐσία - τί ἔστιν that which is most constant, present. C:f. the "origin" of the four causes.