“entity” refer exclusively to empirical, sensible being, we cannot say that the ideal is. Lotze, who introduced the concept of validity into logic, used the term “being” in this narrow sense where “being” means the same as the empirical reality of things, so that “being” equals the empirical realness (out-there-ness) of something. [63] Therefore, if “being” means empirical reality, it cannot mean “ideality.” In other words, we cannot say that [Platonic] ideas are. It is no surprise that, given the dominance of natural scientific research in the nineteenth century, the things of the world, the things of nature, came to be taken as true and proper beings. But it is remarkable that philosophy as well, and even Lotze—who spent his career fighting the predominance of naturalism and who did the real spadework for overcoming it—even Lotze had to pay tribute to naturalism by using the venerable term being in this narrow sense where it equals empirical being, empirical reality.

Now if somehow “there are” [es gibt] ideas,⁴⁵ and if ideas in some sense have (to use Lotze’s terms) actuality, then the problem arises: Since we cannot use “being” in Lotze’s sense of the term, what kind of actuality are we to attribute to the ideas? To avoid any confusion in what follows, let me note again: Lotze uses the word “being” as equivalent to “out-there-ness,” and therefore he uses “being” for sensible beings, material beings in the widest sense. I have already stressed that the currently common term “sensible entity” does not characterize being [Sein], but only determines the way of apprehending being. I use the phrase here only as a concession. As an ontological term, it is absurd. So, how must we indicate and characterize the actuality of the idea?

Lotze used “actuality” in a very broad sense, such that being is a specific form of actuality, and that prompted the question: In contrast to empirically real being, what kind of actuality does the being of the ideas have? “Actuality” is the formal-universal concept, and “being” is a specific form of actuality. But in our terminology—and I say this to avoid confusion—I use “being” in the exact opposite sense, and in connection with the genuine tradition of Greek philosophy broadly speaking. There, “being” can mean both empirical reality or ideality or other possible modes of being. I use “actuality” (Wirklichkeit) in the opposite sense [to Lotze], as meaning [64] empirical reality.

In an earlier investigation of medieval ontology, I too followed Lotze’s distinction and used the term “actuality” for “being.”⁴⁶ But I no longer think that is correct. Hence our question: What kind of actuality

45. [By «ideas,» Heidegger means something like the «Platonic,» «separate» idealities or ideal meanings discussed in §8, and not empirical-real «thoughts in one’s head.»]

46. [Heidegger is referring to his Die Kategorien- und Bedeutungslehre des Duns Scotus (1916), in GA 1, pp. 189–411.]