As Heidegger remarks, it took philosophy two thousand years to formulate the problem of identity in its fully developed form as mediation and synthesis. With Leibniz and Kant preparing the way, the German Idealists Fichte, Hegel, and Schelling place identity in [9] the center of their thought on the foundation of transcendental reflection. These thinkers are concerned not with the simple unity of a thing with itself, but with the mediated syntheses of subject and object, of subjectivity and objectivity as such. If one put Parmenides’ statement “Thought and Being are the same” in the context of German Idealism, one would get a statement something like: Being is thought, i.e., all “Being” is ultimately thought, the absolute Idea (Hegel), and is destined to become thought. Whatever Being there might be outside thought is simply not yet thought, not yet mediated in the absolute synthesizing activity of the Idea. The simplest statement of this can be found in the Preface to Hegel’s Philosophy of Law: “The real is the rational and the rational is the real.” The principle of identity A = A becomes reformulated by Fichte as 1 = 1, and by Schelling’s Philosophy of Identity as the identity, more precisely as the indifference of subject and object. It is perhaps Schelling who in his own way, and still basically although not totally within the framework of Idealism, comes closest to Heidegger’s dimension of the problem of identity when he states in Of Human Freedom that there must be a being before all basis (ground) and before all existence, before any duality at all. Since this being precedes all antitheses, it cannot constitute their identity; it can only be the absolute in-difference of both. Indifference is not a product of antitheses, nor are antitheses [10] implicitly contained in it. It is far rather a unique being apart from all antitheses. It is the groundless. With his idea of the groundless, Schelling is closer to the dimension of Heidegger’s thinking than to German Idealism. Yet he still calls this groundless “a being.”
How does Heidegger treat the problem of identity and in what dimension does this problem now lie if no longer within the framework of metaphysics as the problem of the unity of a thing with itself or as the transcendentally mediated unity of absolute reflection? Heidegger conceives the problem of identity in such a fundamental way that what is “identical,” Being and man, can only be thought from the nature of identity itself. He begins his exposition by questioning the principle of identity as a principle of thinking. He concludes that the principle of identity presupposes the meaning of identity itself. A principle of thought must also be a principle of Being (this “also” is, of course, misleading), the principle: to every being as such there belongs identity, the unity with itself. This is a fundamental characteristic of the Being of beings.
Heidegger then questions Parmenides’ statement that thought and Being are the same, interpreting that statement to mean: Being belongs—together with thought—into the Same. A = A has become A is (transitively) A, and the “is” now takes on the meaning of belonging together. Heidegger understands the “is” in identity as the relation of belonging together, and it is this new meaning of [11] identity which concerns him in this lecture. What is new about this understanding of identity as a relation is that the relation first determines the manner of being of what is to be related and the how of this relation. It is perhaps difficult for us to think of a relation as being more original than what is related, but this is what Heidegger requires of us. This relation is then no relation in the ordinary sense of that term. We do not know and we cannot predict what is related. Man does not have the static essence of the animal rationale or the subject thinking its object. One of Heidegger’s most basic insights is that we do not know what man is, even if he could be understood as a “what” at all. To say that an understanding of Being is “subjective” because man is involved in that understanding is simply thoughtless. Man is, in the language of Being and Time, Being-there (Da-Sein), man is the “there” of Being. This has nothing to do with subjectivity and nothing to do with the concept of human existence of “existentialism.”
Identity is belonging-together. If the element of together in belonging-together is emphasized, we have the metaphysical concept of identity which orders the manifold into a unity mediated by synthesis. This unity forms a systematic totality of the world with God or Being as the ground, as the first cause and as the highest being. But if the element of belonging in belonging together is emphasized, we have thinking and Being held apart and at the [12] same time held together (not fitted together) in the Same. To come closer to an understanding of the belonging together of man and Being, we must leave metaphysical thinking which thinks Being exclusively as the cause of beings and thinks beings primarily as what is caused. But we cannot leave metaphysics by a series of reasoned conclusions. We must simply leap out of it. Thus the principle (Satz) of identity becomes a leap (Satz) out of metaphysics. (1969, p. 8-12)