Identity

IDENTITY. - It indicates the reflected unity of being in the variety of its forms and in the multiplicity of its elements, and it can be either logical or real (Aristotle, Met., V, 9, 1018 a 7). It is therefore the expression of the persistence, or constancy, of something with itself. Identity can be considered in all the degrees and forms of being and under the various points of view that it presents, so that identity in one order can well involve a multiplicity and diversity in another order: a single and identical substance can in fact have, whether simultaneously or successively, a multiplicity of different accidents, and yet for this reason it cannot lose its identity. The problem of identity therefore coincides with that of being (the problem of the one and the many), and it is in this particular form of reconciling the one and the multiple that it especially occupied Greek speculation.

Among the Presocratics, identity presents itself as a "community" of a physical order, as a certain determinate reality that forms the "substratum" (ὑποκείμενον) of the external variety of phenomena. When Thales affirms that "water is the principle of beings" (ἀρχὴν τῶν ὄντων ἀπεφήνετο τὸ ὕδωρ; Doc. graeci, ed. H. Diels, Berlin 1929, 276 a 5), he intends to refer to water all that seems to belong to beings as real, both as regards being and as regards becoming. This resolution, so to speak "dynamic," of identity is common to all the Naturales, with the probable exception of Parmenides, for whom reality was posited under the form of immobility, so that becoming was relegated to the world of unreal appearance: being announces itself only according to a "single way, that it is, is," and its properties are: "unbegotten," "indestructible," all gathered within its "edifice" and "unshakable" (Fragm. der Vorsokratiker, ed. H. Diels-W. Kranz, I, 2nd ed., Berlin 1934, p. 235, 2 ff.). The metaphysical meaning of identity is therefore the following: everything in the world is contrariety and multiplicity; but contraries exclude one another; therefore this world of contraries is false, and only the eternally unchanging ὄν is true. Heraclitus, on the contrary, thinks that contraries condition one another: this is the great mystery of being, that contrast is unity, and everything harmonizes in the process of its oppositions. Opposition — not identity — is therefore the essence of all things, and the world of oppositions is the only true and real world: "from all things comes the one and from the one all things" (καὶ ἐκ πάντων ἐν καὶ ἐξ ἑνὸς πάντα: Fr. B, 10, op. cit., I, p. 153, 11). The Socratic systems, with Plato and Aristotle, resolve identity by proceeding from the sensible to the intelligible, in the affirmation of a higher "unity of multiplicity"; but it must be said that in this resolution, while Plato stands on the line of thought of Parmenides and does not admit in being any coexistence of contraries, Aristotle sees in every being of nature and in its becoming the presence and the struggle of contraries according to the intuition of Heraclitus. Matter in fact, which is the substratum of becoming, is not χωριστή like the ἄπειρον of Anaximander (Phys., II, 1, 329 a 8-14), but is always affected by contrariety (ἀλλ'ἀεὶ μὲν ἐναντιώσεως [op. cit., 329 a 25-26], that is ἀχώριστος μὲν ὑποκείμενον δὲ τοῖς ἐναντίοις [loc. cit., 329 a 30-31]). According to the various modes of diversity, Aristotle also distinguishes various forms of identity: numerical identity (κατ' ἀριθμόν), specific (τῷ εἶδει) or generic according to matter (τῇ ὕλῃ, cf. Met., X, 3, 1054 a 32). Nevertheless, despite so much effort to ground the unity of being, Aristotle remains in dualism (matter and form, nature and spirit), having been unable to envisage creation: later philosophies attain the identity of the entity either because they opt for matter (Stoicism, Epicureanism) or because they reduce everything to spirit (Neoplatonism). Only with the Christian doctrine of creation is there the positing of an identity in duality and of a duality in identity: the creature is distinct from God and at the same time his total effect.

A systematic philosophy of identity begins with the pantheism of Bruno, develops with the Spinozian theory of substance, and takes systematic form with German transcendental idealism, down to the extreme resolution of the pure act, and therefore absolutely unique, of Gentile: dialectical identity for Hegel, insofar as the "concept" (Begriff), or concrete thought, is posited as the "new immediacy" at which dialectical mediation terminates, as the being in-itself-and-for-itself of Spirit (Hegel, Wissenschaft der Logik, II, 2nd ed., ed. G. Lasson, Leipzig 1934, p. 213). While for Hegel identity is a "result," for Schelling on the other hand — and for the philosophies of intuition — identity is a point of departure. One understands therefore how philosophies of "explanatory type" (e.g., Plato, Schelling) refer to the principle of identity, while those of "constructive type" (Aristotle, Hegel) prefer the principle of contradiction. In any case, it is not the principle of identity in its logical meaning (common to all philosophies) that opposes or unites the various philosophies, but rather the content attributed to being, whose identity and diversity in the intelligible order philosophy has precisely the task of indicating.

Cornelio Fabro