DISTINCTION. – In its broadest meaning, d. is the non-identity of something with respect to something else: human life and knowledge, insofar as they entail a multiplicity of situations and objects and a process of development on the part of the subject, presuppose the existence of d. and the possibility, on the part of human consciousness, of taking cognizance of II.
D. thus presents itself in all the spheres of consciousness and knowledge: in perception, in scientific and philosophical knowledge, in moral reflection, in theology, and in revealed faith. In each of these spheres d. is determined within its own type of attribution, or according to the relations of identity and opposition characteristic of the object of the sphere itself. In this way, with respect to one and the same thing, there can simultaneously be a multiplicity of predications which, from one aspect, affirm identity and, from another, d.; this depends in part on our intellect, which can apprehend different aspects in one thing and can form, from many things, a unitary comprehensive apprehension above their particular differences. It is in this way that philosophical thought arose: proceeding from immediate knowledge of an empirical and pragmatic nature, it advances to d. and oppositions in order to rise to considerations of a higher synthetic nature that culminate in the supreme Principle, both in the logical order (the principle of non-contradiction) and in the ontological order (God). D. is therefore not simply separation or absolute otherness, but rather indicates the presence of an opposition between objects which, in another respect, agree or are found within the same sphere of being and knowing.
First of all, there is d. in the field of perception (sensory and spiritual), within which lived life moves, and one can speak of d. both of acts and of objects. The d. of acts refers in itself to the concrete objects to which such acts are applied. The d. of objects, moreover, is a function of the unitary and total content that they present to consciousness, as have shown, against associationist psychology, Ganzheitpsychologie (the School of Krüger) and Gestaltpsychologie (Wertheimer, Köhler, Koffka, Levin, etc.).
D. in the metaphysical field is a function of the conception of reality proper to the various philosophical schools. In monistic metaphysics, whether realist or idealist, unity represents the very form of reality in its ultimate condition, while d. is reduced to a mere appearance or phenomenon (Erscheinung). For Platone there is the formal d. of the “genera” and of separate forms; for Spinoza, that of the modes and attributes of the one Substance; for Hegel, that of the “forms of Spirit” (art, religion, and philosophy) and of their stages of realization, etc. In dualist or pluralist metaphysics, d. depends on the criterion adopted for isolating the various subjects of being and the various objects of knowing: thus one may have an atomistic pluralism (Democrito), a monastic one (Leibniz), or a formal one (Platonism and Neoplatonism), from which derive the medieval positions with a formalist orientation, not only those of Scoto, but also those of the Augustinians and even of authors close to Thomism, such as Egidio Romano, who attributes an esse to each formality of the being. In Thomistic Aristotelianism, metaphysical d. depends on the rigorous opposition of contradiction and is always real d. in its own order: d. of matter and form in corporeal essence, of essence and act of being in the finite being, of Creator and creature within being as such, of substance and accident in the sphere of existence, and of cause and effect in that of becoming.
In the sphere of pure logical thought, d. concerns the relation in which concepts stand to one another: this is regulated by Porfirio’s doctrine of the five “predicables” (genus, species, difference, property, accident). A logical d. has value, for a. Tommaso, insofar as it rests upon and corresponds to a real d.: thus the distinction of genus and difference in the definition of a natural body has as its foundation the real d. of matter and form in bodies, or at least that of essence and act of being, which is also common to spiritual substances (cf. C. Gent., II, 95).
D. in the theological field has divine Revelation as its sole foundation: the real d. of the divine Persons consists, through the relations (“relaciones subsistentes”), in what is signified by the terms Father, Son, and Holy Spirit (Sum. Theol., 1°, q. 29, a. 4); the d. among the divine attributes, on the other hand, is merely one of reason, because they are identified with the formal fullness of the divine essence (ibid., q. 4, a. 2).
In general, one may speak of d. in every field of human knowledge, but its meaning depends on the ultimate reference that can be made to II. Thus one may speak of spatial and temporal, real and intentional, natural and supernatural d., etc., insofar as the being within which one moves belongs precisely to a well-defined sphere that has, immanent in its manifestation, the criterion of d. itself (perceptual, metaphysical, logical, natural, supernatural, or revealed).