SUBSTANCE. — It can indicate both the actual and concrete reality, i.e., the singular (the “first substance” of Aristotelian terminology), and the essence (v.), whether in its metaphysical structure or in its notional and logical content (“second substance”): cf. Cat., 5, 2 a 11 sqq.; or also the particular “this” (τὰ δὲ τῇ) and the “what it is” (τὸ τί ἔστιν: Met., VIII, 1, 1028 a 11).
By “substance” (s.) is therefore understood the “principal” mode of being, and thus the first category of the real, the foundation, cause, and substratum of accidents (v.), whether proper or common. Hence the meaning of “subject” or “substratum” (τὸ ὑποκείμενον) varies according to the modes of substance itself in the logical or real order, namely: 1) insofar as substance is the principal real thing that sustains accidents and is then called, strictly speaking, τὸ εἶδος ἢ μoρφή (Met., VIII, 3, 1028 b 34); 2) the same ultimate subject or prime matter (τὸ μιᾷ) and the “logical substance,” the universal (τὸ καθόλου λόγoν), which is the species and the genus. Insofar as it indicates the consistency of being, 4) substance is the reality in act (ὡς ἐνεργείᾳ) that can be indicated as the complete essence in itself (a synthesis, in corporeal being, of matter and form, τὸ σύνoλoν: Met., VIII, 3, 1023 b 1), or finally 5) the singular subsistence (τὸ δὲ τιν) that is the substance in the full sense in which the real is actualized in its various forms.
In the anti-Platonic polemic (Met., I and VII–VIII), Aristotle maintained that substance must be indicated in sensible reality, with which experience continually puts us in contact and from which we necessarily always depend, both for knowing and for acting. The Platonic problem of the “communion of genera” (ἀγαθῶν γένων), which in Plato remains ever oscillating, becomes in Aristotelianism the problem of the “duality” of matter and form in the essence, and of genus and difference in the definition (v.). Yet this duality of principles does not destroy but rather guarantees the unity of the real on the one hand and of the concept on the other. This unity is indeed guaranteed, in the real, by the unity of form and, in the definition, by the specific difference that constitutes the essence and corresponds to the form. In this way, Aristotelianism closes the process to infinity (which remains open instead in Platonic dialectic), because the form is immanent to the sensible singular, so that informed matter and actualizing form coincide in the unity of the being: ἡ ἐνέργεια ἦτοι καὶ ἡ μoρφή τῷ σύνoλoν καὶ ἕν, καὶ δυνάμει τὸ μὲν ἐνεργείᾳ (Met., VIII, 5, 1045 b 18). Matter and form, therefore, in the structure of substance (and of the definition) are not on equal footing, but form dominates matter and draws it into its ontological degree: “Unumquodque ponitur in sua specie per formam...” (St. Thomas, In VII Met., lect. 1, n. 1531: cf. Sum. Theol., 1a, q. 85, a. 1 ad 2). In the metaphysical structure of corporeal essence, therefore, form and matter (and soul and body) are like the concave and the convex, not two elements requiring an “intermediate principle” of connection. This latter conception betrays a dualism that conceives the two principles separately and, ultimately, a misunderstanding of the metaphysics of act and potency: “Ultima materia, quae scilicet est appropriata ad formam, et ipsa forma, sunt idem. Aliud enim eorum est sicut potentia, aliud sicut actus.... Et sic non oportet ea uniri per aliquod vinculum” (In VIII Met., lect. 5, n. 1767). The theory of the “substantial bond” was developed by Leibniz and his school, but the first explicit indications appear in Suárez, from whom Leibniz himself most probably drew his inspiration (as Ch. Boehm has demonstrated [Le vinculum substantiel chez Leibniz, Paris 1938], correcting in this regard the thesis of M. Blondel [Une énigme historique: Le «vinculum substantiale» d'après Leibniz et l'ébauche d'un réalisme supérieur, ibid. 1930: the French translation of the Latin thesis of 1893]).
For his part, Leibniz (v.) elaborated a theory of substance as a “monad” complete in itself, so that every substance, even material ones, is a world apart; what St. Thomas says of angels—that each is a separate species—according to Leibniz “is true of all substances.... Moreover, every substance is like a whole world and like a mirror of God or of the entire universe, which it expresses each in its own way” (Discours de métaphysique, § IX; ed. H. Lestienne, Paris 1929, p. 37). More restrained in its theoretical demands, the metaphysical tradition elaborated the concept of substance according to the principle of the “emergence of act” (Met., IX, 8, 1049 b 5; cf. De an., II, 4, 415 a 18). Material substance obtains its aptitude and ontological consistency from form: (Quodl., I, q. IV, a. 6; cf. Arist., De an., II, 4, 415 b 13: τῷ γὰρ αὐτῷ τοῦ εἶναι πᾶσι ἡ οὐσία). Consequently, spiritual substances, which are simple forms without matter, are more perfect and consistent than material substances and are therefore called “subsistent” or separate forms, and as such are closer to God, who is pure subsistent being (cf. De spir. creat., a. 1). Thus, in the ontological structure of substance, as “subsistence” (v.) increases, the reason for being a subject or receptacle of accidents diminishes; these, in spiritual substances, are reduced to the qualities and actualizations of intellect and will alone, while God is pure act, fullness of perfection in absolute simplicity.
The disruption of the balance of Aristotelian metaphysics of act and potency, already accomplished in Suárez, who does not accept the Thomistic concept of potency, shows in Leibniz the elimination of potency as receptivity to intensify potency as virtuality and activity. Spinoza (v.), “substance” expresses instead absolute sufficiency, which entails the metaphysical unity of the real in the identity of modes and attributes (extension and thought, intellect and will): “Per substantiam intelligo id quod in se est et per se concipitur: hoc est id cuius conceptus non indiget conceptu alterius rei, a quo formari debeat” (Ethica, ed. Gentile, Bari 1933, p. 3). Hegel, at this point, unified the Leibnizian dynamism and the Spinozist unity in the conception of reality as “process” (cf. Phän. d. Geistes, Vorrede, ed. J. Hoffmeister, Leipzig 1937, p. 45).
English empiricism, on the other hand—in reaction to rationalism—by reducing substance to the function of “substratum,” led to the dissolution of the very concept of substance. Starting from the nominalist principle that the principal value of reality belongs to immediate perception and that “ideas” are but the mental “residue” of sensations, Locke asserts that substances are not properly knowable, nor is it possible to have a precise notion of them (cf. Essay, I, 4, 18; ed. J. A. St. John, I, London 1854, p. 196 ff.). Our knowledge of substance is thus reduced to a complex and entirely vague idea of a certain support of accidents (ibid., II, 23, 3; ed. cit., I, p. 424) and, concretely, to a “complication” of the collocation of those various simple ideas of sensible qualities that are usually found united in things called horse or stone (ibid., p. 425): and this holds not only for material substances but also for spiritual substances and even for our own soul or mind (ibid.).
To break the deadlock, BERGER, ELIE (v.) denied the concept of material substance and with it the notion of substance itself, Locke’s theory of “complex ideas,” and the distinction between primary (v.) and secondary qualities: the existence of things is identified with their being perceived (esse est percipi), so that the concept of material substance or substratum is contradictory (Principles, §§ 3–23). The only substance is the soul, which attests itself as the “cause” of the feelings and ideas we do not continuously experience or produce in ourselves (ibid., § 25). Finally, Hume (v.), starting from Berkeley’s reduction of spiritual substance to the concept of “cause” of its own modifications, cause (v.) has no foundation either a priori or a posteriori in our knowledge, since we lack the corresponding impression. Cause, and with it substance, is reduced to a natural belief, an instinctive feeling whose origin we do not know (Treatise on human nature, pt. 1, sec. 7; pt. 4, sec. 3; ed. Selby-Bigge, Oxford 1928, pp. 17 ff., 219 ff.; see also Appendix, p. 633).
In the metaphysics of imagination substance is either wholly absorbed into the becoming of the Whole of reason or universal history (pantheistic monism) or resolves entirely into the residue that is the single fact of becoming (phenomenism); in the metaphysics of transcendence, by contrast, substance has an absolute foundation in the “form” that structures the individual in time and space, and this form in turn is grounded in the divine intellect from which every essence derives its first origin.