SINGULAR. — In a metaphysical sense, the singular is the subsistent individual or the “first substance” (οὐσία πρῶτη), in contrast to the “second substance” (οὐσία δευτέρα), namely the species and genera of logic (cf. Aristotel, Cat., 5, 2 a 11, and Peritherm., 7, 17 a 40); it is therefore the incommunicable individual and expresses the numerically one reality (id., Met., III, 4, 999 b 33).
The constitutive principle of the singular (the principle of individuation [v.] in material substances) is, according to St Thomas, matter insofar as it is found under real dimensions (“materia corporalis sub determinatis dimensionibus contenuta”: Sup. I. II de anima, lect. 12; ed. Pirotta, Torino 1925, n. 377, p. 132 b). In this sense the material singular is directly accessible to the senses, while the intellect apprehends the universal: τὸ μὲν γὰρ καθὼς καὶ τὰ τῶν λόγων γνωρίζει, τὸ δὲ καθὼς καὶ τὰ τῶν λόγων γνωρίζει (Aristotle, Phys., I, 5, 18a 6; cf. Met., V, 11, 1018 b 33); hence the controversy, debated in the Middle Ages against the Arab philosophers (especially Averroes), concerning the possibility that God directly knows singulars, on which depends the meaning and reality of divine providence itself (cf. Sum. Theol., 1a, q. 14, a. 11; J. Koch, Giles of Rome, Errores philosophorum, Milwaukee 1944; Errores Averrois, nn. 6, 8 and 9). In a social and religious sense, the singular is the individual human person who is distinguished from the mass or multitude and is related by rights and duties to society and to God: KIERKEGAARD, SOEREN AABYE (v.) opposes the Christian principle of personality (the “single individual before God”) to the Hegelian pantheism.