CONCEPT. – Etymologically from *concipere*, *cum-capere* (to conceive, to understand), the *concept* is the intellectual expression of reality in thought, the idea that the mind realizes through thinking, or even thought itself as an act. The expressive value of the term, already unstable in common language, is further divided and at the same time amplified in philosophical language, in relation to the historical systems of epistemological and metaphysical evaluation of thought.
Against the relativism of the Sophists, who defended the impossibility of a universal and objectively valid science, Socrates affirms that such a science is possible through an element of knowledge in which the multiple and relative individual representations are unified into a universal representation: this is the *concept*, the 2.6/7.5, the expression of what the thing is, the object and end of science, which can be attained, particularly in moral matters, through a method of analysis and segregation, inductive, exercised upon the foundation of natural and common thought. Plato, adhering to Socrates’ anti-sophistic assertion that science cannot be based on mutable opinions, and convinced that the material world is entirely immersed in contingency and relativity, seeks the foundation and object of science in the stable world of ideas, or intelligible forms of reality, to which our mind arrives through the *concept*, by means of a process of pure recollection (ἀνάγνωσις), occasioned by the sensible experience of the material world (*Theaetetus*, 201 sg.; *Phaedo*, 72 sg.).
The doctrine of the *concept*, initiated by Socrates, accentuated but also already dispersed in Platonic idealism, is by Aristotle brought back and systematized within the lines of a correct metaphysical realism: it is true that the object of science is the universal and the intelligible, but this is not to be sought in the world of separate, unreal, and fantastic ideas, but rather within the very individual reality, in its immutable essence, realized by the specific determination of form. The *concept* is precisely the intellectual representation of the essence or *quidditas* of things, actualized in the mind by the power of the active intellect (νοῦς ποιητικός), and in its content it is universally nostalgic, immutable, eternal, like the forms and essences (*De anima*, I, 1, 402 a 6; II, 1, 412 a 1-6; *Metaphysics*, I, 1, 981 a 15; ibid., X, 1, 1059 b 26).
The balanced spiritualism of Aristotle and the idealism of Plato are both abandoned by the Epicurean and Stoic schools, where the *concept* is reduced to the level of sensible impressions, crudely interpreted according to Democritus’ theory (v.). From sensible impressions arises the universal *concept*, which in the end is nothing but the persistence of those same impressions and their combined elements (cf. Cicero, *Academica*, II, 10; for Epicurus V. Diogenes Laertius, X, 32). In medieval Scholasticism, the *concept* in a specific sense is the term of the first apprehension (v.) of the intellect, the *verbum mentis*, and as such it is contrasted with judgment as its element. Particular importance attaches to the *concepts* or general ideas (universals), expressions of the generic or specific unity of individual realities («similitudo rei intellectae quantum ad essentiam»: C. Gent., IV, 11, ed. Marietti, p. 436; *Summa Theologiae*, I, q. 85, a. 1, ad 1); and well known is the fervor of disputes that grew up around their value, from which arose and still persist the systematic interpretations of nominalism, conceptualism, and realism.
New theories of the *concept* appear in modern philosophy in relation to the various epistemologies and metaphysics. In empiricism (v.) the *concept* as an abstract and universal representation of knowledge is a further derivative of sensation that essentially does not transcend it: a residue of sensible images (Condillac); a product of reflection (Locke); an association of images (Hume, Mill, Spencer). In Kant the *concept* is in general that by which an object is thought. To think is to perceive in synthetic unity the manifold of sensible representations, according to the original and a priori forms of thought. Kant then divides the *concepts* into pure and empirical: pure *concepts* are the a priori forms of the spontaneous activity of the intellect, by which it thinks every object (the categories); empirical *concepts* are the forms of thought that include a content of sensation, and that are therefore possible only a posteriori. The pure *concepts*, apart from the intuitions of sensibility, are in themselves empty; and since the intuitions are purely phenomenal, it follows that the *concepts*, as formal elements of the a priori synthesis in which all our thought and judgment consist, concern only phenomena and cannot refer to the thing in itself (noumenon), which is impenetrable to human intellectual knowledge (*Critique of Pure Reason*, Italian trans. by G. Gentile and G. Lombardo-Radice, 12th ed., 1940, p. 91 ff.).
In Hegel, having identified reality with the logical development of spirit, the *concept* is elevated to the supreme dignity of an absolute metaphysical position, as the realization of being and substance in its dialectical becoming. Indeed, only through the *concept* in its perpetual triadic cycle of thesis, antithesis, and synthesis does being posit itself as being-for-itself, in absolute universality and unity of the ego, which precisely in the logical expressions of itself gives consistency to universal reality (*Science of Logic*, III, Italian trans. by A. Moni, Bari 1925, p. 9 ff.; *Encyclopedia*, §§ 160 ff., Italian trans. by B. Croce, Bari 1923, p. 143 ff.). For this reason Hegel calls the *concept* «the truth of substance», «the essence of the thing itself», «nothing other than the ego, that is, pure self-consciousness». A conception taken up and developed in Italian neo-Hegelianism by Croce and Gentile. In Gentile, having identified reality with thought in act, «in such a way that the sphere of the real coincides with the sphere of the concept», one arrives at the position of reality as self-contact, or *conceptus sui*: the multiplicity of *concepts* under which reality appears to us is nothing but external and apparent, and a pure abstract objectification of spirit; the true and concrete *concept* is one alone: that of the Subject, center of all things, which unfolds itself in the multiplicity of its positive moments, and in conceiving itself conceives everything, positing the real (*System of Logic*, 3rd ed., I, Florence 1940, ch. 7; II, ch. 6; *General Theory of Spirit*, 5th ed., Florence 1938, ch. 16).
It is clear that these grand, if one wishes, evaluations of the conceptus (c.) are worth only as much as the metaphysical systems that govern them. Both Hegelianism and actualism, as absolute philosophical systems, lack secure consistency. A theory of the conceptus that claims objectivity must be constructed in harmony with the data of experience and unfold in the direction dictated, indeed commanded, by them. Now experience, while affirming on the one hand the purity of conceptual thought that transcends into a sphere of absolute validity the relativity of empirical knowledge, attests on the other hand its dependence on the very same sensible knowledge from which, directly or indirectly, all our intellectual knowledge draws its roots. The development of human knowledge does not reveal itself to individual consciousness (the only one given in experience) as a free expansion of the transcendent creative unity, however understood, but rather as a gradual and laborious adjustment of thought to the reality with which it must measure itself and whose contents of value it strives to penetrate. The conceptus is precisely the intellectual expression of these contents. These would not even be called such if they were not in some way immanent to the real given in sensible experience, of which they constitute the radical intelligible structure, and where thought intuits them or, which is the same, whence it derives them with the gaze of its spirituality. And since these contents are manifold and of varying degrees of intelligible purity, one may retain, but in a quite different sense, the Kantian division, calling pure those conceptus that express a universal intelligible value (being, cause, substance, etc.), empirical those that express, generalized, the essential or quidditative aspects, both substantial and accidental, of empirical reality (sensibility, animal, plant, color, etc.).
The theory of the conceptus thus outlined, besides opposing idealism and empiricism, also comes into essential opposition, in its main lines, with other conceptions that reduce the function of sensible knowledge in the genesis of the conceptus to a level of mere occasionality: with animism, according to which ideas, at least in part, are given a priori with the spirit; with onto-logism, which derives our conceptus from a first intuition of pure intelligibility, God; and finally also with mysticism and Bergsonian intuitionism, according to which knowledge of the inner structure of the real is not proper to conceptual thought but is realized through an intuitive vital contact of the soul with things.
As for the logical position of the conceptus, the prevailing tendency today is to subsume it within judgment. Considering the conceptus in its psychological genesis, it is true that it does not form in thought except through an implicit judgment: the conceptus in fact expresses, in a more or less high degree of metaphysical interiority, what a thing is; and thought does not think what a thing is except through a judgment. But the conceptus can also be considered in its abstract objectivity (conceptus obiectivus according to the Scholastics), and then it is a representative unity that may well be considered distinct from the judgment of which it is an element and term (v. CONOSCENZA; LOGICA; UNIVERSALISTI).