SUBJECT. - The term "subject" presents several meanings. In common usage, one speaks of the subject of a proposition, of a discussion, of a work, of a science, as that of which they treat; it derives in fact from the Latin *subiectum*: that which underlies, which is subjected (to reflection, discussion, etc.).
The Latin term translates the Greek ὑποκείμενον, which already in Aristotle assumes a complex reference, having both a logical and a metaphysical value; logically, it is that of which a predicate is affirmed or denied, metaphysically it is both the indeterminate matter and the determined being that sustains qualities and affections (cf. *Phys.*, I, 2, 185 a 32; *Met.*, VII, 3, 1029 a 1). This latter meaning, along with the logical one, passed directly into tradition as the specific meaning of "subject." Aristotle himself (*Cat.*, 2) clarifies and distinguishes these two uses of the term, demonstrating how the logical subject of a proposition does not always coincide with the real subject or subject of inherence; indeed, it is one thing to affirm or deny an attribute of a subject, as in the case where the genus is predicated of the species or the species of the individual (in "Socrates is a man," "man" in general is attributed to Socrates, but is not in Socrates), and another to refer a quality to the subject, which, even without being its essential attribute, is in the subject itself (e.g., Socrates is wise). Moreover, the distinction between logical subject and grammatical subject must be noted; the latter is determined solely by the form of the proposition and does not always coincide with the former.
The fundamental meaning of "subject" in post-Aristotelian philosophy, up to the modern age, is that deriving from its value as a substantial being, in contrast to the attributes or accidents that are referred to II. It thus becomes equivalent to substance (v.), essence (v.), hypostasis, etc. In scholastic terminology, *esse subiective* means to exist in oneself, *esse obiective* to subsist only in thought. Even Descartes defines as "subjective" that which is proper to things, *formaliter in se ipsis*, and as "objective" that which is precisely the object of thought, which exists *idealiter in intellectu* (cf. *Medit.*, III).
Only from the 17th century onward does that meaning of "subject" begin to be emphasized, which derives from its being also the subject of activity, as well as of qualities, and in particular of cognitive activity. Initially, consciousness itself was considered one of the qualities of a subject, but with the new formulations of the epistemological problem, it increasingly assumes the value of the proper, essential activity of the subject, until it coincides with the subject itself. On the contrary, the term "object" (v.) comes to mean reality in itself, independent of thought. This reversal of meanings is definitively sanctioned by Kantian (Krit. d. r. Vernunft, passim) and idealistic philosophy. "Subject" and "object" undergo the same fluctuations in value and the same distinctions (e.g., transcendental subject, empirical subject, etc.).
The primitive meaning of "subject," retained in common usage, is often confused with the now acquired meaning of "object"; a distinction is nevertheless possible; "subject" is in general that of which one actually treats, "object" more precisely that which a discussion, a scientific inquiry, etc., aims to attain.