SELF-CONSCIOUSNESS. - Consciousness, awareness of self. Whereas consciousness (v.) indicates rather the awareness of the subject's acts in their objective presence, and of the content of the various psychic states, self-consciousness instead designates the awareness that the subject has of himself as subject; that is, the noetic moment in which the I, setting itself against objects and against the very acts of its experience, grasps itself as I; although a beginning of self-consciousness is often not lacking in the ordinary consciousness that accompanies psychic states, apprehended as one's own, as ours.
The concept of self-consciousness, as indeed that of the I (v.) to which it is intimately linked, has had and occupies a very important place in the history of philosophy, especially because of the complexity it has come to assume in modern philosophy. Already Aristotle conceives Pure Act as absolute self-consciousness, Thought of thought (ἡ νόησις νόησως, Met., XII, 9, 1074 b, 34); and moreover he affirms in general the identity of thinker and thought in every knower devoid of matter (De Anima, III, 4, 430 a, 3-4). The concept of absolute self-consciousness returns in Plotinus through the fundamental identity of the Intellect (νόος) with things: "The I is all things, and things and the I are but one." The intellect, therefore, contemplating itself contemplates things, and contemplating things contemplates itself. To this supreme self-consciousness the soul also attains through mystical-contemplative identification with the Intellect and with the One (cf. Enneads, IV, 4, 2). St. Augustine, while affirming in the soul the intuitive cognition of itself, "mens semetipsam per seipsam novit" (De Trin., IX, 3, 2), seeks in self-consciousness the critical foundation of truth and certainty against every skeptical objection (De Civ. Dei, XI, 46). St. Thomas, besides taking up the Aristotelian concept of God as Pure Act, in whom there is absolute identity of being and thought, "in Deo enim idem est esse et intelligere" (De Pot., 8, 1 in c.), does not neglect the reality of human self-consciousness, which is realized in the knowledge that the soul has of itself through its own acts (cf. De Ver., 10, 8; C. Gent., III, 46). The gnoseological value of self-consciousness becomes, as is well known, central in Descartes, who places in the "cogito ergo sum" the principle of all philosophy (cf. Medit., II, in Oeuvres de Descartes, ed. C. Adam and P. Tannery, VII, Paris 1897-1913; Italian trans., I, Bari 1928, p. 95).
In Kant self-consciousness is the pure or original apperception of the "I think" that accompanies every other representation, and is in every consciousness one and identical (cf. Kritik der reinen Vernunft, in I. Kant's Werke, ed. E. Cassirer, II, Berlin 1922-23; Italian trans., part 1, Bari 1920, p. 130 ff.). Thus begins the transfer of self-consciousness to the transcendental plane: a position that idealism would take up again, developing it to its extreme logical consequences. From Fichtean idealism, in which self-consciousness is the conscious activity of the subject that, while unfolding in objective contents, is reflected in itself, one arrives at Gentile's actualism, in which self-consciousness, understood "not as consciousness that presupposes the Self, its object, but rather as consciousness that posits it" (G. Gentile, Teoria gen. d. Spirito come Atto puro, Florence 1938, p. 98), acquires the positivity and the very extension of being, resolving itself in its eternal constituting itself and becoming all of reality (cf. op. cit., pp. 230-31).
The position of Christian philosophy regarding self-consciousness remains dualist and substantialist: dualist, in that against every form of transcendental idealism it affirms the transcendence of absolute self-consciousness with respect to human self-consciousness, which is relative and manifold; substantialist, then - as regards the metaphysical interpretation of human self-consciousness - in that, in the face of the various empiricist-phenomenalist positions (Hume, Taine, Ribot, Wundt), which resolve the I into acts and states of consciousness, of which it would be as it were an illusory superstructure or epiphenomenon, it affirms it instead as a substantial and dynamic principle that produces those very acts and binds them in the immanent unity of consciousness. As for the gnoseological function of self-consciousness in a critical system of knowledge, v. CONOSCENZA.