first-order logic See FORMAL LOGIC, ORDER, SEC -. OND -ORDER LOGI. first philosophy, in Aristotle’s Metaphysics, the study of being qua being, including the study of theology (as understood by him), since the divine is being par excellence. Descartes’s Meditations on First Philosophy was concerned chiefly with the existence of God, the immortality of the soul, and the nature of matter and of the mind. See also METAPHYSIC. P.Bu.