APRIORISM. — A philosophical term derived from the expression a priori. In its most common meaning today, it designates every method of study and research that proceeds and develops on the basis of purely rational principles independently of experience. Theologically, a. instead has a meaning more immediately connected with the medieval use of the expression a priori (v.). It is important in the question of the God (v.). It is common doctrine, founded on divine Revelation and defined by the Church’s magisterium, that man can attain certain knowledge of God through consideration of creatures, in which there is the imprint and reflection of the divine perfections. This form of knowledge is evidently a posteriori. Aprioristic, on the other hand, are the paths proposed by the ontologists (v. ONTOLOGISM), such as Gioberti, by innatists such as Cartesio, and by some scholastics such as s. Anselmo.
Ontologism makes God the first idea directly intuited, from which all human cognition develops. Cartesio claims that the idea of God is innate, clear, and distinct. S. Anselmo derived God’s existence from the very concept of God (the a simultaneo argument). The Church rejects ontologism because it reduces the beatific vision to a natural fact; Cartesian innatism is not condemned by the Church, but finds its full refutation on philosophical grounds. Among Catholics, s. Anselmo’s argument remains open to discussion.
S. Agostino too concedes something to a., when he demonstrates the existence of God from introspection
of the spirit, in which eternal truths shine forth; but it has now been critically established that neither this nor the other affirmation of the divine illumination of the human intellect permits s. Agostino to be attributed with a form of ontologism, because he never speaks of a direct intuition of the divine essence by our intellect considered in its natural condition. Vedi: AGOSTINO; ANSELMO; DIO; ONTOLOGISMO.
A. Farges, L'idée de Dieu, Parigi 1894; B. Geyret, La preuve a priori de l'existence de Dieu chez s. Anselmo, in Reu. de philos., 1909, p. 665 sgg.; C. Boyer, Curios Philosophiae, II, Parigi 1936, p. 297 sgg.; A. Palumbo, Theodicaea, Roma 1942, p. 79 sgg.; Fr. Spedalieri, Anselmus an Gaumilo? seu de recta sancti Doctoris interpretatione, in Gregorianum, 38 (1947), pp. 55-77; A. Chollet, A priori. A posteriori, in DThC, I, coll. 1718-24. Pietro Parente