EN
Thomas Aquinas undertook to examine various definitions of truth in 'Quaestiones disputate', 'De veritate', q.1, a.1; 'Scriptum super I Librum Sententiarum', dist.19, q.5, a.1; 'Summa theologiae', I, q.16, a. 1,2. In these writings Thomas relied on four formulations of truth that were used in his time, namely (i) a definition by Isaac Israeli in 'Liber de definitionibus', par.26, and the formula of the principle of the excluded middle found in Aristotle's 'Metaphysics', IV, 7; (ii) a definition by Avicenna in 'Metaphysics', I, 8; (iii) a definition given by Saint Anselm in his 'De veritate', 11; and (iv) a definition proposed by Saint Augustine in 'Soliloquia', II, 5. After analyzing and comparing them all, the Angelic Doctor adopted the well known definition: 'veritas est aqaequatio rei et intellectus'. It is interesting to note that before this formula won common acceptance, no single definition of truth had been universally recognized either in philosophy or theology. Moreover, as some pronouncements of Albert the Great indicate, it had not been common to assume that truth consists in the agreement between an intellectual judgment of a state of affairs and the state of affairs itself. Consequently, it seems right to claim that the classical concept of truth can be traced as far back as Thomas Aquinas.