In his essay "Faith, Reason and Humility", published in The Priest (May 2001), Professor Peter Forrest quotes John Paul II's Fides et Ratio in which the Pope states: "The Church has no philosophy of her own, nor does she canonise any one particular philosophy in preference to others."
Professor Forrest comments that Thomism was taken by several generations "as 'canonised' in preference to other philosophical systems," after the publication of Leo XIII's Aeterni Patris.
In an address delivered at the Angelicum University and reproduced in L'Osservatore Romano (17 December 1979), Pope John Paul II asserted: "The immortal Pontiff [Leo XIII] recalled that the method, the principles and the teaching of Aquinas had, down the centuries, been especially favoured not only by learned men but by the supreme teaching authority of the Church."
In the same address, Pope John Paul cites Pope Pius XI's Studiorum Ducem: "In honouring St Thomas something greater is involved than the validation of St Thomas and that is the authority of the teaching Church" (id est Ecclesiae docentis auctoritas).
His Holiness observes that the reason why St Thomas' philosophy is pre-eminent is to be found in its realism and its objectivity; it is a philosophy of "what is, not of what appears." What makes the philosophy of the Angelic Doctor so wonderfully apt to be the "handmaid of faith" (ancilla fidei) is that it has gained possession of truths of the natural order which have their origin in God the Creator just as truths of the divine order have their source in God as revealing.
Father Robert O'Connell writes: "In 1879 Leo XIII declared the philosophy of St Thomas Aquinas to be the official philosophy of the Catholic Church and required that all candidates for the priesthood be schooled in it. This endorsement was reinforced when, in 1918, Thomas' name was inserted in the Church's Code of Canon Law. Canon 1366, paragraph 2, legislates that candidates for the priesthood be trained 'according to the method, doctrine and principles of the Angelic Doctor'" (Hooked on Philosophy, page 91).
Fr O'Donnell CSP holds a doctorate from the University of Louvain and is Professor of Philosophy at the New York Archdiocesan seminary.