As Mr Michael Casanova observes, Pope John Paul II, in his encyclical Fides et Ratio lauds St Thomas Aquinas as an authentic model and guide for all who seek the truth (September AD2000).
Mr Casanova asks: "What is happening when the Church on the one hand has 'no philosophy of her own', yet praises St Thomas so much?" He contends that the question can be answered by a careful reading of the encyclical.
Father Robert O'Donnell Ph D, Professor of Philosophy at the New York Archdiocesan Seminary, writes: "In 1879 Leo XIII (in Aeterni Patris) 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" (Hooked on Philosophy, p. 91).
Similarly, Pope St Pius X states that in Catholic schools: "The principles of philosophy laid down by St Thomas Aquinas are to be religiously and inviolably observed" (Doctoris Angelici).
Pope John Paul II explains that the magisterium's eulogy of St Thomas has not been in order to take a position on properly philosophical questions "nor to demand adherence to particular theses" (par 78).
In July 1914 the Sacred Congregation of Studies issued a list of 24 philosophical theses for Catholic institutes. The list was submitted to St Pius X and declared by him to contain the principles and main theses of the Angelic Doctor. His Holiness clearly intended that these theses should be taught in Catholic seminaries.
Such theses were not presented as articles of faith but as demonstrable philosophical truths.
For instance, the first thesis affirmed that potency and act divide being in such a way that whatever is, is either pure act, or of necessity it is composed of potency and act as primary and intrinsic principles. Thomism is an evidential philosophy based on the dual evidence of the data perceived by our senses and our intellectual apprehension of first principles. It is not from its agreement with the Catholic faith but from its rational evidence that Thomism derives its authority precisely as a philosophy. Always its appeal is to reason.