From Pope St. John Paul II’s encyclical Fides et Ratio (1984):
Yet this sapiential function could not be performed by a philosophy which was not itself a true and authentic knowledge, addressed, that is, not only to particular and subordinate aspects of reality—functional, formal or utilitarian—but to its total and definitive truth, to the very being of the object which is known. This prompts a second requirement: that philosophy verify the human capacity to know the truth, to come to a knowledge which can reach objective truth by means of that adæquatio rei et intellectus to which the Scholastic Doctors referred.99 This requirement, proper to faith, was explicitly reaffirmed by the Second Vatican Council: “Intelligence is not confined to observable data alone. It can with genuine certitude attain to reality itself as knowable, though in consequence of sin that certitude is partially obscured and weakened”.100
A radically phenomenalist or relativist philosophy would be ill-adapted to help in the deeper exploration of the riches found in the word of God. Sacred Scripture always assumes that the individual, even if guilty of duplicity and mendacity, can know and grasp the clear and simple truth. The Bible, and the New Testament in particular, contains texts and statements which have a genuinely ontological content. The inspired authors intended to formulate true statements, capable, that is, of expressing objective reality. It cannot be said that the Catholic tradition erred when it took certain texts of Saint John and Saint Paul to be statements about the very being of Christ. In seeking to understand and explain these statements, theology needs therefore the contribution of a philosophy which does not disavow the possibility of a knowledge which is objectively true, even if not perfect. This applies equally to the judgements of moral conscience, which Sacred Scripture considers capable of being objectively true.101
99 Cf., for example, Saint Thomas Aquinas, Summa Theologiae, I, 16, 1; Saint Bonaventure, Coll. In Hex., 3, 8, 1.
100 Pastoral Constitution on the Church in the Modern World Gaudium et Spes, 15.
101 Cf. John Paul II, Encyclical Letter Veritatis Splendor (6 August 1993), 57-61: Acta Apostolicæ Sedis 85 (1993), 1179-1182.
— Fides et Ratio 82