In a book entitled, Le Sens Commun et la Philosophie de lêtre, we have shown that common sense or natural reason is a rudimentary philosophy of being, opposed to the philosophy of pure phenomenon and to that of becoming; that being and the principles implied in it constitute the formal, primary and adequate object of common sense. Here we again take up the study of these first principles, not so much as they are concerned with the functioning of the faculty of common sense, but with reference to the classical proofs for Gods existence. We have set ourselves the task of demonstrating the necessity of these principles, their dependence upon the first principle, and their ontological and transcendent validity. It will seen that the proofs for Gods existence rest ultimately upon the principle of identity or of non-contradiction, their proximate basis being the principle of sufficient reason, and their immediate basis the principle of causality. . . .
Réginald Marie Garrigou-Lagrange, O.P. (February 21, 1877, Auch, France – February 15, 1964, Rome) was a Catholic theologian and, among Thomists of the scholastic tradition, is generally thought to be the greatest Catholic Thomist of the 20th century. He taught at the Pontifical University of St. Thomas Aquinas, commonly known as the Angelicum, in Rome from 1909 to 1960.
Father Garrigou-Lagrange initially attracted attention when he wrote against the theological movement later called Modernism. He is also said to be the drafter or "ghostwriter" of Pope Pius XII's 1950 encyclical Humani Generis, subtitled "Concerning Some False Opinions Threatening to Undermine the Foundations of Catholic Doctrine."
He is best known for his spiritual theology. His magnum opus in the field is The Three Ages of the Interior Life, in which he propounded the thesis that infused contemplation and the resulting mystical life are in the normal way of holiness of Christian perfection.