NATURE AND FOUNDATION OF THE PROOFS FOR THE EXISTENCE OF GOD

3. Thus stimulated and guided, the human intellect approaches that demonstration of the existence of God which Christian wisdom recognizes in those philosophical arguments which have been carefully examined throughout the centuries by giants in the world of knowledge, and which are already well known to you in the presentation of the "five ways" which the Angelic Doctor, St. Thomas, offers as a speedy and safe road to lead the mind to God. We have called these arguments "philosophical." This does not mean that they are a prioristic, as they are accused of being by a narrow-minded and incoherent positivism. Even though they draw their demonstrative force from the power of human reason, they are nevertheless based on concrete realities established by the senses and by science.

4. In this way both philosophy and the sciences, by means of activities and methods which are analogous and mutually compatible, carry on their work. Though in different measures, they all make use of both empirical and rational elements and cooperate in harmonious unity for the discovery of truth.

5. But if the primitive experience of the ancients could provide human reason with sufficient arguments to demonstrate the existence of God, then with the expanding and deepening of the field of human experiments, the vestiges of the Eternal One are discernible in the visible world in ever more striking and clearer light. Hence it seems helpful to re-examine on the basis of new scientific discoveries the classical proofs of the Angelic Doctor, especially those based on motion and the order of the universe (S. Th., 1 p., q. 2, art. 3); that is to say, to inquire if, and in what degree, a very profound knowledge of the structure of the macrocosm and the microcosm contributes toward strengthening these philosophical arguments.

6. It is also helpful to consider, on the other hand, if and to what degree these proofs have been weakened, as is not infrequently affirmed by the fact that modern physics has formulated new basic principles, ruled out or modified certain ancient ideas, whose content was perhaps judged in the past to be fixed and definitive, such as time, space, motion, causality, substance all of which concepts are supremely important for the question which now occupies us. The question, then, is not one of revising the philosophical proofs, but rather of inquiring into the physical foundations from which they flow although limitations of time will oblige Us to restrict Our attention to only some few of these foundations. There is no reason to be fearful of surprises. Not even science itself aims to go outside that world which today, as yesterday, presents itself through these "five modes of being" whence the philosophical demonstration of the existence of God proceeds and draws its force.