Tractatus de Deo uno secundum naturam

The doctrine of the rational knowledge of God belongs also to theology.

« Although the theology of faith presupposes the natural knowledge of the existence of God, just as the supernatural order of elevation generally presupposes the natural order to be elevated, it nevertheless belongs to theology to judge the value of human reason for that very natural knowledge of God, and of the mode of attaining this knowledge. »

I. From what we have said in the Prolegomenon concerning the material and formal object of theology, it is established that God is the principal, or indeed the sole and adequate, object of this sacred discipline, insofar as he has revealed himself through supernatural manifestations to human reason¹, illumined by the light of faith. This illumination does not create or produce reason itself, its natural power and the light of reason, but presupposes them and raises them to a higher order; whence also the supernatural manifestations by which he reveals himself to elevated reason presuppose natural manifestations, through which God presents himself to be known by the natural light of reason. The demonstration and explanation, therefore, of the existence and attributes of God, insofar as they are understood by reason from natural manifestations, belongs to philosophy; in the theology of faith, however, that more distinct natural knowledge is taken up in order to acquire a clearer understanding of those things concerning God that have been revealed by supernatural manifestations: and so theology makes use of what is known of God from the philosophical disciplines, not as principles proper to its own doctrine, but as aids « for the greater manifestation of those things that are handed down in this science, » as St Thomas says, 1. q.1. a. 5. ad 2. Yet because, where the existence of God is concerned, the theology of faith and philosophy, supernatural and natural manifestation, the light of faith and the light of reason, agree in material object although they differ in formal object, hence it is that many theologians too, following the holy Fathers, set up more extended demonstrations from the principles of natural reason concerning the existence of God, which is indeed the foundation of the whole theological science², « as from proper principles, not strictly, but ministerially, » as Cajetan says, ad 1. q. 2. a. 3. The holy Fathers, above all in their apologies against the Gentiles, are accustomed to regard this philosophical treatment as a kind of pedagogy leading to faith and to Christian knowledge; and theologians likewise declare it to be a preamble to theology itself³. Lest we disturb the order of the disciplines that have been assigned to the various schools of this Academy, imitating the example⁴ of the weighty theologians, we shall leave the philosophical demonstration of the existence of God in its own proper seat, which it has in the metaphysics of sacred theology, προπαιδείας.

II. The arguments by which the existence of God is demonstrated in philosophy can be viewed in two ways: a) directly, insofar as reason, by its own power and innate light, knows from the existence of contingent beings, from their perfections connected with imperfection, from the nature of the rational creature and of all others whose existence is understood immediately, and therefore also from the essential dependence of the whole universe, its order and disposition toward an end, and from the absolute and ineluctable binding force of the moral law, that there cannot but exist a necessary being as the creative cause of effects, most wise, most perfect, just and holy provider and legislator, the principle and end of all things. This whole argumentation rests on the evident intrinsic connection of truths known by the light of reason, and therefore belongs to philosophy. The rational arguments can also be viewed as reflexively, when the question is asked what their value is: whether human reason in general has innate powers to know the existing God with certainty, or specifically whether human reason, by its natural light, can attain from the knowledge of creatures to the knowledge of the existence of God the creator, the true God, I mean, personal and altogether distinct and different from this universe. This reflexive consideration has its proper seat both in philosophy and in theology,⁵ but in a way corresponding to the different formal reason of each science. In philosophy indeed, through the direct demonstration itself, the reflexive question is also solved, since reason, knowing the object evidently, understands also reflexively that its knowledge is true. For true science does not exist « unless one knows that one knows; for science must be a perfect intellectual light, which manifests itself » (Suarez Metaphys. disp. I. sect. 4.)⁶. Yet the reflexive knowledge of the truth can be perfected and made more distinct by the analysis of the arguments.

But for theology, under its formal reason, there will undoubtedly belong the judgment on the value of rational demonstration, and on the power of human reason to know God, who exists, from creatures by the light innate to it, if in the revealed word of God, which is the proper objective principle of knowing for theology, this power of reason is explicitly affirmed or denied; or certainly if the principles are contained in revelation from which what is to be affirmed or denied may be legitimately deduced. And yet, both in the written word of God and in the universal and constant interpretation of the same revealed word handed down by the Catholic Doctors of the Church, there are many things which show that God, the author of the rational light, has taught us, even by supernatural revelation, about the innate power and about the mode, by this natural power, of knowing him, whose knowledge is the ultimate, necessary and natural end of reason. For although it were true, as some more recent theologians have remarked, that in the Scriptures and in supernatural revelation generally the existence of the true God is not so much proved by arguments as its most full persuasion is already presupposed, this very presupposition would show above all that a knowledge and persuasion of the existing God is something, and is presupposed as antecedent to and independent of supernatural revelation. Moreover, that same revelation, especially where it rebukes ignorance or the denial of the true God, both indicates theoretically the mode by which men, with nature as their guide, could and should have come to know God; and practically and in exercise, Scripture itself in more than one place presents rational demonstrations of the existence of God, drawn from the fact of the existence of this universe, as legitimate and most sufficient; which the Fathers and Doctors of the Church, cultivating more diligently the sense of the Scriptures and the Catholic understanding derived from it, afterwards vindicated in full disputations. What has now been said somewhat confusedly will be made clearer in what follows; yet it is enough to conclude that there undoubtedly are at hand theological principles, from which a judgment can be made, if not on each of the philosophical arguments, certainly on the value of rational demonstration in general, and on the powers of human reason, innate to it, for knowing from creatures the existence of God the creator. It belongs therefore to theology, considered under its formal reason, though not to it alone, to examine and to test (ἐπιχρίσις) rational knowledge and its mode, when it is asked whether there is, and what is, a legitimate demonstration of the existence of God.