God and Contemporary Thought
The present-day position of the problem of God is wholly dominated by the thought of Immanuel Kant and of Auguste Comte. Their doctrines are about as widely different as two philosophical doctrines can possible be. Yet the Criticism of Kant and the Positivism of Comte have this in common, that in both doctrines the notion of knowledge is reduced to that of scientific knowledge, and the notion of scientific knowledge itself to the type of intelligibility provided by the physics of Newton. The verb "to know" then means to express observable relations between given facts in terms of mathematical relations.  Now, however we look at it, no given fact answers to our notion of God. Since God is not an object of empirical knowledge, we have no concept of him. Consequently God is no object of knowledge, and what we call natural theology is just idle talking.
If we compare it with the Kantian revolution, the Cartesian revolution hardly deserved such a name. From Thomas Aquinas to Descartes the distance is assuredly a long one. Yet, although extremely far from each other, they are on comparable lines of thought. Between Kant and them, the line has been broken. Coming after the Greeks, the Christian philosophers had asked themselves the question: How obtain from Greek metaphysics as answers to the problems raised by the Christian God? After centuries of patient work, one of them had at last found the answer, and that is why we find Thomas Aquinas constantly using the language of Aristotle in order to say Christian things. Coming after the Christian philosophers, Descartes, Leibniz, Malebranche, and Spinoza found themselves confronted with this new problem: How find a metaphysical justification for the world of seventeenth-century science? As scientists, Descartes and Leibniz had no metaphysics of their own. Just as Augustine and Thomas Aquinas had had to borrow their technique from the Greeks, Descartes and Leibniz had to borrow their technique from the Christian philosophers who had preceded them. Hence the vast number of scholastic expressions which we meet in the works of Descartes, Leibniz, Spinoza, and even Locke. All of them freely use the language of the Schoolmen in order to express nonscholastic views of a nonscholastic world. Yet all of them appear to us as seeking in a more or less traditional metaphysics the ultimate justification of the mechanical world of modern science. In short, and this is true of Newton himself, the supreme principle of the intelligibility of nature remains, for all of them the Author of Nature, that is, God.
With the Criticism of Kant and the Positivism of Comte, things become entirely different. Since God is not an object apprehended in the a priori forms of sensibility, space and time, he cannot be related to anything else by the category of causality. Hence, Keant concludes, God may well be a pure idea of reason, that is, a general principle of unification of our cognitions; he is not an object of cognition. Or we may have to posit his existence as required by the exigencies of practical reason; the existence of God then becomes a postulate, it is still not a cognition. In his own way, which was a much more radical one, Comte at once reached identically the same conclusion. Science, Comte says, has no use for the notion of cause. Scientists never ask themselves why things happen, but how they happen. Now as soon as you substitute the positivist's notion of relation for the metaphysical notion of cause, you at once lose all right to wonder why things are, and why they are what they are. To dismiss all such questions as irrelevant to the order of positive knowledge is, at the same time, to cut the very root of all speculation concerning the nature and existence of God.
It had taken Christian thinkers thirteen centuries to achieve a perfectly consistent philosophy of the universe of Christianity. It has taken modern scientists about two centuries to achieve a perfectly consistent philosophy of the mechanical universe of modern science. This is a fact which it is very important for us to realize, because it clearly shows where the pure philosophical positions are actually to be found.
If what we are after is a rational interpretation of the world of science given as an ultimate fact, either the Criticism of Kant himself or some edition of his Criticism revised to suit the demands of today's science should provide us with a satisfactory answer to our question. We might nevertheless prefer the Positivism of Comte, or some revised edition of it. A large number among our own contemporaries actually subscribe to one or the other of these two possible attitudes. The Neo-Criticism has been represented by such men as Paulsen and Vaihinger in Germany, by Renouvier in France; and it has found what will perhaps remain its purest formulation in the works of our own contemporary, Professor Leon Brunschvicg. As to Positivism, it has found important supporters in England, John Stuart Mill and Herbert Spencer, for instance; in France, Émile Littré, Émile Durkheim, and the whole French sociological school; and it has recently been revived, under a new form, by the Neo-Positivism of the Vienna school. Whatever their many differences, all these schools have at least this in common, that their ambition does not extend beyond achieving a rational interpretation of the world of science given as an irreducible and ultimate fact.
But if we do not think that science is adequate to rational knowledge,  if we hold that other than scientifically answerable problems can still be rationally posed concerning the universe, then there is no use for us to stop at the eighteenth-century Author of Nature. Why should we content ourselves with the ghost of God when we can have God? But there is no reason either why we should waste our time in weighing the respective merits of the gods of Spinoza, of Leibniz, or of Descartes. We now know what these gods are: mere by-products born of the philosophical decomposition of the Christian living God. Today our only choice is not Kant or Descartes; it is rather Kant or Thomas Aquinas. All other positions are but halfway houses on the roads which lead either to absolute religious agnosticism or to the natural theology of Christian metaphysics.
Philosophical halfway houses have always been pretty crowded, but never more than they are in our own times, especially in the field of natural theology. This fact is not a wholly inexplicable one. What makes it difficult for us to go back to Thomas Aquinas is Kant. Modern men are held spellbound by science, in some cases because they know it, but in an incomparably larger number of cases because they know that, to those who know science, the problem of God does not appear susceptible of a scientific formulation. But what makes it difficult for us to go as far as Kant is, if not Thomas Aquinas himself, at least the whole order of facts which provides a basis for his own natural theology. Quite apart from any philosophical demonstration of the existence of God, there is such a thing as a spontaneous natural theology. A quasi-instinctive tendency, observable in most men, seems to invite them to wonder from time to time if, after all, there is not such an unseen being as the one we call God. The current objection that such a feeling is but a survival in us of primitive myths, or of our own early religious education, is not a very strong one. Primitive myths do not account for the human belief in the existence of the Divinity; obviously, it is the reverse which is true. Early religious education is no sufficient explanation for the questions which sometimes arise in the minds of men concerning the reality or unreality of God. Some among us have received a decidedly antireligious education; other have had no religious education at all; and there are even quite a few who, having once received a religious education, fail to find in its memory any incentive to think seriously about God. The natural invitations to apply his mind to the problem come to man from quite different sources. These are the very selfsame sources which once gave rise not only to Greek mythology but to all mythologies. God spontaneously offers himself to most of us, more as a confusedly felt presence than as an answer to any problem, when we find ourselves confronted with the vastness of the ocean, the still purity of mountains, or the mysterious life of a midsummer starry sky. Far from being social in essence, these fleeting temptations to think of God usually visit us in our moments of solitude. But there is no more solitary solitude than that of a man in deep sorrow or confronted with the tragic perspective of his own impending end. "One dies alone," Pascal says. That is perhaps the reason why so many men finally meet God waiting for them on the threshold of death.
What do such feelings prove? Absolutely nothing. They are not proofs but facts, the very facts which give philosophers occasion to ask themselves precise questions concerning the possible existence of God. Just as such personal experiences precede any attempt to prove that there is a God, they survive our failures to prove it. Pascal did not make much of the so-called proofs of God's existence. To him, it was incomprehensible that God should exist, and it was incomprehensible that God should not exist; then he would simply wager that God exists - a safe betting indeed, since there was much to gain and nothing to lose. Thus to bet is not to know, especially in a case when, if we lose, we cannot even hope to know it. Yet Pascal was still willing to bet on what he could not know. Similarly, after proving in his Critique of Pure Reason that the existence of God could not be demonstrated, Kant still insisted on keeping God as at least a unifying idea in the order of speculative reason and as postulate in the moral order of practical reason. It may even appear to be true that, out of its own nature, the human mind is equally unable both to prove the existence of any God and "to escape its deep-seated instinct to personify its intellectual conceptions."  Whether we make it the result of spontaneous judgment of reason, with Thomas Aquinas; or an innate idea, with Descartes; or an intellectual intuition, with Malebranche; or an idea born of the unifying power of human reason, with Kant; or a phantasm of human imagination, with Thomas Henry Huxley, this common notion of God is there as a practically universal fact whose speculative value may well be disputed, but hose existence cannot be denied. The only problem is for us to determine the truth value of this notion.
At first sight, the shortest way to test it seems to judge it from the point of view of scientific knowledge. But the shortest way might not be the safest one. This method rests upon the assumption that nothing can be rationally known unless it be scientifically known, which is far from being an evident proposition. The names of Kant and of Comte have very little importance, if any, in the history of modern science; Descartes and Leibniz, two of the creators of modern science, have also been great metaphysicians. The simple truth may be that while human reason remains one and the same in dealing with different orders of problems, it nevertheless must approach these various orders of problems in as many different ways. Whatever our final answer to the problem of God may be, we all agree that God is not an empirically observable fact. Mystical experience itself is both unspeakable and intransmissible; hence, it cannot become an objective experience. If, speaking in the order of pure natural knowledge, the proposition "God exists" makes any sense at all, it must be for its rational value as a philosophical answer to a metaphysical question.
When a man falls to wondering whether there is such a being as God, he is not conscious of raising a scientific problem, or hoping to give it a scientific solution. Scientific problems are all related to the knowledge of what given things actually are. An ideal scientific explanation of the world would be an exhaustive rational explanation of what the world actually is; but why nature exists is not a scientific problem, because its answer is not susceptible of empirical verification. The notion of God, on the contrary, always appears to us in history as an answer to some existential problem, that is as the why of a certain existence. The Greek gods were constantly invoked in order to account for various "happenings" in the history of men as well as in that of things. A religious interpretation of nature never worries about what things are -- that is a problem for scientists -- but it is very much concerned with the questions why things happened to be precisely what they are, and why they happen at all. The Jewish-Christian God to whom we are introduced by the Bible is there at once posited as the ultimate explanation for the very existence of man, for the present condition of man upon earth, for all the successive events that make up the history of the Jewish people as well as for these momentous events: the Incarnation of Christ and the Redemption of man by Grace. Whatever their ultimate value, these are existential answers to existential questions. As such, they cannot possibly be transposed into terms of science, but only into terms of an existential metaphysics. Hence these two immediate consequences: that natural theology is in bondage not to the method of positive science but to the method of metaphysics, and that it can correctly ask its own problems only in the frame of an existential metaphysics.
1 For a general introduction to the criticism of metaphysics by Kant and Comte, see É. Gilson, The Unity of Philosophical Experience (New York: Scribner, 1937), Part III, pp. 223-295.
2 For a contemporary discussion of the scientific notion of cause, see Émile Meyerson, Identité et réalité, 2d ed. (Paris: Alcan, 1912), p. 42. De l'explication dans les sciences (Paris: Alcan, 1921), I, 57; Essais (Paris: J. Vrin, 1936), pp. 28-58.
3 A critical discussion of this unduly restricted notion of rational knowledge is to be found in J. Maritain, the Degrees of Knowledge (New York, Scribner, 1938); and also in W.R. Thomspon, F.R.S., Science and Common Sense, an Aristotelian Excursion (New York: Longmans, Green 1937), pp. 47-50.
4 Cf. the philosophical manifesto of Rudolf Euckien, Thomas von Aquino und Kant, ein Kampf zweier Welten (Berlin: Reuther and Richard, 1901).
5 Thomas Henry Huxley, The Evolution of Theology: an Anthropological Study, as quoted in Julian Huxley, Essays in Popular Science (London: Pelican Books, 1937), p. 123.
E. Gilson, God and Philosophy, 16th ed. (New Haven-London: Yale University Press, 1969), pp. 109-120.