Chapter 7: The Proofs Of God's Existence

To show the structure and style of the treatise De Deo uno, as that treatise is found in the Summa, as understood by the Thomistic school, our first consideration must be given to the proofs there given for God's existence, since these proofs are starting points in deducing all divine attributes. Next, we will dwell on the pre-eminence of the Deity, and the nature and limits of our knowledge, natural and supernatural, of that divine nature. The last chapters, then, will speak of God's wisdom, of His will and His love, of providence and predestination.

In the Summa, St. Thomas reassumes, from a higher viewpoint, proofs for God's existence already given by Aristotle, Plato, Neo-Platonists, and Christian philosophers. After a synthetic exposition of these five arguments, we will examine their validity and point of culmination.

1. Synthetic Exposition

Examining these five ways, the saint finds in them generic types under which all other proofs may be ranged. We have given elsewhere [268] a long exposition of this problem.

St. Thomas does not admit that an a priori proof of God's existence can be given. [269] He grants indeed that the proposition, God exists, is in itself evident, and would therefore be self-evident to us if we had a priori face-to-face knowledge of God; then we would see that His essence includes existence, not merely as an object of abstract thought, but as a reality objectively present. [270] But in point of fact we have no such a priori knowledge of God. [271] We must begin with a nominal definition of God, conceiving Him only confusedly, as the first source of all that is real and good in the world. From this abstract knowledge, so far removed from direct intuition of God's essence, we cannot deduce a priori His existence as a concrete fact.

It is true we can know a priori the truth of this proposition: If God exists in fact, then He exists of Himself. But in order to know that He exists in fact, we must begin with existences which we know by sense experience, and then proceed to see if these concrete existences necessitate the actual objective existence of a First Cause, corresponding to our abstract concept, our nominal definition of God. [272] .

This position, the position of moderate realism, is intermediary, between the agnosticism of Hume on the one hand, and, on the other, that excessive realism, which in varying degree we find in Parmenides, Plato, and the Neoplatonists, and which in a certain sense reappears in St. Anselm, and later, much accentuated, in Spinoza, in Malebranche and the Ontologists, who believe that they have an intuition and not merely an abstract concept of God's nature.

The five classical proofs for God's existence rest, one and all, on the one principle of causality, expressed in ever deepening formulas, as follows. First: whatever begins has a cause. Second: every contingent thing, even if it should be ab aeterno, depends on a cause which exists of itself. Third: that which has a share in existence depends ultimately on a cause which is existence itself, a cause whose very nature is to exist, which alone can say: I am who am. Wherever, then, we do not find this identity, wherever we find composition, union between essence and existence, there we must mount higher, for union presupposes unity.

Most simply expressed, causality means: the more does not come from the less, the more perfect cannot be produced by the less perfect. In the world we find things which reach existence and then disappear, things whose life is temporary and perishable, men whose wisdom or goodness or holiness is limited and imperfect; then above all this limited perfection we must find at the summit Him who from all eternity is self-existing perfection, who is life itself, wisdom itself, goodness itself, holiness itself.

To deny this is to affirm that the more comes from the less, that the intelligence of a genius, that the goodness of a saint, come from blind material fatality. In this general formula are contained all a posteriori proofs, all founded on the principle of causality.

To see the validity of these arguments we may recall here what was said above on the law of necessary subordination in causes. In looking for the cause here and now required for this and that existent reality, we cannot have recourse to causes that no longer exist. Without grandfather and father this son would not exist. But he can now exist, though they and all his ancestors may be dead. They too, like himself, were contingent, not necessary, and, like him, compel us to look for a cause that gave them existence. They had each received existence, life, intelligence. None among them, progenitor or descendant, could ever say: I am the life. In all forms of life the same principle holds good. The first source, the first ancestor, would have to be its own cause. [273] .

Further, must we admit at all that contingent existences necessarily had a beginning? St. Thomas says: No, this is a question of past fact which we cannot know a priori. [274] But contingent existence, though it should be without beginning, can simply not be conceived without origin, without a cause, which had and has an unreceived existence and life, the eternal source of received existence and life.

The saint gives us an illustration. The footprint on the sand presupposes the foot from which it came, but if the foot were eternally placed on the sand, the footprint too would be eternal, without beginning, but not without origin. The priority of the foot is a priority, not of time and duration, but of origin and causality. Thus the whole world, with or without beginning, has its origin in the Supreme Cause. [275] .

The cause demanded by existing facts, therefore, is not to be found in a series accidentally subordinated, in which previous causes are just as poor as subsequent causes, whose order itself might have been inverted. [276] The cause necessarily required for this existing fact can be found only in a series of causes essentially subordinated, and here and now actually existing. This is what metaphysicians term the "search for the proper cause," that is, the cause necessarily required here and now for the effect in question. This is the meaning of the words: Any effect suffices to show that its proper causes exists. [277] We do not say "that its proper cause once existed." From a son's actual existence we cannot conclude that his father still exists. The son's existence which, in becoming, in fieri, at the moment of generation depended on the father's existence, does not thus depend quoad esse, for continued existence. [278] .

This dependence of effect on its proper cause is as necessary and immediate as is the dependence of characteristic properties on the nature of the circle, from which they are derived. Illustrative examples: the murderer murders, light illuminates, fire heats.

Let us see this principle at work in the first of the five ways of proving God's existence. Motion is not self-existent; we instinctively ask for the source, the moving agent. If motion is not self-explanatory, then nothing else that is in motion is self-explanatory. Hence the proper cause of motion is something that is not in motion, an unmoved mover, the source of all movement, of all change, local, quantitative, qualitative, vital, intellectual, voluntary, a mover which is its own uncaused and unreceived activity.

In illustration, take an example already given: the sailor supported, in ascending order, by the ship, by the waves, by the earth, by the sun, by some still higher cosmic center. Here we have a series of causes, necessarily subordinated and here and now existent. Were there here no ultimate and supreme center, no unmoved mover, then there could not be any intermediate center, and the fact we started from would be nonexistent. For the whole universe, with its all but numberless movements and intermediate sources of movement, you still need a supreme mover, just as necessarily, to illustrate, as you need a spring in your watch if the hands are to move. The wheels in the watch, whether few or many, can move the hands only so far as they are themselves moved by the spring. This proof is valid. But a wrong conception of causality can render it invalid. [279] .

Let us now look at the five different ways on which St. Thomas follows the applications of the principle of causality.

2. Fundamental Validity Of The Five Ways

All these proofs rest on the principle of causality: Anything that exists, if it does not exist of itself, depends in last analysis on something that does exist of itself. To deny this principle leads to absurdity. To say "a thing contingent, that is, a thing which of itself does not have existence, is nevertheless uncaused" is equivalent to saying: A thing may exist of itself and simultaneously not exist of itself. Existence of itself would belong to it, both necessarily and impossibly. Existence would be an inseparable predicate of a being which can be separated from existence. All this is absurd, unintelligible. Kant here objects. It is absurd, he says, for human intelligence, but not perhaps in itself absurd and unintelligible.

In answer, let us define absurdity. Absurd is that which cannot exist because it is beyond the bounds of objective reality, without any possible relation to reality. It is agreement between two terms which objectively can never agree. Thus, an uncaused union of things in themselves diverse is absurd. [283] The only cause of union is unity. [284] Union means a share in unity, because it presupposes things which are diverse, brought together by a higher unity. When you say: "Anything (from angel to grain of sand) can arise without any cause from absolute nothing," then you are making a statement which is not merely unsupported and gratuitous, but which is objectively absurd. Hence, we repeat: A being which is not self-existent, which only participates in existence, presupposes necessarily a Being which by nature is self-existent. Unity by participation presupposes unity by essence. [285] .

We have here presented the principle of causality, as St. Thomas does in question three, by the way that ascends from effect to cause. [286] The same truth can be treated in the descending order, from cause to effect, [287] as it is in fact treated later in the Summa. [288] Many modern authors proceed from this second viewpoint. But the first order ought to precede the second. [289] .

To proceed. The denial of the principle of causality is not, it is true, a contradiction as immediately evident as if I were to say: "The contingent is not contingent." St. Thomas [290] gives the reason why this is so. In denying causality, he says, we do not deny the definition itself of the contingent. What we do deny is, not the essence [291] Of the contingent, but an immediate characteristic (proprium) [292] Of that essence. But to deny the principle as thus explained is as absurd as to affirm that we cannot, knowing the essence of a thing (e. g.: of a circle): deduce from that essence its characteristics. Hence to deny essential dependence of contingent being on its cause leads to absurdity, because such denial involves the affirmation that existence belongs positively to a thing which is not by nature self-existent and still is uncaused. Thus we would have, in one subject, the presence both of unessential existence and of non-dependence on any cause of its existence: a proposition objectively absurd.

But we find the denial of this principle of causality in ways that are still less evidently contradictory (in Spinoza, for example) where the contradiction is, at first sight, hidden and unapparent. To illustrate. Some who read the sentence, "Things incorporeal can of themselves occupy a place," cannot at once see that the sentence contains a contradiction. And still it is absurd to think that a spirit, which lives in an order higher than the order of quantity and space, should nevertheless be conceived as of itself filling place, place being a consequence of quantity and space. [293] .

Likewise there are contradictions which emerge only under the light of revelation. Suppose, as illustration, a man says there are four persons in God. Faith, not reason, tells us the proposition is absurd. Only those who enjoy the beatific vision, who know what God is, can see the proposition's intrinsic absurdity.

If denial or doubt of the principle of causality leads to doubt or denial of the principle of contradiction, then the five classic proofs, truly understood, of God's existence cannot be rejected without finding absurdity at the root of all reality. We must choose: either the Being who exists necessarily and eternally, who alone can say "I am truth and life," or then a radical absurdity at the heart of the universe. If truly God is necessary Being, on which all else depends, then without Him the existence of anything else becomes impossible, inconceivable, absurd. In point of fact, those who will not admit the existence of a supreme and universal cause, which is itself existence and life, must content themselves with a creative evolution, which, lacking any raison d'etre, becomes a contradiction: universal movement, without subject distinct from itself, without efficient cause distinct from itself, without a goal distinct from itself, an evolution wherein, without cause, the more arises from the less. Contradiction, identity, causality, all first principles go overboard. Let us repeat. Without a necessary and eternal being, on which all else depends, nothing exists and nothing can exist. To deny God's existence and simultaneously to affirm any existence is to fall necessarily into contradiction, which does not always appear on the surface, in the immediate terms employed, but which is always there if you will but examine those terms. Many of Spinoza's conclusions contain these absurdities. A fortiori, they lie hidden in atheistic doctrine which denies God's existence. Hence agnosticism, which doubts God's existence, can thereby be led to doubt even the first principle of thought and reality, the principle of contradiction.

Having thus shown the validity of the five ways to prove God's existence we now turn to dwell on their unity, the point where they all converge and culminate.

3. Point Of Culmination

This point is found in the idea of self-subsistent being. [294] This idea unifies the five ways as a common keystone unifies five arches. Five attributes appear, one at the end of each way, in ascending order thus: first mover of the universe, corporeal and spiritual, first efficient cause, first necessary being, supreme being, supreme directing intelligence. Now these five attributes are to be found only in self-subsistent being, who alone can say: "I am who am." Let us look at each of the five.

The prime mover must be his own activity. But mode of activity follows mode of being. Hence the prime mover must be his own subsistent being.

The first cause, being uncaused, must have in itself the reason for its existence. But the reason why it cannot cause itself is that it must be before it can cause. Hence, not having received existence, it must be existence.

The first necessary being also implies existence as an essential attribute, that is, it cannot be conceived as merely having existence, but must be existence.

The supreme being, being absolutely simple and perfect, cannot have a mere participated share of existence, but must be of itself existence.

Lastly, the supreme directing intelligence cannot be itself proportioned to an object other than itself; it must itself be the object actually and always known. Hence it must be able to say, not merely "I have truth and life," but rather "I am truth and life."

Here, then, lies the culminating keystone point, the metaphysical terminus of the road that ascends from the sense world to God. This ascending road [295] ends where begins the higher road, [296] the road of the wisdom which, from on high, judges the world by its supreme cause. [297] .

Thus again, at the summit of the universe reappears the fundamental Thomistic truth. In God alone are essence and existence identified. [298] In this supreme principle lies the real and essential distinction of God from the world. This distinction reveals God as unchangeable and the world as changeable (the first three proofs for His existence). It becomes more precise when it reveals God as absolutely simple and the world as multifariously composed (fourth and fifth proofs). It finds its definitive formula when it reveals God as "He who is," whereas all other things are only receivers of existence, hence composed of receiver and received, of essence and existence. The creature is not its own existence, it has existence after receiving it. If the verb "is" expresses identity of subject and predicate, the negation "is not" denies this identification.

This truth is vaguely grasped by the common sense of natural reason, which, by a confused intuition, sees that the principle of identity is the supreme law of all reality, and hence the supreme law of thought. As A is identified with A, so is supreme reality identified with absolutely one and immutable Being, transcendently and objectively distinct from the universe, which is essentially diversified and mutable. This culminating point of natural reason, thus precisioned by philosophic reason, is at the same time revealed in this word of God to Moses: "I am who am." [299] .

Now we understand the formulation given to the twenty-third of the twenty-four theses. It runs thus: The divine essence, since it is identified with the actual exercise of existence itself, that is, since it is self-subsistent existence, is by that identification proposed to us in its well-formed metaphysical constitution, and thereby gives us the reason for its infinite perfection. [300] To say it briefly: God alone is self-subsistent existence, in God alone are essence and existence identified. This proposition, boundless in its range, reappears continually on the lips of St. Thomas. [301] But it loses its deep meaning in those who, like Scotus and Suarez, refuse to admit in all creatures a real distinction between essence and existence.

To repeat. According to St. Thomas and his school God alone is His own existence, uncaused, unparticipated self-existence, whereas no creature is its own existence; the existence it has is participated, received, limited, by the essence, by the objective capacity which receives it. This truth is objective, a reality which antecedes all operation of the mind. Hence the composition of essence and existence is not a mere logical composition, but something really found in the very nature of created reality. [302] Were it otherwise, were the creature not thus composed, then it would be act alone, pure act, no longer really and essentially distinct from God. [303] .

Self-existent understanding [304] is given by some Thomists as the metaphysical essence of God, as the point where the five ways converge and culminate. While we prefer the term self-existent being, self-existent existence, [305] the difference between the two positions is less great than it might at first seem to be. Those who see that culminating point in ipsum esse subsistens, begin by teaching that God is not body but pure spirit. [306] From that spirituality follow the two positions in question: first, that God is the supreme Being, self-existent in absolute spirituality at the summit of all reality; second, that He is the supreme intelligence, the supreme truth, the supreme directive intelligence of the universe.

On this question, then, of God's metaphysical essence according to our imperfect way of understanding, the two positions agree. They agree likewise when the question arises: What is it that formally constitutes the essence of God as He is in Himself, as He is known by the blessed in heaven who see Him without medium, face to face? The answer runs thus: Deity itself, not self-subsistent existence, not self-existent understanding. Self-subsisting existence indeed contains all divine attributes, but only implicitly, as deductions to be drawn therefrom in order, one by one. But Deity, God as He is in Himself, contains in transcendent simplicity all these divine attributes explicitly. The blessed in heaven, since they see God as He is, have no need of progressive deduction.

The pre-eminence of the Deity, this transcendent simplicity, will be our subject in the chapter which now follows.