The Cosmological Argument

Gordon H. Clark

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Thomas Aquinas rejected the Platonic cast of Augustine’s theology and based his thought on Aristotle. Therefore he had no time for the ontological argument, but reconstructed the cosmological argument. To refer again to the question of knowledge, the difference between these two arguments is basically a difference in epistemology: For Augustine it was not necessary to start with sensory experience, for one could go directly from the soul to God; but Aquinas wrote, “The human intellect .... is at first like a clean tablet on which nothing is written” (Summa Theologica I, Q:97, 2). It is sensation that writes on the tabula rasa. The mind has no form of its own. All its contents come from sensation. On this basis, Thomas gave five arguments for God’s existence; but the first four are almost identical, and the fifth is so little different, that only the first will be reproduced here:


The first and more manifest way is the argument from motion. It is certain and evident to our senses that in the world some things are in motion. Now, whatever is moved is moved by another, for nothing can be moved except it is in potentiality to that towards which it is moved; whereas a thing moves inasmuch as it is in act. For motion is nothing else than the reduction of something from potentiality to actuality. But nothing can be reduced from potentiality to actuality, except by something in a state of actuality. Thus that which is actually hot, as fire, makes wood, which is potentially hot, to be actually hot, and thereby moves and changes it. Now it is not possible that the same thing should be at once in actuality and potentiality in the same respect, but only in different respects. For what is actually hot cannot simultaneously be potentially hot; but it is simultaneously potentially cold. It is therefore impossible that in the same respect and in the same way a thing should be both mover and moved, i.e., that it should move itself. Therefore whatever is moved must be moved by another. If that by which it is moved be itself moved, then this also must needs be moved by another, and that by another again. But this cannot go on to infinity, because then there would be no first mover, and consequently no other mover, seeing that subsequent movers move only inasmuch as they are moved by the first mover; as the staff moves only because it is moved by the hand. Therefore it is necessary to arrive at the first mover, moved by no other, and this everyone understands to be God.


The first thing to be noticed is that this is a formal argument. Thomas intended it to be a conclusive demonstration that God exists. It is not a collection of evidences that make it plausible to believe in God. It is an analysis of sensory experience with the conclusion that only God can explain it. Far from being a list of evidences, it appeals only to a pebble that rolls down the hillside or a marble that rolls across the floor. It claims to prove conclusively that on this basis God must of necessity exist. It is a matter of logical necessity.

Five objections can be made against this cosmological argument. First, the original premise says, “It is certain and evident to our senses that in the world some things are in motion.”

Empiricism is perhaps a common sense view. It has also been the view of many philosophers. But it faces insuperable objections. In the first place, the senses of men and animals produce conflicting data. Dogs, for example, are supposed to be color blind, but they have sensations o sound when men hear nothing. For that matter, men differ among themselves. Esoteric artists see colors in grass that no common man finds there. Which of these sensations correctly represent the color of the object seen? In some cases the senses contradict each other, as when a stick half submerged looks bent but feels straight. Then there are mirages and other optical illusions. While they last, we cannot tell that they are illusions; and we cannot tell whether our present sensations are illusions. Again, are we dreaming or not? An elementary textbook on psychology will describe many of these phenomena, with the result that it is impossible to trust what we call sensory perception. Beyond this, the theory of imagination, by which the sensations are supposed to be preserved and later raised to concepts, collapses on the fact that some people do not have images. Many people lack olfactory or tactual imagery; some also lack visual imagery as well. Empiricism then would have to say that these people can know nothing. But some of them are accomplished scholars.

The second objection notes that the quoted passage is more a summary than a complete argument. In fact the complete argument would include a great amount of physics and metaphysics. For example, the second, third, and fourth sentences in the quoted argument need lengthy substantiation. The extent would cover hundreds of pages, as it does in both Aristotle and Aquinas. For the final cosmological argument to be valid, all the subsidiary arguments must be valid. Now, while this is theoretically possible, it is not probable. Surely Aristotle and Aquinas must have made a mistake somewhere. And one mistake breaks the chain of consequences. Of course, someone is sure to complain that this is unfair and begs the question. To avoid this accusation, it may be pointed out that the two philosophers use the concept of potentiality. Aristotle needed the concept of potentiality in order to define motion. But in the third book of the Physics, where Aristotle takes up this problem, he not only defines motion by potentiality, but he also explains potentiality by the concept of motion. If the student wants to spend the time, he may study Aristotle’s Physics to determine whether the argument is circular and whether there are any other flaws in books four to eight.

The third objection can be seen in the summary itself. Toward the end Aquinas talks about a series of motions and movers, and says that this series cannot go on to infinity. The reason it cannot go on to infinity is that if it did there would be no first mover. But unfortunately the argument as a whole claims to prove that there is a first mover. Therefore Aquinas has used for one of his premises the very proposition that he wants as the conclusion.

The fourth objection is more complicated. Because Aquinas holds that God’s existence is identical with his essence, which is not true of any other object of knowledge, he must assert that no predicate can be attributed to God in the same sense that it is said of created beings. When both man and God are said to be good, or rational, or conscious, or anything, the words good and conscious do not mean the same thing in the two cases. If God is a mover and man is am over, the word mover does not mean the same thing. Not only so, but since God’s existence and essence are identical, the verb to be does not have the same meaning in the two cases. If we say God is good, neither the good nor the is means what it means in the created world. Hence when we say God exists, this existence does not mean existence in the same sense we use it for pebbles or marbles. Now, in a valid argument the only terms that can occur in the conclusion are those that occur in the premises. If some additional element is added in the conclusion, the syllogism is a fallacy. But the cosmological argument begins with the existence of a pebble or some sensory object that moves. It ends, however, with an existence that is different. There fore the argument is fallacious. The different meaning of the word in the conclusion cannot be derived from the original meaning in the premises.

Now, finally, the fifth objection is directed against the last sentence of the argument, which is, “and this everyone understands to be God.” But this is not what everyone understands to be God. Particularly Christians deny that this is God. Aquinas claims to have proved the existence of a first mover, a primum movens, an ens perfectissimum, or even a summum bonum. But these neuters are not satisfactory for a concept of the living self-revealing God of the Scriptures. It can even be said that if the cosmological argument were valid, Christianity would be false. The God of the Bible is a Trinity of Persons. No form of the cosmological argument has ever claimed to demonstrate the existence of this only true God.

Despite these objections, Roman Catholics continue to depend on the cosmological argument, so do most Lutherans, and some Calvinists defend it, too. J. Oliver Buswell, Jr. was one of these, at least in his earlier writings, though he seems to have agreed later that it is not strictly valid. Cornelius Van Til of Westminster Seminary, Philadelphia, makes very strong statements on the validity of the argument. Buswell had accused Van Til of disparaging the objective evidences for Christianity and of rejecting the cosmological argument. Van Til replied in A Christian Theory of Knowledge (291-292) and charged Buswell with formulating the argument improperly. Quoting partly from one of his earlier works, Common Grace, he says:


The argument for the existence of God and for the truth of Christianity is objectively valid. We should not tone down the validity of this argument to possibility level. The argument may be poorly stated and may never be adequately stated. But in itself the argument is absolutely sound.... .Accordingly I do not reject the theistic proofs, but merely insist on formulating them in such a way as not to compromise the Scripture. That is to say, if the theistic proof is constructed as it ought to be constructed, it is objectively valid.


This assertion that the cosmological argument is valid, absolutely sound, a formal demonstration, and not merely a probability argument does not hold true of any cosmological argument published in any book. Van Til pays no attention to the fallacies embedded in Thomas Aquinas. The argument he defends is one that no one has ever yet written. But how does he know that it is possible to formulate this ideal argument? What is the argument he defends? He says he insists on formulating it correctly. For many years some of Van Til’s contemporaries have been challenging him to produce this reformulation he insists upon. He has not done so.

Since Van Til and Buswell in the passage cited are engaged in recommending a method of preaching the Gospel to unbelievers, it is doubly unfortunate that Van Til cannot justify his position, for unbelievers cannot be expected to be impressed with an argument that the evangelist himself is unable to present to them.

September 1979