The Argument from Motion

a) Doctrine of Motion

In the widest sense, motion is any activity, internal or external, bodily or spiritual, that can be exercised in a finite being. Thus, in this sense, there is motion in walking, in growing, in singing, in understanding, in making up one’s mind. In a more definite sense, motion may be defined as the transition from potentiality to actuality. This definition needs a word of explanation. A thing is in potentiality, inasmuch as it has the capacity to do or to receive something; and a thing is in actuality, inasmuch as such capacity is realized in fact. Thus, water is actually water (or is water in actuality), but potentially it is hydrogen and oxygen (or is hydrogen and oxygen in potentiality). Conversely, hydrogen and oxygen (taken in proportionate parts of two to one) are actually hydrogen and oxygen, but potentially these gases are water. In a word, a thing is actually what it is; potentially, it is what it may become. And what it may become may affect the thing in its very substance or in its accidents (i.e., quantity, quality, place, etc.). Thus, there is a transition from potentiality to actuality (and hence motion) when hot water tbecomes cold water, when a living body becomes a Ilifeless body, when a body is changed from one placee to another, In everyday speech the term motion conveys the idea of movement in space, or rather as the movement of a body from one place to another. This is local motion, or locomotion. In whatever sense we choose to understand motion, we find that it is always a thing given, conferred, transmitted; it is never self-originating. Motion always requires two things: the thing moved, and the mover or motor. Motion requires a mover that is not one and the same as the thing moved. Whatever is moved is moved by something other than itself. This is a law that has no exceptions. Lifeless matter is inert and cannot move itself: living things “move themselves,” but not in the sense that they are the complete origin and source of their motion, for they require a creator, a conserver, and the concurrence of their conserving cause in their activities or motions. Perhaps a further word on this matter is in order. Lifeless things are inert and do not move themselves. Iron filings that move towards a magnet are not self-moving; they are moved by a pqwer residing in the magnet. Nor does this power give itself origin and activity, but comes from another source. A steam engine “moves” or, rather, is moved, because steam forces the pistons back and forth, and these move rods that move wheels. Nor is the force of steam self-originating. Steam is given reality and power by the action of fire upon water. Nor have fire and water their force of themselves, but depend upon their constituent elements, and these upon other things, and ultimately upon the first cause, which gives all being. Living things move themselves in accordance with set laws of nature (plants) and also in accordance with instinct aroused by sense-knowledge (brutes), and also by free choice exercised after the field of choice is manifested by intellectual knowledge (men). But no living thing gives itself life, the power of selfmotion. Nor does a living thing preserve itself in being and activity. Its being and its motion depend ultimately upon the first cause, which is thus also the first mover. A man’s senses perceive objects; but there must be objects there to perceive, else the senses are not stirred or moved to activity. A man’s mind understands truths, but understanding depends upon sense-knowledge for its beginnings, and senseknowledge depends upon external objects of sensation. Thus neither sensation nor understanding is self-originating, but both are dependent upon an inner life-principle (which did not make itself) and upon objects of knowledge (which did not make themselves). Wherever we find motion, we find that it is stirred into being by something other than the thing which is moved. Thus we have a universally true dictum in the law, “Whatever is moved is moved by something other than itself ” When we speak of things less than the infinite first cause, we use the term “move” in a loose sense; we sho uld properly use the passive voice and say, “is move d” and “are moved.” Now, if everything moved requires a mover, it is obvious that there must be a beginning of the chain of motion, there must be a first mover, which is really first, and is therefore not moved itself by some other thing. In other words, the fact of motion requires as a sufficient explanation, a sufficient reasoin for its existence, a first mover itself unmoved. For there cannot be an infinite series of movers or motors. If A is moved by B, and B by C, and C by D, and D by E, and so on, there must be a first beginning■ of the chain of motion, and of all such chains of motion. For the first mover must be one, since, being truly the first mover, it is not subject to the cause of motion, i.e., is not subject to another mover; it causes motion but is itself uncaused; it must be identified with the first cause of all things, the one and infinite God. If the first mover were distinct from the first and infinite cause of all things (which, as we have seen is one), then this first mover must be the creature of that first and infinite cause, and so it is not first at all, but is moved into being by the first cause.

b) The Argument

If there is motion in the world, there is a mover, and ultimately a first mover, itself unmoved ; Now, there is motion in the world; Therefore, there is a mover, and ultimately a first mover, itself unmoved. This we call God.

The first statement (the major premiss) is obvious in view of what we have learned in discussing the nature of motion and its adequate explanation. The second statement (the minor premiss) is also evident. There have been philosophers (of whom Protagoras, Greek philosopher of the fifth century b. c., is the most notable) who asserted that we need not look for the origin of motion, since everything is motion. “Nothing is” they say, “all is becoming” This doctrine is self-contradictory. It asserts that everything is in a perpetual state of flux, change, motion ; and if this be so, all things are contingent, and the universal moving mass does not explain itself, but still demands a first cause. Thus there is need to look for the origin of motion. Again: in the very idea of movement or motion there is the notion of something new being continually acquired, and of something left behind, by the moving thing,. Movement means the leaving of one state of being for another, the leaving of potentiality for actuality. Now, a thing cannot give itself what it does not possess; the new and perpetually renewed acquisitions or actualities must be given by something other than the thing moved. Nor can moving things progress in a circular series, passing mutations around a universal ring, unless there is a Supreme U amoved Being outside the ring to originate and sustain the motion. In no case, not even in the absurd supposition that the “becoming theory” is true, can reason escape the conclusion that motion requires a first mover itself unmoved. We need not pause to investigate in detail the doctrine of the old Eleatics (Greek philosophers of the sixth and fifth centuries b. c.) that there )s no motion in the world. If that be true, then there i$ no validity in human knowledge. By our senses We perceive motion; by our minds we understand its presence and nature; and if there be no motion, then senses and the mind are deceived about one of the ipost evident facts in the world, and cannot be trusted at all. If there be no motion, there can be no real births or deaths, no growing up, no growing old. There is no need then for the motorist “stalled” on the railway crossing to fear the onrushing train; there is no occasion for planting crops which cannot grow; there is no possibility of taking the food which could not, in any event, be digested. And, since the denial of motion involves, as we have seen, the denial of the validity of human knowledge, there is no occasion to speak of reasons or arguments in support of the theory which denies motion: for, in the hypothesis, men’s minds cannot be trusted to know whether such reasons and arguments are valid or foolish. Denial of motion involves denial of human reason; it involves an intellectual short-circuit; there remains but darkness, nescience, and “the rest is silence.”

Summary of the Article

In this Article we have defined motion and have explained various senses in which the term may be understood. We have investigated the law, Whatever is moved is moved by something other than itself, and we have seen that this “something other” must be traced back to a first mover itself unmoved, which is identified with the first cause itself uncaused. And this first mover is God. In the preceding Article we learned that God, the First Cause, is one, infinite, eternal, necessary. In the present Article we learn that God is also unmoved and unmovable, i.e., that God is immutable.