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The Five Ways
St. ThomaJ AquinaJ (TranAated by Laurence Shapcotej
The First Way: The Argument From Change
The existence of God can be shown in five ways. The first and clearest is taken from the idea of motion. (1) Now it is certain, and our senses corroborate it, that some things in this world are in motion. (2) But everything which is in motion is moved by something else. (3) For noth- ing is in motion except in so far as it is in potentiality in relation to that towards which it is in motion. (4) Now a thing causes movement in so far as it is in actuality. For to cause movement is nothing else than to bring something from potentiality to actuality; but a thing cannot be brought from potentiality to actuality except by something which exists in actuality, as, for example, that which is hot in actuality, like fire, makes wood, which is only hot in potentiality, to be hot in actuality, and thereby causes movement in it and alters it. (5) But it is not possi- ble that the same thing should be at the same time in actuality and potentiality in relation to the same thing, but only in relation to differ- ent things; for what is hot in actuality cannot at the same time be hot in potentiality, though it is at the same time cold in potentiality. (6) It is impossible, therefore, that in relation to the same thing and in the same way anything should both cause movement and be caused, or that it should cause itself to move. (7) Everything therefore that is in motion
Reprinted from Thomas Aquinas, Summa The%gica, trans. Laurence Shapcote (London: O. P. Benziger Brothers, 1911).
St. Thomas Aquinas The Five Ways· 381
must be moved by something else. If therefore the thing which causes it
to move be in motion, this too must be moved by something else, and so on. (8) But we cannot proceed to infinity in this way, because in that case there would be no first mover, and in consequence, neither would there be any other mover; for secondary movers do not cause movement except they be moved by a first mover, as, for example, a stick cannot cause movement unless it is moved by the hand. Therefore it is necessary to stop at some first mover which is moved by nothing else. And this is what we all understand God to be.
The Second Way: The Argument From Causation
The Second Way is taken from the idea of the Efficient Cause. (1) For we find that there is among material things a regular order of efficient causes. (2) But we do not find, nor indeed is it possible, that anything is the efficient cause of itself, for in that case it would be prior to itself, which is impossible. (3) Now it'is not possible to proceed to infinity in efficient causes. (4) For if we arrange in order all efficient causes, the first is the cause of the intermediate, and the intermediate the cause of the last, whether the intermediate be many or only one.
. (5) But if we remove a cause the effect is removed; therefore, if there is
no first among efficient causes, neither will there be a last or an inter-
mediate. (6) But if we proceed to infinity in efficient causes there will be no first efficient cause, and thus there will be no ultimate effect, nor any intermediate efficient causes, which is dearly false. Therefore it is necessary to suppose the existence of some first efficient cause, and this men call God.
The Third Way: The Argument From Contingency The Third Way rests on the idea of the "contingent" and the "necessary" and is as follows: (1) Now we find that there are certain things in the Universe which are capable of existing and of not existing, for we find that some things are brought into existence arid then destroyed, and consequently are capable of being or not being. (2) But it is impossible for all things which exist to be of this kind, because anything which is capable
bf not existing, at some time or other does not exist. (3) If therefore all
things are capable of not existing, there was a time when nothing existed in the Universe. (4) But if this is true there would also be nothing in existence now; because anything that does not exist cannot begin to exist except by
Richard Taylor The Cosmological Argument • 383
no knowledge do not move towards a goal unless they are guided by someone or something which does possess knowledge and intelli- gence-e.g., an arrow by an archer. Therefore, there does exist something which possesses intelligence by which all natural things are directed to their goal; and this we call God.
