The Aristotelian Proof for God

* copied from Edward Feser, Five Proofs of the Existence of God, Ignatius Press, 2017, page 35

1.     Change is a real feature of the world.

2.     But change is the actualization of a potential.

3.     So, actualization of potential is a real feature of the world.

4.     No potential can be actualized unless something already actual actualizes it (the principle of causality).

5.     So, any change is caused by something already actual.

6.     The occurrence of any change C presupposes some thing or substance S which changes.

7.     The existence of S at any given moment itself presupposes the concurrent actualization of S’s potential for existence.

8.     So, any substance S has at any moment some actualizer A of its own existence.

9.     A’s own existence at the moment it actualizes S itself presupposes either (a) the concurrent actualization of its own potential for existence or (b) A’s being purely actual.

10.  If A’s existence at the moment it actualizes S presupposes the concurrent actualization of its own potential for existence, then there exists a regress of concurrent actualizers that is either infinite or terminates in a purely actual actualizer.

11.  But such a regress of concurrent actualizers would constitute a hierarchical causal series, and such a series cannot regress infinitely.

12.  So, either A itself is a purely actual actualizer or there is a purely actual actualizer which terminates the regress that begins with the actualization of A.

13.  So, the occurrence of C and thus the existence of S at any given moment presupposes the existence of a purely actual actualizer.

14.  So, there is a purely actual actualizer.

15.  In order for there to be more than one purely actual actualizer, there would have to be some differentiating feature that one such actualizer has that the others lack.

16.  But there could be such a differentiating feature only if a purely actual actualizer had some unactualized potential, which, being purely actual, it does not have.

17.  So, there can be no such differentiating feature, and thus no way for there to be more than one purely actual actualizer.

18.  So, there is only one purely actual actualizer.

19.  In order for this purely actual actualizer to be capable of change, it would have to have potentials capable of actualization.

20.  But being purely actual, it lacks any such potentials.

21.  So, it is immutable or incapable of change.

22.  If this purely actual actualizer existed in time, then it would be capable of change, which it is not.

23.  So, this purely actual actualizer is eternal, existing outside of time.

24.  If the purely actual actualizer were material, then it would be changeable and exist in time, which it does not.

25.  So, the purely actual actualizer is immaterial.

26.  If the purely actual actualizer were corporeal, then it would be material, which it is not.

27.  So, the purely actual actualizer is incorporeal.

28.  If the purely actual actualizer were imperfect in any way, it would have some unactualized potential, which, being purely actual, it does not have.

29.  So, the purely actual actualizer is perfect.

30.  For something to be less than fully good is for it to have a privation-that is, to fail to actualize some feature proper to it.

31.  A purely actual actualizer, being purely actual, can have no such privation.

32.  So, the purely actual actualizer is fully good.

33.  To have power entails being able to actualize potentials.

34.  Any potential that is actualized is either actualized by the purely actual actualizer or by a series of actualizers which terminates in a purely actual actualizer.

35.  So, all power derives from the purely actual actualizer.

36.  But to be that from which all power derives is to be omnipotent.

37.  So, the purely actual actualizer is omnipotent.

38.  Whatever is in an effect is in its cause in some way, whether formally, virtually, or eminently (the principle of proportionate causality).

39.  The purely actual actualizer is the cause of all things.

40.  So, the forms or patterns manifest in all the things it causes must in some way be in the purely actual actualizer.

41.  These forms or patterns can exist either in a concrete way in which they exist in individual particular things, or in the abstract way in which they exist in the thoughts of an intellect.

42.  They cannot exist in the purely actual actualizer in the same way they exist in individual particular things.

43.  So, they must exist in the purely actual actualizer in the abstract way in which they exist in the thoughts of an intellect.

44.  So, the purely actual actualizer has intellect or intelligence.

45.  Since it is the forms or patterns of all things that are in the thoughts of this intellect, there is nothing that is outside the range of those thoughts.

46.  For there to be nothing outside the range of something’s thoughts is for that thing to be omniscient.

47.  So, the purely actual actualizer is omniscient.

48.  So, there exists a purely actual cause of the existence of things, which is one, immutable, eternal, immaterial, incorporeal, perfect, fully good, omnipotent, intelligent, and omniscient.

49.  But for there to be such a cause of things is just what it is for God to exist.

50.  So, God exists.