(CG 2/34-37) Reasons alleged for the Eternity of the World on the part of?... (Book 2: God The Origin of Creatures) (Summa Contra Gentiles) (Aquinas, Thomas, St.)

Arg. 1. God is the cause of all things (Chap. XV). But a cause must be prior in duration to the effects of its action.

Reply. That is true of things that act by motion, for the effect is not till the termination of the motion: but with causes that act instantaneously there is no such necessity.

Arg. 2. Since the whole of being is created by God, it cannot be said to be made out of any being: whence the conclusion follows that it is made out of nothing, and consequently that it has existence after not existing.

Reply. To the notion of being made out of something, if that is not admitted one must supply the contradictory notion: which contradictory notion is not being made out of anything. Observe, it is not being made out of nothing, except in the former sense of not being made out of anything.

Arg. 3. It is not possible to pass through infinity. But if the world always had been, infinity would have been passed through by this time, there being infinite days, or daily rounds of the sun, if the world always has been.

Reply. An infinite quantity, though not existing in simultaneous actual realisation, may nevertheless be in succession, because every infinite, so taken, is really finite. Any given round of the sun could be passed, because so far the number of them was finite: but when they are all viewed together, on the supposition that the world had always existed, it would be impossible to fix upon any first day, and so to make any transition from that to the present day, since transition always requires two extreme points.

Arg 4. It would follow that addition is made to the infinite, because to past days, or sun-rounds, a new round is daily added.

Reply. There is nothing to hinder addition to the infinite on that side on which it is finite. Supposing time eternal, it must be infinite as preceding, but finite as succeeding, for the present is the limit of the past.

Arg. 5. It would follow in a world always existing that we should have an infinite series of efficient causes, father being cause of child, and grandfather to father, and so to infinity.

Reply. The impossibility of an infinite series of efficient causes, according to philosophers (Aristotle, Metaph. ii, 2), holds for causes acting together: because then the effect has to depend on an infinity of co-existent actions; and the infinity of causes there is essential, the whole infinite multitude of them being requisite for the production of the effect. But in the case of causes not acting together no such impossibility holds, in the opinion of those who suppose an endless series of generations. The infinity in this case is accidental to the causes: for to Socrates's father, as such, it is quite an accident whether he be the son of another man or no: whereas to a stick, inasmuch as it moves a stone, it is not an accident whether it be moved by an hand: for it only moves inasmuch as it is moved.

Arg. 6. It would follow that an infinite multitude exists, to wit, the immortal souls of infinite men who have been in the past.

Reply. This objection is more difficult: nevertheless the argument is not of much use, because it supposes many things. Since these reasons, alleged by some to prove that the world has not always existed, are not necessarily conclusive, though they have a certain probability, it is sufficient to touch on them slightly, without insisting too much, that the Catholic faith may not seem to rest on empty reasonings, and not rather on the solid basis of the teaching of God.