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CHAPTER LXXII: THAT DIVINE PROVIDENCE DOES NOT EXCLUDE CONTINGENCY FROM THINGS
JUST as divine providence does not altogether banish evil from the world, so neither does it exclude contingency, nor impose necessity on things.
For we have already proved that the operation of providence, whereby God operates in the world, does not exclude secondary causes, but is fulfilled by them inasmuch as they act by God's power. Now certain effects are said to be necessary or contingent, in relation to their proximate, not to their remote cause: thus for a plant to bear fruit is a contingent effect, on account of the proximate cause, which is the power of germination that can be hindered and fail, although a remote cause, namely the sun, is a cause that acts of necessity. Since, then, among proximate causes there are many that can fail, not all the effects subject to divine providence will be necessary, but many of them will be contingent.
Again. It belongs to divine providence that the possible degrees of being be fulfilled, as was made evident above. Now being is divided into contingent and necessary: and this is a per se division of being. Therefore, if divine providence excluded all contingency, not all the degrees of being would be preserved.
Besides. The nearer things are to God the more they partake in a likeness to Him: and the further they are from Him the more they fail in their likeness to Him. Now those things that are nearest to God are altogether immovable; these are separate substances who approach nearest to a likeness to God who is utterly immovable; while those that are nearest to them and are immediately moved by those that are unchangeable, retain a certain degree of immobility in that they are always moved in the same way, for instance the heavenly bodies. Consequently those that come after the foregoing, and are moved by them, are further removed from the divine immobility, so that, to wit, they are not always moved in the same way: and in this the beauty of order is evident. But every necessary thing, as such, never varies. Therefore it would be incompatible with divine providence, to whom it belongs to establish and preserve order among things, if all things happened of necessity.
Moreover. That which is of necessity, is always. Now nothing corruptible is always. Wherefore if divine providence requires all things to be necessary, it would follow that nothing in the world is corruptible, and consequently nothing could be generated. Hence the whole range of things subject to generation and corruption would be withdrawn from the world: and this would be derogatory to the perfection of the universe.
Further. In every movement there is generation and corruption of a kind: since in a thing that is moved, something begins, and another ceases to be. Consequently if all generation and corruption were banished, through the withdrawal of all things contingent, as we have just proved, in consequence all movement and all movable things would be taken away.
Besides. If the power of a substance be weakened, or if it be hindered by a contrary agent, this argues some change in that power. Consequently if divine providence does not banish movement from things, it will prevent neither the weakening of their power nor the impediment arising from the resistance of another agent. Now it is because that power is sometimes weakened and hindered that nature does not work always in the same way, but sometimes fails in that which is competent to a thing according to its nature, so that natural effects do not follow of necessity. Therefore it does not belong to divine providence to impose necessity on the things governed.
Moreover. In things that are duly ruled by providence, there should be nothing vain. Since therefore it is evident that some causes are contingent, seeing that they can be hindered from producing their effects, it is clearly inconsistent with providence that all things should occur of necessity. Therefore divine providence does not impose necessity on things, by excluding contingency from them altogether.
|Source: St. Thomas Aquinas, The Summa Contra Gentiles, trans. by The English Dominican Fathers from the latest Leonine Edition, Benzinger Brothers: New York, 1924.|