I wish to know more about Aquinas’ defence of the existence of God from the “argument from evil”, especially his “per se/per accidens” explanations.
For Aquinas, God is the cause of things by causing their existence. Evil is a privation, i.e. it is the lack of some due perfection or existence in something that already has existence. There can be nothing that is “pure evil;” an evil thing is first a thing. Consequently it has some existence, and so has some good, of which God is the cause. Since evil is the lack of existence, God is not the direct, i.e. per se, cause of it; He is the cause of evil only indirectly, i.e. per accidens, insofar as He causes things to exist in which there is found some evil. So, Aquinas believes that the existence of God can be proved from the fact that things exist and do not cause their own existence. This being so, i.e. that God exists, the existence of evil does not undercut the proof, since even the existence of evil presupposes the existence of things. Thus, the answer to the problem of evil is whether God, while not directly willing evil, can indirectly allow evil and still be all-good and all-powerful. His answer is that God is so powerful, that He allows evil in order to bring good from it. Ultimately, I think, Aquinas does not show HOW this is the case in every evil we experience. He believes, however, THAT it must be the case, since we already know that God exists and that He is all-powerful and all-good.
I was wondering if you might be able to help me defend Aquinas and his postion that God is all good and all knowing despite natural disasters? In other words, how can they exist if God is all knowing and good?
Ultimately, I think, Aquinas’ answer is that God can always create a better world than He has, and that the existence of evil in a world does not mean it was not created by God. He rejects the principle behind the atheistic argument that a good God would want to prevent natural evils if he knew about them and he was able, so that if there are evils, either God is not all-good, all-powerful, or all-knowing. For Aquinas, we know God exist and is all-good, -powerful, -knowing from the nature of the world as contingent, good, intelligible, etc. Thus, given that God exists, if there is evil, it must be that God is so powerful as to bring good even from evil (see Summa Theologiae, Ia, q. 2, a. 3, reply to objection 1 and q. 22, a. 2, reply to objection 2).
For a more complete discussion, please see the essay Aquinas and the Problem of Evil