Augustine. De Libero Arbitrio Voluntatis. In On the Free Choice of the Will, On Grace and Free Choice, and Other Writings. Translated by Peter King. Cambridge: Cambridge University Press, 2010.
Excerpt:
Book One
EVODIUS: Please tell me: isn’t God the cause of evil?
AUGUSTINE: I will tell you once you have made clear what kind of evil you are asking about. For we use the word ‘evil’ in two senses: first, when we say that someone has done evil; and second, when we say that someone has suffered evil.
EVODIUS: I want to know about both.
AUGUSTINE: But if you know or believe that God is good–and it is not right to believe otherwise–then he does no evil. On the other hand, if we acknowledge that God is just–and it is impious to deny it–then he rewards the good and punishes the wicked. Those punishments are certainly evils for those who suffer them. Therefore, if no one is punished unjustly–and we must believe this, since we believe that this universe is governed by divine providence–it follows that God is a cause of the second kind of evil, but in no way causes the first kind.
EVODIUS: Then is there some other cause of the evil that God does not cause?
AUGUSTINE: There certainly is. Such evil could not occur unless someone caused it. But if you ask who that someone is, it is impossible to say. For there is no single cause of evil; rather, everyone who does evil is the cause of his own evildoing. If you doubt this, recall what I said earlier: Evil deeds are punished by the justice of God. They would not be punished justly if they had not been performed voluntarily.