In book 5, chapter 10, Augustine is working with definitions and trying to make sense of the arguments around “free will” and this term “necessity”. For his purposes, something happens “of necessity” if it must have happened, and human will is “free” if people can freely choose what will happen. Augustine has no problem arguing that God can know in advance what a person will freely choose. But then he goes on to make a series of interesting and relatively compelling arguments for God’s power working in the midst of human freedom.
First, he shows that God is not less free or omnipotent because he is unable to do or be some things: “we do not make the life of God and the foreknowledge of God subject to necessity if we say that it is ‘necessary’ for God to live forever and to foreknow all things. By the same token, His power is not diminished when we say that He ‘cannot’ die or err. For this is impossible to Him in such a way that, if it were possible, He would have less power. He is indeed rightly called omnipotent even though He cannot die or err. For He is called omnipotent because He does what He wills and does not undergo what He does not will; if this were not so, He certainly would not be omnipotent. But it is precisely be cause He is omnipotent that there are certain things He cannot do: just as we say that it is necessary, when we exercise will, that we do so of our own free will.” And so, God cannot lift a rock so big that He cannot lift it, because that is nonsense. Similar to the way that a green cat cannot be a red dog – because it is simply a matter of nonsense.
Then, he claims that human wills exist and that when we do things against our wills, it is because we are under the power of some other personal will. Ultimately, whoever carries out their will, they are empowered by God: “For if it were simply a will but without the power to do what it willed, it would be impeded by the still more powerful will of God.”
So, God foreknows what humans will freely choose and empowers them to carry out their choices. In this way, then, free human choices to pray, act, praise, etc are all useful and helpful because God chooses to empower those actions. And free human choices to sin are destructive because they are freely chosen: “For a man does not sin because God foreknew that he would sin. On the contrary, there is no doubt that the man himself sins when he sins. For He Whose foreknowledge cannot fail foresaw not that fate or fortune or something else would sin, but the man himself. If a man chooses not to sin, he certainly does not sin; but if he chooses not to sin, this also was foreknown by God.”
I think I am tracking with Augustine’s logic here, but doesn’t this thinking imply that God empowers humans to sin? What am I missing? Is he saying that all human choices are left to us to freely decide except for the choices not to sin? And, how does Augustine’s overall argument stand up if God empowers all the human choices that actually do become actions? How, in other words, is it true that human free will is truly free if some acts of the will are left without reality but others are empowered by God, and that empowering is due to no choice of the person making the choice? I guess that I’m not fully convinced that Augustine can make the case for free will and God’s empowering will in this kind of way. Unless he will have more to say about this.