De libero arbitrio (Augustine book)

In Book I, Augustine outlines basic hamartiological concepts about the nature of sin and answers the basic question "Where does evil come from?" Augustine clearly renounces the Pagan Platonic and Gnostic conceptions of predestination/determinism, writing. And since God gave mankind free will, it is understandable that God "may appear to be the cause of our evil deeds," as the Manichean heretics assert, but he promises to answer that question in the next book.

In Book II, Augustine answers the charge that God should not have given mankind free will, and that somehow he is morally culpable for the actions of mankind. Augustine answers this by expounding upon a body-spirit (internal-external) epistemological paradigm, arguing that the ability to reason is itself of divine origin and necessary for humans to understand common truths.

In Chapter XX he writes, "Everything good is from God. There is nothing of any kind that is not from God." He solves the conflict between ex nihilo and omnibenevolence by arguing that evil perpetrated by humans has no reality, i.e., no form. Thus, when we speak of the divine providence and sovereignty of God, this does not include evil because it is shadow, a movement of free will against Being itself. Sin is defectivus motus, a vacuum of goodness, and not a "thing" with being at all. Thus it is accurate to state that God did not create nor cause evil, and at the same time, is the omnipotent sovereign over all existence.

In Book III, Augustine takes closer aim at the excuses that Determinists use to justify their creed. The Platonic and Gnostic Determinists Augustine is replying to insist that their philosophy does not negate moral responsibility and the agency of humankind. Augustine takes aim at this dodge, stating that no denial of real free will can result in mankind being truly responsible for their own evil. Hard Determinism (Soteriological or Cosmological)  must result in God being inherently evil, which in the Christian tradition is blasphemy. He writes in Book II, Chapter IV: "God's knowledge that man will sin is not the cause of sin. Hence punishment for sin is just.... God's foreknowledge of future events does not compel them to take place."

and in chapter XVII "either the will is the first cause of sin, or there is no first cause. If someone says that a stone sins because it falls down through its weight, I will not say he is more senseless than a stone; he is simply insane. But we accuse a spirit of sin when we prove that it has preferred to enjoy lower goods and has abandoned higher ones… No man is forced to sin, either by his nature or anothers'... If you wish to attribute sin to the Creator, you will acquit the sinner of his sin. Sin cannot be rightly imputed to anyone but the sinner."

"a law that is not just, seems to be no law at all."[5][6]

"The law which is framed for the government of states, allows and leaves unpunished many things that are punished by Divine providence. Nor, if this law does not attempt to do everything, is this a reason why it should be blamed for what it does."[7][8]

"It seems to me that the law which is written for the governing of the people rightly permits these things, and that Divine providence punishes them."[9][10]

"If someone says that a stone sins because it falls down through its weight, I will not say he is more senseless than a stone; he is simply insane. But we accuse a spirit of sin when we prove that it has preferred to enjoy lower goods and has abandoned higher ones… No man is forced to sin, either by his nature or anothers'... If you wish to attribute sin to the Creator, you will acquit the sinner of his sin. Sin cannot be rightly imputed to anyone but the sinner."

"Reason has shown that we commit Evil through the free choice of the will."

"Everything good is from God. There is nothing of any kind that is not from God."

"All sins are included under this one class: when someone is turned away from divine things that are truly everlasting, toward things that change and are uncertain"

"Thus is all good is removed [Free Will being a 'good'] , no vestige of reality persists; indeed, nothing remains. Every good is from God. There is nothing of any kind that is not from God. Therefore, since the movement of turning away from good, which we admit to be sin, is a defective movement [defectivus motus] and since, moreover,every defect comes from nothing, see where this movement belongs; you may be sure it does not belong to God."

"What greater security can there be than to live a life where what you do not will cannot happen to you?"

• Simon Harrison: Augustine's Way into the Will - The Theological and Philosophical Significance of De libero arbitrio, Oxford University Press, Oxford, 2006.