Thomas Aquinas, Disputed Questions on Truth (De Veritate)

1. All knowledge either causes the thing known, is itself caused by it, or at least proceeds from one and the same cause. But God's knowledge is not the cause of evil things, evil things do not cause it, nor does some other thing cause both His knowledge and evil things. Therefore, God does not know evil things.

2. As is said in the Metaphysics, every being is related to truth in the same way as it is related to existence. But evil, as Dionysius and Augustine say, is not a being; therefore, it is not something true. Now, nothing is known unless it is true. Hence, evil cannot be known by God.

3. The Commentator says that an intellect that is always in act does not know a privation at all. But God's intellect is in act in the highest possible degree. Hence, it knows no privations. But, as Augustine says: "Evil is the privation of good." Therefore, God does not know evil.

4. Whatever is known is known either through its likeness or through its contrary. Now, evil is not like the divine essence through which God knows all things; nor is evil its contrary, for evil cannot harm it--and a thing is said to be evil because it is harmful. Therefore, God does not know evil things.

5. That which cannot be learned cannot be known. But, as Augustine says: "Evil cannot be learned through instruction, for only good things can be learned." Therefore, evil cannot be known, and so is not known by God.

6. Whoever knows grammar is grammatical. Therefore, whoever knows evil things is evil. But God is not evil. Hence, He does not know evil.

To the Contrary:

1'. No one avenges what he does not know. But God is the avenger of evil; therefore, He has knowledge of evil things.

2'. There is no good which God lacks. But the knowledge of evil things is good, for by it evils are avoided. Therefore, God knows evil things.

REPLY:

According to the Philosopher, whoever does not understand a thing which is one does not understand anything at all. A thing is one, however, by being undivided in itself and distinct from others. Hence, whoever knows a thing must know its distinction from other things. But the first basis of distinction lies in affirmation and negation. Therefore, whoever knows an affirmation must know its negation. Now, since privation is nothing but a negation having a subject (as is said in the Metaphysics , and since "one of two contraries is always a privation" (as is said both in the Metaphysics and Physics --from the very fact that a thing is known, its privation and its contrary are known. Accordingly, since God has a proper knowledge of all His effects, knowing each one of them as it is, distinct in its own nature, He must know all the opposed negations and opposed privations, as well as all the contrarieties found in things. Consequently, since evil is the privation of good, by knowing any good at all and the measure of any thing whatsoever, He knows every evil thing.

Answers to Difficulties:

1. That proposition is true about knowledge had from a thing through its likeness. But evil is not known to God by its likeness, but through the likeness of its opposite. Consequently, it does not follow that God is the cause of evil things because He knows them. It follows, rather, that He is the cause of the good to which the evil is opposed.

2. From the fact that non-being is opposed to being, it is said in some way to be being, as is clear from the Metaphysics. As a consequence, from the fact that evil is opposed to good, it has the character of something knowable and of the true.

3. It was the opinion of the Commentator that by knowing His essence God does not know individual effects in a determined way, that is, as they are distinct in their own proper nature, but that He knows only the nature of being which is found in all of them. Since evil is not opposed to universal but to particular being, it follows from this that God would not know evil. But this position is false, as is evident from what has been said.* Hence, what follows from this position is also false, namely, that God does not know privations and evil things. For, according to the Commentator, a privation is known by an intellect only by the absence of a form from the intellect--a condition that cannot exist in an intellect which is always in act. But this is not necessary; for, from the very fact that a thing is known, its privation is known. Hence, both thing and privation are known through the presence of a form in the intellect.

4. The opposition of one thing to another can be taken in two ways: first, in general, as when we say that evil is opposed to good, and in this sense evil is opposed to God; second, in particular, as when we say that this white thing is opposed to this black thing, and in this sense an evil is opposed only to that good which can be taken away by this evil and to which it would be harmful. In this second way evil is not opposed to God. Augustine accordingly says: "Vice is opposed to God in the way in which evil is opposed to good." But, to the nature which it vitiates, vice is opposed not merely as evil to good but also as something harmful to that nature.

5. In so far as evil is known, it is a good; for to know evil is a good. Thus, it is true that whatever can be learned is a good--not that it is good in itself, but that it is good only in so far as it is known.

6. Grammar is known by possessing the art of grammar. But evil is not known by possessing it. Hence, no analogy can be drawn.