Summa contra Gentiles1.71 Chapter LXXI. That God knows evil things

It remains now to be proved that God knows evil things.

For if a good be known the opposite evil is known. Now God knows all the particular goods to which evils are opposed. Therefore God knows evil things.

Further. The notions of contraries in the mind are not opposed to one another, else they would not be together in the mind, nor would they be known at the same time. Therefore the aspect under which we know evil is not repugnant to good, rather is it connected with the idea of good. Accordingly if, as we have proved above, all the aspects of goodness are to be found in God, by reason of His absolute perfection, it follows that in Him is the notion by which evil is known. Therefore He knows evils also.

Again. The true is the good of the intellect: for an intellect is said to be good for as much as it knows the true. Now it is not only true that good is good, but also that evil is evil: for just as it is true that what is, is, so is it true that what is not, is not. Hence the good of the intellect consists even in the knowledge of evil. But, since the divine intellect is perfect in goodness, it cannot possibly lack any intellectual perfection. Therefore it has the knowledge of evils.

Moreover. God knows the distinction between things, as shown above. Now the notion of distinction includes negation, for when things are distinct, the one is not the other. Hence primaries which are distinguished by themselves, include mutual negation of one another, and for this reason negative propositions about them are self-evident, for instance, No quantity is a substance. Therefore God 1 Ch. XL 3 6 Ethic, ii. 3. 3 Ch. xli. * Ch. 1.

knows negation. Now privation is negation in a definite subject, as is proved in 4 Metaph. Therefore He knows privation, and consequently evil, which is nothing else than the privation of due perfection.

Further. If God knows all the species of things, as was proved above, and as granted and proved even by some philosophers, it follows that He knows contraries; both because the species of certain genera are contrary, and because the differences of genera are contrary, as stated in 10 Metaph. Now contraries include opposition of form and of privation, according to the same authority. Therefore it follows that God knows privation and, consequently, evil.

Again. God knows not only form but also matter, as was proved above. Now matter, since it is being in potentiality, cannot be known perfectly, unless it be known to what its potentiality extends, and this applies to all kinds of power. But the potentiality of matter extends to both form and privation: for that which can be, can also not be. Therefore God knows privation: and consequently He knows evil.

Again. If God knows anything besides Himself, most of all He knows that which is best: and this is the order of the universe, to which as their end all particular goods are directed. Now in the order of the universe there are certain things intended for the removal of harms that might result from certain other things, as evidenced by the means of defence with which animals are provided. Therefore God knows these harms: and thus He knows evils.

Further. We are never blamed for knowing evils, as regards that which belongs essentially to knowledge, that is, as regards judgment about evil, but only accidentally, for as much as sometimes one is inclined to evil through thinking about it. But it is not so in God, for He is unchangeable, as was proved above. Nothing therefore hinders God from knowing evils.

In agreement with this it is written (Wis. viii.) that no evil can overcome God's wisdom; and (Prov. xv. 11) that Hell and destruction are before the Lord. Also in the psalm it is said: My offences are not hidden from Thee; and (Job xi. 11): For He knoweth the vanity of men, and when He seeth iniquity, doth He not consider it?

It must however be observed that with regard to the knowledge of evil and privation there is a difference between the divine intellect and ours. For seeing that our intellect knows each thing by its respective proper and distinct species, it knows that which is in act by an intelligible species, whereby the intellect is made actual. Hence it is able to know potentiality, in as much as it is sometimes in potentiality to such a species: and thus just as it knows act by means of an act, so it knows potentiality by means of potentiality. And since potentiality belongs to the notion of privation, for privation is a negation the subject whereof is a being in potentiality, it follows that it is becoming to our intellect to know privation, in some way, in as much as it is naturally fitted to be in potentiality; although we may also say that the mere knowledge of actuality leads to the knowledge of potentiality and privation.

On the other hand, the divine intellect, which is nowise in potentiality, knows neither privation nor anything else in the above manner. For if He knew anything by a species other than Himself, it would follow of necessity that He is compared to that species as potentiality to act. It follows therefore that He understands only by a species that is His essence: and consequently that He understands Himself as the first object of His understanding: and yet in understanding Himself He understands other things, as shown above, and not only acts but potentialities and privations.

This is what the Philosopher means when he says (3 De Anima): How does it know evil, or black? For it knows contraries somewhat. And it must know them by a potentiality that is in itself. But if anything there be in which the contrary is not (namely in potentiality), it knows itself, and is in act and separable. Nor is it necessary to admit the explanation of Averroes who maintains that it follows from the above that the intellect which is pure act knows a privation not at all. But the sense is that it knows privation, not through being in potentiality to something else, but through knowing itself and being always in act.

Again, it must be observed that if God knew Himself in such a way that by knowing Himself He knew not other beings which are particular goods, He would have no knowledge whatever of privation or evil. Because there is no privation contrary to the good that is Himself: since a privation and its contrary are naturally adapted to be in relation to the same thing, and so no privation, and therefore no evil, is opposed to that which is pure act. Wherefore, supposing God to know Himself alone, He would not know evil through knowing the good which is Himself. But, since by knowing Himself He knows things in which there is a natural aptness for privations, it follows of necessity that He knows the opposite privation, and the evils contrary to particular goods.

It must also be observed that, just as God by knowing Himself knows other things without any discursion of His intellect, as shown above, so too there is no need for His knowledge to be discursive, if He knows evil through good. For good is the ratio as it were of the knowledge of evil, so that evil is known through good, as a thing through its definition, and not as conclusions through their premisses. Nor does it argue imperfection in the divine knowledge if God knows evil through the privation of good: because evil does not indicate being except in so far as it is a privation of good. Wherefore in this way alone is it knowable: since a thing is so far knowable as it has being.