Commentaria in Summam contra Gentiles, Liber III

Since it has been shown that the good is the accidental cause of evil, St. Thomas now shows in particular that it is its subjective cause ¹. Concerning this, however, he does two things: first, he shows the thesis; second, he infers a corollary, in the following chapter.

Concerning the first, he does two things: first, he shows that every evil is grounded in some good; second, he removes a doubt ².

1. It is argued therefore first as follows. Evil is not existing per se, since it does not have an essence. Therefore it is in some subject. Therefore it is in some good: because every subject, since it is a substance, is a good.

Someone, however, could deny the first consequence in this argument. For although evil does not have an essence, it is not necessary, however, that it be in a subject, since it is a negation and has no real esse.

But this response does not remove the argument. For one must speak in one way of simple negation, and in another way of privation, of which sort evil is when formally taken. For a simple negation, since it is said even of non-being, does not require any subject. But privation and evil is a negation concerning a determinate subject, and therefore it does not denominate anything except being. On this account, since evil is in things, as was shown above ³, and is not per se subsisting, it must be in another as in a subject; not indeed as a being or expressing some essence, but as a privation of perfection, in accordance with what was previously determined ⁴, insofar as it can truly be affirmed of something on account of the absence of the form from that subject.

2. Secondly. The subject of form is being in potency to the form. Which is a good: since potency and act are in the same genus. Therefore evil also is in the good as in a subject: since evil is a privation, while form and privation are in the same subject.

One could deny to this argument that being in potency is a good. Because, if it is called good from the fact that it is ordered to the good, by the same reason, since it is ordered to evil, namely to privation, of which it is receptive, it will be evil.

He answers: and it is said first that, as was said above ⁵, matter is ordered to the good per se, but to evil and privation per accidens: either, namely, insofar as it is receptive of a form in a losable manner, or because it is receptive of a form to which the privation of another form is joined. Therefore from its order to the good it is called a good; but from its order to evil it is not called evil.

It is said secondly, as was said above in chapter VI, that the privation of a form is not an evil of matter: because no determinate form is owed to matter, although it is receptive of all; but evil is called the privation of a form that is owed to be present.

3. Thirdly. Evil is so called because it harms. But it harms nothing except the good. Therefore it is in the good. — The consequence is evident. Because it would not harm the good formally unless it were in it. — But the minor is proved. Because to harm an evil is good, since the corruption of evil is good.

Concerning this proposition, Evil would not formally harm the good unless it were in the good, it should be noted that St. Thomas added the word formally because something harms in two ways, as is said in the Second Book, d. XXXV, a. 1, ad 3: namely formally, and this is the harm itself, or the very taking away or privation of the good; and effectively, and this is what causes the privation of the good. That which harms something actively, therefore, as such, is not in it as regards the proximate receptive subject of the harm; but that which formally harms certainly is.

4. Fourthly. Evil is caused by the good per accidens. Therefore etc. — The consequence is proved. Because, since every per accidens is reduced to what is per se and is grounded in it, it is necessary that along with evil, which is the per accidens effect of the good, there be some good which is the per se effect, in which the evil is grounded.

II. As to the second, St. Thomas removes a certain doubt ⁶. For at first glance it seems that evil is not in the good, since they are opposites. But he answers that, since good is said commonly, just as being is; just as it is not unfitting that non-being be in being, as privation in substance, so it is not unfitting that evil be in the good.

It is said nevertheless secondly that, just as non-being is not in the being opposed to it, but in another, as blindness is not in sight, but in an animal; so also evil is not in the good opposed to it, but in another; as moral evil is in the good of nature; and natural evil, which is the privation of form, is in matter, which is a good, as is also ⁷ being in potency.

III. For the evidence of this, it must be considered that good and evil can be considered in two ways. In one way, as to the common nature, so to speak, of each, according to precision from inferiors. And because in this way one totally removes the other, as directly opposed to it, one cannot be in the other. Hence if something were posited to exist as good per se, as the universal nature of the good, no evil could be in it: as is evident in God, who is goodness itself subsisting per se, in whom there is no evil. And if something were per se and universally evil, it would include no good. But because this cannot be, since evil expresses a negation of the good in a subject, on that account Aristotle says in Ethics IV ⁸ that it would destroy itself.

2. In another way, as to this particular good and evil. And then each of them can also be considered in two ways. In one way, according to the universal notions of good and evil preserved in them. And thus any evil is opposed to any good. And according to this Augustine says ⁹ that the rule of the dialecticians fails, which says that contraries cannot be together at the same time: because in this way evil is found in that to which the universal notion of good belongs. For since the good, universally taken, does not express some determinate perfection, but perfection in common, whatever perfection a thing has, it is called good. Similarly whatever perfection owed to it it lacks, it is called evil. And thus, on account of the amplitude of the notion of good and evil, it can happen that the same thing is good according to something, and evil according to something; and notions which, universally taken, are opposed, can be found together in the same subject with respect to diverse things; just as the same animal lacking sight is at once good and evil, good insofar as it is a being in act, evil insofar as it lacks perfection. On this account St. Thomas assigns as the reason why good and evil can be together, and one be grounded in the other, the very amplitude and unlimitedness of the good. — Nor does it follow that contradictories are true at the same time if the same thing is good and evil: because it is not according to the same thing, but according to diverse things that it is called good and evil.

In another way a particular good and evil can be considered according to their particular notions. And thus not every evil is opposed to every good directly, but to a determinate good: for injustice is opposed to justice, but not to temperance. And in this way evil is not in the opposed good, but in another good: for injustice is not in justice, but in the soul; nor is blindness in sight, but in the animal.

3. But a doubt arises. Because St. Thomas in the First Part, q. XLVIII, a. 3, ad 3, and in other places, seems to approve the opinion of Augustine who says that in good and evil the rule of the dialecticians fails; but in Questions on Evil, q. I, a. 2, ad 5, he says that the rule does not fail even in these according to truth, but according to a certain appearance, insofar as evil absolutely spoken and good seem to have opposition.

It can be said to this that both statements are true, but in diverse ways. For if in a particular good and evil only the universal notions of good and evil are considered, according to truth that rule fails: because then one of the opposites is in the other. For the common notion of the good, and the common notion of evil, are opposed notions: and therefore every evil, insofar as it is evil, is absolutely opposed to every good, insofar as it is absolutely good. If, however, the particular notions of good and evil are considered in them, thus the rule fails according to appearance only. For because in this particular good the universal notion of good is preserved, and in this particular evil the universal notion of evil, it seems that any evil, even according to its particular notion, is contrary to any good, as it is such a good, on account of the contrariety of good and evil in the universal; and thus, while this evil is in this good, it seems that one of the opposites is in the other. But it is not so: because not every evil is contrary to every good, if they are taken according to their particular notions; although according to the universal notions of good and evil they have opposition.

IV. Concerning that proposition, Natural evil, which is the privation of form, is in matter, which is a good, as is also being in potency ¹⁰, it should be considered that for matter to be a good as also being in potency can have a twofold sense. One is, that it is a good in potency, but not in act, just as it is not a being in act, but in potency. The other is that, just as it is a being in potency, so it is a good in act. And each sense is true as to something. For we can speak of the goodness of prime matter in two ways. In one way, of the goodness which it has from the form, while it is actually informed: and in this way it is not good except in potency while it lacks the form itself. In another way, of the goodness which it has from the very order to the form: and in this way it is something good in act in some way. For the order itself, and the aptitude itself to the good, is a certain good, by reason of the term which it regards. And everything ordered to the good, as such, has the notion of the good: hence useful things also fall under the division of the good. St. Thomas touched upon both senses in the First Part, q. V, a. 3, ad 3. But the first sense seems to be intended in this place, on account of the comparison to being in potency: hence in the First Part, in the question cited ¹¹, he expressly says that, just as it is being in potency, so also it is good in potency.