Commentaria in Summam contra Gentiles, Liber I

I. From what has been premised, Saint Thomas infers as a corollary that evil cannot be in God ¹. And this is understood according to the way evil can be found in nature, not however according to the way it is found in the will, for this will be determined below ².

1. It is proved first. God is his own goodness. Therefore evil cannot exist in him. — The consequence is proved. Because all things that are said per se, such as goodness, wisdom, and the like, have nothing admixed in them beyond themselves. If therefore God is goodness, non-goodness cannot be in him, nor consequently evil.

He notes, however, for greater clarity, * that what is good can have something besides goodness:* for what is the subject of one perfection is not prevented from being the subject of another. But each thing ³ is confined within the limits of its own nature, so that it cannot take in anything foreign within itself. Therefore, and so on.

It must be noted that each thing is said to be concluded within the terms of its own rational account, because a definition states only the essential principles, and it encloses the quiddity of a nature in such a way that it permits nothing foreign to enter into the quiddity of the thing. From this we are given to understand that the very quiddity of a thing, which is signified by the definition, if it subsisted of itself, would have nothing conjoined to it, because within the terms of the definition nothing extraneous to the nature is included: for if something extraneous were inherent in it, it would no longer be the quiddity as signified by the definition. But this was also said above ⁴

II. Second. If evil were in God, God could fail. — The consequence is proved. What is opposed to the essence of something cannot be in it unless it ceases to be: just as irrationality cannot be in a man unless he ceases to be a man. But the essence of God is goodness. Therefore evil, being opposed to it, cannot belong to it unless it ceases to be.

Third. If evil were in God, it would be in him essentially: for nothing can be predicated of him participatively, as was shown above. But evil cannot be so predicated of anything as to be its essence: for, just as goodness admits nothing extraneous, neither does wickedness; and thus it would exclude esse, which has the character of the good, and every other perfection. And consequently nothing can exist that is wickedness itself.

III. But it does not seem necessary that, if evil is in God, God be essentially evil, on the ground that nothing is said of Him by participation. First, because that proposition holds true in the case of perfections, since God is ipsum esse; but not in the case of imperfections, of which kind is evil.

Second, because no evil is evil by participation, but by the privation of participation, as is said in the First Part, q. 49, a. 3, ad 4. And yet it does not follow that every evil is evil by essence.

To the first it is answered that, both in perfections and in imperfections, if they are attributed to God, it is true that nothing is said of him by participation, as though distinct from his essence: because, by the fourth argument of the preceding chapter, whatever participates in something is related to it as potency to act; but in God there can be no potency, since he is pure act, being ipsum esse subsistens. Therefore, if evil were posited to belong to God, it could not be so by participation.

To the second it is answered that such esse by participation can be understood in two ways: in one way, by the imperfect reception of something positive; in another way, by the reception of anything distinct from itself, whether it be positive or negative. If it is taken in the first way, then nothing is said to be evil by participation, since evil is not any nature; rather, something is said to be evil by privation of participation, namely in that it lacks some form. Nor, in this way, is anything said to be evil by essence, since evil is no essence. — But if it is taken in the second way, then every evil is evil by participation, insofar as no evil is evil itself, but even it has something of evil joined to it, namely the good in which it is grounded.

Saint Thomas speaks to this sense. For, if evil were said of God, since nothing belongs to God that is distinct from him, whether it be posited as a form or as a privation—because in him there is no receptive potency—it would follow that he would be malice itself, which is to be evil by essence.

IV. Fourth. There is no imperfection in God. Therefore neither is there evil: because evil is a certain imperfection, just as good is perfection.

Fifth. Evil either is a privation or includes privation. But no privation is in God, since in God there is no potency, which is the subject of privation. Therefore, etc. — The antecedent is proved: because, just as something is good and perfect insofar as it is in act, so it is imperfect and evil insofar as it falls short of act.

Sixth. Nothing in God is violent or contrary to nature. Therefore evil is not in him. — The consequence is proved. Because evil, as evil, is present in each thing against the motion of its natural inclination, since each thing flees evil just as each thing desires good. And although sometimes in composite things evil may, according to something of itself, be natural to the thing, this cannot be so in God, since he is not composite.

V. Concerning that proposition, The evil of a thing, insofar as it is evil for it, is violent and contrary to nature; yet it can be natural for it according to something of it, in composite things, doubt arises: because it seems to imply a contradiction. For, if the evil is natural according to something of itself, then evil, insofar as it is evil, is always in the thing as long as the thing exists: because that which is natural, to which the evil is joined, is always in the thing. But if, as evil, it is violent, it follows that it does not always remain in the thing: for what is violent is at some time removed.

It is answered, and first it is said that when some privation accompanies one of the natural principles, then the evil is said to be a natural evil, at least in comparison to universal nature, by reason of something that pertains to it, namely by reason of the very principle in which it is rooted. Just as in one who is born blind or lame, blindness and the crookedness of the legs are in themselves contrary to nature and violent, because they are privations of something due to be present; yet by reason of the eyes and the legs, which belong to him naturally, those evils are said to be natural.

It is said second, that the violent thing which accompanies some natural part need not ever be removed, but only that violent thing which has no concomitance with any of the natural principles. For that thing, although considered in itself it is beyond nature, nevertheless takes on the character of the natural from the substrate to which it is consequent; and it belongs to the secondary intention of universal nature. And consequently, as long as that principle remains, it cannot be removed.

Finally, by the authorities of John 1:1 and Job, the conclusion is confirmed.