Commentaria in Summam contra Gentiles, Liber III

From the premises St. Thomas deduces as a corollary that, However much evil may be multiplied, it can never entirely destroy the good ¹. This he proves, because the subject of evil, which is good, must always remain.

I. But concerning this corollary he raises a doubt. For if from a finite thing something is taken away infinitely, it must at some time be consumed by being taken away. But by the intensification of evil to infinity the good, which is finite, is always diminished. Therefore the whole good will at some time be taken away by evil.

To this some respond by denying the major premise, when the subsequent taking away occurs according to the same proportion. For it is evident in the division of a continuum according to proportional parts, which proceeds to infinity, and yet the whole quantity is never consumed. Now, in this way, they say, the diminution of the good takes place.

But against this response St. Thomas argues thus. In the process of a division of this kind, what is subtracted later is always less: as is evident in the division of quantity. But in the diminution of the good through evil this can by no means happen. Both because, the more the good has been diminished by evil, the weaker it will be: and thus by a second evil it will be able to be diminished more; that is, from it not less, but more will be able to be taken away. And because the subsequent evil happens to be greater than or equal to the prior evil: and consequently it will take away either a greater or an equal good.

Note that St. Thomas, by these words, In the diminution of the good this can by no means happen, does not mean to posit the impossibility of the diminution of the good according to the same proportion, but only the non-necessity of such a division, as is evident in the First Part, q. xlviii, a. 4, ad 3. Hence the sense is that it can by no means be that in the diminution of the good the same proportion is always necessarily preserved: since it happens, either from the weakening of the good remaining after the subtraction, or from the equality or greater magnitude of the subsequent evil in the subsequent subtraction, that either more or an equal amount is subtracted.

II. St. Thomas therefore responds: and he says first, that evil indeed totally takes away the good to which it is opposed, but nevertheless the subject remains. And since this subject, inasmuch as it is a subject, has the character of good, according as it is in potency to the act of the good of which it is deprived by evil, the less it is in potency to that good, the less good it will be.

He says secondly, that it becomes less in potency to the form, not by the subtraction of any part of the subject itself or of its potency, but because by a contrary act it is impeded from being able to issue into the act of the form: just as a thing is so much the less potentially cold, the more heat is increased in it. And thus good is diminished by evil more by the addition of a contrary than by subtracting something from the good. For the more the good from which evil follows outside the intention of the agent is multiplied, the more the potency to the contrary good is diminished. And thus through evil the good is said to be diminished more: namely, inasmuch as through the good to which evil is joined, the potency of the subject to the good that is removed by evil—in which potentiality the goodness of the subject consists—is taken away more.

He says thirdly, that this diminution of the good in natural things cannot indeed proceed to infinity. Because neither the contrary form, nor the power of the contrary agent, can be increased to infinity: since natural forms and powers are determinate. — But in moral matters the diminution can proceed to infinity. Because the intellect also can proceed to infinity in understanding: a sign of which is that the mathematical species of numbers and figures are said to be infinite. Similarly, the will proceeds to infinity in willing: for one willing to commit a theft can also will to commit something else ² to infinity. And thus the good of natural aptitude can be diminished to infinity through moral evil: since the more the will tends toward undue ends, the more difficult it is for it to return to its proper and due end; as is evident in those in whom a habit of vices has already been induced through the custom of sinning. Never, however, is such an aptitude totally taken away, but it always accompanies nature.

From these things it is clear that the objection is null. Because it proceeds concerning a diminution that takes place by subtraction, but not concerning that which takes place by the addition of a contrary. And also because in natural things it is false that evil can be intensified to infinity through an addition of this kind, and the good be diminished to infinity.

2. Note that the further a potency is removed from act, and the less apt the subject is for receiving it, the more difficult it is to reduce it to act: as is evident in natural and artificial things. And therefore a sign of the removal of potency from act is the difficulty of reduction to act. On account of this, St. Thomas, wishing to show the diminution to infinity of the natural aptitude for the good through sin, adduces as a sign that the more the will tends toward undue ends, the more difficult it is for it to return to the due end. And since it can tend toward undue ends to infinity, just as the intellect can also understand diverse things to infinity, it follows that such difficulty can be increased to infinity; and consequently the potency can be removed from act to infinity, and the aptitude be diminished to infinity.

III. For the clarification of this response, it must be considered first, from the doctrine of St. Thomas in the First Part, at the place cited; and II Sent., d. 34, a. 4; likewise in the Questions de Malo, q. ii, aa. 11 and 12; and Iª IIae, q. lxxxv, aa. 1 and 2, that the good is threefold: namely, that to which evil is opposed; the subject of evil; and the fitness of the subject itself for the good, which St. Thomas here calls the aptitude for the good. Evil therefore totally takes away the good to which it is opposed: just as blindness totally takes away sight. — But the entity of the subject it not only does not totally take away, but does not even diminish: just as blindness removes nothing from the substance of the eye. — But the fitness itself and aptitude of the subject for the good, which is potency to the reception of act, it indeed diminishes in the manner stated, namely by accompanying in the subject the form contrary to the good to which it is opposed and which it totally takes away, through which form the subject is impeded from receiving the opposite form: yet it does not totally take away the fitness itself, because, since it accompanies the substance and nature of the subject, while the nature of the subject remains, the fitness itself always remains. St. Thomas gives the example of the fitness of air for light, which, although it can be diminished to infinity by the interposition of an opaque body between it and the sun to infinity, is nevertheless never totally taken away while the air remains. If, however, there were something able to corrupt the subject, that, by corrupting the subject, would totally remove the fitness of the subject. Hence although, where the diminution of something occurs through the subtraction of parts, the finite must at last be totally consumed; yet where the diminution and remission occurs through the interposition of an impediment and obstacle, it is not necessary that the finite be at last consumed: for impediments can be applied to infinity, by which the potency and aptitude are further removed from act, and yet as to something the potency and aptitude always remain.

2. It must be considered secondly that, since the aforesaid fitness and aptitude for the good is understood as intermediate between the nature of the subject, in which it is founded as in a root, and the good toward which it tends; the diminution of fitness by the addition of an impediment is not understood as it holds on the part of the root, since by such an impediment the nature of the subject is not diminished; but it is understood as it tends toward the good; for by an addition of this kind it is impeded from reaching the good toward which it is ordered. Hence the more impediments are added, the more it is impeded and removed from act; which is for the aptitude and fitness or inclination toward the good to be diminished as it is considered on the part of the term itself.

Hence the objections of Durandus in the Second Book, d. xxxiv³, which proceed concerning the diminution of a fitness of this kind as it holds on the part of the subject, do not proceed against St. Thomas. For the diminution and intensification of fitness as it holds on the part of the term does not have to occur through something inhering in the subject: although perhaps this is required for its intensification and remission as it holds on the part of the subject.

Similarly, it is clear that the objections of Scotus in the thirty-fifth distinction of the Second Book⁴ do not proceed against this determination: because they proceed concerning the diminution that is by subtraction, but not concerning that which is by the addition of an impediment, and which is not per se, but through another.

IV. But a doubt occurs concerning what has been said. For we see that a blind man cannot naturally recover sight. Therefore there does not remain in him a natural fitness and aptitude for sight: because a natural aptitude can be reduced to act by a natural agent. Therefore evil totally takes away the aptitude of the subject for the good.

2. To this it is said first, that this is universally true: that, while the potency to some act remains, its fitness for the act, which is immediately founded in it, always remains, and when the potency is removed, it is removed: because it necessarily accompanies the potency itself. And because no privation, as such, takes away its subject or potency, since it determines that subject to itself as that in which it is in its own way; therefore no privation, and no evil, removes from its subject the fitness for the form immediately founded in it; although it may sometimes happen that by some agent the potency and the fitness are corrupted together.

3. It is said secondly, that although the blind man has totally lost the proximate aptitude for the act of seeing, which was founded in the visual power; nevertheless there remains in him an aptitude for the visual power, as is stated in de Malo, q. 2, a. 12, ad 3; and there remains also an aptitude for the act of seeing as in a root and remote foundation.

When it is proved because he cannot naturally recover sight: — it is said that this is not on account of a defect of aptitude; but because, as is stated in Iª II^ae, q. lxxxv, a. 2, ad 3, there is lacking a cause that can reduce that aptitude to act, by forming the organ that is required for seeing.

When, however, it is said that a natural aptitude can be reduced to act by a natural agent: — it is answered, as can be gathered from the doctrine of St. Thomas in the Third Book, d. I, q. 1, a. 3, ad 4, that certainly natural aptitude, considered absolutely according to its species, can be reduced to act by some natural agent: but it is not necessary that every singular aptitude be able to be reduced to act, because on account of some impediment it can happen that it cannot be reduced to act. And thus it is said that natural aptitude for sight, considered according to its species, can be reduced to act by a natural agent, for we see that through natural generation such an aptitude is fulfilled: but in him who is deprived of sight, it cannot be reduced to act by a natural agent on account of the impediment that supervened. For since it regards sight and blindness in a certain order, because namely it does not arrive at blindness except through sight; a return from it to sight cannot be made by a natural agent, because, when matter is related to diverse things according to an order, there cannot be a return from what is posterior to what is prior, as St. Thomas says in VIII Metaph.⁵, for the reason that there is a determinate mode of generation for every thing. Therefore, when blindness is posited in an animal, an impediment is posited against the fitness for sight being able to be reduced to act by a natural agent. — Nor does it stand in the way that sometimes a man is blind from birth: and thus it does not seem that matter always arrives at blindness through the visual power. For it is said that, although he does not then have the visual power beforehand, he nevertheless would have had it had it not been impeded. Hence just as one corrupting the eye is said to corrupt the sight existing in it, and the accompanying blindness is the corruption of the sight that preceded; so one causing an impediment or a contrary disposition to sight in the generation of an animal is said indirectly to corrupt the sight that would have been present had it not been impeded; and the accompanying blindness is the corruption of the sight that ought to have been present.