Summa contra Gentiles3.10 Chapter X. That the cause of evil is a good

We may conclude from the foregoing that evil is not caused except by a good.

For were some evil caused by an evil; since evil does not act save by virtue of a good, as proved above,! it follows that good itself is the primary cause of evil.

Again. That which is not, is not the cause of anything. Therefore every cause must be some being. Now evil is not a being, as shown above.” Therefore evil cannot be the cause of anything. Hence if evil be caused by something, this must be a good.

Again. Whatever is properly and by itself the cause of something intends its proper effect. Hence, if evil by itself be the cause of something, it would intend its proper effect, namely evil. But this is false, for it has been shown? that every agent intends a good. Therefore evil is not the cause of anything by itself, but only accidentally. Now every accidental cause is reduced to a per se cause. But good alone can be a per se cause, and evil cannot be a per se cause. Therefore evil is caused by good.

Further. Every cause is either matter, or form, or agent, orend. But evil cannot be either matter or form: for it has been shown above‘that being whether actual or potential is agood. Neither can it be an agent: since a thing acts forasmuch as it is actual and has a form. Nor again can it be an end, since it is beside the intention, as we have shown. Therefore evil cannot be the cause of a thing: and if anything be the cause of an evil, that evil must be caused by a good.

Since, however, evil and good are opposite to each other: and one opposite cannot be the cause of the other except accidentally; thus a cold thing causes heat as stated in Phys.

viii. 1; it follows that good cannot be the effective cause of evil except accidentally.

In the physical order, this accident may be on the part of the agent, or on the part of the effect. On the part of the agent, as when the agent’s power is defective, the result being that the action is defective, and the effect deficient: thus when the power of the digestive organ is defective, the result is imperfect digestion of the food and an indigested humour, which are physical evils. Now it is accidental to the agent as such, that its power be defective: for it acts, not as having a defective power, but as having some power: for if it lacked power altogether, it would not act at all. Accordingly evil is caused accidentally on the part of the agent, forasmuch as the agent’s power is defective. Hence it is said that evil has not an efficient, but a deficient, cause: because evil does not follow from an active cause, except in so far as this cause is defective in power, and in this respect it is not effective—And it comes to the same if defect in the action and effect, results from a defect in the instrument, or in any thing else required for the agent’s action: as when the motive power causes a limp on account of crookedness in the tibia: for the agent acts by both, its power and its instrument.

On the part of the effect, evil is caused by good accidentally, either on the part of the matter of the effect, or on the part of its force. For if the matter be indisposed to receive the impression of the agent the effect must needs be defective: thus a deformed offspring results from an indisposition of matter. Nor is it put down to defect in the agent, if it fail to transform an indisposed matter to perfect actuality: since to each natural agent there is appointed a power in proportion to its nature, and if it go not beyond that power, it will not on that account fall short of its power, but only when it falls short of the measure of power due to it by nature.

On the part of the effect’s form, evil occurs accidentally, in so far as one form necessarily involves the privation of another, wherefore the generating of one thing is necessarily followed by the corruption of another. But this evil is not an evil of the effect intended by the agent, as was made clear above,’ but of the other thing.

Accordingly it is evident that evil is caused only accidentally by a good.—And the same applies to things produced by art, for Art, im tts work, copies nature, and faults occur in both in the same way.

In morals, however, the case would seem to be different: because moral fault does not apparently follow from a defective power: since weakness of power either wholly excludes, or at least diminishes, moral fault: for weakness does not deserve punishment which is due to guilt, but rather mercy and pardon: seeing that moral fault must be voluntary and not necessary. But if we consider the matter carefully, we shall find that there is a likeness in one respect, and unlikeness in another. There is unlikeness in that moral fault is considered in the action alone, and not in some effect produced, for moral virtues are directed not to making but to doing. Whereas the arts are directed to making, for which reason it has been stated that faults occur in them in the same way as in nature. Therefore moral evil is considered as resulting not from the matter or form of the effect, but only from the agent.

Now, in moral actions four active principles are to be found in due order. The first of these is the executive power, namely the motive force, whereby the members are moved to execute the will’s command. Hence this power is moved by the will which is a second principle. And the will is moved by the judgement of the apprehensive power, which judges that a particular thing is good or evil, which are objects of the will, the one moving to pursuit, the other to flight. Again the apprehensive power is moved by the thing apprehended. Hence the first active principle in moral actions is the thing apprehended; the second is the apprehensive power; the third is the will; and the fourth is the motive force, which carries out the command of reason.

Now the act of the executive power already presupposes moral good or evil. For these external acts do not belong to morals, except forasmuch as they are voluntary. Wherefore if the act of the will be good, the external act will also be good, and evil, if it be evil. And there would be nothing savouring of moral-evil if the defect in a defective external act has nothing to do with the will: for limping is not a moral but a physical evil. Therefore a defect in this executive power, either wholly excuses or diminishes moral fault——Again, the act whereby the object moves the apprehensive power is devoid of moral fault: for the visible object moves the sight according to the natural order of things; and so too does every object move a passive power.—Again the act, considered in itself, of the apprehensive power is devoid of moral fault; since a defect therein either excuses or diminishes moral fault, in the same way as a defect in the executive power: for weakness and ignorance equally excuse or diminish sin.—It follows, then, that moral fault is found first and chiefly in the sole act of the will: and an act is logically called moral, precisely because it is voluntary. Therefore the root and origin of moral fault is to be sought in the act of the will.

But there is a difficulty, seemingly, attendant upon this inquiry. For since a defective act results from a defect in the active principle, we must presuppose a defect in the will to precede the moral fault. And if this defect be natural, it will always adhere to the will: so that the will must be guilty of moral fault whenever it acts: whereas acts of virtue prove this to be false. But if the defect be voluntary, it is already a moral fault, the cause whereof will still remain to be sought: and thus the reason will carry on indefinitely. Accordingly we must say that the defect already existing in the will is not natural, lest it follow that the will sins in every act: and that neither is it casual or fortuitous, for then there would be no moral fault in us, since casual things are unforeseen and outside the domain ofreason. Thereforeit is voluntary. Yet it isnot a moral fault: lest we be forced to proceed indefinitely. How this may be, remains to be considered—The perfection of every active principle depends on a higher active principle; for the second agent acts by virtue of the first. While, therefore, the second agent remains subordinate to the first, it acts unfailingly: but it fails in acting, if it happen to stray from the order of the first agent: as in the case of an instrument that falls short of the first agent’s movement.

and the apprehended object, which is the end. And since for each movable there is a corresponding proper motive power, every apprehensive power is not the motive force and another to that. Accordingly, just as the proper motive force of the sensitive appetite is the apprehensive power of the senses, so the proper motive force of the will is the reason.

Again, since the reason is able to apprehend many goods and many ends; and each one has its proper end: the will also must have as its end and first motive force, not any, through being moved by the apprehension of reason that presents to it its proper good, a right action follows. Whereas when the will breaks away at the apprehension of the sensitive power, or even of the reason which presents some good other than its proper good, there follows in the will’s act a moral fault.

Consequently, the sin of action in the will is préceded by lack of order to reason, and to its proper end: to reason, as when the will, on the sudden apprehension of a sense, tends to a good that is pleasurable to sense:—to its due end, as when by deliberating the reason arrives at some good which is not good now, or in some particular way; and yet the will tends to that good as though it were its proper good. Now this lack of order is voluntary: for it is in the will’s power to will or not to will. Again it is in the will’s power that the reason actually consider the matter, or cease from considering it; or that it consider this matter, or that. Nor is this lack of order a moral evil: for if the reason were to consider nothing, or to consider any good whatever, as yet there is no sin, until the will tends to an undue end: and this itself is an act of the will. ' Accordingly both in the physical and in the moral order it is clear that evil is not caused by good except accidentally.