Chapter 3 — That every agent acts for a good

Hence we must go on to prove that every agent acts for a good.

For that every agent acts for an end clearly follows from the fact that every agent tends to something definite. Now that to which an agent tends definitely must be befitting to that agent, since the latter would not tend to it save on account of some fittingness to it. But that which is befitting to a thing is good for it. Therefore, every agent acts for a good.

Further. The end is that wherein the appetite of the agent or mover is at rest, as also the appetite of that which is moved. Now it is the very notion of good to be the term of appetite, since good is the object of every appetite. (Aristotle, Nicomachean Ethics 1, [1].) Therefore, all action and movement is for a good.

Again. All action and movement would seem to be directed in some way to being, either for the preservation of being in the species or in the individual, or for the acquisition of being. Now this existence itself is a good, and for this reason all things desire being. Therefore, all action and movement is for a good.

Furthermore. All action and movement is for some perfection. For if the action itself be the end, it is clearly a second perfection of the agent. And if the action consist in the transformation of external matter, clearly the mover intends to induce some perfection into the thing moved, towards which perfection the movable tends if the movement be natural. Now when we say a thing is perfect, we mean that it is good. Therefore, every action and movement is for a good.

Also. Every agent acts according as it is actual. Now by acting it tends to something similar to itself. Therefore, it tends to an act. But an act has the ratio of good, since evil is not found save in a potency lacking act. Therefore, every action is for a good.

Moreover. The intellectual agent acts for an end as determining on its end. The natural agent, however, though it acts for an end (as proved above), (Ch. 2.) does not determine on its end, since it does not know the ratio of end, but is moved to the end determined for it by another. Now an intellectual agent does not determine the end for itself except under the aspect of good, for the intelligible object does not move except it be considered as a good, which is the object of the will. Therefore, the natural agent is also not moved, nor does it act for an end except insofar as this end is a good, since the end is determined for the natural agent by an appetite. Therefore, every agent acts for a good.

Again. To shun evil and to seek good are in the same ratio, even as movement from below and upward movement are in the same ratio. Now we observe that all things shun evil, for intellectual agents shun a thing for the reason that they apprehend it as an evil, and all natural agents resist corruption, which is the evil of everything, in proportion to their strength. Therefore, all things act for a good.

Again. That which results from the agent’s action beside his intention is said to happen by chance or luck. Now we observe in the works of nature that either always or more often that happens which is best: thus in plants the leaves are so placed as to protect the fruit, and the parts of an animal are so disposed as to conduce to the animal’s safety. Therefore, if this happens beside the intention of the natural agent, it will be the result of chance or luck. But that is impossible, because things that happen always or frequently are not casual or fortuitous, but those which occur seldom. Therefore, the natural agent tends to that which is best: and much more evidently is this so with the intellectual agent. Therefore, every agent intends a good in acting.

Moreover. Whatever is moved is brought to the term of movement by the mover and agent. Therefore, mover and moved tend to the same term. Now that which is moved, since it is in potency, tends to an act, and consequently to perfection and goodness: for by its movement it passes from potency to act. Therefore, mover and agent by moving and acting always intend a good.

Hence the philosophers, in defining the good, said: The good is the object of every appetite; and Dionysius says that all things desire the good and the best. (Pseudo-Dionysius, On the Divine Names, ch. 4.)

Evil