Chapter 82 — That the souls of dumb animals are not immortal

From what has been said it may be clearly proved that the souls of dumb animals are not immortal.

For it has been already shown. (Cc. 66–67.) that no operation of the sensitive part can possibly be without the body. Now we cannot find in the souls of dumb animals any operation superior to those of the sensitive part, for they neither understand nor reason. This appears from the fact that all animals of the same species operate in the same way, as though moved by nature and not as operating by art: thus every swallow builds its nest, and every spider spins its web, in the same way. (Cf. Aristotle, Physics 2.8, 199a20–30.) Therefore, the souls of dumb animals have no operation that is possible without the body. Since, then, every substance has some operation, the soul of a dumb animal cannot exist apart from the body. Therefore, it perishes when the body perishes.

Again. Every form that is separate from matter is actually understood: for the active intellect makes species to be actually intelligible, insofar as it abstracts them, as appears from what has been said. (Ch. 77.) But, if the dumb animal’s soul remains after its body has perished, it will be a form separate from matter. Therefore, it will be a form actually understood. Now, in things separate from matter, that which understands is the same as that which is understood, as Aristotle says in On the Soul 3. (Aristotle, On the Soul 3.4, 429b26–430a3.) Therefore, the soul of a dumb animal, if it survive the body, will be intellectual, which is impossible.

Again. In everything that is able to attain to a certain perfection we find a natural desire for that perfection, since good is what all desire, (Aristotle, Nicomachean Ethics 1.1, 1094a2.) yet so that each thing desires the good proper to it. (Aristotle, Nicomachean Ethics 8.2, 1155b23–26.) Now, in dumb animals we do not find a natural desire for perpetual existence except as regards perpetuity of species, inasmuch as we find in them the desire for begetting whereby the species is perpetuated. This desire is found in both plants and inanimate things, but not as regards the appetite that is proper to an animal as such, which appetite is consequent upon apprehension. For, since the sensitive soul does not apprehend except here and now, it cannot possibly apprehend perpetual existence. Neither, therefore, does it desire it with animal appetite. Therefore, the soul of a dumb animal is not capable of perpetual existence.

Moreover. Since pleasures perfect operations, as Aristotle says in 10 Ethics, (Aristotle, Nicomachean Ethics 10.4, 1174b31–33.) the operation of a thing is directed to that in which it takes pleasure as in an end. Now all pleasures of dumb animals are referred to the preservation of the body: for they delight not in sounds, perfumes, and sights, except insofar as they are indicative of foods or venereal matters, which are the objects of all their pleasures. Hence all their operations are directed to the preservation of their bodily existence as their end. Therefore, they have no existence apart from the body.

The teaching of the Catholic faith is in keeping with this statement. For it is said of the dumb animal’s soul: its (Vulg., of all flesh.) life is in the blood (Gen 9:4), (Cf. Lev 17:14.) as though to say: Its existence depends on the blood remaining. It is also said in the book De ecclesiasticis dogmatibus: (Pseudo-Augustine, De ecclesiasticis dogmatibus, cc. 16–17.) we declare that man alone has a subsistent soul, that is, which has life of itself: and that the souls of dumb animals perish with the body.

Moreover, Aristotle says in On the Soul 2 that the intellective part of the soul is distinguished from the other parts as incorruptible from corruptible. (Aristotle, On the Soul 2.2, 413b24–31.)

This excludes the opinion of Plato (Cf. Plato, Phaedo 77b–d; 80a–81e; 84c–85d.) who held that the souls even of dumb animals are immortal.

And yet it would seem possible to prove that the souls of dumb animals are immortal. For if a thing has an essential operation belonging to itself, it is also self-subsistent. Now the sensitive soul in dumb animals has an essential operation in which the body has no part, namely, to move, because a mover is composed of two parts, one of which is mover and the other moved. (Aristotle, Physics 8.5, 256b13–257a33.) Therefore, since the body is something moved, it follows that the soul alone is mover; therefore, it is self-subsistent. Consequently, it cannot be corrupted accidentally when the body perishes, since those things alone are corrupted accidentally which do not have essential being. Nor can it be corrupted essentially, seeing that it has no contrary, nor is it composed of contraries. It follows, therefore, that it is altogether incorruptible.

The argument of Plato, (Plato, Phaedrus 245c–e; cf. Phaedo 77d–78b; 80a–81a.) by which he proved that every soul is immortal, would seem to come to the same as this, namely, the soul moves itself, and whatever moves itself must be immortal. For the body does not die except when it is abandoned by that which moved it, and a thing cannot abandon itself. Consequently, according to him, that which moves itself cannot die. And so he concluded that every moving soul, even that of dumb animals, is immortal. We have said that this argument comes to the same as the preceding, because, since in Plato’s opinion nothing moves unless it be moved, that which moves itself is an essential mover, and therefore has an essential operation.

Again, Plato held that the sensitive soul has an operation of its own not only in moving, but also in sensing. (Cf. Plato, Theaetetus 186a–187b.) For he declared that sensation is a movement of the soul itself which senses: and that the soul, being moved thus, moved the body to sensation. (Cf. Plato, Philebus, ch. 19, 33b–34c; Laws, bk. 10, 896a–e.) Therefore, when he defined sense, he said that it is the movement of the soul through the body. (Cf. Plato, Timaeus 43a–e.)

Now it is clear that these statements are false. For to sense is not to move, but to be moved, because from being potentially sentient, the animal is made actually sentient through the sensible objects by which the senses are impressed. But it cannot be said that the sense is passive to the sensible in the same way as the intellect is passive to the intelligible object, so that sensation could be an operation of the soul without a bodily instrument in the same way as understanding is. For the intellect apprehends things as abstracted from matter and material conditions, which are the principles of individuality, but the sense does not. This is evidenced by the sense being confined to particular objects, while understanding is of universals. It is therefore clear that the senses are passive to things as existing in matter, while the intellect is not, but according as they are subject to abstraction. Therefore, the passion of the intellect is without corporeal matter, but the passion of the senses is not.

Again. Different senses are receptive of different sensibles: for instance, sight of colors, hearing of sounds. Now this difference clearly arises from the different dispositions of the organs, for the organ of sight needs to be in potency to all colors, and the organ of hearing to all sounds. But if this reception took place without any corporeal organ, the same faculty would be receptive of all sensible objects, since an immaterial power, for its own part, stands in an equal relation to all such qualities. Therefore, the intellect, through not using a corporeal organ, takes cognizance of all sensible objects. Therefore, there is no sensation without a corporeal organ.

Further. Sense is corrupted by excellence of its object, but the intellect is not, because he who understands higher objects of intelligence is able to understand others not less but more. (Aristotle, On the Soul 3.4, 429b1–4.) Consequently, the passion caused in the sense by the sensible differs in kind from that which is caused in the intellect by the intelligible: the passion of the intellect occurs without a corporeal organ, while the passion of the sense is connected with a corporeal organ, the harmony of which is destroyed by the excellence of the sensible.

Plato’s statement that a soul moves itself may seem to be well founded by reason of what we observe in regard to bodies. For it seems that no body moves unless it is moved: hence Plato said that every mover is moved. And since we cannot go on to infinity, as though every thing moved were moved by another, he stated that in each order the first mover moved itself. From this, it followed that the soul, which is the first mover in the movement of animals, is something that moves itself.

But this is shown to be false, on two counts. First, because it has been proved (Bk. 1, ch. 13.) that whatever is moved of itself is a body: therefore, since a soul is not a body, it is impossible for it to be moved save accidentally.

Second, because since a mover as such is in act, while the thing moved as such is in potency, and since nothing can be in act and potency in the same respect, it will be impossible for the same thing to be mover and moved in the same respect. But if a thing is stated to move itself, one part of it must be mover and the other part moved. It is in this way that an animal is said to move itself, because the soul is mover and the body moved. Since, however, Plato did not hold that the soul is a body, although he made use of the word “movement” which belongs to bodies properly speaking, he did not mean movement in this strict sense, but referred it in a more general way to any operation. In this sense Aristotle also says that sensation and understanding are movements: but in this way movement is the act not of that which is in potency but of that which is perfect. (Aristotle, On the Soul 3.7, 431a4–13.) Consequently, when he said that the soul moves itself, by this he meant to say that it acts without the help of the body, whereas it is the other way about with other forms which exercise no action apart from matter: for that which heats is not heat by itself but something hot. Hence he wished to conclude that every soul which causes movement is immortal: because that which has an essential operation must also have essential existence.

But it has been already proved that the operation of the soul of a dumb animal (namely, sensation) cannot be without the body. And this is much more evident as regards its operation of appetite. Because all things pertaining to the appetite of the sensitive faculty are manifestly accompanied by a certain bodily transmutation, and are known as passions of the soul.

From this it follows that not even is movement an operation of the sensitive part without an organ. For the soul of a dumb animal does not move except through sense and appetite, because the power which is said to execute movement makes the members obedient to the command of the appetite. Hence the body is perfected with powers directed to its being moved rather than with powers of moving.

It is accordingly clear that no operation of the dumb animal’s soul can be independent of the body. From this we necessarily conclude that the dumb animal’s soul perishes with the body.