Chapter 59 — That man’s possible intellect is not a separate substance

There have been others who discovered another reason for maintaining that the intellectual soul cannot be united to the body as its form. For they say that the intellect which Aristotle calls possible (Aristotle, On the Soul 3.4.) is a separate substance, not united to us as a form.

They endeavor to prove this from the words of Aristotle, who says, speaking of this intellect, that it is separate, not mixed with the body, simple, and impassible (Aristotle, On the Soul 3.4.)—which, if it were the body’s form, could not be said of it.

Also, from the demonstration by which he proves (Aristotle, On the Soul 3.4.) that, since the possible intellect receives all the species of sensible things through being in potency to them, it must lack them all. Even so the pupil, which receives the species of all colors, lacks all color; for if it had any color by itself, that color would prevent it seeing other colors; in fact it would see nothing but under that color. The same would happen with the possible intellect, if by itself it had any form or nature of sensible things. Yet it would have to be so if it were bound up with the body. Likewise if it were the form of a body, because, since one thing is made from form and matter, the form must participate in something of the nature of which it is the form. Consequently, it is impossible that the possible intellect be bound up with the body, or be the act or form of a body.

Further. If it were the form of a material body, the receptivity of such an intellect would be of the same kind as the receptivity of prime matter, because that which is the form of a body receives nothing without its matter. Now prime matter receives individual forms: in fact, they are individualized through being in matter. Therefore, the possible intellect would receive forms as they are individual: and consequently would not be cognizant of universals, which is clearly false.

Further. Prime matter is not cognizant of the forms which it receives. Consequently, if the receptivity of the possible intellect were the same as of prime matter, neither would the possible intellect know the forms it receives: and this is false.

Moreover. There cannot possibly be an infinite power in a body, as proved by Aristotle in Physics 8. (Aristotle, Physics 8.10, 266a23–b6.) Now the possible intellect is, in a manner, of infinite power, since by it we judge of an infinite number of things insofar as by it we know universals, under which potentially infinite particulars are contained. Therefore, the possible intellect is not a power in a body.

For these reasons Averroes (Averroes, On the Soul, bk. 3, text. 5.) was moved, and likewise some of the ancients, as he says, to hold that the possible intellect, by which the soul understands, has a separate being from the body, and is not the form of the body.

Since, however, such an intellect would in no way belong to us, nor would we understand by it unless it were in some way united to us, he defines the way in which it comes into touch with us, (Averroes, On the Soul, bk. 3, text. 5.) saying that the species actually understood is the form of the possible intellect, just as the actually visible is the form of the visual power. Hence there results one thing from the possible intellect and the actually understood form. Consequently, the possible intellect is united to whomever the aforesaid understood form is united. Now it is united to us by means of the phantasm, which is a kind of subject of that understood form: and in this way the possible intellect also is in touch with us.

But it is easy to see that all this is nonsensical and impossible. For the one who understands is the one who has intellect. And the thing understood is the thing whose intelligible species is united to the intellect. Consequently, though the intelligible species united to the intellect is in a man in some way, it does not follow that the man is the one who understands, but only that he is understood by the separate intellect.

Further. The actually understood species is the form of the possible intellect, as the visible species in act is the form of the visual power, or of the eye itself. Now the understood species is compared to the phantasm as the visible species in act is compared to the colored object outside the soul: in fact, he uses this comparison himself, as also does Aristotle. (Aristotle, On the Soul 3.5, 430a10–16; cf. Averroes, On the Soul, bk. 3, text. 5.) Therefore, by the intelligible form the possible intellect is in touch with the phantasm which is in us, in the same way as the visual power with the color that is in the stone. But this contact does not make the stone to see, but to be seen. Therefore likewise the aforesaid contact of the possible intellect with us does not make us to understand, but only to be understood. Now it is clear that it is properly and truly said that man understands, for we would not inquire into the nature of the intellect except for the fact that we understand ourselves. Therefore, the aforesaid manner of contact is not sufficient.

Again. Every knower by its cognitive power is united to its object, and not vice versa, just as every operator by its operative power is united to the thing operated. Now man is intelligent by his intellect as by his cognitive power. Therefore, he is not united to the intellect by the intelligible form, but by the intellect he is united to the intelligible.

Moreover. That by which a thing operates must be its form, for nothing acts except insofar as it is in act, and a thing is not in act except by that which is its form: hence Aristotle proves that the soul is a form from the fact that an animal lives and senses through the soul. (Aristotle, On the Soul 2.2, 413b2–13.) Now man understands, and this by his intellect only: thus Aristotle, when inquiring into the principle whereby we understand, describes to us the nature of the possible intellect. (Aristotle, On the Soul 3.4.) Therefore, the possible intellect must be united to us formally and not merely by its object.

Further. The intellect in act and the intelligible in act are one, (Aristotle, On the Soul 3.4, 430a2–4.) just as the sense in act and the sensible in act. (Aristotle, On the Soul 3.2, 425b26–27.) Not so, however, are the intellect in potency and the intelligible in potency, nor the sense in potency and the sensible in potency. Therefore the species of a thing according as it is in the phantasms is not actually intelligible, for it is not thus that it is one with the intellect in act, but as abstracted from the phantasms: even so, neither is the species of color actually perceived according as it is in the stone, but only according as it is in the pupil. Now, according to the opinion stated above, the intelligible species is in contact with us only according as it is in the phantasms. Therefore, it is not in contact with us according as it is one with the possible intellect as its form. Consequently, it cannot be the means of bringing the possible intellect into contact with us, since according as it is in contact with the possible intellect it is not in contact with us, nor vice versa.

Now it is evident that he who devised this opinion was deceived by an equivocation. For colors existing outside the soul, given the presence of light, are actually visible as being able to move the sight, and not as actually perceived, according as they are one with the sense in act. In like manner, the phantasms are made actually intelligible by the light of the active intellect, so that they can move the possible intellect, but not so that they be actually understood, according as they are one with the possible intellect made actual.

Again. Where the living thing has a higher operation, there is a higher kind of life corresponding to that operation. For in plants we find only an action pertaining to nutrition. In animals we find a higher operation, namely sensation and local movement: and hence the animal lives by a higher kind of life. But in man we find a yet higher vital operation than in the animal, namely intelligence. Therefore, man must have a higher kind of life. Now life is through the soul. Therefore, man will have a higher soul by which he lives, than is the sensitive soul. But none is higher than the intellect. Therefore, the intellect is man’s soul, and consequently it is his form. (Ch. 57.)

Further. That which is consequent on the operation of a thing does not give a thing its species, because operation is a second act, whereas the form by which a thing has species is the first act. Now the union of the possible intellect with man, according to the above opinion, is consequent on man’s operation: for it takes place through the medium of the phantasm which, according to the Philosopher, (Aristotle, On the Soul 3.3, 406a30–b15.) is a movement resulting from the sense in act. Therefore, man does not take his species from that union, and consequently man differs from dumb animals by the fact that he has an intellect.

Moreover. If man takes his species from being rational and having an intellect, whoever is in the human species is rational and intelligent. But a child, even before leaving the womb, is in the human species: and yet it does not have phantasms that are actually intelligible. Therefore, a man does not have an intellect through the intellect being in contact with man by means of an intelligible species, the subject of which is a phantasm.