Chapter 62 — Against the opinion of Alexander about the possible intellect

Having taken these sayings of Aristotle into consideration, Alexander asserted that the possible intellect is a power in us, (Cf. Alexander of Aphrodisias, Enarratio De Anima, “De int. pract. et sp.”; Averroes, On the Soul, bk. 2, text. 5.) so that the common definition of a soul given by Aristotle in On the Soul 2 (Aristotle, On the Soul 2.1; see ch. 61.) might apply to it. But as he could not understand how an intellectual substance could be the form of a body, he said that the aforesaid power is not rooted in an intellectual substance, and that it is consequent on the mixture of the elements in the human body. For the particular mode of mixture in the human body makes man to be in potency to receive the inflow of the active intellect, which is always in act, and according to him is a separate substance, the result of which inflow is that man is made to understand actually. Now in man that by which he is potentially understanding is the possible intellect. Consequently, it seemed to follow that the possible intellect in us is a result of a particular mixture.

But at the first glance this opinion is seen to be in contradiction with both the words and the proof of Aristotle. For as already stated (Ch. 59.) Aristotle proves in On the Soul 3 that the possible intellect is not mixed with the body. (Aristotle, On the Soul 3.4.) Now this could not be said of a power resulting from the mixture of the elements: for a thing of the kind must be rooted in the mixture itself of the elements, as we see in the case of taste, smell, and the like. Therefore, seemingly the aforesaid opinion of Alexander is inconsistent with the words and proof of Aristotle.

To this Alexander replies that the possible intellect is merely the preparedness in the human nature to receive the inflow of the active intellect. And preparedness is not a particular sensible nature, nor is it mixed with the body: for it is a relation and the order of one thing to another.

But this clearly disagrees with the intention of Aristotle. For Aristotle proves that the reason why the possible intellect is not confined to any particular sensible nature, and consequently is not mixed with the body, is because it is receptive of all the forms of sensibles, and cognizant of them. Now this cannot be understood of preparedness, for it denotes not receiving but being prepared to receive. Therefore, Aristotle’s proof refers not to preparedness, but to a prepared recipient.

Moreover. If what Aristotle says of the possible intellect applies to it inasmuch as it is a preparedness, and not on account of the nature of the subject prepared, it follows that it applies to every preparedness. Now in the senses there is a preparedness to receive sensibles actually. Therefore, the same applies to the senses as to the possible intellect. And yet Aristotle clearly says the contrary, when he shows the difference between the receptivity of sense and of intellect, from the fact that sense is corrupted by the excellence of its objects, but not the intellect.

Again. Aristotle says of the possible intellect that it is passive to the intelligible, that it receives intelligible species, that it is in potency to them. He also compares it to a tablet on which nothing is written. None of which things can be said of preparedness, but only of the subject prepared. It is, therefore, contrary to the intention of Aristotle that the possible intellect should be the same as preparedness.

Again. The agent is more noble than the patient, and the maker than the thing made, (Aristotle, On the Soul 3.5, 430a17–18.) as act in comparison with potency. Now the more immaterial a thing is, the more noble it is. Therefore, the effect cannot be more immaterial than the cause. But every cognitive power, as such, is immaterial: hence Aristotle says in On the Soul 2 of sense that it is receptive of sensible species without matter. (Aristotle, On the Soul 2.12, 424a17.) Consequently, it is impossible for a cognitive power to result from a mixture of elements. Now the possible intellect is the highest cognitive power in us: for Aristotle says in On the Soul 3 that the possible intellect is whereby the soul knows and understands. (Aristotle, On the Soul 3.4, 429a10–23.) Therefore, the possible intellect is not caused by the mixture of the elements.

Moreover. If the principle of an operation proceeds from certain causes, that operation must not surpass those causes, since the second cause acts by virtue of the first. Now even the operation of the nutritive soul exceeds the power of the elemental qualities: for Aristotle proves in On the Soul 2 that fire is not the cause of growth, but its concause so to speak, while its principal cause is the soul, (Aristotle, On the Soul 2.4, 416a13–14.) to which heat is compared as the instrument to the craftsman. Consequently, the vegetative soul cannot be produced by the mixture of the elements, and much less, therefore, the sense and possible intellect.

Again. To understand is an operation in which no bodily organ can possibly communicate. Now this operation is ascribed to the soul, as also to man, for we say that the soul, or man by his soul, understands. Consequently, there must be in man a principle, independent of the body, which is the source of that operation. But the preparedness that results from the mixture of the elements is clearly dependent on the body. Therefore, preparedness is not this principle. And yet this latter is the possible intellect, since Aristotle says in On the Soul 3 (Aristotle, On the Soul 3.4, 429a10–23.) that the possible intellect is whereby the soul knows and understands. Therefore, preparedness is not the possible intellect.

If, however, it be said that the principle of the aforesaid operation in us is the intelligible species made actual by the active intellect: this is seemingly insufficient. For, since man from being intentionally understanding is made actually understanding, it follows that not only does he understand by the intelligible species, by which he is made to understand actually, but also by an intellective power, which is the principle of the aforesaid operation, as happens also with the senses. Now Aristotle affirms that this power is the possible intellect. Therefore, the possible intellect is independent of the body.

Further. The species is not actually intelligible except insofar as it is cleansed of material being. But this cannot happen so long as it is in a material potency, which is caused from material principles, or is the act of a material organ. Therefore, it must be granted that we have in ourselves an intellective power which is immaterial.

Again. The possible intellect is described by Aristotle as being part of the soul. (Aristotle, On the Soul 3.4, 429a10–23; 2.3.) Now the soul is not a preparedness, but an act, since preparedness is the order of potency to act. And yet act is followed by a certain preparedness to a further act: for instance, the act of transparency is followed by an order to the act of light. Therefore, the possible intellect is not a mere preparedness, but is an act.

Moreover. Man obtains species and human nature according to that part of the soul which is proper to him, namely, the possible intellect. (Ch. 60.) Now nothing obtains species and nature according as it is in potency, but according as it is in act. Since, then, preparedness is nothing more than order of potency to act, it is impossible that the possible intellect be merely a certain preparedness in human nature.