Commentaria in Summam contra Gentiles, Liber II

After Saint Thomas had disputed against the fiction of Averroes, he further begins to dispute against the position of Alexander ¹.

I. Alexander first posited, having considered Aristotle's words by which he seems to will that the intellect is not a separate substance but is in us, that the possible intellect is some power in us: for thus the definition of the soul will be able to apply to it.

He posited, second, that this power is not grounded in any intellectual substance, but follows from the commixture of the elements in the human body, in accordance with which man is in potency to receiving the influence of the agent intellect, which exists always in act and which is, according to him, a separate substance; from this influence man becomes actually understanding. And because that in man by which he is in potency to understanding is the possible intellect, it seemed to him that the possible intellect arises in us from a determinate commixture.

II. Against this position, therefore, Saint Thomas argues. And first, from the words of Aristotle, thus. The power which follows upon the mixture of the elements is grounded in the very mixture of the elements themselves: as is clear in the case of taste, smell, and other things of this kind. But this cannot, according to what seems to be Aristotle's mind, be attributed to the intellect, since he says, in III De Anima, that the possible intellect is unmixed with the body. Therefore, etc.

Note that Saint Thomas uses this manner of speaking, it seems, not because it is not the express mind of Aristotle that the intellect is not a virtue mixed with the body, but because, as far as appears at first sight from the position of Alexander, it cannot be explained otherwise, the possible intellect is a certain nature consequent upon the mixture of the elements; and consequently this position is contrary to the words and demonstration of Aristotle.

Yet, although at first sight, as the words sound, it may seem to concern the position of Alexander; nevertheless Alexander, in declaring his position, so that it not be contrary to the words and demonstrations of Aristotle, says that the possible intellect is indeed a preparation in human nature for receiving the influence of the agent intellect; yet that very preparation is not some determinate sensible nature, nor is it mixed with the body, but is a certain relation and order of one thing to another.

Against this position, however, as thus expounded, Saint Thomas argues.

III. First. The possible intellect, according to Aristotle, is receptive of all sensible forms and cognizant of them; and from this he posits that it does not have any determinate nature of sensible things. But these things cannot be understood of the preparation which is a disposition: for it is not its part to receive, but to be prepared. Therefore, etc.

Second. It would follow that the same must be said of the senses and of the possible intellect. But Aristotle shows the opposite of this, text 7. Therefore, etc. — The consequence is proved: because those things which the Philosopher says of the possible intellect apply to every preparation; but in the senses there is a preparation for receiving sensible things in act.

It must be noted that the foundation of this argument is that the preparation in the sense for receiving sensible things is of the same kind as in the intellect, if "preparation" imports nothing other than an order and relation of one thing to another. And universally, in every receiver there is an order and relation to its receivables. Therefore, if all that Aristotle says about the possible intellect belongs to it insofar as it is a relation and order to its receivables, and not from the nature of the prepared subject, then the same things will belong to the sense and to every other preparation, in its order to its receivables; for what belongs to something insofar as it is such belongs to everything such. And thus Aristotle would unsuitably place a difference between the reception of sense and of intellect, saying that from the excellence of its objects the sense is corrupted, but not the intellect.

IV. Third. Concerning the possible intellect, Aristotle says that it is acted upon by the intelligible, that it receives intelligible species, that it is in potency to them, and that it is like a tablet on which nothing is written. But these things cannot be said of the preparation, but of the prepared subject. Therefore, etc. Note that Alexander, in his book On the Soul, says that the intellect is more like the absence of inscription than like a tablet not yet written on. For thus he says ²: The material intellect alone, therefore, is a faculty and a certain readiness for receiving forms, similar to a tablet not yet written upon: nay rather, to the very agraphon of the tablet, that is, the absence of inscription, which is more like the tablet itself than the tablet is. For the tablet already belongs among beings. Wherefore what the soul is endowed with can better be compared to the tablet; but the absence of inscription itself is almost the intellect. From these words it is clear that what Aristotle says of the intellect cannot be said of that preparation which Alexander posits: since those attributes belong to a prepared tablet, not to an absence or negation of writing. It is also clear that those have badly interpreted Alexander's meaning who say that Alexander understood by the name "preparation" a power of the soul, and that this is a quality, namely a natural potency by which the rational soul is prepared for all intelligibles, just as matter, by reason of its potency, is prepared to receive its forms. For if he understood by the name "preparation" a quality and natural potency, he would liken it more to a tablet not yet written upon than to the agraphon, that is, the absence of inscription.

V. Fourthly ³. It is impossible that any cognitive power be caused from the commixture of the elements. Therefore the intellect is not caused from the commixture of the elements. — The consequence is evident, because the possible intellect is the supreme cognitive power in us, as is clear in III de Anima. — But the antecedent is proved thus: because an effect cannot be more immaterial than its cause, since the agent is nobler than the patient and the maker than what is made, just as act is than potency; and the more immaterial a thing is, the nobler it is. Now every cognitive power, as such, is immaterial: hence even sense, according to Aristotle, is receptive of species without matter. Therefore etc. For the clarification of this proposition, every cognitive power, as such, is immaterial, it must be noted, from the teaching of St. Thomas in Prima, q. xiv, a. 1, and De Veritate, q. ii, a. 2, that the immateriality which universally accompanies cognitive power is not complete separation from matter, but is—to speak universally—some excess of form over matter. For insofar as certain things transcend matter more, namely because they are not wholly immersed in matter, so are they of greater cognition. Hence the intellect, which transcends matter entirely, inasmuch as it is attached to no material organ, has the greatest power of knowing. But a form which is in matter is said to transcend matter not because some essential part of it is not in matter, but because, though it is wholly in matter, it is nevertheless not wholly comprehended by matter: for there remains in it a power toward something above the condition of matter, which is a sign that the essence of the form is not wholly comprehended by matter; for power demonstrates the essence of a thing. The sense, then, of the proposition of St. Thomas is that every cognitive power, as such, transcends matter, because it can extend to something above the condition of matter. And this is indeed shown, because every cognitive power, as cognitive, receives species without matter, that is, without the determinate esse which they have in matter. For a knowable form is received in the knower not according to the determinate esse by which it constitutes a thing in nature, but insofar as, being a perfection of one thing in nature, it is apt to exist in another and to become one with it.

VI. In this argument, however, doubt is raised concerning that proposition, an effect cannot be more immaterial than its cause. For the form of a sensible thing in the sense is more immaterial than it is outside the sense. And yet, as it is in the sense, it is caused by the form existing outside. Therefore some effect is more immaterial than its cause. And I am speaking of the principal cause, of which Saint Thomas intends to speak. 2. To make this evident, it must be considered that a nature is said to be immaterial in two ways: namely, either according to its substance, or according to its esse. A nature is said to be immaterial according to its substance when it is not composed of matter and form, as an intelligence. That is said to be immaterial according to its esse alone which, although it includes matter in its definition, nevertheless has an immaterial esse: as the nature of a stone in the intellect. For the nature of a stone is essentially composed of matter and form, and includes matter in its definition, though universal matter. Therefore, existing in the intellect, it is material according to its essence, since it is of the same definition in the intellect and outside the intellect; yet it is immaterial according to its esse, because its esse is not received in matter, but in an immaterial thing, namely in the intellect. — Note, however, that when I say the nature of the stone in the intellect is material, I do not understand this as though its entity, insofar as it is an accident of the intellect, were composed of matter and form; for this cannot be, since it is a simple form actualizing the intellect. Rather, I speak of it as it is a species, that is, as it is representative of the nature of the stone existing outside the intellect and is its quiddity, in the way that the definition of stone belongs to it. For thus, because it represents the nature of the stone, which is material according to its essence, inasmuch as it includes common matter in its definition, it too is said to be material as the species of the stone; although, as it is an accident of the intellect, it is immaterial both according to its essence and according to its esse. But something is also said to be immaterial according to its esse in two ways: namely, either according to its natural esse, which belongs to the nature as found in a supposit, or in the subject which it denominates; or according to the intentional esse which it has in a medium, or in a cognitive power. 3. It is said, therefore, first, that Saint Thomas's proposition is understood of the immaterial according to essence, and concerns the immaterial according to natural esse. For no effect is simpler or more immaterial according to its essence than its principal cause; nor even according to the natural esse which the effect is naturally suited to have according to its nature and definition. And this suffices for his purpose. For since the intellect is immaterial both according to its essence and according to its natural esse, it follows that it cannot be caused from the commixture of the elements, which implies something material. It is said, second, that it is not unfitting for an effect, according to intentional esse, to be more immaterial than its principal and proper cause, since that esse is diminished with respect to such a nature. And thus it is not unfitting for the form of a sensible thing to be more immaterial in the sense than outside, although it is caused by the sensible thing: because the esse of that form in the sense, insofar as it is a sensible form, is intentional esse. Hence it is no objection against the sense of that proposition, since it is understood of the immaterial either according to essence or according to natural esse; whereas the objection proceeds from the immaterial according to intentional esse. — How, however, a form having material esse can, as principal agent, cause a form having immaterial intentional esse, has been declared in the preceding ⁴, according to the mind of Saint Thomas, Potentia, q. 5, a. 8.

VII. Fifth. The vegetative soul cannot be produced from the mixture of the elements; therefore much less can sense and intellect. The antecedent is proved: if the principle of any operation proceeds from certain causes, that operation itself does not exceed those causes, since a second cause acts in the power of the first. But the operation of the nutritive soul exceeds even the power of the elemental qualities, as is clear from the Philosopher in II De Anima, text 41, where he shows that fire is not the cause of growth but an instrument of the soul. Therefore the vegetative soul cannot proceed from the mixture of the elements.

Sixth. The preparation following the commixture of the elements depends on the body. Therefore it is not the possible intellect, of which it is said in III De Anima that by it the soul opines and understands. — The antecedent is evident. — But the consequence is proved: because the possible intellect does not depend on the body. For since understanding is an operation in which it is impossible for a bodily organ to share, that principle in man to which this operation is attributed, which is the possible intellect, must be independent of the body. Therefore etc.

2. It will perhaps be said that the principle of the aforesaid operation in us is the intelligible species made actual by the agent intellect, and not the possible intellect.

But this does not seem to suffice ⁵. Then, because when a man goes from being potentially understanding to actually understanding, it must be that he understands not only by means of a species but also by means of some intellective power, just as happens in the case of the senses. And thus, besides the species, one must posit the possible intellect as the principle of intellection, a principle certainly not dependent on the body. —

Then, because the species is not actually intelligible unless it is purified from material esse—and this esse cannot be so long as it exists in some power that is the act of a material organ, or is caused by material principles—it is therefore necessary to posit, besides the species itself, a possible intellect, which must be immaterial.

VIII. Seventh. The possible intellect is a part of the soul, according to Aristotle. But the soul is not a disposition, but an act. Therefore, etc.

Saint Thomas notes, for the greater part of the doctrine, that although preparation is not an act, that is, something absolute, but rather the order of a potency to act, there nevertheless follows upon act some preparation toward a further act, just as upon the act of the diaphanous there follows an order to the act of light; by this he intimates that, although the intellect is an act and not a preparation, it is not thereby ruled out that there should follow upon it a preparation and order to a further act, namely, to the intelligible species and to the operation which is intellection.

It must be noted that the foundation of this argument can be interpreted in two ways. First, by interpreting the intellect as a part of the soul that is not integral or subjective but potential. For since the soul is first act, it is necessary that its powers also, which are called the parts into which the soul is divided, be absolute acts, not merely relations or orders: for through its powers the soul, which is first act, is ordered to operations. And thus the powers have the character of what is prepared and proximately ordered.

Second, by "part of the soul" understanding the subjective part: and by the possible intellect the intellectual substance that understands through the possible intellect. For if the intellectual substance understanding through the possible intellect is the soul; and the soul is an act, not a preparation: it follows that the possible intellect is not a preparation consequent upon the commixture of the elements, but is an act grounded in the intellectual substance. Alexander said the opposite of this.

The first interpretation, however, seems to be the better one: because, when Aristotle calls the possible intellect a part of the soul, by "part of the soul" he understands its power, as Saint Thomas explains there ⁶.

IX. Eighth. Man is assigned his species according to the part of the soul proper to him, which is the possible intellect. But he is not assigned his species by way of preparation. Therefore, etc. — The minor is proved: because nothing is assigned its species insofar as it is in potency, but only insofar as it is in act. Now preparation is nothing other than the ordering of a potency to act.

Concerning the greater part of this argument, note that it is said that man comes to have the human species through the possible intellect, not as though he were constituted in the species by the intellective power itself; but because, being animate, he comes to have the species through the soul, whose proper property is the possible intellect. And the soul having such a power as its own cannot constitute the human species except insofar as it grounds that property. Therefore it is necessary that the intellective property itself be an act, and not an ordering of a power toward act.