Commentaria in Summam contra Gentiles, Liber III

After the opinion of Avempace and Alexander, Averroës' opinion comes to be confuted ¹. Therefore St. Thomas first explains that opinion; secondly, he refutes it ².

I. As to the first point, he says that, because the greatest difficulty in Alexander's opinion arises from his positing that the possible intellect in habit is entirely corruptible, Averroës thought he had found an easier way to show that we sometimes understand separate substances, on the ground that he posits the possible intellect to be incorruptible, and separated from us in its esse, just like the agent intellect.

Hence he said first, in De Anima III, comm. 36, that the agent intellect is related to the principles naturally known by us either as agent to instrument, or as form to matter: because to make things understood in act is the action both of the intellect in habit and of the agent intellect; but one action does not belong to two things unless one of them is compared to the other as agent to instrument, or as form to matter.

For the clarification of the first proposition, he notes that the intellect in habit, by which we understand, has not only this action which is to understand, but also this one which is to make things understood in act. This indeed he makes clear, because through the intellect in habit itself, as to the first principles, which are made understood in act, they are made understood in act through the agent intellect alone, and other things we acquire from study. But although both of these actions belong to the intellect in habit, nevertheless to make things understood in act makes known the intellect in habit more than to understand: because to make things understood in act is prior to understanding.

He said secondly, that in this way the agent intellect is compared to the first understood things in the way that form is to matter. For, since the possible intellect, according to him, is a separate substance, it understands the agent intellect and other separate substances, and also the first speculative understood things. Therefore it must be the subject of both. But whatever things agree in one subject and have an order to one another, as have the speculative understood things and the agent intellect, which makes them understood in act, one of them is as the form of the other: as is clear in light with respect to color, both of which are received in the diaphanous. From which it follows that, since the speculative understood things are conjoined to us through phantasms, the agent intellect also is conjoined to us, inasmuch as it is their form.

He said thirdly, that according as the speculative understood things are conjoined to us either in potency, or in complete act, or partly in act and partly in potency, so proportionally the agent intellect also is conjoined to us. Hence the more understood things in act have been made in us, the more perfectly the agent intellect is continued with us. But the perfect movement ³ toward this continuation comes about through study in the speculative sciences: and men help one another toward this progress, just as in the speculative sciences.

He said fourthly that, when all things understood in potency have been made in act in us, then the agent intellect will be perfectly conjoined to us as form; and then through it we shall understand separate substances, just as now we understand perfectly through the intellect in habit. And this will be man's ultimate happiness, in which man will be as a kind of God.

II. Regarding the first statement of Averroës, it must be considered first, that when two things concur in a certain order to one operation, namely so that the operation belongs to one through the other, one must be compared to the other either as principal agent to instrument, as the craftsman in sawing is related to the saw; or as form to matter, as in heating heat is related to fire. But these two modes agree, as St. Thomas says in the First Part, q. lxxxviii, a. 1, because in both cases one is compared to the other as perfection to perfectible, and as act to potency. Since therefore the agent intellect and the intellect in habit agree in one operation, which is communicated to the intellect in habit through the agent intellect, the agent intellect must be compared to the intellect in habit in one of those modes. And although it is compared in both modes, yet, passing over the first mode, Averroës pursues the second, as serving his purpose more and being more congruent with his position, while he thinks that both the agent intellect and the intellect in habit are received in the possible intellect: for things that agree in one subject as ordered to one operation that also belongs to that subject are more suitably said to be related as form and matter than as principal agent and instrument; although that too can sometimes be truly said of them.

I do not approve, however, the interpretation of certain Averroists who say that in the beginning the agent intellect is the agent with respect to the speculative intellect, and the intellect in habit is the instrument with respect to the same; but in the end one is as form, the other as matter. For Averroës assigns the reason why one is as form and the other as matter to be that this action, which is to make speculative understood things in act, is the action of both. But it is clear that this action belongs to them in the beginning of the generation of the speculative habit with respect to us. Therefore this relation of form to matter does not belong to them only in the end, but also in the beginning.

2. It must be noted secondly, when it is said that it belongs to the intellect in habit to make intelligibles in act and to understand, that by the intellect in habit we can understand two things: namely, either the habit of first principles only, as it is distinguished, namely, from the habit of conclusions deduced from first principles, which in Averroës is called the speculative intellect; or the habit comprehending all things made understood, both first and secondary, namely. It does not seem to be taken in the first way by Averroës. For since to understand takes place with a certain reception of the thing understood in act, by reason of which Averroës says, De Anima III, comm. 36 ⁴, that it is an action of the genus of passion; this which is to understand will not belong to the habit of first principles itself either by reason of the principles themselves, or by reason of the agent intellect, whose instrument they are; and thus it cannot be said of the intellect in habit that both of those actions belong to it.

It is taken therefore in the second way. For from this it is clearly evident that both of those actions belong to the intellect in habit: yet by reason of different things included in it. For to it, inasmuch as it is about first principles, belongs this which is to make things understood in act by virtue of the agent intellect, of which they are as it were instruments and as it were matter: for such an action belongs primarily to the agent intellect; but to the first principles themselves by reason of the agent intellect, inasmuch as from them, naturally known by us through the agent intellect, other things become known to us by study and exercise. Hence St. Thomas, according to the mind of Averroës, says that to make secondary understood things in act is the action of the intellect in habit, as to the first principles, and of the agent intellect: as if to say: It is the action of the intellect in habit, not indeed as to all things contained under it, but only by reason of the first principles.

The other action, however, which is to understand those things that have been made understood in act from our study and will, such as are the intentions of material things, belongs to this intellect inasmuch as it is about those secondary understood things, but by reason of the possible intellect. For just as the agent intellect is the first to which it belongs to make things understood in act, so the possible intellect is the first to which it belongs to receive and understand them.

3. It must be noted thirdly, when it is said by Averroës, according to the mind of Alexander ⁵, that to make things understood in act is prior to understanding, and on that account makes known the intellect in habit more, that we can understand a threefold priority here: namely, the priority of nobility; the priority of presupposition; and the priority of appropriation. For in all these ways it can be verified that to make things understood in act is prior to understanding, as it means, namely, the reception of the thing understood in act. For it is prior in nobility: because, as Averroës says ⁶, the former is of the genus of action, but the latter of the genus of passion; but it is clear that to act is nobler than to receive, at least with respect to one and the same thing. It is also prior naturally, as presupposed to the other: for we understand things to be made understood in act prior to their being received. It is also prior according to appropriation: because this is proper to the intellect, but that is not; because to make things understood in act belongs to no animal power, not even proportionally; but to receive things understood in act belongs even to sense proportionally, for sense also receives things sensed in act.

On account of these priorities, it is suitably said that the nature of the intellect in habit is more properly made known by this, that it makes things understood in act, than by this, that it understands. For the nature of something is more properly made known through its proper and more worthy and naturally prior operation, than through that which is common to it and to others, and is less worthy and posterior.

4. It must be noted fourthly, when St. Thomas says that the first understood things are the beginning of the intellect in habit, that this can be understood in two ways. In one way, as the first part of a thing is called its beginning. For thus it is clear that the first understood things are the beginning of the intellect in habit: for first through the agent intellect alone the first understood things themselves are made in act; then through the agent intellect together with the first understood things, other understood things are made, which we acquire by study and exercise. — In another way, as the effective cause of a thing is called its beginning. And thus also the first principles are the beginning of the intellect in habit as to secondary understood things: for they are their cause. — On account of both of these Aristotle called the habit of first principles, as it is distinguished from the habit of other things, whether as the first part from the second or as cause from effect, intellect: because, namely, from it our whole intellective cognition originates, just as also from the intellective power.

III. Regarding the second statement of Averroës ⁷, it must be noted that in order for the possible intellect to understand something essentially, it is necessary that from it and the intelligible one thing be made, as has many times been said above ⁸ according to the mind of Aristotle. But this cannot be unless either the intelligible itself is entirely the same as the one understanding; or it is received in the intellect itself. Therefore Averroës, thinking that the agent intellect is a substance separated from matter and understood in act per se, and distinct from the possible intellect; from the fact that the possible intellect understands the agent intellect itself, concludes that the possible intellect is the subject of the agent intellect, just as of other understood things.

2. But a doubt arises regarding that which is said, that the possible intellect is the subject of the intellect in habit. For the opposite seems to be said by Averroës in De Anima III, comment 20 ⁹, where he maintains that the habits of the sciences are in the cogitative power as in a subject: which St. Thomas also, in the second Book ¹⁰, brought forward according to the mind of Averroës.

He answers that the habit of science that is in the cogitative power, according to the Commentator, and the intellect in habit, which is posited by him in the possible intellect, are not taken for the same thing. For by the habit of science that is in the cogitative power, he understands a certain disposition and readiness, caused by study and exercise in the cogitative power, by which man is easily and promptly disposed to conjunction with the possible intellect, as is clear in the cited comment. But by the intellect in habit, he understands the understood things themselves, or the intentions and likenesses of the intelligibles themselves, which are posited in the possible intellect, and are conjoined with us through phantasms.

IV. Regarding the last statement ¹¹, when Averroës says that in the perfect conjunction of the agent intellect with man, man will be as God, note that we can interpret that likeness in two ways. First, that it is a likeness as to the cognition of immaterial substances only, and especially of God Himself. And then the sense is that man is ultimately happy as God is, because just as God perfectly knows separate substances, and above all Himself, in which His beatitude consists, so also man, when he has been perfectly conjoined to the agent intellect, will understand separate substances and God.

In the second way, a likeness can be implied as to the universality of beings and of things known. For just as God contains in Himself the perfections of all things and knows all things, so also man, when both all understood things and the agent intellect have been perfectly conjoined to him, will be all things intelligibly, and will know all things.

The other things that are touched upon regarding this opinion are explained in the second Book ¹².

V. But against it St. Thomas argues in many ways ¹³: since it proceeds from the supposition of many things that have been disproved in what precedes.

First. This foundation, namely that the possible intellect is a separate substance, has been disproved above. Therefore on account of that foundation it does not have to be the subject of separate substances, as this opinion argues.

It is confirmed. Because it seems in Aristotle that it is the subject only of those things that are made understood in act: since he says that it is that by which it is to become all things.

Note that separate substances are indeed understood in act, because they are entirely abstracted from matter. But this belongs to them by nature, not through the action of the agent intellect. Therefore they do not have to be received in the possible intellect: whose function is to receive only those things that through the agent intellect are made understood in act.

VI. Secondly. The agent intellect is not a separate substance, but a part of the soul, to which Aristotle attributes this operation, namely to make things understood in act, which is in our power. Therefore to understand through it does not have to be for us the cause that we can understand separate substances. — The consequence is proved. Because otherwise we would always understand them.

2. It must be noted first that, according to the aforesaid position, the whole reason why we can understand separate substances is because the agent intellect, whose function is to understand separate substances, can be continued with us, and that through its perfect continuation with us we shall understand them. If however we posit that the agent intellect is a part of the soul, it follows that it is always united to us according to its essence. Therefore St. Thomas excellently deduces that through it we would always understand separate substances.

If anyone should say, however, that although the agent intellect is a part of the soul, and consequently is always united to us according to substance, yet it is not always united to us according to all its action and power, but only then when the possible intellect has been perfected by all understood things in act; therefore it does not follow that man always understands separate substances: — this is nothing. Because it is not posited, according to the aforesaid position, that understood things in act are required to be continued with us in order that we may understand separate substances, except because they are the medium and disposition for the agent intellect to be conjoined to us according to its substance: because then through it we can understand separate substances. Therefore, according to Averroës, the union of the substance of the agent intellect with us alone is the cause of our understanding separate substances: for union according to the action and power of understanding separate substances follows the conjunction of its substance with us. Therefore, if we posit that no acquired disposition is required for the substance of the agent intellect to be united to us, but that it is always naturally united to us, as being a part of the soul; it follows that through it we would always understand separate substances.

3. Regarding what St. Thomas says, that Aristotle attributes to the agent intellect this operation which is to make intelligibles in act, which operation is in our power, it must be noted that by the understood in act two things can be signified: namely, either the intelligible species alone caused in the possible intellect; or whatever understood thing terminates the act of understanding. By the understood in act, therefore, not any object terminating the act of understanding is to be taken in this place: because to do this pertains to the possible intellect and to the habit of first principles, according as the intellect forms the concept of the quiddity of a thing, or through discourse arrives at actual cognition of that which it knew only in potency. But the intelligible species are to be taken: for these the agent intellect itself, together with the phantasm, causes immediately in the possible intellect. And this is said to be in our power, because it is in our power to form phantasms, and so to order the phantasms in the imagination that they may be a suitable instrument of the agent intellect for causing a species of this kind: for not just any confused and disordered phantasms are its suitable instrument.

VII. Thirdly. According to this position, neither the agent intellect nor the possible intellect is conjoined with us except through species made understood in act. Things understood in act are not conjoined to us except through phantasms. Phantasms, according to Aristotle, are related to the possible intellect as colors to sight; to the agent as colors to light. Therefore neither the action of the possible intellect can be attributed to man, so that he understands separate substances ¹⁴: nor the action of the agent intellect, so that it makes things understood in act. — The consequence is proved. Because it is clear that to a stone, in which there is color (as, namely, phantasms in man), neither the action of sight can be attributed, so that it sees; nor the action of light, so that it illuminates.

VIII. Fourthly. According to this position, the agent intellect cannot be a form in us except according as speculative understood things share in its action. But in this operation which is to understand separate substances, they cannot share: since they are species of sensible things. Therefore etc. — The major is clear. Because the agent intellect is not posited to be continued with us as form except through this, that it is the form of the speculative understood things. It is also posited as the form of these through this, that of them and of the agent intellect there is the same action, namely to make things understood in act.

Note that this reason has for its foundation that, since two actions belong to the intellect in habit, as was shown above ¹⁵; just as the agent intellect is not posited as the form of speculative understood things as to the first understood things, except inasmuch as the action of the agent intellect which is to make things understood in act is also the action of those understood things themselves; so also it ought not to be posited as their form as to secondary understood things, to which another action belongs, which is to understand (in that way, namely, in which they are said to understand: because, namely, the possible intellect and man understand through them), except because the action of the agent intellect which is to understand separate substances is also their action. Since this is not so, because such secondary understood things are species of sensible things, and from sensible quiddities separate substances cannot be known, as was shown against Avempace ¹⁶: it follows that the agent intellect cannot be their form; and consequently neither a form in us. And thus it is clear that this position, which posits that we can understand separate substances through this, that the agent intellect is continued with us as form, is vain and frivolous.

IX. Fifthly. In one way the agent intellect is compared to speculative understood things, of which it is productive; and in another way to separate substances, of which it is only intellective; according to Averroës' position. Therefore it does not follow, if it is conjoined to us through this, that it is productive of the former, that it is conjoined also according as it is cognitive of separate things: but it is a fallacy of the accident.

Note that in this argumentation—The agent intellect is united to us as a form through the fact that it is productive of sensible understood things. But it understands separate substances. Therefore, in this way too it is conjoined to us—there is clearly committed, as St. Thomas says, a deception and a fallacy of the accident; for from the fact that the agent intellect and man are in some way united, an argument is made as if they were united in every way, in which the fallacy of the accident is committed. Hence, granting the Commentator's opinion that the agent intellect is a separate substance, it is said in reply to that minor premise, The agent intellect understands separate substances, that it is accidental to the agent intellect that it understands separate substances according to the respect in which it is united to us, because this belongs to it not according to the respect in which it is conjoined to us, but according to the respect in which it is separate from us; just as it is accidental to animal that it is a genus insofar as it is the same as man, although animal is truly a genus.

X. Sixth. Through the agent intellect we are able to understand separate substances insofar as it becomes a form in us. Therefore, man is able to do this from the beginning. But this position does not say this. Therefore, etc. — The consequence is proved. Because it becomes a form in us also through the first speculative understood things: (supply) which are present in us from the beginning.

If it should be said that the agent intellect does not perfectly become a form through certain speculative understood things, so that through it we can understand separate substances, but through all of them: on the contrary. This is only because those speculative understood things do not equal the power of the agent intellect in understanding separate substances. But not even all of them together equal that perfection, since they are not intelligible except because they have been made understood, whereas those substances are intelligible according to their own nature. Therefore, etc.

Note that this reason presupposes that the agent intellect, according to the aforesaid position, does not become a form in us except because it becomes the form of the speculative understood things; but of those it does not become a form except because they share in the action which is to understand separate substances, as was shown in the fourth reason ¹⁷. For in this way it is clear that either we are able to understand separate substances from the beginning, because from the beginning the first naturally known understood things, by means of which the agent intellect becomes a form in us, are in us; or, if this cannot be, because the first understood things, since they do not equal the power of the agent intellect, cannot share in that operation, it follows that we can never do so, because not even all things that have been made understood can share in that operation, since not even all of them taken together equal the power of the agent intellect.