Commentaria in Summam contra Gentiles, Liber II

After Saint Thomas has disputed against the positions of Plato, he begins to treat against the error of Averroes ¹. Concerning this he does three things: first, he lays down the foundations of the position; second, he explains the position itself ²; third, he argues against it ³.

I. As to the first, he says that there were others who, using a different invention, maintained that an intellectual substance cannot be united to the body as form: namely, those who say that the possible intellect is a certain separate substance not joined to us as form. This opinion belongs to Averroes, III de Anima, comment. 5, and in many other places; and he also attributes it to the ancient philosophers themselves.

But he tries to confirm this position and fiction of his both by certain words of Aristotle and by certain frivolous arguments.

First. Because Aristotle, speaking of this intellect, says that it is separate, unmixed with the body, simple, and impassible.

Second. Because, if it were mixed with some body, and likewise if it were the form of some body, it would have of itself some form or nature belonging to sensible things: since, when one thing is made out of matter and form, the form must share something of the nature of that thing whose form it is. But if this were so, it could not understand other sensible natures: as is clear from Aristotle's demonstration.

Third. Because then the reception of the intellect and the reception of prime matter would be of the same kind. And thus it would receive forms as individual. — The consequence is evident. Because the form of the body does not receive anything without its matter.

Fourth. Because it would follow that it would not know the forms received in it, just as prime matter does not.

Fifth. Because the possible intellect is in a certain way of infinite power, since by means of it we judge the infinite things contained in number under universals. But it is impossible for an infinite power to be in a body.

II. As to the second ⁴, since this intellect would be of no concern to us, nor would we understand through it, unless it were in some way joined with us, Saint Thomas shows the manner in which Averroes held that this intellect is joined to us, so that we may be said to understand through it. For he says that, since the species understood in act, from which and from the possible intellect one thing is made, is united to us through the phantasm, because the phantasm is a certain subject of that form, therefore the possible intellect itself must be united to us by means of the phantasm.

Note that when the Commentator says that the phantasm is the subject of the intelligible form, "subject" is not taken in the sense of a subject of inhesion. For since it inheres as a form in the possible intellect itself, it cannot be present subjectively, by way of inhesion, in the phantasm; and also because, as long as it is in the phantasm, it is only intelligible in potency, not actually understood. But by the name "subject" is meant the foundation and origin. For the phantasm is the foundation of the intelligible form, from which it has it that it is proportioned to an intelligible nature. For this species, say of a horse, is proportioned to the nature of a horse because it represents universally the nature of a horse, which its phantasm, existing in us, represents particularly.

III. Concerning this position of Averroes, it must be considered that certain younger Averroists, seeing the greatest difficulties that arose in defending this position, said that it was not Averroes' mind that the intellect is united to us only through phantasms for the purpose of understanding, as Saint Thomas falsely imputes to him: but rather that it is united to us according to esse, even though it is one in number in all men.

They show, however, that this was his intention from many passages, but especially from his words in Ethics X ⁵, where he says that the existence of any man, insofar as he is a man, is through that substance which is the intellect called separate, since it is the better and more honorable thing in him.

Item, from III de Anima, commentary 20 ⁶, where he says that the possible intellect is joined to us by nature in the first union.

Item, from Metaphysics VII, commentary 12 ⁷, where he says that man is composed of animality and rationality.

2. But that this is not Averroes's meaning, it suffices for the present to show, first, from his words in III de Anima, commentary 5. For since in his view there is one intellect of all men in number, it follows, if it is united to man according to esse, that there would be one esse of all men. And thus the argument he makes against himself in III de Anima, comm. 5 will have force ⁸, namely that you would be through the esse of me, and I through the esse of you. But Averroes considers this argument ineffective: hence he does not deign to answer it. Therefore one must say, so that this inconvenience may be avoided, that the intellect is not united to man as a form giving esse.

Second, in the same Third book, commentary 36 ⁹, he says as follows: The material intellect is not joined to us per se and primarily, but is joined to us only through its conjunction with imaginable forms. Therefore, according to him, it is not united to us in respect of esse: for in that case it would not be joined to us only through its conjunction with imaginable forms.

Third, in I Metaphysics, commentary 33 ¹⁰, he says that it is impossible for forms to remain while the things of which they are forms perish, since then there would be neither generation nor corruption. But when the individual perishes, the intellect still remains. Therefore, according to him, the intellect is not a form giving esse to the individual.

This same point could be confirmed from other passages; but since this question has been discussed by others, and men of the highest authority, such as Albert, Saint Thomas, Scotus, and many others besides the most obstinate followers of Averroes, attribute this very thing to him, therefore I need not linger here any further on the mind of Averroes.

3. But what they first object from the tenth book of the Ethics does not compel. For it can be said, first, that there the Commentator speaks not according to his own view, but according to the opinion of the common crowd. — Second, it can be said that he speaks not of the existence of man as a substance, in virtue of which man is said to be among things in nature—for this, according to him, belongs to man through the cogitative power—but of existence in relation to the operation that is understanding. For insofar as man has this operation which is understanding, intellect is united to him in the way in which a form having a foundation in something is said to be united to the foundation of that form; or even in the way in which an art is united to an instrument. Now that by which man understands principally is the intellect: just as that by which the instrument of an art operates principally is the art itself. And thus it is said that the existence of man qua man—that is, the existence and esse of man by which he is able to understand—belongs to him through the intellect: because intellect, being united to man, is the more honorable being, and to it, as to what is more principal, the action of understanding is attributed, while to man it is attributed as to an instrument. — Third, it can also be said that the existence of man belongs to him through the intellect only extrinsically: not essentially and intrinsically, although intellect has some unity with man.

He does not think about what is objected in the second place either. For it is said that he speaks of a potential continuation. Such a continuation is indeed the first, and it is natural. — It can also be said that he calls that continuation first which is first by reason of the first principles. For since the knowledge of the first principles is naturally implanted in us, the union of the intellect with us for understanding those principles will be natural.

To the third authority, one may first say that by "rationality" he means the power of thinking, for the cogitative power is called particular reason. — One may secondly say that by "rationality" he does indeed mean the power for understanding, but it does not follow from this that the intellect is united to us according to esse. For man is born to understand through the cogitative power as through an instrument of the possible intellect; or as through that by which man is able to be conjoined with the intellect. In this way Aristotle says in Metaphysics XII, commentary 38 ¹¹, that the form of man, insofar as he is man, is nothing other than his continuation with the intellect. Hence also, on his view, man differs from brutes intrinsically and essentially through the cogitative power, but extrinsically through the intellect, insofar as man is not born to understand through the cogitative power except insofar as it is born to be joined to the possible intellect.

IV. As to the third part ¹², Saint Thomas argues against this fiction of Averroes. First, attacking it absolutely ¹³; second, showing that it conflicts with the sayings of Aristotle, cap. LXI.

As to the first, he argues along two paths. The first is taken from man's very operation, which is to understand. The second from the nature and species of man; and it begins at the seventh argument of this chapter ¹⁴.

In the first way it is assumed as manifest that man understands, for each person experiences this in himself. But it is shown that, on account of the continuation of the intellect with the phantasm, man cannot be said to understand if the intellect is posited as a substance separate from man in its esse.

It is argued first as follows. That which has intellect is intelligent, and that which is understood is that whose intelligible species is united to the intellect. Therefore, from the fact that the species united to the intellect is in us in some way—namely through the phantasm, in which it has the foundation of truth—it does not follow that man understands, but rather that he is understood.

Note that the foundation of this first argument is, as is clear in the Qu. de Anima, art. 2, that something is not cognitive because a cognizable species is present to it, but because a cognitive power is present to it. Now, from the fact that the intelligible species is in some way united to man by reason of the phantasm, no cognitive power is present to man, but only the intelligible species itself: since the intellect remains separate as to its esse from man. Therefore, from such a union of the intellect with us by reason of the phantasm, it does not follow that man understands, but rather that he is understood: since the species of his phantasm is united to the intellect.

V. Second: and it is a kind of declaration and explication of the preceding argument. The continuation of the possible intellect through the intelligible species to the phantasm that is in us is similar to the continuation of the visual power to the color that is in the stone. But this continuation does not make the stone see, but be seen. Therefore the said continuation of the intellect with us does not make us understand, but only be understood. Therefore the aforesaid mode of continuation is not sufficient. — Note the consequences, with the minor. — The major, however, is proved from the comparison which Averroes himself and Aristotle employ: namely, that the intelligible species stands to the phantasms just as the actual visible species to the colored thing outside the soul.

2. To this argument, according to the Averroists, a twofold reply can be made. First, that the argument supposes something false, namely, that the intellect is said to be joined to us because it itself understands the phantasm that is in us. For this is not Averroes's meaning: rather, according to him, the intellect is said to be joined to us because the same thing is known by the intellect and by our cogitative power, but by the intellect universally, while by the cogitative power particularly; for they are related as art and axe, which are continued in one operation about the same object, art indeed principally, but the axe instrumentally. Hence the comparison brought forward, although it agrees in some respect, and on account of that respect was adopted by Aristotle, nevertheless does not agree in all respects. And therefore it is said that the major premise of the argument adduced is false: for sight is not united with the colored thing by reason of an operation about the same object, as the possible intellect is with the phantasm.

Second, it can be answered that, according to Averroes, man does not have from that union alone with the phantasm that he understands, but from the assistance of the intellect to the human body as to its proper mobile essentially corresponding to it, just as an intelligence is related to its orb. Hence it is true to say, on account of such a union, that Socrates understands: just as that the heaven moves itself.

3. But against the first of these replies it is argued first, because the continuation of the intellect with us through the phantasm does not seem to be assigned according to the mind of the Commentator, namely that the cogitative power and the intellect agree in one operation. For when Averroes assigns, in III De Anima ¹⁵, the mode of this continuation, he says that the intellect is continued with us for this reason: because the intelligible species which is in the intellect has a twofold subject, namely the intellect itself and the phantasm existing in us. From these words it is clear that he does not posit the continuation of the intellect with us because the same thing is known by the intellect through an intelligible species and by the cogitative power through an imagined form; but rather because through the intelligible species some bond is made between the intellect and us, insofar as it has a subject in us, namely the phantasm, just as it has the intellect as its subject—though in different ways; for the intellect is its subject by way of inherence, whereas the phantasm is so because it grounds its truth. The argument therefore proceeds according to this continuation, not according to that one whereby the intellect knows the phantasm existing in us. And the major premise assumed is true: for just as the intelligible species has a twofold subject, so too does the visible species, namely the visual power and the color from which it is caused; and hence the continuation is similar in both cases. From this it is clear that the reply was given neither according to the mind of the argument nor according to the mind of the Commentator.

Second. Suppose that Averroes intends that continuation which the response posits; it follows that man would know nothing universally from that union (the opposite of which each person experiences), and consequently man would not understand, since understanding is of universals. The consequence is proved. The intellect is continued with us because the same thing is comprehended by the intellect and by the cogitative power, by the intellect universally, by the cogitative power particularly. But the intellect is nothing of man's: rather, it exists in its esse separate from him. Therefore, from the fact that the intellect understands universally what the cogitative power knows particularly, it does not follow that man understands universally, but only that he comprehends particularly through his cogitative power: just as from the fact that God knows universally what we apprehend particularly, it does not follow that we understand universally.

Third. The union of two knowing subjects in some extrinsic object does not make the cognition of one numerically identical with that of the other; for the same thing can be apprehended at once by different subjects through different cognitions. Therefore, the fact that the same thing is grasped by the intellect and by the cogitative power of a man does not make it the case that the thinking man understands with the same intellection by which the intellect itself understands. Therefore, since he cannot be said to understand by another operation, understanding being an operation of the intellect alone, it follows that through such a continuation the man can in no way be said to understand.

Fourth. Understanding is not through a bodily organ. Therefore the intellect and the cogitative power do not concur in the apprehension of the same object in such a way that the intellect would be the principal agent, as art is, and the cogitative power, which resides in a bodily organ, its instrument.

4. Against the second reply, Saint Thomas argues in Prima, q. LXXVI, and in the Treatise on the Unity of the Intellect ¹⁶, with several reasons that have been expounded by other Thomists. Therefore we need not linger further in refuting it.

VI. Third, it is argued to the conclusion. Man is intelligent through the intellect as through a cognitive power. Therefore he is not joined to the intellect by means of an intelligible form, but conversely it is through the intellect that he is joined to the intelligible. Therefore it is wrongly said that man is joined to the intellect by reason of the intelligible species founded in the phantasm. — The inference is proved: because one who knows is joined to the object through a cognitive power, and not conversely joined to the cognitive power through the object; just as everything acting is joined to what is acted upon through an operative power.

VII. Fourth. Man understands. And only through the intellect. Therefore it must be united to us formally, and not merely through its object. — The consequence is proved. Because that by which something operates must be its form. Which is proved. First, because nothing acts except insofar as it is in act; but a thing is in act only through form. Second, because Aristotle proves by this, in II De Anima, text 24, that the soul is the form.

2. Concerning this proposition, "That by which something operates is its form, namely that which gives esse to it," it must be noted that it holds true of that by which something first operates, if it be distinct from the operator: as is clear from the Philosopher, in the place cited above. Now, that by which something first operates is said to be that to which it belongs to be that by which something operates, and which does not possess this through something else; rather, if anything has this, namely that it be that by which something operates, it has it through itself. In this sense the proposition is most true: because the first principle by which something operates must actualize the operator, since nothing acts except insofar as it is in act. — It also holds universally true of that by which something operates as an operative power.

And by this the objection is excluded which could be raised concerning the divine essence united to the intellect of the blessed: for by it the blessed intellect sees the divine essence, and thus by it the blessed one operates, and yet it does not inform the intellect according to esse. For it is clear that it is not that by which first, nor that by which as by an intellective power, the blessed one sees the divine essence: but the very substance of the soul is that by which first the blessed one sees the divine essence, while the intellect is the very intellective power. For the divine essence supplies, in place of the intelligible species, both the soul; and the intellect, through which the soul is capable of the divine vision; and the light of glory elevating the intellect; but the divine essence supplies the place of an intelligible species, from which the vision itself takes its character, so that it may be an understanding of such a thing. For, since the intelligible species gives a certain immaterial and accidental esse to the intellect, and is for it a principle of understanding as perfecting it unto understanding: the divine essence supplies the place of the species not with respect to the first, but with respect to the second; as will be shown below in Book III ¹⁷.

3. Concerning that proposition, "Man understands, and not except through the intellect," note that by that exclusive term the intelligible species is not excluded; rather, another power, or another thing by which man first understands, is excluded. For by nothing else, as a first power of understanding, does man understand than by the intellect—making no distinction, for now, between the intellect and the intellective soul.

4. To this argument the Averroists reply by denying its foundation, namely, that that by which something operates is its form, if this is understood of a form giving esse. For it is not necessary that that by which something operates give esse to the one operating; it suffices that it be an intrinsic principle of operating. And when it is proved on the ground that the agent must be in act through that by which it operates, but it is not in act through it unless it is united to it according to esse: the reply is that for a composite to be in act through something can occur either because the esse of one part is received in the other, as the esse of form is received in matter; or because what is united to another is an actual being in itself. Now it is not necessary that what operates through something be in act through it in the first way; it suffices that it be in act through it in the second of those ways.

Against this response it is objected, as we argued in our Questions on the Soul ¹⁸: first, because among the philosophers it is never found that something is said to be one by its being made actual through another thing, on the ground that that thing, existing in itself actually, is united to itself for the sake of operating. For since being actual is opposed to what is in potency, just as a thing is not said to be in potency to a form because the form itself is naturally apt to be united to it in some other way than by esse, but because it is naturally apt to have esse through that form — for by this is known the difference of matter from form, and that its nature is pure potency, namely because it is naturally apt to be actualized by forms with respect to esse — so too, for something to be actual through a form will mean not merely that the form, existing in itself actually, is united to itself, but that it has esse through that form.

Second, because Aristotle's argument for proving that the soul is the form giving esse to the body would be vain. And universally, from operations it could be proved of no form that it gives esse to the thing operating. For it could be said that that by which we are first moved, sense, etc., is not a form giving esse to the thing operating, but that it, existing in itself in act, is united to the body as a mover: and thus the soul need not inform the body.

It is confirmed. Because then, according to this response, when several men pull a ship, it could be said that one is in act through another, and that he acts insofar as he is in act through him. Which is alien to all philosophy.

VIII. Fifth. The intelligible species, insofar as it exists in the phantasms, is not actually intelligible: just as neither is the species of color actually sensed insofar as it exists in the stone. And consequently it is not one with the possible intellect: for what is actually intelligible is one with the intellect in act, but not what is intelligible in potency with the intellect in potency. Therefore it is not continuous with us insofar as it exists in the possible intellect. Therefore it cannot be the medium by which the possible intellect is joined to us. — The first inference is proved. Because according to the position stated above, the intelligible species is joined to us only insofar as it exists in the phantasms. — The second inference is also proved. Because thus such a species, insofar as it is joined to the possible intellect, is not joined to us, nor conversely.

St. Thomas then adds that the author of this position was deceived through equivocation. For, since "intelligible in act" is said in two ways—either because it can move the possible intellect, or because it is understood in act as made one with the intellect in act (just as "visible in act" is said either because it can move the sight, as colors do when light is present, or because it is actually sensed insofar as it is one with sight in act, as the visible species)—this position did not distinguish one mode from the other, but supposed that in the phantasm itself there was a form actually understood, because by the light of the agent intellect phantasms can move the intellect. And therefore, since what is understood in act is united to the intellect, he supposed that through such a form there takes place a coupling between the intellect and man, as it were through a certain medium and uniting bond.

2. It must be noted here that what is said of the form understood in act, or sensed in act, is when it is actually united to the intellect or to sense and represents its object to it, either in perfect act or habitually. This occurs when it is actually the form of the intellect or of sense: for while it is separate from the intellect or from sense, it is not one with the intellect or with sense, nor does it represent its object to them. And therefore this Saint Thomas seems here to posit no difference between the form insofar as it is understood or sensed in act, and itself as it is one with the intellect or with sense.

From this it is clear that, if we speak properly, it is one thing for a form to be actually intelligible or sensible, and another for that form itself to be actually understood or sensed. For a form is said to be actually intelligible or sensible when it has esse in such a way that it can move the intellect or the senses, causing in them a form understood or sensed in act. And thus colors existing outside, with light present, are said to be actually visible: because according to the esse they have outside, with the assistance of light, they can move the sense. But material things, according to their natural esse, are not actually intelligible, because according to that esse they cannot move the intellect. Yet according as they are in the phantasy through the phantasm, with the light of the agent intellect present, they are actually intelligible: because through the light of the agent intellect they can move the possible intellect. — A thing is said to be actually understood or sensed, however, because it is actually united to the intellect or the sense and is actually set before it, either perfectly or habitually: as happens in the case of the intellect.

3. But against this argument of St. Thomas it could be said that it proceeds from a misunderstanding of the Commentator's position. For the Commentator does not posit that the intellect is joined to us through the intelligible species because the same species in number which actualizes the intellect also actualizes the phantasm, as the argument seems to suppose, but because the species existing in the intellect has its foundation in the phantasm and represents it in some way. And thus the intellect is conjoined to the phantasm just as a mirror is conjoined to the man whose image appears in the mirror.

Against this response it is argued, from the doctrine of Saint Thomas in the Treatise on the Unity of the Intellect ¹⁹, that by no agreement can what the Commentator intends be saved under this mode of union. For he wishes to show that, notwithstanding the separation of the intellect according to esse, it may be attributed to man that he understands, on account of the continuation of the intellect with the phantasm. But this has no appearance of truth at all, once that mode of union is posited. For it is not because of the continuation which a mirror has with a man that it follows that the man has the action of the mirror, which is to represent. Therefore, in order that his position have any appearance of truth, we must understand that union of the intellect with the phantasm through the species in such a way that the species is actually in the intellect and is also in the phantasm: although even so the position itself does not contain the truth, as has been shown.

IX. Sixth. In man there is a higher operation of life than in animals, namely understanding. Therefore man has a higher species of life than the life of an animal. Therefore he has a higher soul by which he lives than the sensitive soul. Therefore the intellect is the soul of man, and consequently his form. — The antecedent is evident from the admission of all. — The first consequence is proved: because wherever a higher operation of a living thing is found, there is found a higher species of life corresponding to that action, as is clear from comparing animals to plants. — The second is also proved: because life is through the soul. — The last is evident: because no soul is higher than the sensible except the intellect, that is, the intellectual soul.

Note that this argument cannot be countered by saying that, according to Saint Thomas, understanding is not from the soul actively but only passively, while it is active on the part of the object: as Scotus seems falsely to attribute to himself, IV Sent., d. XLIII, q. II ²⁰. For according to Saint Thomas the intellect does not concur merely passively in intellection, but also in some way actively, inasmuch as it elicits intellection itself; although it can do this only by receiving a species from the object, which is a kind of being acted upon. But enough has been said about this above ²¹.

X. As to the second way ²², it is argued first by this seventh reason, thus. For it follows that man does not differ from the brutes by the fact that he has intellect. This is manifestly false. Therefore, etc.

The consequence is proved. For if there were an intellect separate in its esse from man, and united to him only in the manner described, man would not receive his species through union with the intellect, but only through the sensible form. For such a union follows upon man's operation: it accompanies the phantasm, which is a motion produced by sense in act. But what follows upon the operation of a thing does not confer its species upon it: for operation is a second act, whereas the form by which a thing has its species is a first act.

Eighth, the same point is argued in this way. If man belongs to his species by virtue of being rational and having intellect, then whoever is in the human species is rational and has intellect. A child, even before it leaves the womb, will be rational and have intellect, since it is in the human species. And yet phantasms are not yet present in it. Therefore it will not be a man who is rational and has intellect on account of the said continuation.

Note, concerning this argument, that Saint Thomas takes the antecedent of the conditional as conceded. For if this were not so, then man would not differ in species from the brutes by the fact that he is rational and possesses intellect. To this, as to an absurdity, he had drawn out the preceding argument.