Lecture 4 — The agent intellect

Now, since in all nature there is something that is as matter in the genus (and is potentially all that is in the genus) and something else which is as cause and agent as making everything in it, as art with respect to its material, so there must be these differences in the soul. There is, in fact, an intellect of the sort that is able to become everything; and there is that which is able to make everything, as a sort of habit, like light; for light too, in a way, makes potential colors actual.

And this intellect is separable, impassible, and unmixed, in its substance a being in act. For the agent is always more honorable than the recipient, and the principle than its material.

But knowledge in act is the same as the thing itself. But what is potential is prior in time within one thing, yet this is not true universally, even with respect to time. But it does not understand at one time and not understand at another time.

When separated, however, this alone exists truly. And this alone is immortal and perpetual.

It does not remember, however, because it is impassible; but the passive intellect is corruptible, and the soul understands nothing without that.

728. Now, since in all nature (430a10). Having examined the potential intellect, the Philosopher now turns his attention to the agent intellect. And about this, he does two things.

First, he shows by argument and illustration that there is such a thing as the agent intellect beyond the potential intellect;

second, at and this intellect (430a17; [732]), he explains its nature.

The argument he uses is this. In all nature, which is sometimes in potency and sometimes in actuality, we must posit something that is as matter in the genus (that is, what is potentially all the things that are in that genus); and another thing that is as an active and productive cause, as art with respect to its material. But soul in its intellectual part is sometimes in potency and sometimes in act. Therefore, there must be these differences in the intellectual soul: first, an intellect of the sort that it can become all intelligible things (this is the potential intellect already discussed); (Lect. 1–3.) and also another intellect such that it can make everything intelligible in act. And this latter is called the “agent intellect”; and it stands as a sort of habit.

729. This last phrase has led some to suppose that the agent intellect is the same as the intellect that is the habitual possession of the principles.

But it is not so; for the intellect that is the habit of the principles presupposes certain things that have already been actually understood, namely, the terms of the principles, through the grasping of which we know the principles. And then it would follow that the agent intellect did not make all intelligible objects in act, as the Philosopher here maintains.

Therefore, I hold that the term “habit” is used here in the sense in which the Philosopher often calls any form and nature a “habit,” insofar as a habit is distinct from privation and potency. In this case, the agent intellect is called a “habit” to distinguish it from the potential intellect, which is in potency.

730. So he calls it a habit like light, which in a way makes potential colors actual. He says, “in a way,” because, as we have seen, color is visible of itself; like only makes a color be in act insofar as it makes the transparent actual, such that it can be moved by color, and thereby the color is seen. (Bk. 2, lect. 14, n. 400.) The agent intellect, on the other hand, makes the intelligible objects themselves, which before were in potency, to be in act, through abstracting them from matter; for it is thus that they are intelligible in act, as was said. (Lect. 2, n. 716.)

731. The reason why Aristotle is led to assert that there is an agent intellect is to rule out Plato’s view, which asserted that the whatnesses of sensible realities exist separately from matter, in a state of actual intelligibility. This is why, for Plato, there was no need to posit an agent intellect. But because Aristotle asserts that whatnesses of sensible realities exist in matter and are not intelligible in act, he had to assert that there is some intellect that abstracts them from matter and thus makes them intelligible in act.

732. Next, at and this intellect (430a17), he states four conditions of the agent intellect: first, its being separable; second, its being impassible; third, its being unmixed, that is, not composed of bodily natures nor conjoined with a bodily organ. Now, these three are also found in the potential intellect; but the fourth condition is that it is in act according to its own substance, and in this it differs from the potential intellect, which is in potency according to its own substance, but is in act only insofar as it has received a species.

733. To demonstrate these four conditions he argues as follows. For the agent is always more honorable than the recipient, and the active principle than its material. But the agent intellect, as we have said, is to the potential intellect as an agent to its material; therefore the agent intellect is nobler than the potential; but the potential intellect is (as has been shown) separate, impassible, and unmixed; therefore the agent intellect will be even more so. (Lect. 1, nn. 677–83.) From which also it is clear that the agent intellect is in act according to its own substance, for an agent is nobler than its patient and matter only insofar as it is in act.

734. Now, what is said here has led some to assert that the agent intellect is a separated substance, and that it differs in its substance from the potential intellect.

But this does not seem to be true; for man would not be adequately established by nature if he lacked within himself the principles whereby he can carry out his own activity, which is understanding; this of course cannot be brought to completion except through both the potential intellect and the agent intellect. Hence, the completion of human nature requires that both of these be something within a man.

Moreover, we see that just as the potential intellect’s activity, which is perceiving the intelligible, is attributed to the man, so too is the activity of the agent intellect, which is the abstracting of intelligible objects. And this is not possible unless a formal principle of this activity were joined to him in his being.

735. Nor is it enough, to attribute the action to the man, to say that the intelligible species made by the agent intellect have as their subject in some way the phantasms, which are internal to us. For, as we have already observed in treating of the potential intellect, the species become actually intelligible only insofar as they are abstracted from the phantasms; thus the act of the agent intellect could not be attributed to us by their mediation. (Lect. 1, n. 692.) Besides, the agent intellect is to the actually understood species as the art is to the species of the artifacts, and obviously the artifacts do not have the activity of the art; hence, even granted that the species made actually intelligible were in us, it would not follow that we can have the action of the agent intellect.

736. Nor does the above position agree with the intent of Aristotle, who expressly states that these two distinct things, the agent intellect and the potential intellect, are in the soul; thus, he expressly teaches us to understand that they are parts or powers of the soul and not separate substances.

737. The chief difficulty arises from the fact that, while the potential intellect is in potency to intelligible objects, the agent intellect stands to the latter as a being already in act. And the same thing cannot be in act and in potency relative to the same thing, and therefore it seems that it is not possible that the agent and the potential intellects should come together in the one substance of the soul.

738. But this is easily resolved if we understand how the potential intellect is in potency to intelligible objects, and how the intelligible objects are in potency with respect to the agent intellect. For the potential intellect is in potency to the intelligible as the indeterminate to the determinate; for the potential intellect does not have determinately the nature of any sensible thing, whereas each intelligible object is some determinate nature of some species—hence Aristotle’s earlier comparison of the potential intellect’s relation to intelligible objects with that of a tablet to determinate pictures. (Lect. 3, n. 722.) And from this point of view, the agent intellect is not in act.

739. For if the agent intellect had with itself the determination of all intelligible things, the potential intellect would not need the phantasms; rather, it would be reduced to the act of all intelligible things by the agent intellect alone. And thus, the agent intellect is not related to intelligible objects as a maker to the thing made, as the Philosopher here says, but as being the intelligible things themselves. Therefore, it is related as to the intelligible objects as an act insofar as it is a certain immaterial active power capable of making other things like itself—that is, making them immaterial; and in this way things that are potentially intelligible it makes actually intelligible. For so too does light make colors actual, but it does not have within itself the determination of all the colors. But this active power is a certain participation in the intellectual light of separated substances, so the Philosopher compares it to a habit, or a light, which would not be an appropriate way of describing it if it were itself a separate substance.

740. Next, at but knowledge in act (430a19), he states his conclusions concerning intellect as in act. And about this he does two things.

First, he states the conditions of the intellect in act.

Second, at when separated (430a22; [742]), he shows how the intellectual part of the soul in general differs from the rest of the soul.

Regarding the former point, he states three conditions of the intellect in act.

First, its actual knowledge is the same as the thing known, which is not true of the intellect in potency.

Second, though within one and the same thing potential knowledge is prior in time to actual knowledge, yet, speaking universally, this is not the case, neither in nature nor with respect to time. In Metaphysics 9, Aristotle had said that act is by nature prior to potency, but potency is prior to act in time within one and the same thing, since a thing is first in potency and afterwards in act. (Aristotle, Metaphysics 9.8, 1049b14–1050b6; cf. Aquinas, Commentary on Metaphysics, bk. 9, lect. 8, nn. 1856–66.) But universally speaking, act is prior even in time, because no potency would ever be actualized unless something were already in act. So, even in the case of potential knowledge, someone does not become an actual knower, whether by discovery or by learning from a teacher, unless through some preexisting knowledge, since all intellectual teaching and learning arise from preexisting knowledge, as it is said in Posterior Analytics 1. (Aristotle, Posterior Analytics 1.1, 71a1–2; cf. Aquinas, Commentary on Posterior Analytics, bk. 1, lect. 1–2.)

741. The third condition of the intellect in act distinguishes it from both the potential intellect and the agent intellect, both of which sometimes understand and sometimes do not understand. But this cannot be said of the intellect in act, for it consists in understanding itself.

742. Next, at when separated (430a22), he states the conditions of the whole intellectual part.

And first, he points to the truth;

second, he refutes an objection, at it does not remember (430a23; [744]).

He says, then, that the intellect alone, when separated, truly exists; and this cannot be understood only of the agent or potential intellect, but of both together, since both have been described as separated. (Lect. 1, n. 688.) And thus it is clear that he is speaking of the whole intellectual part, which indeed is called “separate” because it has an activity without a bodily organ.

743. And because he said at the beginning of this book that if any activity of the soul is proper to it, the soul could be separated, he concludes that only this part of the soul (that is, the intellectual part) is incorruptible and perpetual. (Bk. 1, lect. 2, n. 21.) This is what he has said in book 2, namely, that this kind of soul was separable from others as the perpetual from the corruptible—perpetual in the sense that it will always exist, not in the sense that it always has existed; (Bk. 2, lect. 4, n. 268.) for as he shows in Metaphysics 12, forms cannot exist before their matter. (Aristotle, Metaphysics 12.3, 1070a21–26; cf. Aquinas, Commentary on Metaphysics, bk. 12, lect. 3, nn. 2450–54.) The soul, then (not all of it, but only the intellect) will survive its matter.

744. Next, at it does not remember (430a23), he meets an objection. For someone might suppose that, because part of the soul is incorruptible, after death the knowledge of things would remain in the way as it is now. But already in book 1, he has disallowed this, where he observed that understanding must cease with the decay of something else within; and that after death the soul does not remember or love. (Bk. 1, lect. 10, nn. 163–67.)

745. So now he adds that what we have known in life it does not remember after death because it is impassible, that is, that part of the intellectual soul is impassible; it is, therefore, not subject to the passions of the soul, such as love and hatred and recollection and so forth, which all depend on some passion of the body. But the passive intellect—that is, the part of the soul that is subject to the passions mentioned—is corruptible, for it pertains to the sensitive part. Nevertheless, this part of the soul is called an “intellect” just as it is also called “rational”: inasmuch as it in some way participates in reason by being obedient to reason, and by following its movement, as is said in the Ethics. (Aristotle, Ethics 1.13, 1102b13–1103a3; cf. Aquinas, Commentary on Ethics, bk. 1, lect. 20.) But without this corruptible part of the soul, our intellect understands nothing; for the intellect understands nothing without a phantasm, as we shall see below. (Lect. 6, n. 772.) Hence, after the body’s destruction, there does not remain in the separated soul knowledge of things in the same way as it understands now. But how it does understand anything then is not part of our present inquiry.