Lecture 6 — Sense and intellect compared, the practical intellect, and abstraction

And it appears that the active sense-object brings the sense power from a state of potency to one of act; for it is not acted upon or altered.

Hence it is a distinct species of motion. For movement is the actuality of the incomplete; whereas this act is simply different, as being of the complete.

Sensation, therefore, is like mere uttering and understanding; but, given a pleasant or painful object, the soul pursues or avoids as though affirming or denying. Feeling pleasure and pain are acts done by the sensitive power as a mean in relation to the good or the bad as such; and the avoidance and appetite of a thing are things in act. And the powers of appetite and avoidance are not distinct from each other, nor distinct from the sensitive power; although in being they differ.

Now, phantasms are to the intellectual soul as sense-objects. But when it affirms or denies goodness or badness, it pursues or avoids. Hence the soul never understands without a phantasm.

For just as air itself affects the pupil in some way, and this in turn affects something else, and hearing does something similar, the last is one thing, a single mean whose being, however, is manifold.

But how it discerns the sweet as different from the hot has been stated already, but it should be said again now.

For it is something one, but as a terminus; these too are according to proportion or number, and being one, it is related to distinct objects as they are to one another. For what difference indeed does it make whether it judges non-homogeneous things or contraries, like black and white? Thus, as A (white) is to B (black) so is C to D; hence, also, alternating the proportions. If, then, C and D pertain to one thing, they are to each other as A and B, the same though not the same in being; so too is the aforesaid. The same relation holds if A is the sweet and B the white.

The intellectual power, therefore, understands species in phantasms. And as in them the pursuable and what is to be avoided is determined for it, so too is it moved when these are in the phantasms, apart from sensation. For instance, when one senses that something should be fled, because he senses a fire, he knows by something common; seeing it move, he knows a battle is occurring.

Sometimes, however, by means of the phantasms or concepts in the soul, someone reasons and deliberates, as if seeing something, and deliberates on future matters in relation to present matters; and when one has said that the pleasing or the disagreeable is present, then one pursues or avoids it as before.

And generally, both in practical action and apart from such action, truth and falsehood are in the same genus as good and evil. But they differ in terms of what is simply speaking so and what is so in a certain respect.

Now, one understands by abstraction, so-called; as one might understand the snub as snub, yet not as separated; but he understands it as curved, if he has actually understood anything; he has certainly understood the curve without the flesh in which it exists.

Thus, in understanding mathematical objects, the intellect understands things not separated as if separated. And in general, the intellect in the act of understanding is the reality.

Whether it is possible for an intellect that is not separated from magnitude to understand anything of things separated from magnitude or no, is to be considered later.

765. And it appears that the active sense-object (431a4). After the Philosopher has treated the intellect in itself, he treats the intellect as compared with the senses. And regarding this he does two things:

first, he explains the sort of movement that sensation is;

second, he shows how this movement resembles the motion of the intellect, at sensation, therefore (431a8; [767]).

On the former point, he observes that the sense-object appears to make the sensitive part be in act from being in potency. For the sense-object does not act on the sense as a contrary on its contrary, such that, when transforming and altering it, it had to remove something from it.

Rather, it only reduces it from potency to act; so he adds that sensitivity is not acted upon or altered by the sense-object, taking “passion” and “alteration” properly, that is, insofar as this occurs from one contrary to another contrary.

766. Since, as he shows in the Physics, the motion that is in bodily things goes from contrary to contrary, it is clear that if we call sensing a motion, we mean a distinct species of motion from the one defined in the Physics. (Aristotle, Physics 3.1–5, 200b12–202b29; 5.5, 229a7–229b22; cf. Aquinas, Commentary on Physics, bk. 3, lect. 2–4; bk. 5, lect. 8.) For that motion is the actuality of a thing existing in potency; for while the thing is losing one contrary, and so long as it is moving, it does not reach the other contrary, which is the terminus of the motion; rather, it is still in potency to it. And because everything that is in potency as such is incomplete, that movement is the actuality of the incomplete, whereas this motion is the actuality of what is complete—for the activity of a sense power is brought into act through its own species, for sensing belongs to the sense only by being in act. So their movement is simply different from physical movement. It is this movement also which, together with understanding and willing, is properly called “activity”; and this also is what Plato referred to when he said that the soul moves itself through knowing and loving itself.

767. Next, at sensation, therefore (431a8), he likens the intellect’s movement to that of the senses. And regarding this, he does two things:

first, he shows how the senses move;

second, at now, phantasms (431a14; [770]), he shows how a similar movement takes place in the intellect.

As regards the former point, he says that, since the sensible object actualizes our sensitivity without a passion or alteration (as was said of the intellect earlier), it is clear that sensation is like when one understands—yet such that when one is merely sensing, that is, apprehending and judging according to a sense, this is like mere uttering and understanding, that is, when the intellect only judges and apprehends something. (Lect. 3, n. 722; lect. 4, nn. 738–39.) This is to say that the simple apprehension and judgment of sensation is like the speculation of the intellect, but when the senses sense something pleasant or painful as if affirming or denying what is perceived by the sense is pleasant or painful, then it seeks it by appetite (that is, it desires it) or avoids it. And note the phrase, as though affirming or denying; for to form affirmation and denial is something proper to the intellect (as was said earlier), but the senses do something similar to this when they apprehend something as pleasant or painful. (Lect. 5, nn. 746–51.)

768. And to show what pleasure and pain are, he observes further that feeling pleasure and pain are acts done by the sensitive power as a mean; that is to say, it is a certain act of the sensitive power, which is called a “mean” insofar as the common sense is related to the proper senses as a certain middle, like the center of a circle in relation to lines drawn from the circumference. But not every act of the sensitive part is a feeling of pleasure or pain, but only what is relative to the good and the bad as such. For the good of a sense—that is, what is congruent with it—causes pleasure; while what is bad, that is, repugnant and harmful to it, causes pain. And pain and pleasure are followed, respectively, by avoidance and appetite (that is, desire), things in act.

769. Thus, it is clear that the movement of the sense-object to sense passes through three stages, as it were.

First, the sense-object itself is apprehended as congruent or harmful;

second, pleasure or pain follows this;

third, desire or avoidance follows.

And although having an appetite, avoiding, and sensing are different acts, still their principle is the same in subject, though it differs in account.

This is what he means by adding that the powers of appetite and avoidance—that is, that part of the soul which desires or avoids—are not different in subject, neither from each other nor from the sensitive part; although in being they differ, that is, are different in account. He says this against Plato, who maintained that desire and sensation had distinct organs in different parts of the body.

770. Next, at now, phantasms (431a14), he compares the intellect’s movement to the process of sense-knowledge as he has described it. And he does two things here.

First, he shows how the intellect is related to sense-objects.

Second, at now, one understands by abstraction (431b12; [781]), he shows how it is related to things separated from the sense-objects.

The first divides into two parts:

first, he gives an explanation of the way the intellect is related to sense-objects in things that are to be done;

second, at and generally, both in practical action (431b10; [779]), he offers a comparison of the practical and speculative intellects.

And with regard to the former point he does two things:

first, he states the resemblance between the progression of the intellect and the progression of the senses;

second, at for just as air itself affects the pupil (431a17; [773]), he illustrates this resemblance.

First, then, he observes that phantasms are to the intellectual part of the soul as sense-objects to the senses; this is why, as the sense is moved by sensible things, so is the intellect by phantasms. And just as when the sense apprehends something as pleasant or painful, it seeks or avoids it, so also the intellect, when the intellect apprehends something as affirming or denying its goodness or badness, it avoids or pursues it.

771. But note that Aristotle’s use of terms here suggests a twofold difference between intellect and senses, because in the sense there were three things.

For in the first place, when the senses apprehend their good and evil, this awareness is not immediately succeeded by desire or avoidance (as is the case here with the intellect), but by pleasure and pain, and from this there further follows desire and avoidance. The reason is that as the senses do not apprehend the universal good, so appetite of the sensitive part is not moved by the universal good or evil, but by a certain determinate good, the pleasant in sensation, and by a certain determinate evil, the painful to sense. In the intellectual part, on the contrary, there is an apprehension of the universal good or evil, so the appetite of the intellectual part is also moved immediately by the good or evil apprehended.

772. The other difference appears in Aristotle’s observing that the intellect affirms or denies, simply speaking, whereas of the senses he only says that they, as it were, affirm or deny. The reason for this has already been given. And from what has been said he draws the further conclusion that if intellect is related to phantasms as the senses to their object, then just as the senses cannot sense without a sense-object, so the soul cannot understand without a phantasm.

773. Then, where he says, for just as air (431a17), he explains the resemblance still further:

first, as regards what he said before, that phantasms are to the intellectual soul as sense-objects (431a14);

and second, at the intellectual power, therefore (431b2; [777]), he said that when it affirms or denies goodness or badness, it pursues or avoids.

First, then, he remarks that color-affected air, when modified by color, affects the pupil in some way, that is, it makes it of a certain quality, impressing on it the species of the color, and this then, that is, the pupil so modified, modifies something else, that is, the common sense. Similarly our hearing, itself modified by the air, modifies the common sense. And though there are several exterior senses, their modifications are terminated at one last, and this is a certain single mean between all the senses, like a center upon which lines from a circumference all converge.

774. And while this midpoint is one in subject, still its being is manifold, that is to say, its account varies insofar as it is related to the different senses. This is the power by which the soul discerns the sweet as different from the hot, which has been stated already when we were considering it in itself; but it should be said again now, in relation to the intellect, since it is something one relative to all the sense-objects as (he says) terminus (this is what we have said); and so too is the intellect as the terminus of all the phantasms. (Bk. 2, lect. 27, nn. 609–10.)

And as in the one case those many objects were said to be discerned by one thing, so on the side of the intellect these also stand in a certain proportion; that is, the intellect is what corresponds proportionally to that one judge of sense-objects. Or again, there is a likeness as regards the number of things judged; this terminus, he says, which is the intellect, is one being related to distinct objects whose distinction it discerns as they are to one another, that is, just as the single common sense to the different sense-objects whose differences it discerns.

775. It makes no difference whether we take as example either the non-homogeneous, that is, different sensibles that do not belong to one genus—for instance, white, which is in the genus of color, and sweet, which is in the genus of flavor—as the things between which the common sense discerns; or we take contraries that belong to one same genus, like black and white. For the common sense discriminates between both.

776. Let us put A for white and B for black; so that, as A (white) is to B (black), so is C to D, the latter standing for the phantasms of white and black. Hence, also, alternating the proportions, A is to C as B to D: that is, white is to the phantasm of white as black to the phantasm of black; and as the intellect is to C and D, the phantasms of white and black, so is the sense to A and B, the white and the black. If, then, C and D, the phantasms of white and black, pertain to one thing, that is, they are judged by one intellect, so they are to each other as A and B, namely white and black, which are judged by one sense; so that, just as the sense that discriminates these two was one in subject but twofold in its account, so too will be the intellect. The same relation holds valid if we take non-homogeneous objects—taking, for instance, A as the sweet and B the white.

777. Next, at the intellectual power (431b2), he explains what he said above, that in affirming or denying good or evil, the intellect avoids or pursues; and so he concludes that the intellectual part of the soul understands species in the phantasms. And as something is determined for the intellect as pursuable and to be avoided as something in them, that is, in the sense-objects when present, so too, it is moved to pursuing and fleeing when these are in the phantasms, apart from sensation, that is, when the phantasms are represented in the absence of the sensible objects.

778. And he gives examples of each. First, when it is moved at the presence of sense-objects—as when a man senses that something should be fled, that is, something frightening, for example, some roaring, as when he sees that there is a fire raging in the city; seeing the flames in motion, he knows something by something common—that is, by some common power of judging, or by some common thing in the sense of what commonly happens—he knows, I say, that battles are occurring or some struggle is occurring; and thus, the intellect is moved sometimes to pursue or flee by the sensible objects that are present.

Sometimes, however, due to phantasms or concepts in the soul, someone reasons and deliberates on future matters in relation to present matters, as if one were actually seeing them, and when one judges something is pleasing or disagreeable, one pursues or avoids it as before, that is, just as when one was moved by a present sense-object.

779. Next, at and generally (431b10), he compares the intellect’s speculative and practical knowledge. Truth and falsehood, he says, that is, true and false knowing, of the intellect in practical action (that is, insofar as the knowledge pertains to the practical intellect) and apart from such action (that is, insofar as it pertains to the speculative intellect) are in the same genus, that is, that genus is the good or evil. This can be taken in two ways:

in one way, that the reality understood, either speculatively or practically, is sometimes good, sometimes bad, and by being considered speculatively or practically the thing’s genus is not distinguished on account of this;

or in another way, that true knowledge itself is a certain good of the intellect, whether it be speculative or practical; whereas false knowledge is a certain evil for the intellect, whether speculative or practical.

780. Thus, he does not intend to relate, according to an agreement of genus, truth and falsehood to good and evil, but truth and falsehood in action to truth and falsehood without action. This is clear from the difference which he adds, saying that they differ, namely, what is in-action and what is not-in-action, in terms of what is simply speaking so and what is so in a certain respect. For the speculative intellect considers something true or false universally, which is to consider it simply speaking, whereas the practical intellect does this by making an application to the particular thing to be done; for doing is always in the particular.

781. Then, at now, one understands (431b12), having already said that the soul never understands without a phantasm, and that phantasms are taken from sensation, the Philosopher begins to explain how our intellect understands things that are separated from the senses. Here he proceeds in two stages:

first, he explains how it understands mathematical objects, which are abstracted from sensible matter;

and second, he inquires whether we understand things that are according to their own being separated from matter, at whether it is possible (431b17; [785]).

As regards the first point, note that of things joined in reality the intellect may think, and think truly, of one without the other, provided that the account of the one is not included in the account of the other. If Socrates is both white and musical, his whiteness can be understood without regard to his musical character; but I cannot understand “man” if I do not understand “animal,” for the account of man includes animal. Thus, it is possible to separate in the intellect things that are conjoined in reality in this way, and yet not fall into error.

782. But if the intellect were to separate them, understanding things that are conjoined as being separate, then the intellect would be false—as, to take our former example, if it were to assert that the musical person is not white. The intellect, then, abstracts things that exist within sense-objects, not in fact understanding them to be separate, but understanding them separately or distinctly.

And he says this, that the intellect understands (431b12) things that exist by abstraction, so-called (that is, the mathematical objects), in the way it understands the snub as snub, understanding it yet not as separated, that is, the snub in separation from sensible matter, since its sensible matter, the nose, is included in the definition of a snub.

783. But if the intellect understands actually anything as curved, it has understood the curve without the flesh in which the curve exists; not such that it understands the curved to exist without the flesh, but because it understands curved without understanding flesh, because flesh does not enter into the definition of a curve. And thus the intellect understands all mathematical objects separately*—as if* they were separated, although they are not separated in being.

784. But we do not understand natural things in this way; for in their definition sensible matter is included, unlike in the definition of mathematical object. Yet regarding natural things the intellect abstracts the universal from the particular in a similar way, insofar as it understands the nature of the species without individuating principles, which do not enter into the definition of the species. And in general, the intellect in act is the reality understood; for just as the reality in its own account has or does not have matter, so too, it is perceived by the intellect. And because Plato overlooked this mode of abstraction, he was forced to posit separated mathematical objects and species, in the place of which, to accomplish this abstraction, he asserted that there is an agent intellect.

785. Next, at whether it is possible (431b17), he poses a question about things that are separated from matter in their being, saying that it is to be considered later whether it is possible for our intellect, not having been separated from magnitude (that is, from the body), to understand anything of the things separated, that is, any separated substance.

For he could not determine this question, since it was not yet evident that there are such separated substances, nor what things they are and what sort of thing they are. This is why this is a question that pertains to metaphysics. Yet we do not find Aristotle’s solution of this problem, as the completion of that science has not yet come down to us, either because the entire book is not yet translated or possibly because he died before he could complete it. (See Aquinas, Commentary on Metaphysics, bk. 9, lect. 11, n. 1916.)

786. We should note, however, that when he speaks of the intellect here as not separated from the body he refers to the fact that it is one of the powers of the soul, which is the actuality of the body; whereas earlier he said the intellect is separated from the body, because it does not have any organ devoted to its activity. (Lect. 1, nn. 688, 699.)