Lecture 11 — Potency and act in sensation continued

Distinctions, however, must be made concerning potency and act; for at present we are speaking of these in a simple way.

For there is such a thing as a “knower,” in one sense, as when we say that man is a knower because man is among things able to know and have knowledge. But we also say it in the way we speak of a man who already has knowledge of grammar. These two are not possible in the same way; but the former’s power is, as it were, generic and matter; whereas the latter has the power to consider at will, so long as no extraneous obstacle intervenes. Yet again, he who is actually attending to the letter A is properly speaking the one knowing.

Therefore the first two are knowing in potency. But one has been altered through teaching and is often altered from the contrary state, whereas the other is moved to activity from having sense or grammar without acting, but in a different way.

Nor is being acted upon simple. Rather, it is one thing to be somehow destroyed by a contrary, and something else when there is more the preservation of what is in potency by what is in act and like it, the way that potency stands relative to act.

For when a man possessed of knowledge thinks, there is certainly either no alteration—there being an advance into itself, and into actuality—or it is a different genus of alteration. Hence it is not well said to say that a wise man is “altered” when he thinks, as neither is it to say this of the builder when he builds. Therefore the progression from being in potency to being in act, as regards understanding and thinking, is not instruction, but rightly has some other name.

But the change from being in potency, in one who learns and receives knowledge from another (who actually has it and teaches), either should not be called a “being acted upon” (as we have said), or there are two modes of alteration, one a change to a privative disposition, the other to a possession and nature.

358. Distinctions, however, must be made (417a21). Having explained how the sensitive powers are both in act and in potency, the Philosopher now goes on to say how they are brought from potency into act. This he does in two parts.

In the first, he distinguishes between act and potency and between the diverse ways in which a thing is led from potency to act, taking his example from the intellect.

In the second, at the first change in the sensitive being (417b16; [373]), he applies all this to the case of sensation.

As regards the first of these parts, he does three things:

first, he states his intention;

second, he distinguishes, at for there is such a thing as (417a22; [359]), between act and potency in the intellect;

third, he explains, at therefore the first two (417a30; [362]), how what is potential becomes actual.

First of all, then, he says that there is a division concerning potency and act to show the diverse ways in which things can be said to be actual or potential—because, so far, the two terms have been used in a simple way, that is, without distinctions. (Lect. 10, nn. 352–57.)

359. Then, at for there is such a thing as (417a22), he distinguishes act and potency in the intellect.

And he says that we say that in one sense a thing, that is, a man, is a knower because he has a natural capacity for knowledge. This is the way we say that man is among the number of things able to know and have knowledge, inasmuch as he has a nature ordered to knowing and to having the habit of knowledge.

In another sense, however, we say one knows something in the way we speak of a man who has the habit of a certain knowledge—for example, grammar—that he already has knowledge.

360. Now, obviously, these two capacities are implied by calling him a knower, but not in the same way in both cases.

In the first case, man’s power is said to be generic and matter, that is, because he has a natural potency for knowing through his being placed in a certain sort of genus, and because he is in potency, for example, to knowledge as matter is to its form.

But in the second case, one who has the habit of knowledge is called “able to know” because when he wishes, he can consider at will his knowledge—unless, of course, he is accidentally prevented, for example, by exterior preoccupations or by some bodily indisposition.

361. A third case would be that of a man who was actually thinking about something here and now. He it is who most properly and perfectly is a knower in any field, for example, knowing the letter A, which belongs to the above-mentioned science of grammar. (Lect. 1, n. 216.)

Of the three, then, the third is only in act; the first is only in potency; while the second is in act as compared with the first and in potency as compared with the third. Clearly, then, to be in potency is taken in two senses (the first and second); and to be in act is also taken in two senses (the second and third).

362. Then, where he says, therefore the first two (417a30), he explains how each of these potencies is brought to act. And concerning this, he does two things.

First, he shows how both these types of potency are actualized;

second, at nor is being acted upon (417b2; [365]), he discusses whether this actualization is the result of a being acted upon.

First, then, he remarks that while in the first two cases there is knowing in potency and that which is reduced to act, there is a difference, in respect of actualization, between a first and a second potency.

For one in potency in the first way is brought into act through being, as it were, altered through teaching, and being moved by someone else who is already in act (the teacher). And often, he says, this change is from the contrary state, alluding to those who come to actual knowledge from a state of ignorance.

363. “Ignorance” is spoken of in two ways. In one way, it can be purely negative, when the ignorant person neither knows the truth nor is involved in the opposite error; and in this case he is simply brought into actual knowledge, not changed by being rid of a contrary habit.

On the other hand, one is called “ignorant” in a different way, according to a bad disposition, insofar as he is involved in error contrary to the truth; and in this way to acquire knowledge, then, is to be changed from a contrary habit.

364. But one in potency in the second sense—that is, as already possessing the habit—passes from having sense or knowledge but not exercising it, to activity, because he becomes active as regards the knowledge. And he becomes actual in a different way from the first.

365. Then, at nor is being acted upon (417b2), he discusses the question whether both kinds of actualization can be called “being acted upon.” And about this, he does two things.

First, he explains the different ways in which something is said to be acted upon.

Second, at for when a man possessed of (417b5; [367]), he applies these distinctions to the present problem.

First, then, he remarks that just as potency and act are not spoken of in a simple way, but in many ways, so to be acted upon is not in one way, but in many.

In one sense, “being acted upon” (pati) implies some kind of destruction caused by a contrary. For in the strict sense, “suffering” (passio) seems to connote, on the side of the one being acted upon (patientis), a certain loss of something, insofar as it is overcome by the agent; and this loss to the one acted upon occurs insofar as something is cast out of the one acted upon and something is somehow destroyed, either simply speaking, as when substantial form is lost, or in a certain respect, as in the loss of an accidental form. And the loss of form comes from a contrary agent; for the form is removed from the matter or subject through the introduction of a contrary form, from a contrary agent. In the first sense, then, “suffering” properly speaking means being somehow destroyed by a contrary.

366. In another sense, something is called a “suffering” (passio) in a common sense but less properly, that is, any reception of something. And because a receiver is to what it receives as potency to act, and actuality is the perfection of potency, so “suffering” is said in this way, not according to a certain corruption of the patient taking place, but rather there is more the preservation, that is, the perfection, of what is in potency by what is in act**.

For only the actual can perfect the potential, and actuality is not, as such, contrary to potency; indeed, the two are really similar, for potency is nothing other than a certain order to act. (And without this likeness between act and potency, there would be no necessity that a proper act come to be in its proper potency.) Hence, “suffering” spoken of in this way does not occur due to a contrary, as was the case with “suffering” spoken of in the first way; rather, it occurs due to a thing that is like it, in the sense that a potency stands relative to act in likeness.

367. Next, at when a man possessed of (417b5), Aristotle discusses whether being led from potency into the act of knowledge is being acted upon.

And he first discusses that which is led from second potency into pure act;

second, at but the change from being in potency (417b12; [369]), he discusses that which is led from first potency into the habit of knowledge.

Now, as to the former point, he asserts that one possessed of knowledge, that is, habitually knowing, actually thinks, but this is certainly and properly speaking not a being altered and acted upon (pati). For, as we have seen, suffering (passio) and alteration are not when one progresses from potency to act, but when something is changed from contrary to contrary. But when one who knows habitually comes to actually think, he is not being changed from contrary to contrary; rather, he is being perfected in what he already has. As Aristotle says here, it is an advance into itself, and into actuality; for the perfection is being added to him insofar as he progresses into act. Or, if it is going to be referred to as “being altered” and “being acted upon,” it will be a distinct genus of alteration and suffering, one that is not being said properly. And to illustrate the point, he adds that it is not well said to say that a habitually wise man is “altered” when he thinks in act, as neither do we say that the builder is altered when he builds.

368. A further conclusion: if it be granted that when one passes from habit to act, he does not newly receive knowledge, but rather he progresses and is perfected in what he has, whereas to be taught is to receive knowledge, therefore, when a man is brought from potency to act as regards actually understanding and thinking, not rightly does such a going forward from potency to act hold the name* “*instruction,” but something else, though perhaps no other name has in fact been found for it, even though it could be.

369. Then, at but the change from being in potency (417b12), he discusses whether, when someone passes from first potency into the act of knowledge, he is altered and acted upon. He says that when a learner, previously knowing only potentially, learns and receives knowledge from one who actually knows and is a teacher, this either should not be called a being acted upon, or else one should say that there are two modes of alteration.

One of these is a change to a privative disposition, that is, to a contrary disposition whereby a previously existing disposition is taken away, since the one contrary is the privation of the other.

The other is by a change to a possession and nature, that is, through receiving the habits and forms that are perfections of the nature and involve no loss of what it already has. And the one who learns knowledge, therefore, is neither being altered nor acted upon in the first mode, but only in this second sense.

370. Now, this seems to contradict what was said above, that a learner is often altered from a contrary state, and thus, it would seem, that it is an alteration according to a change to a privative disposition.

But one should say that, when one is brought from error to the knowledge of truth, there is indeed a certain likeness to the alteration from contrary to contrary, but this is still not truly an alteration. For where there is true alteration from contrary to contrary, both contraries are involved through themselves and essentially; for example, becoming white involves not only white, but also black, or some intermediary color which in relation to white is a sort of blackness. But where knowledge is acquired, it is accidental that the learner was previously in error, for he could be led to the knowledge of the truth without this. Hence it is not truly an alteration from contrary to contrary.

371. Another difficulty occurs where he says that the learner becomes an actual knower because of one who actually knows and is a teacher. For it does not always happen thus; a man may acquire knowledge not only by learning from a teacher, but also by finding out for himself. To this we reply that whenever a potential knower becomes an actual knower, he must indeed be actualized by what is already in act.

But note that something is brought from potency to act sometimes from only an extrinsic principle, as when air is lit up by an already actual light, but sometimes by an intrinsic cause as well, as a man is healed both by nature and by a doctor. In this latter case, both causes of healing are health in act; for obviously the account of health exists in the mind of the doctor (in virtue of which he can heal) and, in one who is healed naturally, it must also be in some healthy part (that is, the heart), in virtue of which the rest of the man recovers health. And when the doctor heals he does it as nature would do it, such as by heating or cooling or in changing one in some other way. Thus a doctor does nothing other than help nature drive out sickness; if nature were strong enough, she would not need this help.

372. And the case is the same when a man acquires knowledge. For a man acquires knowledge both from an intrinsic principle, when he discovers something, and an extrinsic principle, as when he learns. But in both cases, a potency is actualized by something already in act. For a man, by the light of the agent intellect, right away actually knows the first principles that are naturally known, and, when he elicits conclusions from them, from what he actually knows he comes to actual knowledge of things that he previously knew potentially. In like manner, too, a teacher can help him from the outside towards knowledge, leading him, from principles already known to the student, to conclusions previously unknown, by way of demonstration. Nor would this external aid be necessary if the human intellect were so insightful that it could through itself elicit conclusions from the principles it knows; and, indeed, this insightfulness is present in men in varying degrees.