Chapter 4

Thus far we have considered what some maintain: namely, that the intellect is not the soul, which is the form of the body, or a faculty of it, but that it is a separate substance. It remains now to discuss their contention that the possible intellect is one for all men. Now, perhaps, to say this in regard to the active intellect might possess a certain amount of reason, and many philosophers have held this position. For no difficulty would seem to result if many beings were perfected by the one agent: just as by the one sun all the visual potentialities of animals are perfected so that they may actually see; but even this comparison with the active intellect is not in accord with the intention of Aristotle, who thinks that the active intellect is a certain power in the soul; wherefore he compares it to a light. But Plato, judging that there is one separate intellect, compares it to the sun, as Themistius says. For there is one sun, but many rays of light diffused by that sun in order that there may be vision. But, whatever be said in regard to the active intellect, to say that there is one possible intellect for all men cannot be true, for many reasons.

1. If the possible intellect is that by which we understand, then one must say either that this individual intelligent man is intellect, or that intellect formally inheres in him; not, indeed, in such a way as to be the form of the body, but because it is a power of the soul, which is the form of the body. Moreover, if anyone says that this individual man is himself intellect, It follows that this individual man is not distinct from that other individual man, and that all men are one man, not merely by participation in the same species, but after the manner of one individual. But if an intellect is in us formally, as has been said, it follows that for different bodies there are souls that are different. For as man in general is constituted of body and soul, so this man—Callias, for example, or Socrates—is composed of this body and this soul. But if souls are individually distinct, and the possible intellect is that power of the soul by which the soul understands, then it must follow that it is numerically different in every man; for it is impossible to conceive of there being numerically but one such power for things that are diverse. 2. Furthermore, if anyone says that man understands through the possible intellect, as through something that belongs to him as his own, but that it is not a part of him as form, but as mover, then, as has been previously shown, it is not possible according to this position to claim that Socrates himself understands.

But should we grant that Socrates understands because his intellect understands—even though the intellectus be only the mover—then he understands just as a man sees because his eye sees. And, to carry out the comparison, let it be supposed that there is numerically but one eye for all men. It must then be asked whether all men will see as one man, or whether they will see as many. To discover the true answer to this question, we must consider what the relation, on both sides, is between a principal agent and an instrument. Now, if many men make use of numerically one and the same instrument, there will be said to be many operations: as, for example, when many use the one machine to hurl or lift a stone. But if one principal agent employs many instruments, notwithstanding that he who acts is one, the operations may chance to be diverse because of the different instruments used. Sometimes, however, there is but one operation even though many instruments are required for it. Thus, therefore, the unity produced by a worker is determined, not by the instruments, but by the principal agent who uses the instruments.

According to the previously stated position, therefore, if the eye should be the principal thing in man, in such a way that it would use all the powers of the soul and the parts of the body as its instruments, then many, having the one eye, would see as one. But if, on the other hand, the eye is not principal in man, but there is in him something superior that uses the eye as an instrument and that is diversified in different subjects, then there would be many seeing, but only one eye.

However, it is clear that the intellect is that which is principal in man, and that which uses all the powers of the soul as well as all the members of the body; wherefore Aristotle has accurately said: "Man is principally intellect." If, therefore, there should be but one intellect for all men, it would follow necessarily that there would be but one intelligent being and consequently one will and one agent using, according to the dictates of his own will, all those attributes by which men are differentiated from one another. Furthermore, from this fact it would likewise follow that there would be no difference among men as regards free election of the will; but the same things would be done by all if the intellect (in which alone resides the sovereignty and command over all the other powers) is one and the same in different men—a supposition evidently false and impossible. For such a doctrine is in opposition to facts that are clearly apparent. And it likewise would destroy the whole science of morality and all that pertains to the conservation of organized society which, as Aristotle says, is natural to all men.

Furthermore, if all men understood by means of one intellect, no matter in what way it were united to them (whether as form or as mover), it would necessarily follow that there would be numerically but one act of understanding for all men: that is, at one and the same time and in respect to the same intelligible object. For example: if I know a stone and you likewise know it, it must be that one and the same intellectual act is both mine and yours. For there can be numerically, on the part of the same principal active agent (whether that agent is form or mover), only one operation of the same species in respect to the same object at the same time. This fact is clear from what the Philosopher determines in V Physic. Hence, if many men should possess one eye in common, the vision of all could be but one in regard to the same object at the same time.

And similarly, if there be but one intellect for all men, it follows that for all men understanding the same thing at the same time, there is only one in intellectual act; and, more remarkable still, none of those qualities by reason of which men are considered to differ from one another will be changed in the intellectual act. Now, the phantasms are the prerequisites [or predecessors] for the act of intellect, just as colors are for seeing. But, according to this theory, by their diversity the act of intellect is not diversified, especially the act of understanding a single intelligible object. It is by reason of these phantasms, nevertheless, that we judge the knowledge of one man to differ from that of another, inasmuch as the one understands those things that he possesses certain images of, while the other man understands those that he possesses phantasms of. But [according to this theory], in two men who know and understand the same thing, the operation of the intellect cannot be said to be diversified in any way because of different phantasms.

4. Moreover, it can also be shown that this position is evidently at variance with the doctrine of Aristotle. For, after stating that the possible intellect is separate and that it is in potency to all things, he adds: "When it comes to know anything at all, it is in act; just as the one knowing is called the knower, according to the act, this title being derived from the act itself." In this way, science is an act, and the knower is said to be in act inasmuch as he possesses the habit of science. Thereupon Aristotle continues: "This, without doubt, is the case when 'a thing is able to act through itself. It is then still potential, in a certain way, but not in the same way as before learning or discovering something." And, later, when he had inquired, "If the intellect were simple and impassible, having nothing in common with matter, as Anaxagoras said, how, then, could it understand if to understand is said to mean to be passive to something?" To solve this difficulty, he replies: "The intellect is, in a certain way, in potency to intelligible objects, but it is not in act before it actually understands something. It must be, therefore, like a tablet upon which nothing has been written, and this is, indeed, the case in regard to the intellect." Therefore it is Aristotle's opinion that the possible intellect, before it learns or discovers anything, is in potency, as a tablet is upon which nothing has actually been written. But after it has learned and discovered something, by virtue of its aptitude for knowledge—an aptitude or power by which it operates through itself—it is in act, although even then it is in potency to reflect further.

5. Here three things must be noted.

First, this aptitude for knowledge is the first act of the possible intellect itself which, because of it, comes to be in act and is enabled to operate through itself. For knowledge is not only because of the phantasms' being illuminated, as some say, nor is it a certain faculty acquired in us by frequent meditation and exercise so that we may be united with the possible intellect through our phantasms.

Secondly, before our learning or discovering anything, the possible intellect itself is in potency, as a tablet is on which nothing has been written.

Thirdly, by our learning or discovering something the possible intellect is rendered active.

These statements, however, cannot be established as true if there is but one possible intellect for all men who are, who will be, and who have been. Now, evidently the species are preserved or stored, as it were, in the intellect; for it is the locus of the species, as the Philosopher has said above, and as is also evident from the fact that science is a permanent habit. If, then, the intellect of any man has been activated as regards an intelligible species, through the enlightenment given him by a predecessor, and perfected by the habit of science, this acquired habit and the species remain in him. But, since any recipient must be [previously] without that which it receives, I cannot learn and discover what is received in the possible intellect. If, nevertheless, some one says that, by reason of our power of discovery, the possible intellect is rendered active in regard to something for the first time-for example, if I come upon something intelligible, that it is found by reason of no predecessors—still it is not possible to establish this in the matter of learning; for I cannot understand a thing by learning it from another unless he who teaches me knows it. In vain, therefore, has he said that before learning anything the intellect is in potency.

But if any one adds that, according to Aristotle's opinion, men have always existed, it follows that there would have been no first man to understand anything, and so the intelligible species are not acquired by the possible intellect through the phantasms of any man, but are the intelligible species of an eternal possible intellect. In vain, therefore, has Aristotle stated that there is an active intellect which renders those species that are potentially intelligible actually so. In vain has he declared that the phantasms are related to the possible intellect as colors are to vision, if the possible intellect receives nothing from the phantasms. However, it seems to be unreasonable that substances separated from phantasms should receive ours, and that they should be unable to know themselves except after our learning, discovery, or understanding, since Aristotle has added to the foregoing words: "It is also, then, able to know itself either by learning or discovery." For a separated substance has intellection. through itself. Therefore the possible intellect, if it were a separate substance, would know itself through its own essence, and would have no need of those intelligible species that might supervene to it as a result of our intellection or discovery.

6. If, however, our opponents try to avoid this difficulty by saying that Aristotle makes all the foregoing statements in regard to the possible intellect as it exists in a restricted way in us, and not as it is in itself, we may reply that they do not understand the words of Aristotle; for, indeed, what is said is about the possible intellect and what is proper to it, as it is differentiated from the active intellect. But if there is insistence as to Aristotle's words, let us suppose, as our opponents say, that the possible intellect possesses, from all eternity, intelligible species, through which a union is established with us, according as there are phantasms in us. Then it will be necessary to agree that the intelligible species in the possible intellect and the phantasms in us are related in one of three ways,

of which one is: that the intelligible species in the possible intellect are received by the phantasm in us, as the words of Aristotle signify. But this cannot be the situation according to the former position, as has been shown.

The second possible mode is that these species are not received by the phantasms, but that they cast a radiance over the phantasms, illuminating them; just as, for example, certain images (species) in the eye might cast a light upon the colors that are on a wall.

And the third possible mode is that the intelligible species in the possible intellect neither are received by the phantasms nor make any impression upon them.

Now, if the second mode is accepted as true,—namely, that the intelligible species illuminate the phantasms, and that as a result they come to be understood—then the following must be true.

First, that the phantasms are rendered intelligible in act, not by the active intellect, but by the possible intellect and through its own species.

Secondly, that this illuminating of the phantasms could not bring about the rendering of the phantasms actually intelligible, for they become intelligible only through abstraction; but this process would be one of reception rather than of abstraction. And furthermore, since every act of reception is according to the nature of the thing received, the illumination by the intelligible species in the possible intellect of phantasms existing in us will not be in an intelligible mode, but only in a sensible and material way. Consequently, as a result of such illumination, we would not be able to understand anything universally. But if the intelligible species of the possible intellect are neither received by the phantasms nor considered to illuminate them, they will be altogether unrelated and will possess no proportionality at all; and the phantasms will contribute nothing to the act of intellection. But this evidently runs counter to truth. Thus, in view of every conceivable mode of relationship, the possible intellect cannot be one for all men.