LESSON 16

Composition in Sensible Substances. Non-Substantiality

of Unity and Being. Plato's Doctrine of Ideas

  Chapter 16: 1040b 5-1041a 5

             677. It is also evident that many of the things which are thought to be substances are potential, as the parts of animals; for none of them are separate. But when they have been separated, all are then like matter, for example, earth, fire and air; for none of them constitute a unity but they are like a heap of things before they are arranged and some one thing is produced from them. But someone might very easily suppose that the parts of living things and the parts of the soul which are close to them exist in actuality as well as in potency, because they have principles of motion consisting in something in their joints; and for this reason some animals live when they have been divided. Yet all parts exist potentially when they are one and continuous by nature, not by compulsion or by being joined together; for such a thing is a mutilation.

             678. And since the term one is used in the same senses as the term being, and the substance of unity is one, and those things whose substance is one are numerically one, it is evident that neither unity nor being can be the substance of things, as neither can the being of an element or a principle. But we look for the principle in order to reduce the thing to something better known. Therefore, among these unity and being are substance to a greater degree than principle, element or cause.

             679. But neither are these substance, if nothing that is common is substance; for substance is not present in anything else but itself and in that which has it, of which it is the substance.

             680. Furthermore, unity will not be present in many things at the same time; but what is common is present in many things at the same time. Hence it is evident that nothing universal exists apart from singular things.

             681. But those who speak of the Forms are right in a sense when they make them separate, if they are substances; but in a sense they are wrong, because they say that a Form is one in many things. And the reason for this is that they cannot explain what are the incorruptible substances of this kind which exist apart from singular, sensible substances. Therefore they make them specifically the same as corruptible things (for we know these things); i.e., they invent a man himself and a horse itself by adding the word itself to sensible things. Hence, even if we did not see the stars, none the less, as I should presume, there would be eternal substances besides those which we see. Hence, even if we do not now know what they are, perhaps it is still necessary that there should be some. It is evident, then, that no universal predicates are substance, and that one substance is not composed of substances.

COMMENTARY

             1631. Here the Philosopher clears up a point which remained a difficulty above, namely, how a substance is composed of parts, when he showed above (518:C 1318) that a substance could be composed neither of its accidental attributes nor of actually existing substances (657:C 1588). Therefore he shows here (677) that the parts of which substances are composed are not actually existing substances but potential ones. He says that, since it was stated above (565:C 1263) that there are some things which are thought by all to be substances, namely, sensible substances and their parts, it is evident that most substances of this kind are potential and not actual, as is clear of the parts of animals and all other parts.

             1632. He says that the parts of these substances are many, because since each whole is composed of many parts, there must be more component parts than composite wholes. And it is evident that parts exist potentially, because none of them are separate, but all parts as parts are rather united in the whole.

             1633. For everything which is actual must be distinct from other things, because one thing is distinguished from another by its own actuality and form, as was stated above (658:C 1588). But when those things which are assumed to be parts have been separated from each other when the whole is dissolved, they are then actual beings, not as parts but as matter existing under the privation of the form of the whole. This is evident, for example, of earth, fire and air, which, when they are parts of a compound, are not actually existing things but exist potentially in the compound; but when they are separated, they are then actually existing things and not parts. For none of the elements "before they are arranged," i.e., before they reach their proper state of mixture by way of alteration, and before one compound comes from them, together form a unity, except in the sense that a heap of stones is one in a qualified sense and not in an unqualified one. Or better "none of them," i.e., they do not constitute a unity before some one thing is produced from them by arrangement.

             1634. For even though all parts exist potentially, someone might very readily suppose that the parts of living things and those of the soul which are close to them are actual as well as potential, i.e., they are in potentiality close to actuality; and the reason is that living bodies are organic bodies having parts which are formally distinct. Hence they most of all are close to being actual; and this is because they have a principle of motion in some determinate part, since one part moves another. This is clear, for instance, in the case of their joints, in which the principle of motion of one of the two connected parts seems to be found, since one can be moved and another at rest, as is stated in The Motion of Animals.

             1635. And since not only the parts of the body are in potentiality close to actuality, but also the parts of the soul, therefore some animals live after they have been divided, as segmented animals. And this is possible because in the whole animal there is one soul actually and there are many souls potentially. But when division is made the several souls become actual. This happens because of the imperfection of such animals which require very little diversity in their parts, for they have a soul with imperfect ability to function and incapable of acting in different ways, for which a number of different organs are necessary.

             1636. Yet even though these parts of the soul and the parts of living things are close to actuality, nevertheless they are all potential when the whole is one and continuous by nature. But this would not be the case if one thing came into being by force, as, for example, when the parts of one living thing are tied to those of another; or by grafting, as happens in the case of plants. For before the scion which is to be inserted is united with the plant, it is actual, but afterwards it is potential. "For such a thing," namely, to be one by force or grafting, "is a mutilation," i.e., something injurious to nature and opposed to nature.

             1637. And since (678).

             Here he shows in a special way that unity and being are not substances; and in regard to this he does two things. First, he states his thesis. He says that unity is predicated of things in the same way that being is, since they are interchangeable, and unity is predicated of a thing because of its substance. For one thing has one substance, and those things are numerically one whose substance is numerically one. And it is also evident that a thing is called a being because of its own substance.

             1638. Since this is true, I say, it is clear that neither unity nor being can be the substance of things, but they are predicated rather of substance as their subject. And in a similar way neither does "the being of an element or a principle," i.e., the very notion of a principle or element, express the substance of the thing called a principle or element. But we look for the principle or element in order to refer it to something better known, namely, to the substance of the subject.

             1639. Yet being and unity are substance to a greater degree than a principle, element and cause, since they are closer to the substance of things; for principle, element and cause signify only the relationship of one thing to another, but being and unity signify something proper to a thing by reason of its own substance. Yet neither being nor unity is the substance itself of a thing.

             1640. But neither (679).

             Second, he proves his thesis by two arguments. He gives the first of these when he says that since these--unity and being--are common attributes, they cannot be substances if nothing common is substance, as has been proved (655:C 1585). That nothing common is substance is clear from the fact that substance can only be present in the thing to which it belongs and of which it is the substance. Hence it is impossible that substance should be common to several things.

             1641. Furthermore, unity (680).

             Here he gives the second argument. He says that unity itself cannot be present in many things at the same time; for this is opposed to the notion of unity even though it is maintained that there is a unity which exists by itself as a substance. But what is common is present in many things at the same time, for common means what may be predicated of many things and be present in many things. Hence it is clear that a common unity cannot be one in the sense that it is one substance. Furthermore, it is evident from all the points already discussed above in this chapter that no universal--either being or unity or genera or species--has a separate being apart from singular things.

             1642. But those who (681).

             He shows in what sense Plato's statements are true, and in what sense they are not. He says that the Platonists, who assume that there are certain ideal forms, are right insofar as they claim that these are separate, because they hold that they are the substances of singular things; for by definition a substance is something that exists of itself. Now unity cannot be something that exists of itself if it exists in some singular thing, and the reason is that if it does exist in one singular thing it cannot exist in others; for, as has already been stated (680:C 1641), no self-subsistent unity can be present in many things. Hence considering Plato's doctrine that the separate Forms are substance, he was right insofar as he maintained that they are separate.

             1643. But the Platonists were not right when they said that there is one form in many things; for these two statements seem to be opposed, namely, that something may be separate and exist of itself, and that it may still have being in many things. The reason why the Platonists were led to posit separate substances of this kind, yet have them existing in many things, is that they discovered through the use of reason that there must be some incorruptible and incorporeal substances, since the notion of substance is not bound up with corporeal dimensions. But "they cannot explain" which substances are of this kind which are incorruptible and exist apart from these singular and sensible substances, i.e., they cannot describe and make them known, because our knowledge begins from the senses and therefore we can ascend to incorporeal things, which transcend the senses, only insofar as we may be guided by sensible substances.

             1644. Therefore in order that they might convey some knowledge of incorporeal, incorruptible substances, "they make," i.e., they suppose, them to be specifically the same as corruptible substances, just as they find among these corruptible substances a singular corruptible man and similarly a singular corruptible horse. Hence they claimed that among those separate substances there is a substance which is man, and another which is horse, and so on for other things, but in a different way; because according to the doctrine of the Platonists we know these separate substances on the grounds that we speak of "man himself," i.e., man-in-himself, "and horse itself," i.e., horse-in-itself. And thus in order to designate separate substances "we add this word," i.e., the term "itself," or in itself, to each sensible substance.

             1645. From this it appears that the Platonists wanted those separate substances to be specifically the same as these sensible substances; and to differ only in that they gave to separate substances the name of a form in itself, but not to sensible substances. The reason for this is that singular substances contain many things which are not parts of the form, and they said that separate substances contain only those elements which pertain to the specific form and to the nature of the specific form. Hence this separate man was called man-in-himself, because he contained only those elements which pertain to the nature of the form; but this singular man contains many other things besides those which pertain to the form, and for this reason he is not called man-in-himself.

             1646. Now there is a defect in this position comparable to that of maintaining that we do not see the stars and other incorruptible bodies but that it was nevertheless certain by reason that there existed incorruptible bodies, and then maintaining that incorruptible bodies were specifically the same as the bodies of corruptible things; as if we were to say that ox and man and horse and other substances of this kind were incorruptible bodies, as the poets imagined a ram (Aries) and a bull (Taurus) and the like to be present in the stars. Therefore even if we did not see the stars, none the less, "as I should presume," there would be "eternal corporeal substances," i.e., the stars, in addition to those substances which we did then see, namely, corruptible bodies of this kind, and they would be of a different species than these. And in a similar way, even if we do not now know how to express what separate substances are and of what nature they are, perhaps it is still necessary that there should be some separate substances in addition to sensible ones, and of a different species than these. And he says "perhaps" because he has not yet proved that there are any separate substances apart from matter. However, he will prove this in later books (XII & XIII).

             1647. Last of all he draws the conclusion at which he aims throughout the whole chapter. He says that two things are evident from what has been said: first, that no universal predicates are substances; and second, that no substance consists of substances having actual existence, or according to another text, "one substance is not composed of substances." For he has shown above (655:C 1584-5) that substance in the sense of this particular thing does not consist of common attributes which signify of what sort a thing is.