LESSON 16

The Senses of Quality

Chapter 14: 1020a 33-1020b 25

             487. Quality (the qualified or of what sort [quale]) means in one sense substantial difference; for example, How is man's quiddity qualified? as a two-footed animal. How is a horse's? as a four-footed animal. A circle's? as a figure which is non-angular; as if substantial difference were quality. In this one sense, then, quality (qualitas) means substantial difference.

             488. In another sense the term applies to immobile things and to the objects of mathematics, as numbers are of a certain type (quales), for example, those which are compound, and not only those of one dimension but also those of which surface and solid are the counterpart (for there are numbers which are so many times so much and so many times so many times so much). And in general it means what is present in substance besides quantity. For the substance of each number is what it is once; for example, the substance of six is not two times three but six taken once, for six times one is six.

             489. Again, all the modifications of substances which are moved, such as heat and cold, whiteness and blackness, heaviness and lightness, and any other attributes of this sort according to which the bodies of changing things are said to be altered, are called qualities.

             490. Further, the term quality is used of virtue and vice, and in general of good and evil.

             491. The senses of quality, then, come down to two; and one of these is more basic than the other. For the primary kind of quality is substantial difference. And the quality found in number is a part of this, for this is a substantial difference, but either of things which are not moved, or not of them insofar as they are moved. The others, however, are the modifications of things which are moved inasmuch as they are moved, and are the differences of motions. And virtue and vice are parts of these modifications, for they indicate clearly the differences of the motion or activity according to which things in motion act or are acted upon well or badly. For what is capable of being moved or of acting in this way is good, and what cannot do so but acts in a contrary way is bad. And good and bad signify quality especially in the case of living things, and especially in those which have the power of choice.

COMMENTARY

             987. Here he gives the various senses in which the term quality is used, and in regard to this he does two things. First (487:C 987), he gives four senses of the term quality; and second (491:C 966), he reduces them to two ("The senses of quality").

             He accordingly says, first (487), that the term quality is used in one sense as "substantial difference," i.e., the difference by which one thing is distinguished substantially from another and which is included in the definition of the substance. And for this reason it is said that a difference is predicated as a substantial qualification. For example, if one were to ask what sort of (quale) animal man is, we would answer that he is two-footed; and if one were to ask what sort of animal a horse is, we would answer that it is four-footed; and if one were to ask what sort of figure a circle is, we would answer that it is "non-angular," i.e., without angles; as if a substantial difference were quality. In one sense, then, quality means substantial difference.

             988. Now Aristotle omits this sense of quality in the Categories because it is not contained under the category of quality, which he deals with there. But here he is dealing with the meaning of the term quality.

             989. In another sense (488).

             Here he gives a second sense in which the term quality is used. He says that the term quality or "qualified" is used in another sense insofar as immobile things and the objects of mathematics are said to be qualified in a certain way. For the objects of mathematics are abstracted from motion, as is stated in Book VI of this work (536:C 1161). Such objects are numbers and continuous quantities, and of both we use the term quality. Thus we say that surfaces are qualified as being square or triangular. And similarly numbers are said to be qualified as being compound. Those numbers are said to be compound which have some common number that measures them; for example, the number six and the number nine are measured by the number three, and are not merely referred to one as a common measure. But those which are measured by no common number other than one are called uncompounded or first in their proportion.

             990. Numbers are also spoken of as having quality in a metaphor taken from surface and from "solid," i.e., body. They are considered like a surface inasmuch as one number is multiplied by another, either by the same number or by a different one, as in the phrase "twice three" or "three times three." And this is what he means by "so many times so much"; for something like one dimension is designated by saying "three," and a sort of second dimension by saying "twice three" or "three times three."

             991. Numbers are considered like a solid when there is a twofold multiplication, either of the same number by itself, or of different numbers by one; as in the expression "three times three times three" or "two times three times two" or "two times three times four." And this is what he means by "so many times so many times so much." For we treat of three dimensions in a number in somewhat the same way as in a solid; and in this arrangement of numbers there is something which is treated as a substance, as three, or any other number that is multiplied by another. And there is something else which is treated as quantity, as the multiplication of one number by another or by itself. Thus when I say "twice three," the number two is signified after the manner of a measuring quantity, and the number three after the manner of a substance. Therefore what belongs to the substance of number besides quantity itself, which is the substance of number, is called a quality of it, as what is meant in saying twice or three times.

             992. Another text reads "according to quantity," and then the substance of number is said to be the number itself expressed in an unqualified sense, as "three." And insofar as we consider the quality of a quantity, this is designated by multiplying one number by another. The rest of the text agrees with this, saying that the substance of any number is what it is said to be once; for example, the substance of six is six taken once, and not three taken twice or two taken three times; and this pertains to its quality. For to speak of a number in terms of surface or solid, whether square or cube, is to speak of its quality. And this type of quality is the fourth kind given in the Categories.

             993. Again, all the modifications (489).

             Then he gives the third sense in which quality is used. He says that qualities also mean the modifications of mobile substances according to which bodies are changed through alteration, as heat and cold and accidents of this kind. And this sense of quality belongs to the third kind of quality given in the Categories.

             994. Further, the term quality (490).

             Next he gives the fourth sense in which quality is used. He says that quality or "qualified" is used in a fourth sense insofar as something is disposed by virtue or vice, or in whatever way it is well or badly disposed, as by knowledge or ignorance, health or sickness, and the like. This is the first kind of quality given in the Categories.

             995. Now he omits the second of these senses of quality because it is contained rather under power, since it is signified only as a principle which resists modification. But it is given in the Categories among the kinds of quality because of the way in which it is named. However, according to its mode of being it is contained rather under power, as he also held above (470:C 960).

             996. The senses of quality (491).

             Then he reduces to two the four senses of quality so far given, saying that a thing is said to be qualified in a certain way in two senses, inasmuch as two of these four senses are reduced to the other two. The most basic of these senses is the first one, according to which quality means substantial difference, because by means of it a thing is designated as being informed and qualified.

             997. The quality found in numbers and in other objects of mathematics is reduced to this as a part. For qualities of this kind are in a sense the substantial differences of mathematical objects, because they are signified after the manner of substance to a greater degree than the other accidents, as was stated in the chapter on quantity (485:C 980). Further, qualities of this kind constitute substantial differences, "either of things which are not moved, or not of them insofar as they are moved"; and he says this in order to show that it makes no difference to his thesis whether the objects of mathematics are self-subsistent substances, as Plato claimed, and are separate from motion; or whether they exist in substances which are mobile in reality but separate in thought. For in the first sense they would not be qualities of things which are moved; but in the second sense they would be, but not inasmuch as they are moved.

             998. The second basic sense in which quality is used is that in which the modifications of things which are moved as such, and also the differences of things which are moved, are called qualities. They are called the differences of motions because alterations differ in terms of such qualities, as becoming hot and becoming cold differ in terms of heat and cold.

             999. The sense in which virtue and vice are called qualities is reduced to this last sense, for it is in a way a part of this sense. For virtue and vice indicate certain differences of motion and activity based on good or bad performance. For virtue is that by which a thing is well disposed to act or be acted upon, and vice is that by which a thing is badly disposed. The same is true of other habits, whether they are intellectual, as science, or corporal, as health.

             1000. But the terms well and badly relate chiefly to quality in living things, and especially in those having "election," i.e., choice. And this is true because good has the role of an end or goal. So those things which act by choice act for an end. Now to act for an end belongs particularly to living things. For non-living things act or are moved for an end, not inasmuch as they know the end, or inasmuch as they themselves act for an end, but rather inasmuch as they are directed by something else which gives them their natural inclination, just as an arrow, for example, is directed toward its goal by an archer. And non-rational living things apprehend an end or goal and desire it by an appetite of the soul, and they move locally toward some end or goal inasmuch as they have discernment of it; but their appetite for an end, and for those things which exist for the sake of the end, is determined for them by a natural inclination. Hence they are acted upon rather than act; and thus their judgment is not free. But rational beings, in whom alone choice exists, know both the end and the proportion of the means to the end. Therefore, just as they move themselves toward the end, so also do they move themselves to desire the end and the means; and for this reason they have free choice.