55 On the Category of Quality
55: On the Category of Quality The fourth category is the category of quality. As in the case of the first three categories, | shall first deal with the view which, whether true or false, seems compatible with the principles of Aristotle's philosophy. Then [ shall outline the contrary position. It seems that according to the principles of Aristotle's philosophy, one should say that the category of quality is a concept or sign containing under it all such terms as do not express a substantial part of a substance and can be used to answer the question posed about substance
'How is it qualified?' For the present, I shall not consider whether concrete or abstract terms more properly belong in the category of quality.
In the genus of quality there are certain terms which designate things that are distinct from substances, things that are not themselves substances.
Examples are 'whiteness', 'blackness', 'color', 'knowledge', and 'light'. But the category of quality also embodies terms that do not designate things different from substance and the aforementioned qualities. Examples are 'figure', 'curvature', 'straightness', 'denseness', and 'thinness'.
To determine when a quality should be construed as a thing distinct from substance and when not, one can employ the following test: predicables which, while incapable of being truly applied to one thing at the same time, can successively hold true of an object merely as the result of a local motion, need not be construed as signifying distinct things. 'Curved' and 'straight', for example, can be successively affirmed of one and the same thing merely as the result of a local motion. Thus, take something straight. If as a result of a local motion its extreme parts become closer, then it is said to be curved.
No additional entity is required. Therefore, 'curvature' and 'straightness' do not signify things that are distinct from the things that are curved and straight. The same holds true in the case of shape, for merely as a result of a local motion in some of its part an object can take on a new shape. And so it is with 'rare', 'dense', and similar terms. But it is different in the case of terms like 'whiteness', 'blackness', 'heat', and 'cold'. For it is not simply because a thing or its parts undergo local motion that the thing becomes hot or cold. Consequently, these terms designate things distinct from substance.
It should be noted that Aristotle posits four modes or species of quality.!
The first he calls habit or disposition. Every quality, whether spiritual or corporeal, that is firmly established is called a habit; and every quality, whether spiritual or corporeal, that is easily changed is called a disposition.
It follows that a quality in one object can be a habit and a quality of the same species in another object a disposition.
On the Category of Quality And it should be noted that under this mode are included not only those terms which designate something different from substance, but also those which do not designate anything different; for every quality which can, by a change in the thing be taken away from its subject either easily or with difficulty, is included in this mode. As I shall note later, every quality is contained under this mode. Therefore, this is called a species of quality not because there is some quality that is neither a habit nor a disposition, but because some qualities are not habits and some are not dispositions. Or, possibly it is called a species because it connotes something more specific than the name
Another genus of quality includes natural capacities and incapacities.
Thus, everything by which something can easily act or resist action is placed in this genus.
The third species is called affection and affective quality; every sensible quality is placed in this third species of quality.
The fourth genus of quality includes the form and determinate shape of a thing. 'Straight', 'curved', and similar terms fall under this genus. It should be noted that a quality on account of which something is said to be beautiful or ugly is called form. The names in this genus do not designate things different from substance and the qualities already mentioned.
It should be noted that, for Aristotle, one and the same thing falls under different species of quality. This is clear, for he says that heat and cold are in the first species of quality and also in the third. Thus, he does not want to say that these species are mutually exclusive, but that they can be predicated of each other at least particularly. The same point holds, for Aristotle, in the case of the categories: they can be predicated of each other particularly.
The Philosopher attributes many properties to quality." The first property is that quality admits of contraries, for one quality can be the contrary of another. Likewise, the concrete names designating these qualities in an oblique way are contrary. Nonetheless, not every quality has a contrary. Some qualities such as light have no contrary.
The second property is that quality admits of more and less, for a concrete form from this category is sometimes predicated of a thing with the adverb
'more' and sometimes with the adverb 'less'. Thus, sometimes this is true:
'A is more white than B'; and sometimes this is true: 'A is less white than B'. But this property does not apply in the case of all qualities; for one thing is not said to be more triangular than another, nor is one thing said to be more square than another.
The third property is that things are said to be similar and dissimilar with respect to quality. Thus, two white things are similar and, likewise, two black things, but the white and the black are dissimilar.