Cursus Philosophicus Thomisticus, Secunda Pars Artis Logicae

Aristotle posited four pairs of species in the division of this category: the first is habit and disposition, the second power and lack of power, the third affection and affective quality, the fourth form and figure.

Concerning these, THE QUESTION IS ABOUT THE SOUNDNESS AND ADEQUACY OF THIS DIVISION. The common opinion is that this division is adequate; there is, however, disagreement about how these species are gathered together and what account should be given of them. Scotus, on the chapter on Quality, question 1, gathers them in this way: Quality in itself is a certain disposition of substance. Therefore it is either interior or exterior. If exterior, it is either per se and primarily sensible or not. If it is per se and primarily sensible, it belongs to the third species, which is called affection or affective quality. But if it is an interior disposition, it either disposes as an innate principle of operation, and thus is a power or lack of power, or it is a principle of operation that is not innate but comes from outside, and thus is the first species, habit or disposition.

Other more recent authors gather them in this way: Quality is ordered either to adorn substance or to act. If to act, it either comes as a principle of operation or as its term. If as a principle, it is either an implanted and intrinsic principle or one coming from outside. If intrinsic, it is a power or lack of power. If it comes from outside, it is a habit; or, if it is the term of an operation, it will belong to disposition, as do the terms of cognition, which are concepts. But if it is ordered to perfecting or adorning substance, it either serves to preserve and sustain the substance itself, and thus is the third species, or to perfect extension, and thus is the fourth.

These accounts nevertheless fail in many ways. First, they proceed by accounts that are very extrinsic and in themselves quite uncertain: for example, that quality inheres only in the surface, or also within; that it is primarily and per se sensible; that every habit or disposition is called an operative quality, or even that every power is. For a passive power is not operative; grace, health, and beauty, which belong to the first species, are not operative either. Nor is disposition only the term of an immanent operation, as a concept is, since there are also qualities that are easily changeable by their nature and are not terms of an immanent act as such, such as opinion or vice, a passing illness, and so on. Finally, the fact that quality, speaking generally, adorns substance does not explain why this should not also belong to quantity, which likewise adorns by extending, since it orders. Conversely, why should adorning substance by sustaining and preserving it not belong to the first species, disposition, which, if it disposes its subject well, sustains and preserves it—especially since health, which most of all preserves an animal, is placed in the first species by the Philosopher in Physics 7, text 17¹ and by St. Thomas, 1. 2. q. 50. art. 1?

Divus Thomas, then, gathers these species differently, in 1. 2. q. 49. art. 2. Since quality implies an accident, whose proper function is to impose an accidental determination and mode on a subject, and every mode and determination can be considered either in relation to the very nature or according to action and passion, which follow upon the principles of nature, or in relation to quantity, the mode according to quantity belongs to the fourth species, which is form and figure: figure results from the termination of quantity. The mode of a subject according to action and passion is considered in the second or third species of quality. For power is per se ordered to action or passion, whereas affection or affective quality results from some affection or motion. A mode and determination in conformity with the nature of a thing, however, belongs to habit and disposition, because these are first and per se ordered to the suitability or unsuitability of a nature; and because nature is the term of generation and motion, while motion is followed by ease or difficulty of coming to be, these accounts too are considered in habit and disposition.

AGAINST THIS ACCOUNT, HOWEVER, YOU WILL OBJECT that, according to it, there will be no impossibility in placing the same quality in two species. For example, heat, insofar as it is caused by condensation, is an affection or affective quality; yet, insofar as it is suitable to a nature, as it is in fire, it will be the first species of quality.

Again, Divus Thomas proceeds obscurely in distinguishing the second and third species of quality. For he says that a mode according to action and passion belongs to the second and third species of quality. But he does not explain how it belongs to one and to the other, or distinguishes the second from the third. Nor is it enough to assign what is easily or with difficulty changed, what is transient or lasting; these are not per se differences and do not apply equally to the second and third species, nor do they distinguish powers and lacks of power from one another.

Again, habit and disposition also function as a determination or mode in relation to action, since operative habits are principles for eliciting an operation. Therefore not every habit is to be explained by its suitability to the subject.

Finally, to constitute the third species of quality by its being the term of an operation or motion seems a very accidental condition of quality, indeed an insufficient one. For if only qualities that terminate a motion of alteration are said to belong to the third species, it follows that light produced in the air, which comes to be without alteration, does not belong to the third species of quality; this is commonly denied. But if qualities that terminate every motion, even an instantaneous one, belong to it, it follows that immanent acts and concepts produced by them, and intentional species, will belong to the third species of quality, even though they are commonly placed in the first.

To the first objection it is answered that no quality belongs to more than one essential species, although with respect to its state and accidental mode it can take on the mode and state of another; it does not do so essentially. This frequently happens among these qualities: one takes on the mode of another with respect to state and accidental mode. Thus a disposition can, from an extrinsic cause, become difficult to change, not because of its intrinsic principles; and a habit can, because its state is imperfect, be easily changed, since it has not yet been perfectly acquired. Heat likewise is per se and primarily the term of alteration, but accidentally and from an extrinsic cause it has the mode of suitability or unsuitability to a nature, insofar as it is the proper affection of something—not because it is ordered to that by its formal account, or because the due temperament arises from it, as health does, which expresses suitability to a nature. Conversely, it can primarily and per se express suitability to a nature, while accidentally or as a consequence being the term of an action. Thus it is not placed essentially in two species: it is essentially in one, and has the mode or state of another. This is how St. Thomas is to be understood in 1. 2. q. 49. art. 2. ad 1., and it follows from q. 50. art. 1. ad 3. at the end.

What, in the case of each particular quality, is primary and per se, and what is accidental and secondary, is to be judged either from the effects of the quality—for example, if we see that one formal character is always found in a quality, as being the term of alteration is found in heat, while another is not always found, the latter is an accidental state—or from the principles by which the quality is caused. That is, if by those principles it is ordered to action or passion, to suitability or unsuitability to a nature, and so forth, then this is essential to it.

To the second objection it is said that the distinction between the second and third species is not stated expressly by Divus Thomas there, but is drawn from what he teaches in Metaphysics 5, lect. 16²: that affections of mobile subjects, according to which bodies are changed by alteration, belong to the third species of quality. Therefore the third species of quality is that which belongs to a subject through alteration, or to a subject insofar as it is moved, taking alteration broadly for every physical change of quality. Power and lack of power, however, which constitute the second species, belong to a subject as a principle of action or passion, primarily and per se, but not to a subject insofar as it has been altered; for powers do not presuppose alteration in order to belong to a subject. In the second species, “easily” and “with difficulty changeable” are not taken as they are in the first, but as explaining the force of resisting or yielding to an active agent: thus they constitute active or passive power, since what is passive yields easily, and what is active resists with difficulty. Lasting and quickly passing qualities, however, belong not to the second but to the third species.

To the third objection it is said that habit and disposition are primarily and per se for disposing a nature according to suitability and unsuitability. If the nature is active and is disposed toward action, this is not because habits are primarily and per se active, but because the nature they dispose is active and is suitably disposed only toward action, as we shall say in the following article from Divus Thomas, 1. 2. q. 49. art. 3.

To the final objection it is said, first, that being the term of alteration is not extraneous to quality. Since there is a per se motion toward quality, namely alteration, as is said in Physics 5³, some qualities must per se be qualities of a subject insofar as it is moved and altered. Next, we say that in this third species are placed qualities that primarily and per se terminate motion, or are qualities of a subject insofar as it has been altered, even by instantaneous alteration or change, as in the case of illumination in the air. Yet immanent acts or concepts will not for that reason belong to the third species, as light does, because they do not change the subject or constitute terms of alteration, which is found properly only in bodily things. Rather, they have another, prior, and more principal consideration: suitably disposing a nature insofar as it is cognizing. Thus they belong to the first species of quality, and this account is more principal in them because it is proper and per se; immanent acts, however, have alteration accidentally, as occurs in the senses on the part of the organs.

From what has been said it is clear that this division is adequate and sufficient.

To the first species, besides habits and dispositions, which are plainly such, are reduced all immanent acts and concepts, indeed even impressed species, which seem to be numbered among habits by St. Thomas, 1. 2. q. 50. art. 16. For in them there is the character of a good or bad disposition of a power, insofar as the object is represented well or badly. Grace also belongs to this species, as St. Thomas teaches in 1. 2. q. 110. art. 3. ad 3., as do supernatural habits, because they are given to elevate a power and thus presuppose it, although, in the order of elevation, they provide it with the whole power for an act that has no being except as elevated.

To the second species are reduced all instrumental powers, because they are given for acting simply or for assisting a power, not for disposing a nature well or badly. Therefore St. Thomas, 3. p. q. 63. art. 2., reduces character to this species, because it is not given for acting well or badly, but for validly and truly receiving or performing the sacraments. Finally, some reduce rough and smooth, rare and dense, to the different arrangement of the parts alone, because rough things have parts arranged unequally, smooth things equally; rare things have parts more spread out, dense things more contracted and in a smaller space. All this pertains to position. This is indeed true in itself. But because hardness is sometimes joined to roughness, and some softness to smoothness, which Aristotle in this chapter⁴ numbers among the qualities, these are also commonly called qualities on account of this concomitant feature.

But is this division essential? The answer is affirmative. Quality is a highest genus and must have species essentially distinct beneath it, and no others can be assigned. Certainly, there is no doubt that specific distinction intervenes among some qualities, as between habit, power, and figure; indeed, it intervenes among some belonging to the same pair, as between two habits or two powers. One might only doubt because sometimes the same quality seems to belong to two species, as heat belongs to the third because it is the term of alteration, and to the first because it is suitable to some nature. But we have already said above that it belongs per se to only one, according to the formal character that per se and always belongs to something, or according to the principles from which it arises per se. Thus it always belongs to heat to be the term of alteration, but not always to dispose a nature. Therefore, if it sometimes has this second feature, that is accidental to it, not essential or primarily and per se belonging to it, and hence not constitutive of its species.