Cursus Philosophicus Thomisticus, Secunda Pars Artis Logicae

Having omitted contradictory opposition, of which we treated at length in q. 7 of the Summulae¹, and relative opposition, of which enough has been said above in q. 17², we shall resolve a few brief questions concerning the remaining kinds.

First, then, you will ask whether this division of opposition into the four members set out in the chapter on Opposites is adequate and sufficient.

The answer is affirmative. St. Thomas gathers its sufficiency in Metaphysics V, lect. 12³, because whatever is opposed to another is opposed either by reason of dependence or by reason of removal—that is, because it removes the other. If by reason of dependence, that is, because it cannot exist without the other, but not because it is caused by it, then the opposites are relatives. If by reason of removal, either one removes the other by wholly taking it away, and this is contradiction, which is opposition in the highest degree; or something remains. Either it leaves the subject in which the opposites agree, but not the entity and genus in which they disagree, and thus the opposition is privation and habit, since they can belong to the same subject, but one is a lack and the other a positive state; or they agree in the same genus and belong to the same subject, and thus they are contraries.

Others gather it this way: opposition is either between being and being or between being and nonbeing. The second case is divided in two: either between being and nonbeing absolutely, and this is contradiction, or in a determinate subject capable of both, and this is privation. The first case is also divided in two: either between beings that exclude one another, and these are contraries, or between beings that refer to one another, and this is relative opposition.

Second, you will ask whether this division is univocal or analogical.

St. Thomas, in Opusculum 37, ch. 2⁴, answers that it is analogical, because contradiction is opposition without qualification, since it simply removes what the other extreme posits. The other kinds of opposition have opposition only insofar as they participate in something of contradiction—namely, in the negation of the other, although not as simply as contradiction does. If they did not negate and remove something, they would not be opposed. Hence relatives are said to have the least opposition, because they do not remove one another but refer to one another, although they require their extremes to be distinct.

Others prove this because opposition belongs to things in different categories, and some opposites are real while others are beings of reason. But this is material to opposition. It often happens that things which are not univocal materially in the account of being are formally univocal in the account of an opposite, or of something knowable, intelligible, or another property that follows upon being. Therefore, the first proof is more solid and correct.

Third, you will ask how it should be understood that some of these opposites have a mean, while others have none.

St. Thomas, in the cited Opusculum 37, ch. 1⁵, answers that to have no mean is to have no way of agreeing, and the more completely some opposites lack a mean, the less they agree. “A mean,” St. Thomas says, “shows a distance of agreement and therefore diminishes the account of opposition. Since, then, a mean is found in all the other kinds of opposition, they all fall short of the account of contradictory opposition. Hence it follows that when we say there is no mean, it is because one extreme so perfectly removes the other that it leaves nothing of it, either formally or virtually. Thus, when one extreme is posited, the other must be removed, and conversely; and in this way some things are said to be immediately opposed. Contraries are likewise immediate when one of them must be in the subject, even though contrariety has a mean in the account of opposition, insofar as the contraries agree in some way in the same genus and can also be in the same subject.”

Fourth, you will ask wherein lies the difference between privative and contradictory opposition, since in both one extreme is a negation that wholly removes its opposite.

The answer is that privation expresses negation on the part of one extreme, but modifies it differently from contradiction, and thus constitutes a different kind of opposition. The modification comes from the subject it connotes, namely, that the subject be apt for the form of which it is deprived. Hence, although privation removes the form wholly, no less than contradiction does, it does not remove the aptitude for that form, but leaves the capacity for it. Thus, while it formally removes the entire form, it nevertheless leaves something of it virtually. Likewise, privation in becoming—that is, privation that removes a disposing form and stands, as it were, as the becoming of a further form—although it wholly removes the disposition opposed to it, never reaches the point of removing the form in being, toward which the disposition tends. Thus, privation of health removes health but not life, and sin removes virtue but not the ordering toward the good.

Fifth, you will ask how we should understand the Philosopher's statement that there is no return from privation to possession, when this is challenged by many examples of privation from which a return is possible: from darkness to light, from rest to motion, and from ignorance to knowledge.

St. Thomas, in Metaphysics VIII, lect. 4⁶ and Opusculum 37, ch. 1⁷, distinguishes privations as follows. Sometimes a subject is equally and immediately capable of both privation and form; at other times, a necessary order must be followed in receiving the form and privation. For example, there cannot be death in a subject that has not first lived, nor blindness in something that has not first seen or been due sight. For this reason, a puppy is not called blind before its ninth day, but merely not seeing; afterwards, if it lacks sight, it is called blind. But for there to be a privation of light, motion, or knowledge in a subject, it is not required that these forms have first been present in that subject: it can indifferently begin from either the form or the privation. In these latter cases, then, there is a return from privation to possession, and conversely; in the former there is not, because privation is had only in a certain order, after the form. Hence, when the form is removed, the potency for it does not remain, because the order does not remain: the order is that privation be had after the form, not that the form be had after privation. Or, second, as St. Thomas says in On Evil, q. 2, a. 12, ad 3⁸, some privations remove aptitude or potency—that is, a form that orders or enables something per se and primarily for something else—as blindness removes sight and deafness hearing. Some privation removes only act—that is, a form that gives act alone, or a habit, but not the first and per se potency for act—as do privation of grace, privation of light, privation of motion, and the like. Privations of the first kind do not admit a return to possession; those of the second kind can admit one.