Cursus Philosophicus Thomisticus, Secunda Pars Philosophiae Naturalis

These two difficulties are connected, and the resolution of one depends on the resolution of the other.

Regarding the first, the doubt is whether corruption is in any way an action, at least secondarily, or whether it has no place at all in the character of action, and how it is distinguished from generative action.

On this the authors hold various views. Some deny that generative action in any way, as an action, terminates in the corruption of a form. For wherever the touch of an action reaches—whether primarily or secondarily—it is an act of efficiency. But everything that efficiency touches, it touches by giving being; where it does not give being but removes it, it ceases to touch. Therefore corruption occurs through the very suspension of concurrence or through an omission, not through a secondary touch of action.

Others think that efficiency or action touches corruption secondarily, at least under a distinct formal aspect. On this one may consult Master Báñez on On Generation and Corruption I, ch. 3, explaining the axiom “the generation of one thing is the corruption of another,” where he also cites Cajetan. The reason is that generation and corruption are one motion, although it includes two changes, as is clear from the passages cited in the preceding article; therefore they are one action. Also, if suspension of concurrence alone occurs, it does not corrupt but annihilates; when it is joined to or follows upon an action, it belongs at least secondarily to that action. Producing a term belongs no more to an action than removing its opposite. Just as being corrupted is truly undergoing and truly changing, so corrupting and destroying is truly acting, at least secondarily.

The two views seem to be reconciled by saying that corruption is not formally an action, even mediately, but virtually. An action can be understood to touch a term mediately in two ways. First, it may touch one term principally and, by continuing the same influx or account of acting, touch another as less principal and contained under the first—as when some nature is produced principally and immediately, while its proper attribute is produced mediately, though by mediation of the same influx and causality. Second, once the principal term has been produced, the active influx ceases; but through the formal causality or informing by the produced form, another form incompatible with it is expelled or removed. In this way, someone who makes a thing incompatible with another is said effectively to corrupt the other through virtual, not actual, efficiency: that is, through the term whose informing expels and corrupts the other form as a secondary formal effect.

We say, therefore, that corruption is not an action in the first way but in the second. Once a form has been produced, the action no longer flows onward to corrupt; no influx can be understood, since with respect to the form to be corrupted it gives nothing but removes it. Therefore a positive influx is not continued, because no further positive term is given, and an influx is not necessary for negation. But once the form that is the term of the action has been posited, it is said to contain the action virtually, namely, terminatively. This involves the incompatibility of the opposite form, because it has the privation of that form joined to it. Thus it touches and expels the opposite form not through efficiency, but through the incompatibility arising from the form’s effectivity—that is, from the effected form that terminates the efficiency.

This resolution follows from St. Thomas, Sentences II, dist. 34, q. 1, a. 2, ad 5,¹ where he says: “What corrupts and generates does not generate and corrupt by the same aspect. It generates by introducing its own form; it corrupts because its own form is necessarily joined to the privation of another form.” St. Thomas does not place corruption in the action’s influx, but in the very addition of the form that has privation joined to it. Therefore corruption should not be reduced to the mere suspension of the concurrence preserving the opposite form, but to the action that produces a form incompatible with it; once that incompatibility is posited, concurrence ceases by its force. In this way the unity of action or motion is also preserved because the positive term is one, while there are two changes through the force of that efficiency, because two terms are touched: one by acting, the other by destroying, as explained.

Regarding the second difficulty—how these two changes, generation and corruption, are ordered so that the generation of one thing is called the corruption of another—some think that the changes are ordered only consecutively and successively, not identically in the same action or motion. But St. Thomas clearly says in On Truth, q. 28, a. 6, at the end,² “the generation of one thing is called by the Philosopher the corruption of another by concomitance, because they necessarily occur together, or because of the unity of motion, since motion terminates at these two changes.” Here “motion” means an action having this twofold change. And in Summa Theologiae I–II, q. 113, a. 6, ad 2, he says “that the infusion of grace and the remission of guilt are the same in the substance of the act.” He compares generation and corruption in the same way. He therefore holds that they are identified in the character of action.

Therefore, when the generation of one thing has the corruption of another joined to it, it is called the corruption of that other thing for two reasons:

First, because of the succession and order of forms following upon one another, since the forms are incompatible and, as one enters, the other departs. In that case the generation of one thing is the corruption of another causally, because corruption is connected with and follows upon generation.

Second, in a stricter sense, the generation of one thing is called the corruption of another not only because of the succession of forms and changes, but because of the unity of action or motion. Corruption is not an action distinct from generation; rather, the very same action that is formally generative is virtually corruptive by reason of the generated term, insofar as it is incompatible with the opposite form. In this incompatibility, the positive influx virtually remains, as terminated at the generated form, as was said.

In the conclusion we said “when generation has corruption attached to it” to indicate what we explained in the preceding article: corruption that is a true and real change occurs only when there is a positive form to be corrupted. For if only a privation to be removed by the generated form precedes—as when air in darkness is illuminated—the removal of that privation does not occur through a negative change distinct from the generation of light. Rather, the privation is corrupted through the very positive generation of light, without another change, since it is removed only through positive being, and therefore through generation, which is a passage or change from nonbeing to being, from privation to form. It is true that through our concepts we can distinguish in light the positive concept of making something luminous from the privative concept of removing darkness or the nonbeing of privation, because we take privation as a being of reason and therefore as something like being that is corrupted. In reality, however, that privation is nonbeing and is physically removed only through being. St. Thomas teaches all of this in On Truth, q. 28, a. 6, in the body of the article.³

Hence the objections that may be raised because generation sometimes occurs without corruption have no force. We admit that corruption is not essentially joined to every generation, but only to one to which a positive form to be corrupted is joined. If the form to be corrupted is partial, then the corruption is partial too, and the production is adgeneration. Nor did St. Thomas, in Sentences II, dist. 34, cited above,⁴⁵ say that generation and corruption differ only in reason. He said that the form of fire and the privation of air are the same in subject but differ in reason, which means that privation and form are not really distinct, since privation is not a real extreme. It does not mean, however, that generation and corruption themselves are not distinct changes in the way explained.

The objections are resolved.

First, it is argued: Corruption is privation, at least on the side of its terminating term, whereas generation is a positive action. Therefore they cannot be identified in any way, for true reality cannot be identified with what is nothing and a being of reason.

Second: By the same reasoning that proves generation and corruption to be identified in the character of motion and action, they should be identified in the character of change. For just as the same dispositional action and motion suffice primarily to introduce a form and secondarily to destroy its opposite, so one simple and single positive change will primarily be a passage to the generated form and secondarily a passage from the opposite form. For there is no contradiction in a negative change being identified with a positive one, just as a negative action, that is, destruction, is identified with positive generation.

Third, it is argued: If generation is identified with corruption, it will be true motion, which the Philosopher nevertheless denies in Physics V, ch. 1.⁶ The inference is clear: insofar as generation is identified with corruption, it has something positive as its starting term; and, by reason of itself, as generation, it has a positive terminating term. Therefore, at least identically, it is between two positive terms, a starting term and a terminating term, which is to be a motion at least identically.

Fourth: If generation and corruption are ordered to one another, this order must be founded on some causality or order of priority and posteriority of one with respect to the other. But there is no such order. Either they cause one another, which is impossible, since corruption, being privation, cannot have causality with respect to generation; or they do not cause one another, but one alone is cause and the other effect. This too is impossible: first, corruption cannot cause, as was said, and so it cannot itself be the cause with generation as its effect; moreover, corruption would then be intended per se and primarily, with generation as what follows. But if generation is the cause and corruption the effect, the generated form will be received before the opposite form is expelled, and thus the generated form will not be received in bare matter or on the supposition that the form has already been expelled.

Finally: If the generation of one thing is the corruption of another, they must be in the same instant. For if they occur at different times, they are not identified. But this cannot be, because corruption belongs on the side of the ultimate disposition, which removes the form incompatible with the generated form; and the ultimate disposition precedes the form in the very subject in which corruption occurs. Therefore corruption is not identified with generation.

To the first, we reply that the negation of another form can indeed be identified with some positive form. Privation and the negation of different things are not opposed; rather, such a negation is contained in and identified with the very form on which it is founded, just as faith has obscurity, heat has the privation of cold, and anything has the negation of what is distinct from it.

To the second, we deny that change and motion are subject to the same reasoning, insofar as motion signifies an action by way of influx. It is not impossible for one numerically identical action to reach several terms that are ordered or consequent upon one another, whether negative or positive, since an action can be virtually multiple and extend to many things, just as the power from which it proceeds can. Change, however, does not signify anything efficient, but a pure passage between terms; it signifies something effected rather than something effecting. Thus where there is a distinct passage between terms, there is a distinct change; but where there is an effect distinct even materially, there is not necessarily a distinct efficient action. What is material with respect to the character of action does not multiply that action, but it is formal with respect to the character of change and multiplies it, because the formality of change consists only in that effected passage, as was said.

To the third, we deny the inference. For it is not enough for the character of motion strictly so called, as distinguished from change, to have a positive starting term concomitantly and because of an attached incompatibility; it must have one formally and per se. But substantial generation is formally and per se not from a positive term, but from privation of the form. That it corrupts a preexisting substantial form is not because it has that form as its formal starting term. For it is per accidens and materially related to the form of fire that is generated that it be made from straw, paper, or wood; per se, however, it is made from what is not fire. Yet it corrupts whatever form preceded, because forms are incompatible in the same subject on account of the privation attached to them: each is a substantial form and consequently primary in the subject, so neither admits another as secondary. The preceding form is nevertheless not related as a formal starting term. It is a formal starting term when it contributes to constituting a positive distance or range between the starting and terminating terms. A positive range and distance between terms is constituted when the terms are positive and have a mean, so that the extremes contribute to such a range insofar as a mean is constituted from their proportion or combination, and per se require a passage from one form to another through that mean. Substantial forms, however, are not extremes from whose proportion or combination a mean is constituted, nor does a passage per se occur from one form to another through some mean. Rather, any form that is immediately receivable in matter is received if no contrary disposition stands in the way. Hence it is only by reason of a disposition that a passage through some intermediate form is required.

To the fourth, we reply that there is a mutual order of priority and posteriority between corruption and generation, as there is between the expelled form and the generated form. The expulsion of the corrupted form is prior in the order of material causality, while the generated form is prior in the order of formal causality. Hence St. Thomas says in On Truth, q. 28, a. 7,⁷ “the expulsion of the preceding form is naturally prior in the order of material causality. For every disposition toward a form is reduced to material causality, and stripping matter of a contrary form is a certain disposition for receiving the form.” He teaches that the introduction of the form is prior in the order of formal causality in Sentences IV, dist. 17, q. 1, a. 4, question 1,⁸ saying: “Removal of a form is naturally prior to the introduction of a form according to the order of material causality; but according to the order of formal causality, the reverse is true.” He says the same in Summa Theologiae I–II, q. 113, a. 8, ad 1: the agent acts through a form to remove its contrary, as the sun through its light acts to remove darkness. Therefore, on the sun’s part, to illumine is prior to removing darkness; on the air’s part, however, being cleared of darkness is naturally prior to receiving light, although both occur at the same time. Thus one should reason about corruption and generation as about the ultimate disposition and the form, as was said above.⁹ This priority on the side of material causality does not require priority in existence as well; it is enough that existence in reality accompanies it, while that priority explains only the formal aspect and function of the dependence and causality. Although corruption is a secondary effect of the generated form, as is the ultimate disposition, it can nevertheless have the character of a cause and priority in another order of causality and under another aspect, namely, insofar as it belongs on the side of the dispositive cause.

To the last, we reply that generation and corruption occur in the same instant of time, but under different priorities of nature. The ultimate disposition does not exist for any duration before the generated form, nor does it exist in the corrupted subject, although according to different priorities of nature it precedes and follows in the same generated subject, as was explained above;¹⁰ exactly the same must be said of corruption and generation.