Commentaria in Summam contra Gentiles, Liber II

In the second place, he responds to the arguments that have been drawn from the side of created things ¹.

I. To the first, then, he says that the necessity of being which is in creatures is a necessity of order. But such a necessity does not compel the subject in which it inheres always to have been. For since such a necessity does not follow from its substance ², it therefore induces the impossibility of not-being only when the subject has already been established in esse—and not otherwise.

2. But against this answer a doubt is raised. For a contradiction seems to be implied when it is said that the necessity of being which is in creatures is a necessity of order, and yet does not follow upon the substance of the thing. For this necessity of being is a necessity of order because it is a necessity by reason of order to the formal cause: namely, either because the thing itself is form alone, not existing in matter, or because the form fills the whole capacity of the matter, as was shown above ³. But what follows upon the form of a thing follows upon its substance, since the form belongs to the substance of the thing; and in things separate from matter the very form is the substance of the thing. Therefore such a necessity of order follows upon the substance of the thing. Therefore it is repugnant that it be a necessity of order of this kind and yet not follow upon the substance of the thing.

3. The answer is given in two ways, assuming the truth of this text. First, that something can follow upon the substance of a thing in two ways: namely, either as considered absolutely, or as already constituted in esse. What follows in the first way belongs to its ratio or is a proper passion of it. And such a thing befits the thing eternally according to intellectual esse, at least according to the apprehension of the divine intellect: for in propositions of this kind there is only a necessity of order of predicate to subject; thus "Man is rational" is an eternal truth, and likewise "Man is risible," considered according to the nature of the terms. But what follows in the second way does not befit the thing eternally unless the thing itself is from eternity. — Therefore, since something created has a necessity of being (essendi) with respect to its form, that necessity follows upon the nature in the second way, namely, as already constituted in esse: because it is thus constituted in esse that it has no potency to non-being. But not in the first way: so that it would be necessary for it to befit it eternally.

To the second objection one may reply that this necessity of being indeed follows the substance of a thing in the order of formal cause, but not in the order of efficient cause—as if the thing had its necessity of being from itself and not from another effective cause; for it does not have esse from itself but from another. And therefore, once the substance is posited in act, such a necessity follows it as a formal effect follows its form. Yet it does not follow that the thing exists from eternity: because its esse depends on the will of its producer, not on itself as having effectively the necessity of being. — And thus it is clear that there is no contradiction.

I think, however, that this text is corrupted ⁴: as can be seen from chapters XXX and XXXI, to which passages Saint Thomas refers back. For it should not read "non tamen" (not however), but rather thus: "eius tamen necessitas sequitur eius substantiam" (yet its necessity follows from its substance). And so the response remains clear. For if necessity follows from substance, it cannot belong to a thing unless that very substance is posited in act. And therefore it cannot be argued from necessity itself that the substance did not begin to be through a divine agent.

II. To the second, he says that the power of being always presupposes the production of the substance. Therefore the consequence does not hold.

For a fuller understanding of this response, it should be known, from the doctrine of Saint Thomas, Potentia, q. III, a. 17, ad 2, that no power of being or of acting regards the past, but only the present or the future: for nothing has the power to have done something, but only to do something now or hereafter. Hence it is rightly said here that the power of being always presupposes the production of the substance, and does not argue the eternity of the thing.

2. But a doubt arises. For a power which is now directed toward something present or future can be the same as that which was the cause of what is now past: just as it can happen that the same power by which fire can heat wood has heated stone. Thus, therefore, the power of being can also be directed toward the past as toward an effect already produced: for it is true that the power which now gives esse to the heavens formally and will give it in the future also gave esse in the past. And so, if something has the power to be always, it follows that by the power by which it is now, it has also always been in the past: for a thing has esse as long as its power of being extends itself. And thus by this reply the argument does not seem to be satisfied.

3. It is answered that, although a power taken materially can regard the past materially—that is, because through it certain things were at some time produced—nevertheless a power taken formally, insofar as it regards the producible, does not regard the past formally, that is, under the aspect of something producible by it. For it has no power to produce a thing that has passed away; nor can a past thing have the character of the producible, such that what is past as past could be produced. And if by its power something produced some effect in past time, then the time when it produced was not past but present. Likewise, nothing can produce in a time preceding the esse of its power: for a power must be either simultaneous with its effect in time or prior to it, never posterior. Therefore the power of being, as productive of esse formally, regards esse not as past but as present or future—although the very same form can be that by which in past time a thing was, and now is and will be in the future; yet when it was the cause of being in a time now past with respect to us and to the power, that time was present, not past. From these considerations it is clear that the power of being necessarily presupposes the production of the substance: since a form's power cannot cause esse for this or that length of time unless it be in act at the time at which it causes; for a power cannot cause when it does not exist, because a power in no way regards the past.

When, therefore, it is argued, The same power can have produced something in the past which now produces something in the present or will produce something in the future. Therefore, if something has a power so as to be always, it follows that by the power by which it now is, it has always been: the consequence is denied. And when it is proved because a thing has esse as long as its power of being extends itself: it is said that this assumption does not prove the consequence. For a power of being always does not extend itself to the past, namely so as to be able to cause something in past time, but only to the future. Therefore from that very power it follows well that what has such a power, insofar as it depends on itself, will always be in the future: but not that it has been from eternity, unless it is supposed that that very power of being has existed from eternity. On account of this Saint Thomas says well that, when the production of the substance of the heavens is under discussion, such a power of being cannot be a sufficient argument for sempiternity.

III. To the third, he denies the assumption. Nor does the proof hold: for, as is clear from what was said above, without any change in God the agent it can be that he acts newly and not eternally.

To the fourth, he denies the consequence. For the intention of natural agents toward the perpetuity of species presupposes that natural agents have already been produced.

To the fifth argument, which is Aristotle's, in Book VIII of the Physics ⁵, which denies the assumption. In proof of this he says that Aristotle rather supposes the eternity of motion than proves it. For it is not necessary that every instant be a beginning and an end, unless every moment taken in time is a mean between what is prior and what is posterior in motion—which is to posit motion as eternal. Hence one who posits that motion is not eternal can say that the first instant of time is the beginning of what is future and the end of nothing past.

To the sixth, which is also Aristotle's ⁶, he denies the assumption. In proof of this, he says that when it is posited that time previously did not exist than that it exists, the word previously does not posit any part of time in reality, but only in imagination. Therefore it does not follow that, if time is posited not to exist, existence is posited.

To the seventh, it is said that the truth of those propositions has the necessity of the predicate's order to the subject. Therefore it does not compel any thing to be always: unless perhaps in the divine intellect, which apprehends their truth from eternity.