Commentaria in Summam contra Gentiles, Liber II

As to the third, there are set forth the arguments of those wishing to demonstrate that the world is not eternal ¹. And because these are not demonstrative arguments, though they have probability, there are also set forth the responses of those who posited the eternity of the world, lest the faith, which holds that the world began, should seem to rest on empty arguments.

On this point, however, Saint Thomas does two things: first, he sets forth ineffective arguments and resolves them; second, he sets forth a certain argument which he himself considers more effective ².

I. As to the first, he touches on six arguments. The first is that a cause must precede its effect in duration.

The second reason is that all being was made from nothing. And consequently it is necessary that it have esse after non-being.

The third is, because infinite essences have been traversed.

The fourth is, because an infinite addition would thereby be made.

The fifth is, because among efficient causes one would proceed to infinity.

The sixth is, because there are infinitely many souls.

II. But as to the first of these, he says the assumption is true in those things which act by means of motion, but not in those things which act instantaneously.

To the second, he says that what is created comes to be from nothing, that is, not from any being. From this, however, it does not follow that it comes to be after non-being.

Regarding this response, in which St. Thomas seems to deny that what is created comes to be after non-being, note that this is to be understood according to the order of duration, not according to the order of nature. For it is not the case that what is created necessarily has esse after non-being by a posteriority of duration; but it does have such a posteriority of nature.

2. But a doubt arises. For those things which have between them an order of nature only, and not of duration, are simultaneous in duration. If, therefore, non-being precedes being in nature alone, they will be simultaneous in duration; and thus the same thing will at once be and not be.

It is answered that something's belonging to one thing prior in nature to another can be understood in two ways. In one way, because it is presupposed by that other thing in a subject, and it is necessary for it to be pre-understood as being in such a subject. In another way, because, if the subject were left to itself alone, that would belong to it, but not the other. Those things which have an order of nature in the first way are simultaneous in duration; but not those which have such an order in the second way. Now non-being is said to belong to a thing prior in nature than esse in the second way, namely because, if it were left to itself, it would have non-being; but not in the first way. Therefore the argument does not follow.

III. To the third, he says that there would indeed be infinitely many, each of which would have been traversed, because it would be finite; but not all of them would have been traversed at once, because a traversal requires two extremes.

To the fourth, he says that nothing prevents an addition from being made to the infinite, insofar as it is finite.

To the fifth, he says that it is impossible for agent causes to proceed to infinity, according to the philosophers, in causes acting simultaneously, which are called per se infinite causes; but not in causes not acting simultaneously, which are called infinite per accidens.

2. Concerning this response, it must be noted that it is one thing to say that some single cause is per se the cause of some effect, and another thing to say that several causes of one effect have among themselves a per se and essential order in causing such an effect. For in order that something be the per se cause of another, it is required that the effect not be able to proceed except from that cause, speaking of a complete cause. In this way Socrates is the per se cause of Plato: because Plato cannot be generated except from Socrates. But in order that several causes be per se and essentially ordered with respect to one effect, it is required that the second cause not cause except as moved by the first, and that all cause simultaneously. On account of this, if there were infinitely many causes of one effect per se and essentially ordered, there would have to be infinitely many actions existing simultaneously, on which the effect would depend. But the philosophers consider this impossible. Therefore, according to them, it is impossible for anything to depend on infinitely many essentially ordered causes.

But if there were infinite causes, one of which was indeed per se the cause of another, and yet they did not have among themselves an essential order in causing some effect, such an infinity would be related to the effect only per accidens, as Saint Thomas says. And therefore it makes no difference to the effect that causes of this kind be infinite. And in this way it is not unfitting for there to be an infinite number of agent causes. For although one man generating has a per se order to another man generating absolutely considered, and he to another, and so on to infinity, if generation were eternal; nevertheless not all the men who preceded have a per se order among themselves toward generating this man. For one man does not generate insofar as he is begotten by that other: since even if he were not begotten by him, he could still generate. Nor do all the men who preceded act together all at once toward this generation: since they are not all together at once.

IV. To the sixth, he says that this argument is not very useful: although it is difficult, and therefore it is solved in different ways by different people. For some posited that the soul does not exist after the body. Others, that of the souls only the intellect remains, either agent or possible. Still others posited a circulation of souls. Yet others do not consider it an inconvenience for there to be an actual infinite in things that have no order among themselves.

Note that when Saint Thomas says that the very argument for the infinity of souls is difficult and yet not very useful, he says this because, even if all the things presupposed by this argument are granted—namely, that souls are multiplied with the multiplication of men, and that the soul is immortal, and also that no infinite exists in act, all of which true philosophy seems to hold—it is difficult to show how the world could be eternal; but nevertheless the argument is useless, because the things which the argument itself presupposes are not conceded by everyone, since some deny one of them, others another; and therefore it has little force among the philosophers themselves. But on this matter a fuller discussion will be given below, chapter 81.

V. As to the second point ³, he introduces an argument which he himself considers more efficacious: namely, that because things have not always existed, the divine goodness—which is the end of the divine will, and the divine power—is most especially made manifest. For it is clearly shown by the beginning of creatures that other things have their esse from God; that He does not act from the necessity of nature; and that His power is infinite. It was also most fitting to the divine goodness ⁴ that it should give to created things a beginning of duration.

2. Concerning this proposition, The end of the divine will in the production of things is its goodness insofar as it is manifested through created effects, it must be noted that it can have a twofold sense. First, so that the term insofar as specifies the formal reason of the divine goodness by which it is the end of the production of creatures. And then the sense is that the very manifestation of the divine goodness is the formal reason of the divine goodness under which it has that it is an end. And this sense is false, nor is it intended by Saint Thomas. Rather, he himself, in the De potentia, q. 3, a. 15, ad 14, speaking of the communication of the divine goodness, says that the communication of the divine goodness is not the ultimate end, but the very goodness itself, out of love for which God wills to communicate it: since He does not act as one desiring to have what he does not have, but as one willing to communicate what he has.

The second sense is that inasmuch as expresses the condition of what is produced and is willed on account of the end. For the sense, taken in this way, is that God wills creatures for the sake of his goodness insofar as his goodness is manifested through them: so that he wills creatures with reference to his goodness for no other reason than that they are manifestive of it; for out of love for his own goodness he wills its communication and manifestation through creatures. Just as if we were to say that the sick man wills medicine for the sake of health for no other reason than that through it health can be caused: for the ability to cause health would be a reason and condition holding on the side of what is desired on account of the end, but it would not be the reason for health itself as end. And this sense is true and this is what is intended. For since God acts not from appetite for an end but from love of it, as is said in Potentia above, divine goodness as loved is the reason and final cause on account of which he wills to produce creatures, insofar as in the very production of creatures divine goodness—which he loves supremely—is manifested: so that he would not will the production of creatures unless they manifested divine goodness; just as the sick man does not will medicine except insofar as it is causative of health.

From all that has been said above, Saint Thomas deduces that the various errors of the philosophers are refuted—those who posited something eternal besides God, concerning which Book I and Book VIII of the Physics and Book I of the Heavens treat.

VI. Besides the arguments given above, by which some have proved that the world was not always in existence, there is the argument brought forward by Scotus, Book II, distinction 1, question 3 ⁵, and by Capreolus, on Book II of the Sentences, distinction 1, question 1 ⁶, which is as follows. If time had always existed and would always exist in the future, it would follow that a part would be greater than the whole. This is contrary to the first and most well-known principle. Therefore, and so on.

The consequence is proved. And it is supposed that then the past and the future will be equal, because each will be infinite. Let noon of this day therefore be A, and let noon of tomorrow's day be B. Then thus: at whatever time the past relative to B is greater, the future relative to B is greater, because they are equal. But relative to the future at A, the past relative to B is greater. Therefore, relative to the future at A, the future relative to B is greater. But the future relative to B is a part of the future relative to A. Therefore, and so on. — The minor premise of the principal argument is proved: whatever time is greater than the past relative to A is greater than the future relative to A, since they are equal. But the past relative to B is greater than the past relative to A. Therefore it is greater than the future relative to A.

2. For the solution of this argument, it must be considered that equal, greater and lesser are always taken according to the terms of quantities: for one quantity is said to be equal to another because its terms do not exceed the terms of the other. Hence, where quantities are posited as having no terms, as happens in infinite quantities, there is properly no equality or inequality. Nevertheless, infinite quantities can in some way be called equal or unequal on one side only, if they are compared according to that side in which they are finite; but not if they are compared according to the side from which they are posited as infinite.

It must be considered, second, that if a comparison of this kind is to be made, the magnitudes and the terms must be taken from the same side: namely, either from the side of the beginning or from the side of the end. For if two lines are taken, one of which is infinite toward the east and the other infinite toward the west, both terminated at the middle of the world, they will not be said to be equal: because that middle point is not the terminus of each in the same way, but is the beginning of one and the end of the other. But rightly so, if two lines are taken that are infinite on the side of the east and terminated at equal points toward the west, they could in some way be said to be equal. Similarly, therefore, if two infinite times are posited, one infinite on the side of before and the other on the side of after, even though they are terminated at the same instant, they cannot be said to be equal; but rightly so if both are infinite on the same side and finite on the same side.

To the argument, therefore, the consequence is denied. In proof of this, the supposition on which the argument rests is denied, namely, that past time and future time, each of which is posited as infinite, are equal; and consequently that what is greater than one is also greater than the other; and that whatever one is greater than, the other is greater than as well. For in them the terms are not taken from the same side, so that a comparison according to equality or inequality could be made.

3. But a doubt arises concerning what was said, namely that times finite on the same side, if they terminate at the same instant, are equal. For thus it seems that in infinite time on the side before, the days are equal to the years, since they terminate at the same instant. But no one would say this.

It is answered that days and years can be taken in two ways: in one way, by taking the time of the years as one continuum, and likewise the time of the days; in the other way, taking each as discrete, according as the continuous time itself is divided into days and years. In the first way, it is not unfitting for days to be equal to years: indeed, the time of days and of years is one and the same. In the second way, days are something greater than years are, and are not equal to them. Just as on one and the same line there are more cubit-long parts than two-cubit-long parts, if both are taken as discrete quantities: but if they are taken as a continuum, they are one and the same quantity. For as Saint Thomas says in the Third Part, q. 10, art. 3, ad 3, although nothing in some order is greater than an infinite thing in that order, nevertheless that infinite can be taken as greater outside that order. And so, although in the order of months nothing is greater than infinitely many months, nevertheless an infinity in the order of days is something greater than infinitely many months, and infinitely many days are more than infinitely many months.

But when it is said that they are terminated at the same terminus, this is said to be untrue insofar as they are discrete. For their end, as such, is not an instant but a unity. Hence in the order of months, the unity of the last month is the terminus; and in the order of days, the terminus is that one day which is last, or its unity.

The other things that cause difficulty in this matter, see in Capreolus, at the place cited above.