Commentaria in Summam contra Gentiles, Liber I

After Saint Thomas has treated of the absolute necessity of the divine will, he now treats of its conditional necessity¹. Concerning this he does two things: first, he shows in respect of what things it is necessary; second, he draws two corollaries².

I. As to the first, he proposes this conclusion: Although God wills nothing among caused things necessarily in an absolute sense, nevertheless He wills something necessarily by condition or supposition.

For an understanding of this point, it must be considered, according to the doctrine of Saint Thomas in the First Part, q. 19, a. 3, and in De Veritate, q. 23, a. 4, ad 1, that the absolutely necessary is so called on account of a necessary relation of the terms to one another, as that man is an animal; whereas the necessary ex suppositione is what is not necessary of itself, but only given something else posited, as that Socrates ran, supposing that he did run.

Regarding which distinction it should be noted that, just as something is said to be possible either by reason of some power existing in reality, or on account of the non-repugnance of the terms; so too the necessary can be said to be so either by reason of a certain necessity existing in reality (for necessity is a condition of a thing), or by reason of a necessary relation of the terms. But, just as what is possible by reason of some power existing in reality includes logical possibility—for if something is in potency to another thing, that thing is not repugnant to it in itself—so too what is necessary by reason of a necessity existing in reality includes logical necessity. For if a thing has from its own nature that it be such necessarily, it must be that this has a necessary relation to it, so that its removal is impossible. And if it has this not indeed by reason of its nature absolutely, but from some added condition, it is necessary that this have a necessary relation to it upon such a condition being posited. Hence it is then called simply and absolutely necessary when the predicate has a necessary relation to the subject according to its nature as considered: which is for the terms to have a necessary relation from their formal significates. But it is called necessary ex suppositione when the predicate does not have a necessary relation to the subject according to its nature as considered, although it has one when considered under some condition.

II. The conclusion is therefore proved first as follows. The divine will is immutable. Therefore, given that it wills something, it is necessary ex suppositione that it wills thus. — The consequence is proved: because in anything immutable, if something belongs to it once, it cannot afterwards fail to belong to it; since we say a thing is moved when it is otherwise disposed now than before.

Note that immutability is not required for everything necessary ex suppositione: for, while Socrates is sitting, it is necessary that he sit; and yet Socrates can be changed from sitting to not sitting. But from every immutable thing there does follow what is necessary ex suppositione: because the necessity of immutability is itself also a necessity ex suppositione; just as every inferior includes the superior in its definition, as we have said elsewhere.

2. Concerning this argument a doubt arises. For, although in an immutable thing, if something real is once present, it cannot afterwards fail to be present; nevertheless, if something of reason is present, it can afterwards fail to be present: for it is evident that at one time there was in God the relation of actually creating the universe, but now such a relation is not in God, especially according to those who hold that creation is distinct from conservation. But when I say, God wills this creature, I state an act of the divine will together with a relation of reason to the creature: and if he were to cease willing that creature, such a relation to the creature would cease to be, but not the act of the will itself, which is the divine essence itself; just as, after God created the universe, the relation of reason to the universe ceased, but not the substance of the act of creating itself. Therefore it stands with God's immutability that he cease to will what he once willed. Therefore it is argued badly from the divine immutability that, if God wills something, he wills it necessarily ex suppositione.

It is answered, and first it is said that certainly from the mere cessation of the respect of reason in God, God is not said to change: because a being of reason, insofar as it is such, posits nothing in God.

It is said secondly that the proposition of St. Thomas adduced is to be understood of real being. And the argument proceeds thus: if God could not will what He wills, not only would the respect of reason cease, but the very act of willing itself; and thus it would follow that God is really changed. Hence the minor is denied as regards its second part. — But when it is proved by a parallel from creation, I say that the same reasoning does not hold for creation and volition. For, since creation has the mode of a transient action, the relation which accompanies creation requires some real disposition co-existing in the term of the creation. Therefore by the mere change of the term away from that disposition which it co-requires in the term, the relation itself ceases, even with no change made on the part of the act: for as soon as the thing ceases to receive esse anew, inasmuch as it formally terminated the relation of creation, the relation itself ceases to be; for the variation of one extreme suffices for the variation of a relation. Volition, however, is an immanent action: and the relation which accompanies it, as such, does not require in the term of the volition any real disposition that could be removed. Therefore it cannot cease except through the cessation of the act in which it is founded. Hence, if God, while willing, were to cease having the habitude of one willing toward what He willed, it is necessary that the very act of willing also cease. But since this is impossible, on account of God's immutability, that the act of divine volition should cease, therefore it is likewise impossible that God cease to will what He once willed. And so it is evident that St. Thomas argues most fittingly from the divine immutability that God wills, from the necessity of supposition, whatever He wills.

III. Second. God's willing something is eternal. Therefore, etc. — The antecedent is proved: because just as God's esse is measured by eternity, so too is His willing. — The consequence is proved: because everything eternal is necessary, either simply or on a supposition—that is, inasmuch as it cannot be changed.

Third. God cannot now not will what is posited as having willed, because his will cannot be changed. Therefore he could never have not willed whatever he willed, since whatever God could do, he can do, as his power is not diminished, just as neither is his essence. Therefore it is necessary ex suppositione that he willed whatever he willed. But it is not necessary absolutely; rather it is possible in the manner described in the preceding chapter, namely by logical possibility.

Note that when we say God could not have not willed what he willed, this must be understood of the possible according to some power separated from the act: for there was never in God a power by which he might not have willed what he willed from eternity, on account of the perfect actuality and immutability of his esse. For if it were understood of the possible according to the non-repugnance of the terms, it would be false. For it is not repugnant to God not to have willed something in the divided sense. Indeed, it is always true to say, God can not will this, some thing being shown that he wills: because it is always true that the predicate has no repugnance to the subject; and the act of the divine will never passes into the past.

Hence there is no contradiction when he says that God could never have failed to will whatever He wills, and when he says below that it is possible for God to have willed and not to will whatever He willed and wills. For in the first place he speaks of the possible as said from some power considered apart from act; in the second, however, of the logical possible. Hence also that proposition, "Whatever God could do, He can do," is to be understood of the possible as said from some active power: for to whatever the divine power could extend itself, it can extend itself to the very same thing in number, since its power is not diminished. It could also be understood of logical power: namely, because what did not conflict with God absolutely does not even now conflict with Him, although by supposition it conflicts.

2. But then a doubt arises. For God was able to produce a past day, since in fact he did produce it. And yet now he cannot produce it, because a successive continuum cannot be restored as the same in number, as is said in Quodlibet IV, a. 5 ³. Therefore not everything that he was able to do can he do.

It is answered, according to the teaching of the Prima Pars itself, q. 25, a. 4, ad 2, that whatever God could do, He can do, insofar as it depends on His power itself: since His power admits of no variation. Not however insofar as it depends on the thing to be done: because certain things had the character of possibles while they were yet to be made, which, once made, fall short of the character of the possible. Therefore the proposition is to be understood thus: Whatever God could do among the number of possibles, He can do, if that possible remains: but not if it passes into being impossible to produce.

IV. Fourth. Whoever wills something necessarily wills those things that are necessarily required for it, unless there is a defect on his part, whether through ignorance or through a passion drawing him away from right reason regarding what is ordered to the end. But neither can be said of God. Therefore, if God, in willing himself, wills other things, he must will everything that is necessarily required for what is willed: just as, supposing that he wills man to be, he must will the rational soul to be.