Commentaria in Summam contra Gentiles, Liber I

After Saint Thomas has shown that truth is in God, he now shows what the divine truth is like, ¹. Concerning this he does two things: first, he shows that it is most pure; second, that it is first and highest, in the following chapter.

First, therefore, he shows that in God there is the purest truth, to which, namely, no deception or falsity can be admixed.

And it is proved first as follows. Truth, namely abstract and subsistent, does not admit falsehood, just as whiteness does not admit blackness — understand this, if whiteness were subsistent, as is signified by the abstract term. God is truth itself. Therefore, and so on.

Second. The divine intellect is related in the manner of an intellect knowing what a thing is. Therefore, etc. — The consequence is proved. Because in that intellect there is no falsity, just as neither in the sense with respect to its proper sensible object, except, namely, per accidens, as was said above ² But in God nothing can be per accidens.

Third. The divine intellect is not discursive. Therefore, etc. — The consequence is proved. Because, since there is no error in first principles, there will be error only in conclusions, insofar as the intellect runs on from principles to conclusions.

But someone might say that error occurs not only with respect to conclusions which the intellect reaches by discursive reasoning, but also with respect to propositions taken in themselves. For we experience ourselves being deceived about certain propositions even when we are not reasoning discursively: as when we say and judge that Socrates, who is present, is Plato.

It can be said that in deception there is always some discursive reasoning, even if perhaps it sometimes occurs in imperceptible time. For when Socrates, bearing a resemblance to Plato, say, in the roundness of his face, presents himself to me, the intellect argues imperceptibly: This one has a round face; therefore he is Plato. And so with other cases.

Fourth. All knowable things are compared to the divine intellect as properly and per se knowable, that is, as its proper and per se object. Therefore, etc. — The consequence is proved. Because in such a case the cognitive power does not err. —

The antecedent is proved. For the divine intellect is at the summit of sublimity: that is, it has no cognitive power more sublime than itself, and it possesses every sublimity that can be, namely the infinite. Now the higher a cognitive power is, the more its object contains beneath itself: as is evident in the case of the common sense and imagination with respect to the particular sense. Therefore all knowables must be contained under the proper object of the divine intellect.

Fifth. The divine intellect is by its nature more perfect than the human intellect perfected in its intellectual power, such as wisdom and knowledge, since it itself is at the end and summit of perfection. But this intellect does not speak falsely, but always truly: for it belongs to a virtue to render its act good; and to speak truth is a good act of the intellect. Therefore, etc.

Sixth. If the divine intellect were said to be false, the falsity on account of which it would be said to be false would not be in God, but in things. But neither is it in things: because each thing has as much of truth as it has of esse. Therefore, etc. — The antecedent is proved. Because the comparison of the divine intellect to things is such as that of things to the human intellect: since, just as the truth of the human intellect is measured by things, so conversely things are measured by the divine intellect, as God is the cause of things through his knowledge. Therefore, since things are not said to be false except on account of the falsity of the human intellect, namely insofar as they are apt to give rise to a false estimation of themselves, or because they are signified by a false intellect; conversely the divine intellect would be said to be false on account of the falsity of things, namely insofar as they did not imitate the form of the divine intellect.

Note, for the falsity of the consequent, from the doctrine of Saint Thomas in the place cited above ³, that with respect to the divine intellect things cannot be called false, since whatever happens in things proceeds from the ordering of the divine intellect—except perhaps in voluntary agents, in whose power it is to withdraw themselves from the order of the divine intellect, insofar as it is the cause of things. Hence there is no thing which, according to all the being existing in itself, is not conformed to the divine intellect.