Thomas Aquinas - Summa Theologica, Part I (Prima Pars)

Reply Obj. 3: Although the truth of our intellect is caused by the thing, yet it is not necessary that truth should be there primarily, any more than that health should be primarily in medicine, rather than in the animal: for the virtue of medicine, and not its health, is the cause of health, for here the agent is not univocal. In the same way, the being of the thing, not its truth, is the cause of truth in the intellect. Hence the Philosopher says that a thought or a word is true "from the fact that a thing is, not because a thing is true." _______________________

SECOND ARTICLE [I, Q. 16, Art. 2]

Whether Truth Resides Only in the Intellect Composing and Dividing?

Objection 1: It seems that truth does not reside only in the intellect composing and dividing. For the Philosopher says (De Anima iii) that as the senses are always true as regards their proper sensible objects, so is the intellect as regards "what a thing is." Now composition and division are neither in the senses nor in the intellect knowing "what a thing is." Therefore truth does not reside only in the intellect composing and dividing.

Obj. 2: Further, Isaac says in his book On Definitions that truth is the equation of thought and thing. Now just as the intellect with regard to complex things can be equated to things, so also with regard to simple things; and this is true also of sense apprehending a thing as it is. Therefore truth does not reside only in the intellect composing and dividing.

On the contrary, the Philosopher says (Metaph. vi) that with regard to simple things and "what a thing is," truth is "found neither in the intellect nor in things."

I answer that, As stated before, truth resides, in its primary aspect, in the intellect. Now since everything is true according as it has the form proper to its nature, the intellect, in so far as it is knowing, must be true, so far as it has the likeness of the thing known, this being its form, as knowing. For this reason truth is defined by the conformity of intellect and thing; and hence to know this conformity is to know truth. But in no way can sense know this. For although sight has the likeness of a visible thing, yet it does not know the comparison which exists between the thing seen and that which itself apprehends concerning it. But the intellect can know its own conformity with the intelligible thing; yet it does not apprehend it by knowing of a thing "what a thing is." When, however, it judges that a thing corresponds to the form which it apprehends about that thing, then first it knows and expresses truth. This it does by composing and dividing: for in every proposition it either applies to, or removes from the thing signified by the subject, some form signified by the predicate: and this clearly shows that the sense is true of any thing, as is also the intellect, when it knows "what a thing is"; but it does not thereby know or affirm truth. This is in like manner the case with complex or non-complex words. Truth therefore may be in the senses, or in the intellect knowing "what a thing is," as in anything that is true; yet not as the thing known in the knower, which is implied by the word "truth"; for the perfection of the intellect is truth as known. Therefore, properly speaking, truth resides in the intellect composing and dividing; and not in the senses; nor in the intellect knowing "what a thing is."

And thus the Objections given are solved. _______________________

THIRD ARTICLE [I, Q. 16, Art. 3]

Whether the True and Being Are Convertible Terms?

Objection 1: It seems that the true and being are not convertible terms. For the true resides properly in the intellect, as stated (A. 1); but being is properly in things. Therefore they are not convertible.

Obj. 2: Further, that which extends to being and not-being is not convertible with being. But the true extends to being and not-being; for it is true that what is, is; and that what is not, is not. Therefore the true and being are not convertible.

Obj. 3: Further, things which stand to each other in order of priority and posteriority seem not to be convertible. But the true appears to be prior to being; for being is not understood except under the aspect of the true. Therefore it seems they are not convertible.

On the contrary, the Philosopher says (Metaph. ii) that there is the same disposition of things in being and in truth.

I answer that, As good has the nature of what is desirable, so truth is related to knowledge. Now everything, in as far as it has being, so far is it knowable. Wherefore it is said in De Anima iii that "the soul is in some manner all things," through the senses and the intellect. And therefore, as good is convertible with being, so is the true. But as good adds to being the notion of desirable, so the true adds relation to the intellect.

Reply Obj. 1: The true resides in things and in the intellect, as said before (A. 1). But the true that is in things is convertible with being as to substance; while the true that is in the intellect is convertible with being, as the manifestation with the manifested; for this belongs to the nature of truth, as has been said already (A. 1). It may, however, be said that being also is in things and in the intellect, as is the true; although truth is primarily in the intellect, while being is primarily in things; and this is so because truth and being differ in idea.

Reply Obj. 2: Not-being has nothing in itself whereby it can be known; yet it is known in so far as the intellect renders it knowable. Hence the true is based on being, inasmuch as not-being is a kind of logical being, apprehended, that is, by reason.

Reply Obj. 3: When it is said that being cannot be apprehended except under the notion of the true, this can be understood in two ways. In the one way so as to mean that being is not apprehended, unless the idea of the true follows apprehension of being; and this is true. In the other way, so as to mean that being cannot be apprehended unless the idea of the true be apprehended also; and this is false. But the true cannot be apprehended unless the idea of being be apprehended also; since being is included in the idea of the true. The case is the same if we compare the intelligible object with being. For being cannot be understood, unless being is intelligible. Yet being can be understood while its intelligibility is not understood. Similarly, being when understood is true, yet the true is not understood by understanding being. _______________________

FOURTH ARTICLE [I, Q. 16, Art. 4]

Whether Good Is Logically Prior to the True?

Objection 1: It seems that good is logically prior to the true. For what is more universal is logically prior, as is evident from Phys. i. But the good is more universal than the true, since the true is a kind of good, namely, of the intellect. Therefore the good is logically prior to the true.

Obj. 2: Further, good is in things, but the true in the intellect composing and dividing as said above (A. 2). But that which is in things is prior to that which is in the intellect. Therefore good is logically prior to the true.

Obj. 3: Further, truth is a species of virtue, as is clear from Ethic. iv. But virtue is included under good; since, as Augustine says (De Lib. Arbit. ii, 19), it is a good quality of the mind. Therefore the good is prior to the true.

On the contrary, What is in more things is prior logically. But the true is in some things wherein good is not, as, for instance, in mathematics. Therefore the true is prior to good.

I answer that, Although the good and the true are convertible with being, as to suppositum, yet they differ logically. And in this manner the true, speaking absolutely, is prior to good, as appears from two reasons. First, because the true is more closely related to being than is good. For the true regards being itself simply and immediately; while the nature of good follows being in so far as being is in some way perfect; for thus it is desirable. Secondly, it is evident from the fact that knowledge naturally precedes appetite. Hence, since the true regards knowledge, but the good regards the appetite, the true must be prior in idea to the good.