Thomas Aquinas, Disputed Questions on Truth (De Veritate)

1. The true is predicated from the relation of being to intellect. But the first operation by which an intellect is related to things is that in which the intellect forms the quiddities of things by conceiving their definitions. Truth, therefore, is principally and more properly found in that operation of the intellect.

2. The true is a "conformity of thing and intellect." Now, although the intellect, in joining and separating, can be conformed with things, it can also be conformed with things in understanding their quiddities. Truth, therefore, is not merely in the intellect joining and separating.

To the Contrary:

1'. In the Metaphysics we read: "The true and the false are not in things but in the mind. In regard to simple natures and quiddities, however, it is not in the mind."

2'. In The Soul the statement is made that the true and the false are not to be found in simple apprehension.

REPLY:

Just as the true is found primarily in the intellect rather than in things, so also is it found primarily in an act of the intellect joining and separating, rather than in an act by which it forms the quiddities of things. For the nature of the true consists in a conformity of thing and intellect. Nothing becomes conformed with itself, but conformity requires distinct terms. Consequently, the nature of truth is first found in the intellect when the intellect begins to possess something proper to itself, not possessed by the thing outside the soul, yet corresponding to it, so that between the two--intellect and thing--a conformity may be found. In forming the quiddities of things, the intellect merely has a likeness of a thing existing outside the soul, as a sense has a likeness when it receives the species of a sensible thing. But when the intellect begins to judge about the thing it has apprehended, then its judgment is something proper to itself--not something found outside in the thing. And the judgment is said to be true when it conforms to the external reality. Moreover, the intellect judges about the thing it has apprehended at the moment when it says that something is or is not. This is the role of "the intellect composing and dividing."

For these reasons, the Philosopher says that composition and division are in the intellect, and not in things. Moreover, this is why truth is found primarily in the joining and separating by the intellect, and only secondarily in its formation of the quiddities of things or definitions, for a definition is called true or false because of a true or false combination. For it may happen that a definition will be applied to something to which it does not belong, as when the definition of a circle is assigned to a triangle. Sometimes, too, the parts of a definition cannot be reconciled, as happens when one defines a thing as "an animal entirely without the power of sensing." The judgment implied in such a definition--"some animal is incapable of sensing"--is false. Consequently, a definition is said to be true or false only because of its relation to a judgment, as a thing is said to be true because of its relation to intellect.

From our discussion, then, it is clear that the true is predicated, first of all, of joining and separating by the intellect; second, of the definitions of things in so far as they imply a true or a false judgment. Third, the true may be predicated of things in so far as they are conformed with the divine intellect or in so far as, by their very nature, they can be conformed with human intellects. Fourth, true or false may be predicated of man in so far as he chooses to express truth, or in so far as he gives a true or false impression of himself or of others by his words and actions; for truth can be predicated of words in the same way as it can be predicated of the ideas which they convey.

Answers to Difficulties:

1. Although the formation of a quiddity is the first operation of the intellect, by it the intellect does not yet possess anything that, properly speaking, is its own and can be conformed to the thing. Truth, accordingly, is not found in it.

2. From this the solution of the second difficulty is clear.