Thomas Aquinas, Disputed Questions on Truth (De Veritate)

1. The human intellect knows by abstracting the form from matter. Now, the abstraction of a form from matter does not destroy its particularity, for mathematics, which abstracts from matter, considers particular lines. Consequently, the fact that our intellect is immaterial does not prevent it from knowing singulars.

2. Singulars are not distinct according to their participation in a common nature, for the fact that many men participate in the species of man makes them one man. Therefore, if our intellect knows only universals, it does not know one singular as distinct from another. Consequently, our intellect would not direct us to those objects of operations in regard to which we are guided by choice; for choice presupposes the distinction of one thing from another.

3. But it was said that our intellect knows singulars inasmuch as it applies the universal form to some particulars.--On the contrary, our intellect cannot apply one thing to another unless it already knows each. Consequently, knowledge of the singular precedes the application of the universal to the singular. Therefore, the above-mentioned application cannot be the reason why our intellect knows the singular.

4. According to Boethius, whatever a lower power can do a higher power can do. Now, as he says in the same place, the intellect is superior to imagination and the imagination is superior to sense. Therefore, since sense knows the singular, our intellect should also know it.

To the Contrary:

Boethius says: "What is sensed is singular, what is understood is universal."

REPLY:

All action is determined by the condition of the form of the agent, the principle of action, just as the process of heating is measured by the amount of heat. Now, the likeness of the thing known, by which the knowing power is informed, is the principle of actual knowledge, just as heat is of heating. Hence, all cognition is necessarily determined by the limitations of the form in the knower. Consequently, since the likeness of a thing existing in our intellect is received as separated from matter and all the conditions of matter, which are the principles of individuation, it follows that our intellect, of itself, does not know singulars but only universals. For every form as such is universal, unless it happens to be a subsistent form, which, from the very fact of its being subsistent, is incommunicable.

It happens, however, that our intellect knows the singular indirectly. For, as the Philosopher says, phantasms are related to our intellect as sensible objects are related to sense and as colors outside the soul are related to sight. Therefore, just as the species in the sense is abstracted from things themselves and by its means the cognition of the sense is extended to the sensible things themselves, so also our intellect abstracts the species from the phantasms, and, by means of this species, its cognition is extended, in a certain sense, to the phantasms.

There is, however, this difference: The likeness in sense is abstracted from the thing as from an object of knowledge, and, consequently, the thing itself is directly known by means of this likeness. The likeness in the intellect, however, is not abstracted from the phantasm as from an object of knowledge but as from a medium of knowledge--after the manner in which our sense receives the likeness of a thing which is in a mirror; it is directed to it not as to a thing but rather as to a likeness of a thing. Consequently, from the species which it receives, our intellect is not applied directly to knowing the phantasm but rather the thing whose phantasm is presented. Nevertheless, by a certain reflection our intellect also returns to a knowledge of the phantasm itself when it considers the nature of its act, the nature of the species by which it knows, and, finally, the nature of that from which it has abstracted the species, namely, the phantasm. It is like the case of sight, which is brought through a likeness received from a mirror directly to a knowledge of the thing reflected, but by a sort of reflection to the image itself in the mirror. Therefore, inasmuch as our intellect, through the likeness which it receives from the phantasm, turns back upon the phantasm from which it abstracts the species, the phantasm being a particular likeness, our intellect gets some kind of knowledge of the singular because of its dynamic union with the imagination.

Answers to Difficulties:

1. There are two kinds of matter from which abstraction is made: intelligible matter and sensible matter--as is clear from the Metaphysics. I call that matter intelligible which is considered in the nature of a continuum, and sensible, that which is physical matter. Each, however, can be taken in two ways: as designated and as not designated. I call matter designated if it is considered together with the determination of its dimensions, that is, with these or those dimensions. I call it not designated, however, if it is considered without the determination of its dimensions. In this connection, it must be noted that designated matter is the principle of individuation, from which every intellect abstracts inasmuch as it is said to abstract from the here and now. The intellect of the natural philosopher, however, does not abstract from non-designated sensible matter; for it considers man, flesh, and bone, in whose definitions non-designated sensible matter is included. The intellect of the mathematician, however, abstracts entirely from sensible matter, though not from non-designated intelligible matter. Hence, it is clear that abstraction, which is common to all intellects, makes a form universal.

2. According to the Philosopher, in us the intellect is not the only motive principle. The imagination is also such, and, by its means, the universal knowledge of the intellect is applied to some particular thing to be done. For this reason, the intellect is, as it were, a remote mover; but particular reason and the imagination are proximate movers.

3. Man has prior knowledge of singulars through imagination and sense. Consequently, he can apply his universal intellectual knowledge to a particular; for, properly speaking, it is neither the intellect nor the sense that knows, but man that knows through both--as is clear from The Soul.

4. What a lower power can do a higher power can do; not in the same, but in a more noble, way. Consequently, the intellect knows the same thing that sense knows, but in a more noble, because a more immaterial, way. Hence, it does not follow that the intellect knows the singular if the senses know it.