Thomas Aquinas, Disputed Questions on Truth (De Veritate)

1. As is said in The Soul: "The intellect is always correct." Now, since the intellect is the superior part of man, his other parts must also pursue correctness--just as the disposition of lower bodies in the universe depends on the motion of the higher bodies. Therefore, sense, which is the inferior part of the soul, will also always be correct; there is, then, no falsity in it.

2. Augustine says: "Our eyes do not deceive us: they can report to the mind only their own modification. And if all the bodily senses report as they are affected, I do not know what more we can require of them." Hence, there is no falsity in the senses.

3. Anselm says: "It seems to me that truth or falsity is not in the sense but in opinion." This confirms our thesis.

To the Contrary:

1'. Anselm says: "Truth is, indeed, in our senses, but not always; for they sometimes deceive us."

2'. According to Augustine: "A thing is called false because it is far from being a likeness of the true, even though it does in some way imitate the true." Now, a sense has at times a likeness of certain things other than they are in reality. For example, when the eye is pressed, one thing is sometimes seen as two. Consequently, there is falsity in sense.

3'. The answer was given that sense is not deceived with regard to proper sensibles, but only with regard to common sensibles.--On the contrary, whenever something is apprehended about a thing other than it is, the apprehension is false. Now, when a white body is seen through a green glass, the sense apprehends it other than it is, for it sees it as green and judges accordingly--unless a higher judgment is present, detecting the falsity. Therefore, sense is deceived even with regard to proper sensibles.

REPLY:

Our knowledge, taking its start from things, proceeds in this order. First, it begins in sense; second, it is completed in the intellect. As a consequence, sense is found to be in some way an intermediary between the intellect and things; for with reference to things, it is, as it were, an intellect, and with reference to intellect, it is, as it were, a thing. Hence, truth or falsity is said to be in sense in two respects. The first is in the relation of sense to intellect. In this respect, the sense is said to be true or false as a thing is, namely, in so far as it causes a true or false judgment in the intellect. The second respect is in the relation of sense to things. In this, truth and falsity are said to be in sense as they are said to be in the intellect, namely, in so far as the sense judges that what is, is or is not.

Hence, if we speak of a sense in the first meaning, in a way there is falsity in sense, and in a way there is not. For sense, in itself, is a thing; and it also passes judgment on other things. If, in its relation to the intellect, it is considered as a thing, then there is no falsity in sense; for a sense reveals its state to the intellect exactly as it is affected. Hence, Augustine says, in the passage referred to: "The senses can report to the mind only how they are affected." On the other hand, if sense is considered in its relation to the intellect as representing some other thing, it may be called false in view of the fact that it sometimes represents a thing to the intellect other than it actually is. For, in that case, as we said about things, it is such as to cause a false judgment in the intellect--but not necessarily, since the intellect judges on what is presented by sense just as it judges about things. Thus, in its relation to the intellect, sense always produces a true judgment in the intellect with respect to its own condition, but not always with respect to the condition of things.

If sense is considered in its relation to things, however, then there are truth and falsity in sense in the manner in which these are in the intellect. For truth and falsity are found primarily and principally in the judgment of the intellect as it associates and dissociates, and in the formation of quiddities, only in their relation to the judgment following upon this formation. Hence, truth and falsity are properly said to be in sense inasmuch as it judges about sensible objects, but inasmuch as it apprehends a sensible object, there is not properly truth or falsity, except in the relation of this apprehension to the judgment, in so far as a judgment of this or that sort naturally follows upon a particular apprehension.

The judgment of sense about certain things--for example, proper sensibles--takes place spontaneously. About other things, however, it takes place by means of a certain comparison, made in man by the cogitative power, a sense power, whose place in animals is taken by a spontaneous estimation. This sensitive power judges about common sensibles and accidental sensibles. However, the spontaneous action of a thing always takes place in one way, unless by accident it is impeded intrinsically by some defect or extrinsically by some impediment. Consequently, the judgment of sense about proper sensibles is always true unless there is an impediment in the organ or in the medium; but its judgment about common or accidental sensibles is sometimes wrong. Thus, it is clear how there can be falsity in the judgment of sense.

As regards the apprehension of the senses, it must be noted that there is one type of apprehensive power, for example, a proper sense, which apprehends a sensible species in the presence of a sensible thing; but there is also a second type, the imagination, for example, which apprehends a sensible species when the thing is absent. So, even though the sense always apprehends a thing as it is, unless there is an impediment in the organ or in the medium, the imagination usually apprehends a thing as it is not, since it apprehends it as present though it is absent. Consequently, the Philosopher says: "Imagination, not sense, is the master of falsity."

Answers to Difficulties:

1. In the macrocosm the higher bodies do not receive anything from the lower. Just the opposite occurs. In man, the microcosm, the intellect, which is superior, does receive something from sense. Hence, no parallel can be made.

2-3. Our previous discussion* will easily answer the other difficulties.