Appendix 34.
(901) [Indication and perception in sensation]
Hearing and smell indicate distant bodies, but I am not considering these senses under this aspect. I am discussing them only in so far as they receive the direct sensation of sound and smell. In the following Chapter [12], I will deal with sight in so far as it indicates distant bodies, but not with hearing and smell because it is easy to apply the same observations to them as to sight. It is sufficient to observe here that one of the greatest sources of error in discussing the senses is to confuse direct perception with the indication given by perception, and to claim that perception gives what in fact is given only by indication, just as it is erroneous to confuse the knowledge we obtain about bodies from different senses. Reid, for example, in his attempt to rebut Locke's teaching that the primary qualities we perceive of bodies are likenesses of the bodies themselves, argues as follows:
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Taking it for granted that, by the ideas of primary and secondary qualities, he [Locke] means the sensations they excite in us, I observe that it appears strange, that sensation should be the idea of a quality in body, to which it is acknowledged to bear no resemblance. If the sensation of sound be the idea of that vibration of the sounding which occasions it, a surfeit may, for the same reason, be the idea of a feast. |
I do not know what Locke might have replied to these words, but in my opinion they are foreign to the discussion. We need to bear in mind:
1. The sensation of sound is direct. On the other hand, we do not in any way perceive the vibration of the sonorous body with our hearing except as a result of an association of ideas through which, when we hear the sound, we remember the oscillation of the strings or of the sonorous body which we have perceived at other times with touch and sight. It is therefore impossible for sound to represent and imitate what it merely arouses in our memory. When I say that the perceived primary qualities of a body resemble the body, I am indicating something totally different from what Reid is saying here.
2. The primary qualities are perceived only confusedly by hearing, smell and taste. We cannot therefore appeal to these senses to discover the likeness of which I am speaking.
3. It is false to say that the first qualities, when perceived, are sensation; they are only a part of sensations, the extrasubjective part.
4. Finally, it is totally inexact and false to say that a sensation is an idea of a thing. Such language may have been tolerated by Locke, but in itself it can lay no claim to tolerance. As I have shown, there is an infinite distance between ideas and sensations.