Bertrand Russell: The Analysis of Mind

6. LECTURE VI. INTROSPECTION (continued)

I wish to distinguish three distinct questions, any one of which may be meant when we ask whether introspection is a source of knowledge. The three questions are as follows:

(1) Can we observe anything about ourselves which we cannot observe about other people, or is everything we can observe PUBLIC, in the sense that another could also observe it if suitably placed?

(2) Does everything that we can observe obey the laws of physics and form part of the physical world, or can we observe certain things that lie outside physics?

(3) Can we observe anything which differs in its intrinsic nature from the constituents of the physical world, or is everything that we can observe composed of elements intrinsically similar to the constituents of what is called matter?

Any one of these three questions may be used to define introspection. I should favour introspection in the sense of the first question, i.e. I think that some of the things we observe cannot, even theoretically, be observed by any one else. The second question, tentatively and for the present, I should answer in favour of introspection; I think that images, in the actual condition of science, cannot be brought under the causal laws of physics, though perhaps ultimately they may be. The third question I should answer adversely to introspection I think that observation shows us nothing that is not composed of sensations and images, and that images differ from sensations in their causal laws, not intrinsically. I shall deal with the three questions successively.

(1) PUBLICITY OR PRIVACY OF WHAT IS OBSERVED. Confining ourselves, for the moment, to sensations, we find that there are different degrees of publicity attaching to different sorts of sensations. If you feel a toothache when the other people in the room do not, you are in no way surprised; but if you hear a clap of thunder when they do not, you begin to be alarmed as to your mental condition. Sight and hearing are the most public of the senses; smell only a trifle less so; touch, again, a trifle less, since two people can only touch the same spot successively, not simultaneously. Taste has a sort of semi-publicity, since people seem to experience similar taste-sensations when they eat similar foods; but the publicity is incomplete, since two people cannot eat actually the same piece of food.