History of Western Philosophy - Bertrand Russell [407]
The arguments with regard to time are essentially the same, except that arithmetic replaces geometry with the contention that counting takes time.
Let us now examine these arguments one by one.
The first of the metaphysical arguments concerning space says: 'Space is not an empirical concept abstracted from external experiences. For in order that certain sensations may be referred to something outside me [i.e. to something in a different position in space from that in which I find myself], and further in order that I may be able to perceive them as outside and beside each other, and thus as not merely different, but in different places, the presentation of space must already give the foundation [zum Grunde liegen].' Therefore external experience is only possible through the presentation of space.
The phrase 'outside me [i.e. in a different place from that in which I find myself]' is a difficult one. As a thing-in-itself, I am not anywhere, and nothing is spatially outside me; it is only my body as a phenomenon that can be meant. Thus all that is really involved is what comes in the second part of the sentence, namely that I perceive different objects as in different places. The image which arises in one's mind is that of a cloak-room attendant who hangs different coats on different pegs; the pegs must already exist, but the attendant's subjectivity arranges the coats.
There is here, as throughout Kant's theory of the subjectivity of space and time, a difficulty which he seems to have never felt. What induces me to arrange objects of perception as I do rather than otherwise? Why, for instance, do I always see people's eyes above their mouths and not below them? According to Kant, the eyes and the mouth exist as things in themselves, and cause my separate percepts, but nothing in them corresponds to the spatial arrangement that exists in my perception. Contrast with this the physical theory of colours. We do not suppose that in matter there are colours in the sense in which our percepts have colours, but we do think that different colours correspond to different wave-lengths. Since waves, however, involve space and time, there cannot, for Kant, be waves in the causes of our percepts. If, on the other hand, the space and time of our percepts have counterparts in the world of matter, as physics assumes, then geometry is applicable to these counterparts, and Kant's arguments fail. Kant holds that the mind orders the raw material of sensation, but never thinks it necessary to say why it orders it as it does and not otherwise.
In regard to time this difficulty is even greater, because of the intrusion of causality. I perceive the lightning before I perceive the thunder; a thing-in-itself A caused my perception of lightning, and another thing-in-itself B caused my perception of thunder, but A was not earlier than B, since time exists only in the relations of percepts. Why, then, do the two timeless things A and B produce effects at different times? This must be wholly arbitrary if Kant is right, and there must be no relation between A and B corresponding to the fact that the percept caused by A is earlier than that caused by B.
The second metaphysical argument maintains that it is possible to imagine nothing in space, but impossible to imagine no space. It seems to me that no serious argument can be based upon what we can or cannot imagine; but I should emphatically deny that we can imagine space with nothing in it. You can imagine looking at the sky on a dark cloudy night, but then you yourself are in space, and you imagine the clouds that you cannot see. Kant's space, as Vaihinger pointed out, is absolute, like Newton's, and not merely a system of relations. But I do not see how absolute empty space can be imagined.
The third metaphysical argument says: 'Space is not a discursive, or, as is said, general concept of the relations of things in general, but a pure intu ition. For, in the first place, we can only imagine [sich vorstellen] one single space, and if we speak of 'spaces'