This, however, on the kind of view I am considering, would be a mistake. I shall have more to say about this example in a moment. Some elephants are not grey, and serve, therefore, as a clue to the impropriety of flying these two 'flags' together. There is a color other than red which something looks to somebody to have, and these are incompatible. But one would have to be cautious in using these clues.
Some sense data have a determinate shade of pink.
After all, x looks red to S . Yet although the logical relations between sentences in a theoretical language are, in an important sense, under the control of logical relations between sentences in the observation language, nevertheless, within the framework of this control, the theoretical language has an autonomy which contradicts the very idea of a code. If this essential difference between theories and codes is overlooked, one may be tempted to try to eat his cake and have it. By thinking of sense-datum talk as merely another language , one draws on the fact that codes have no surplus value. It could scarcely be a theoretical fact that I am directly knowing that a certain sense content is red.