of the data — which seems to be a rather misleading expression — we have to say that the data have no owner or bearer. This neutrality of experience — as against the subjectivity claimed for it by the idealist — is one of the most fundamental points of true positivism. The sentence 'All experience is first-person experience' will either mean the simple empirical fact that all data are in certain respects dependent on the state of the nervous system of my body M, or it will be meaningless. Before this physiological fact is discovered, experience is not 'my' experience at all, it is self-sufficient and does not 'belong' to anybody. The proposition 'The ego is the centre of the world' may be regarded as an expression of the same fact- and has meaning only if it refers to the body. The concept of 'ego' is a construction put upon the same fact, and we could easily imagine a world in which this concept would not have been formed, where there would be no idea of an insurmountable barrier between what is inside the Me and what is outside of it. It would be a world in which occurrences like those corresponding to proposition R and similar ones were the rule, and in which the facts of 'memory' were not so pronounced as they are in our actual world. Under those circumstances we should not be tempted to fall into the 'egocentric predicament', but the sentence which tries to express such a predicament would be meaningless under any circumstances.
After our last remarks it will be easy to deal with the so-called problem concerning the existence of the external world. If, with Professor Lewis(143), we formulate the 'realistic' hypothesis by asserting, "If all minds should disappear from the universe, the stars would still go on in their courses", we must admit the impossibility of verifying it, but the impossibility is merely empirical. And the empirical circumstances are such that we have every reason to believe the hypothesis to be true. We are as sure of it as of the best founded physical laws that science has discovered.
As a matter of fact, we have already pointed out that there are certain regularities in the world which experience shows to be entirely independent of what happens to human beings on the earth. The laws of motion of the celestial bodies are formulated entirely without reference to any human bodies, and this is the reason why we are justified in maintain thating
