Footnote zzz7

zzz7. From "Psychology in Physical Language" (German version published in 1931) by Rudolf Carnap in Logical Positivism, ed. A.J. Ayer (Collier Macmillian 1959):

To every sentence of the system language there corresponds some sentence of the physical language such that the two sentences are inter-translatable. It is the purpose of this article to show that this is the case for the sentences of psychology. Moreover, every sentence of the protocol language of some specific person is inter-translatable with some sentence of physical language, namely, with a sentence about the physical state of the person in question. The various proto- col languages thus become sub-languages of the physical language. The physical language is universal and inter-subjective. This is the thesis of physicalism.
If the physical language, on the grounds of its universality, were adopted as the system language of science, all science would become physics. Metaphysics would be discarded as meaningless. The .vari- ous domains of science would become parts of unified science. In the material mode of speech: there would, basically, be only one kind of object — physical occurrences, in whose realm law would be all-encompassing.
Physicalism ought not to be understood as requiring psychology to concern itself only with physically describable situations. The thesis, rather, is that psychology may deal with whatever it pleases, it may formulate its sentences as it pleases — these sentences will, in every case, be translatable into physical language.

---