Postwar librarians have sacrificed the humanistic basis of librarianship and regard the use of science in librarianship as a settled issue. American librarianship is currently dominated by the physical thinking of scientific systems theory, which includes Bertalanffy's general system theory, Wiener's cybernetics, and the Hartley-Shannon theory of information. It is therefore following the wrong theoretical perspective on human communications, because librarians must deal with the subjective immateriality of ideas, whereas systems theory is concerned with the controlled movement of physical signals from one place to another. But symbolic interactionism, the humanistic alternative to the scientific view of human communications, concentrates on the psychophysical interplay of physical signals with their ideative referents. Librarians should turn to this latter perspective on communications theory because the relationship between a physical symbol and its nonphysical referent is inherently metaphysical, which explains why science is utterly incapable of resolving the specifically philosophical problems of human symbolism. The mysteries surrounding the communication of information can never be resolved unless the physical presuppositions of science are abandoned. (Author/ESR)