 Wundt defines consciousness as “inner experience;” it is only the “immediately  real”[16]  phenomena constituting this experience, and nothing behind or beyond it, that is the object of psychological, as opposed to physiological or psychophysical investigation (PP II: 636). Wundt’s project is not only a “psychology without a soul”, in F.A. Lange’s phrase, but also a science without a substrate tout  court.[17]  Wundt therefore presents himself as a radical empiricist. The subject of psychology “is itself determined wholly and exclusively by its predicates”, and these predicates derive solely from direct, internal observation (on which below). The basic domain of inquiry, accordingly, is that of “individual psychology” (cf. e.g. L III: 160, ff), i.e. of the concrete mental contents appearing to particular human beings, and not some mental substance or bundle of  faculties.[18]  In Wundt’s declaration that individual psychology must become a science via the experimental manipulation of inner phenomena, we see a pragmatic attitude perhaps peculiar to the working scientist: the future science as doctrine takes shape in and through the present practice of experimentation, its essays, assays, trials, and errors. Instead of simply submitting to Kant’s injunctions against the very possibility of a scientific psychology, Wundt finds that certain aspects of our inner experience can be, and in fact have been, made susceptible to experiment and mathematical representation: Weber and Fechner did this.