Renouvier was among the first philosophers in France to break with the nineteenth-century inductivist tradition and defend the use of hypotheses in science. Earlier in the century, the humanistically-educated eclectic spiritualist philosophers who dominated French academic life had followed Reid in proscribing the use of hypotheses. Renouvier, who was educated in the sciences, took up the Comtean positivist alternative and developed it further. He began by defending hypotheses that anticipate laws governing the phenomena, but then eventually adopted a more liberal (...) attitude towards hypotheses that postulate unobservable entities and processes as well. He also came to the realization that, from an epistemological point of view, all of empirical science is hypothetical. Renouvier used the tentative character of scientific knowledge as a premise from which to critique those who would claim scientific status for their social philosophies, and maintained a distinction between normative philosophical and empirical scientific inquiries.Keywords: Charles Renouvier; Auguste Comte; Positivism; Hypothesis; Eclectic spiritualism. (shrink)