Abstract. Over the last century and a half, discussions of Darwin in Arabic have involved a complex intertwining of sources of authority. This paper reads one of the earliest Muslim responses to modern evolution against those in more recent times to show how questions of epistemology and exegesis have been critically revisited. This involved, on the one hand, the resuscitation of long-standing debates over claims regarding the nature of evidence, certainty, and doubt, and on the other, arguments about the use (and limits) of reason in relation to scripture. Categories of knowledge and belief, alongside methods of scriptural hermeneutics, were repositioned in the process, transforming the meaning and discursive reach of the former as much as the latter. Indeed, this paper argues that the long-run engagement with Darwin in Arabic led to the mutual transformation of both “science” and “religion,” whether as objects of knowledge (and belief) or as general discursive formations.