Abstract
This article considers the epistemology of Classical rhetoric and Hippocratic medicine, focusing on two key terms: semeion and tekmerion. Through an analysis of the specific case of ancient Greek medicine and rhetoric, we hope to bring out the conjectural and fallible nature of human knowledge. The paper focuses on the epistemological and methodological affinity between these two ancient technai, and considers the medical uses of semeion and tekmerion in the light of their meaning in the rhetorical sphere. Chronologically, the analysis follows an inverse pathway: it starts from Aristotle and from Rhetorica ad Alexandrum, and then moves on to Antiphon’s texts (chosen as an exemplary case) and ends with the Corpus Hippocraticum.