There is a recent scholarly trend drawing similarities between Aristotle’s conceptions of ethics and demonstrative science. One such similarity has become widely and rightly recognized: for Aristotle both ethics and demonstrative science seek essential definitions of phenomena. The task of the paper is to show that German philosopher and classicist Hans-Georg Gadamer not only prefigured this interpretative trend, he also identified a problematic feature of Aristotle’s method so construed. The problematic feature is semantic. For Aristotle essential definitions must consist of (...) univocal terms, but such univocity cannot be maintained if the definienda and definientes are concepts to be usefully employed in everyday ethical judgements. Gadamer therefore points out a problematic tension in Aristotle’s ethics. On the one hand, ethical inquiry should have practical application, but, on the other hand, the semantic assumptions underlying inquiry imply that it cannot. (shrink)