This study reframes irony as a rhetorical and epistemological practice situated at the intersection of ethics and rhetoric in sixteenth-century French and Italian literature. While scholars have explored the diachronic and lexical evolution of irony, comparatively little attention has been devoted to irony as a rhetorical practice in the French and Italian Renaissance, and to its ethical and epistemological dimensions. This book seeks to fill this gap by offering a new account of irony's rhetorical agency across a corpus including Erasmus, Ariosto, Marguerite de Navarre, Rabelais, and Montaigne. It argues that irony in the Renaissance is not merely a stylistic figure but a mode of inquiry that transforms classical and medieval traditions. Through close readings, the study explores how irony reconfigures genre, authorship, and moral discourse, showing that its elusiveness demands contextual, practical analysis rather than fixed definition. It argues that in the sixteenth-century Renaissance, irony shifts from being a tool subject to ontological investigation (is irony a lie or a truth?) to becoming a gnoseological instrument of inquiry. The dichotomy between true and false, which underpinned medieval discourse on rhetoric, is overridden as irony shifts from being an object of study to an instrument that investigates the limits and functions of language, as well as the forms of the texts to which language must rigorously conform.