A comparative taxonomy of medieval and modern approaches to Liar sentences * C. DUTILH NOVAES University of Amsterdam, the Netherlands Abstract: Two periods in the history of logic and philosophy are characterized notably by vivid interest in self- referential paradoxical sentences in general, and Liar sentences in particular: the later medieval period (roughly from the 12 th to the 15 th century), and the last hundred years. In this paper, I undertake a comparative taxonomy of these two traditions. I outline and discuss eight main approaches to Liar sentences in the medieval tradition, and compare them to the most influential modern approaches to such sentences. I also emphasize the aspects of each tradition that find no counterpart in the other one. It is expected that such a comparison may point in new directions for future research on the paradoxes; indeed, the present analysis allows me to draw a few conclusions about the general nature of Liar sentences, and to identify aspects that would require further investigation. Key-words: Liar sentences; medieval; modern; taxonomy; insolubilia. Two periods in the history of logic and philosophy are characterized notably by vivid interest in self-referential paradoxical sentences in general, and Liar sentences in particular: the later medieval period (roughly from the 12 th to the 15 th century – they were then known as ‘insolubles’, insolubilia) and the last hundred years – roughly since the discovery of what is now known as Russell’s paradox. If only for this reason, a comparative analysis of these two frameworks, the purpose of the present study, is an endeavor worth undertaking. But beyond this historical interest, it is to be expected that * Forthcoming in History and Philosophy of Logic.