This chapter considers the relationship between the rational-discursive faculty and species identity through the lens of the concepts of error and errancy. In a variety of cultural contexts, medieval audiences imagined that the act of “erring” – both in the etymological sense of wandering and the extended sense of moral fault – could function as an experience that troubled distinctions of species. The chapter uses this recurring fantasy as a lens to explore an intriguing phenomenon observable in manuscripts of the Roman de Renart: Scribes and the trickster fox whose tales they copied sometimes “err” in tandem with one another, with scribal slips of the pen overlapping ambiguously with beastly slips of the tongue. It argues that these disruptive situations enable unresolved questions about the place of the rational-discursive faculty to come to the fore, confronting readers with a surprising question: In whose subjectivity do the errors in question originate?