The current picture of the history of taxonomy incorporates A. J. Cain's claim that Linnaeus strove to apply the logical method of definition taught by medieval followers of Aristotle. Cain's argument does not stand up to critical examination. Contrary to some published statements, there is no evidence that Linnaeus ever studied logic. His use of the words “genus” and “species” ruined the meaning they had in logic, and “essential” meant to him merely “taxonomically useful.” The essentialism story, a narrative that has most pre-Darwinian biologists steeped in the world view of Plato and Aristotle, is ill-founded and improbable.