Category mistakes are sentences such as "Green ideas sleep furiously," "Saturday is in bed," and "The theory of relativity is eating breakfast." Such sentences strike most speakers as highly infelicitous but it is a challenge to explain precisely why they are so. Ofra Magidor addresses this challenge, while providing a comprehensive discussion of the various treatments of category mistakes in both philosophy and linguistics.

The phenomenon of category mistakes is particularly interesting because a plausible case can be made for explaining it in terms of each of syntax, semantics, and pragmatics--making it a fruitful case for exploring the relations between, and nature of, these three fundamental realms of language. Category Mistakes follows this division, discussing four types of accounts: the syntactic approach to the phenomenon, two distinct semantic approaches, and the pragmatic approach. Magidor argues that the first three ought to be rejected, and addresses the challenge by developing and defending a novel version of the pragmatic approach: the presuppositional account of category mistakes.