This course presents an account of deductive inference in natural language. The logical relations of mutual consistency and equivalence are defined for sentences of English, as is the notion of a valid deductive argument expressed by sentences of English. Theoretical and technical devices are introduced both from standard symbolic logic and from generative grammar, with a focus on grammatical structures that determine logical force. Also considered are philosophical issues about language, mind, meaning, and truth. Readings introduce such important figures in 20th-century thought as Gottlob Frege, W.V.O. Quine, Paul Grice, and Noam Chomsky.