This course presents and account of deductive inference in natural language, providing resources for assessing the logic of various grammatical constructions and for determining the meaning and reference of various expressions as they apply to given situations. The course defines the logical relations of mutual consistency, consequence, and equivalence among sentences of English, and develops techniques for recognizing when these relationships hold. The course introduces theoretical and technical devices both from standard symbolic logic and from generative linguistics. Students consider linguistic diversity, minority and creole languages, and endangered languages. Technical issues about Universal Grammar come into focus and philosophical issues about language and mind are illuminated.