Can we reasonably speak of 'linguistic realities'? Do theoretical linguists devise accounts of a reality which exists outside of their theories? In this provocative and insightful study of the philosophy of linguistics, the author first investigates the realist/instrumentalist debate in the philosophy of science, and shows what relevance it has for the sort of questions linguists might ask themselves about the nature of their discipline. He proposes a realist philosophy of linguistics, which takes as its starting point Popper's falsificationist philosophy of science, coupled with his objective knowledge ontology. The automist methatheory he proposes for generative linguistics holds, in contradistinction to Chomskyan psychologism, that there are such realities, but that they are neither Platonic, nor normative in nature. Rather, they belong properly to Popper's category of objective knowledge. Linguistic Realities is a major contribution to the philosophy and methodology of linguistics. Its application of Popperian philosophy of science to the philosophy of linguistics will arouse much debate among philosophers and linguists alike.