This paper discusses the validity and role of linguistic theory in terms of philosophy and logic and considers the relationship among these fields of human knowledge. The main objective of linguistic science is to discover the composition laws actually used by speech communities at any given moment in history. Linguistics is therefore not prescriptive but, rather, seeks knowledge of the true structure of language. The empirical and explanatory nature of linguistic statements is considered at length, as are the means for judging the validity of those statements. (VM)