Axiomatic functionalism is a highly distinctive and challenging approach in the European functionalist tradition, which has been developed over the last 50 years. It emphasises clarity and accuracy of theory and methods with philosophical awareness for the analysis of languages. Axiomatic Functionalism is even more relevant at a time when functionalism is widely adopted and speculative universalism is being refuted. This book gives a clear orientation in the Axiomatic Functionalist approach with a new introduction, recent previously unpublished work, the latest version of the theory, a reference bibliography, key previously published articles, and an assessment of the contribution of Axiomatic Functionalism. The book covers the key areas of theory, methods, grammar, phonology, and semantics. It provides clear perspectives on a wide range of fundamental and current issues in linguistics.