Formal syntax as a phylogenetic method

Historical explanations in science are primarily concerned with the reconstruction of initial conditions determining observable later events. Historical linguistics focuses on the reconstruction of at least two different types of initial conditions: protolanguages and phylogenetic relationships. The fundamental tool for reconstructing phylogenetic relationships is language comparison. To date, the classical historical-comparative method qualifies as the most significant contribution to historical reconstruction in linguistics. This chapter reviews the design, tenets, and results of the parametric comparison method. Parametric models presuppose that the human language faculty is characterized by a certain amount of species-invariant knowledge, and encode grammatical diversity in the form of binary values that define the availability of various morphosyntactic properties for each language. The chapter summarizes the main distinctive properties attributed to syntactic parameters and shows that parametric distances do not saturate even when moved toward the discrimination of close dialectal varieties.