In this dissertation, I defend the view that natural languages are concrete biopsychological phenomena to be studied empirically. In Section One, I begin with an historical explanation. Some analytic philosophers, I argue, misapply formal logic as an analysis of natural language, when it was in fact originally developed as an alternative to natural language, employed for scientific purposes., quasi-mathematical philosophies of language, I argue, are partially a result of this misunderstanding. I respond to Jerrold Katz’ argument that a proper understanding (...) of analytic truth requires this quasi-mathematical philosophy of language through a model-theoretical analysis of analytic truth in modal and intuitionist logics. In Section Two, I offer a positive argument for a biopsychological philosophy of language. While Chomsky and others have emphasized the metaphysical basis of natural languages in psychological representations, I further contribute to understanding by emphasizing the basis of natural language in psychological representations of relevant properties of a specifically constrained biological implementation base. I defend this ontological perspective through a thorough engagement with the subfield of linguistic phonology and its important relations to physiological articulation and perception, along with an analysis of crucial interface relations among phonology, morphology and syntax. In the final section, I engage with the objections to this biopsychological philosophy of language stemming from concerns related to linguistic normativity and communication. If natural language is based metaphysically in the biopsychological representations of individuals, there are apparent paradoxes in the notion of public rules for language use, and in the notion of shared content for the purpose of communication. Drawing on David Forrest Wallace’s pragmatic conception of linguistic prescription, together with analogies from anti-realist metaethical systems, I defend the intelligibility of public linguistics norms without the need for abstract ontological commitment. Drawing on Ray Jackendoff’s internalist semantic and metasemantic analysese, together with Burtrand Russell’s analogy argument on other minds, I also defend intelligibility of linguistic communication equally without need for abstract ontological commitment. (shrink)