The document discusses the universal grammar hypothesis proposed by Chomsky. It argues that human languages share many important universal properties that are part of our biological endowment, as evidenced by the universality, complexity, and rapid acquisition of language across cultures. It presents arguments that the faculty of language is specific to humans and not shared by other species, as seen by the lack of any non-human communication systems resembling human language. The document also discusses how this innate universal grammar interacts with linguistic input to produce the grammar of particular languages.