Innateness and maturation in linguistic development

Language is species-specific, species-wide, and highly structured. Its principles (Universal Gram-mar) are innate (genetically determined) in the child, although some linguistic capacity is subject to a maturational schedule, examples of which are given. Some particular aspects of language are learned, in a way driven by Universal Grammar. However, empiricist "learning theories " of all types are far too weak to be useful in explaining either the final adult language or the precise timing of developmental processes. The assumption of Universal Grammar is, in fact, crucial in explaining what kind of learning actually takes place. Imagine a symposium on "The Idea of Innateness: Effects on Research on Physical Development. " And consider some of the questions that one might ask, questions that parallel the questions asked in our symposium. What are the advan-tages and disadvantages incurred if a theory of physical growth assumes that some aspect of this growth is innate? Do we incur, in assuming innateness, logical problems in our explanation of the origin of physical structure of organisms because defining a structure as innate entails accepting the null hypothesis that learning and experience have no effect? Do we direct our attention away from measurin