The explanatory aim of research within the transformational-generative paradigm is to account for language acquisition. A theory consistent with such an explanatory goal can be conceived of as consisting of three separate (although interactive) parts: (a) hypotheses about what it is that the child brings to the task of attaining any language, (b) hypotheses about what the final state attained looks like, and (c) a specification of the linguistic data available to the child that allow him to attain (b) for any language on the basis of (a). In generally accepted terms, the three parts are (a) 'universal grammar' (UG for short), (b) a 'particular grammar', and (c) the 'triggering experience' or 'primary linguistic data' respectively. In this framework, the investigator will specify the experience to which the child can realistically be assumed to have access and which could mediate between a proposed principle of UG and rules of a particular grammar. Any such triggering experience consists only of the haphazard set of utterances which constitute the child's natural linguistic environment: the child has no systematic information about ungrammaticality of sentences, about paraphrase relations, about ambiguities, etc. -- from http://www.jstor.org (Feb. 14, 2014).