Parameter setting is feasible

In the first few years of life, a child's language undergoes tremendous changes. While it is a primary task for the student of language acquisition to document these changes, a mere description of child language, however accurate or insightful, cannot be regarded as adequate. A complete theory of language acquisition must also include a detailed account of how these changes take place, that is, the mechanism of language learning. The study of this mechanism must take into account contributions from both the internal knowledge of language, innate or otherwise, and the external linguistic experience, which determines the outcome of learning. The goal of language acquisition research is to establish the right combination of the theory of grammar and the theory of learning such that the development of language can be successfully accounted for.