Structure-Building Processes and Functional Categories in Language Acquisition

Language acquisition seems to be subject to a paradox like probably all matters connected with the human language: every-one acquires his or her first language with relative ease in a few years – it is a matter of course (except if disabilities or social deprivations obstruct this natural process) - but even the most learned scholars cannot offer a satisfactory and all-encompassing explanation about how this process works. A number of different approaches exists which can be subsumed under the headings "behaviourist", "interactionist", "nativist", "cognitivist" or the like1, and each of these major currents bifurcates into sub-theories which often enough seem to be incompatible with each other again.
In this essay I am going to present and discuss two hypotheses of language acquisition which follow the generative approach, i.e. which presuppose the existence of an innate language acquisition device (LAD) helping us solve the task of acquiring the complicated linguistic system by providing a "ready-made" underlying fundamental structure, the Universal Grammar (UG). Accordingly Andrew Radford, and Harald Clahsen et al. assume that the rules of UG are with the child from the very beginning, yet that the final build-up of the internal grammatical structure is triggered by lexical learning processes. Radford identifies three major stages of developmental phases with children acquiring English syntax, whereas Clahsen et al., studying children acquiring German, find plausible explanations for the developmental process by a notion of underspecified functional categories.

1 cf. Crystal p. 234 f., Clahsen p. xv