Principles, parameters and probabilities

This chapter discusses three kinds of linguistic knowledge that pose a challenge to experience-based accounts of language development. The examples are based on the principles and Parameters framework of generative-transformational grammar. We discuss relevant findings on child language reported in the literature. First, it has been found that children converge on linguistic principles which prevent errors from occurring that would otherwise be expected if children were basing their hypotheses on the probabilistic nature of the input (e.g., the constraint prohibiting contraction across a wh-trace). Second, children sometimes adopt parameter values for which there is no decisive input (e.g., the medial-wh phenomenon and inversion in why-questions). Third, children’s recovery from such ‘incorrect’ parameter settings (for which there had been no decisive input) is sometimes too sudden to be accounted for by statistically-based learning mechanisms; an example is a parameter that dictates the placement of negation in combination with verbal morphology. These findings suggest that at least some aspects of children’s emerging linguistic competence resist explanation on experience-based accounts of language learning.