A Theory of Language Acquisition Is Not So Easy

The first part of this commentary discusses the minimal requirements that any serious theory of language acquisition must meet. It must take into account the particular properties of the human language processor and the (linguistic and nonlinguistic) input, as well as the specific motivation which causes the learner to apply the former to the latter. Neglecting, or even not keeping constant, some of these factors leads to a very distorted picture of the nature of language acquisition. In particular, claims about the difference between first (L1) and second language (L2) acquisition that ignore major variation in one of these components go astray.