Gold ’ s Theorem and Cognitive Science

A variety of inaccurate claims about Gold's Theorem have appeared in the cognitive science literature. I begin by characterizing the logic of this theorem and its proof. I then examine several claims about Gold's Theorem, and I show why they are false. Finally, I assess the significance of Gold's Theorem for cognitive science. 1. Introduction. Over the years, negative evidence in language acquisition has received a lot of attention. (Negative evidence is information regarding what possible sentences are not sentences of the language to be learned.) It is often thought that children lack negative evidence when they acquire their native language (e.g., Marcus 1993), and that this fact supports a rationalist view of the mind over an empiricist view. One argument from 'No negative evidence' to rationalism centers on the 'Logical Problem of Language Acquisition' (LPLA). Briefly, LPLA goes like this. If a child learning a given language doesn't use negative evidence, then it is logically possible that she would begin to acquire a language whose grammatical sentences included all those of the target language, plus some more. E.g., if a child was learning English, she could begin to acquire a language that included all the grammatical sentences of English, plus sentences of VSO clausal order, like *Kicked Mary the boy and *Sang Susan. If the child received no information that these extra sentences aren't part of English, then she would have no way of knowing that she was not learning English, but a syntactically more expressive language instead. Thus, we would predict that the child would end up acquiring the 'larger' language. However , this does not happen: children acquire their target language, and