  What does the existence of a sensitive period for language mastery tell us about the innateness of language? In this section, we will look at a case, namely phonological learning, in which the existence of a sensitive period has received much press, and in which the inference from sensitivity to the existence of language-specific innate information has been made explicitly (see Eimas 1975). One can argue that even in this case, the inference to linguistic nativism is weak.