 Problematic of the behaviourist approach is its assumption that all learning, verbal and non-verbal, occurs through the same processes.A more general problem is that, as Pinker (1995) notes, almost every sentence anybody voices is an original combination of words, never previously uttered, therefore a language cannot consist only of word combinations learned through repetition and conditioning; the brain must contain innate means of creating endless amounts of grammatical sentences from a limited vocabulary.This is precisely what Chomsky (1965) (reprinted as ) argues with his proposition of a universal grammar (UG).