Ambridge's proposal cannot account for the most basic observations about phonological patterns in human languages. Outside of the earliest stages of phonological production by toddlers, the phonological systems of speakers/learners exhibit internal behaviours that point to the representation and processing of inter-related units ranging in size from sub-segmental (featural) and segmental to larger prosodic units ranging from the syllable all the way to the phonological utterance. Only theories which embrace these units can make proper predictions about phonological behaviours.
Keywords: acquisition; categories; linguistic structure; phonology; theory.