Categorical and gradient ungrammaticality in optional processes

Abstract

Current theories of optionality often take a gradient view of grammaticality: unattested variants are not categorically excluded but rather highly improbable. Vowel harmony in Eastern Andalusian challenges this view. Unstressed vowels optionally harmonize in a coordinated fashion. For example, if one posttonic vowel harmonizes, they all must. Different implementations of noisy harmonic grammar are tested for their ability to account for this pattern. Only the implementation that categorically excludes forms with uncoordinated harmony succeeds; other implementations, which can only make such forms unlikely outputs, provide inferior models. This contrast indicates that there remains a need for a categorical approach to (un)grammaticality alongside a gradient approach.