Optional agreement in Santiago Tz’utujil (Mayan) is syntactic

Abstract Some Mayan languages display optional verbal agreement with 3pl arguments (Dayley 1985; Henderson 2009; England 2011). Focusing on novel data from Santiago Tz’utujil (ST), we demonstrate that this optionality is not reducible to phonological or morphological factors. Rather, the source of optionality is in the syntax. Specifically, the distinction between arguments generated in the specifier position and arguments generated in the complement position governs the pattern. Only base-complements control agreement optionally; base-specifiers control agreement obligatorily. We provide an analysis in which optional agreement results from the availability of two syntactic representations (DP vs. reduced nominal argument). Thus, while the syntactic operation Agree is deterministic, surface optionality arises when the operation targets two different sized goals.