Clause size, negation and aspect in Polish and Serbian subjunctives

Abstract

This paper investigates the interaction between negation and aspect in Slavic subjunctive complements, focusing on a systematic contrast between Polish żeby -clauses and Serbian da -clauses. While both languages freely allow perfective aspect in affirmative contexts, a sharp asymmetry emerges under negation: Polish strongly disfavors the perfective, preferring the imperfective, whereas Serbian allows both aspects without restriction. Building on the Implicational Complementation Hierarchy and Exfoliation Theory, we argue that this contrast is a structural consequence of clause size. Polish żeby -subjunctives are analyzed as complements that lack a TP layer, forcing negation to merge low within the verbal domain. This low negation interacts directly with event structure, creating a semantic incompatibility with the bounded nature of perfective aspect. Conversely, Serbian da -clauses exhibit properties of a full TP, allowing negation to merge high in the inflectional domain. In this higher position, negation takes scope over the entire proposition, leaving the internal aspectual structure intact. An acceptability judgment task supports these claims, showing a robust penalty for perfective morphology in Polish that is absent in Serbian. Ultimately, the study proposes that aspectual behavior under negation serves as a novel diagnostic for clausal defectivity and structural height in Slavic complementation.