This article studies the formal variation of the existential quantifiers u/un ('one; a, an'), algú/algun ('someone; some'), ningú/ningun ('no one, anyone; any') and the distributive universal quantifier cada u/cada un ('everyone') in Catalan. The research is based on an extensive diachronic corpus of texts written between the 15th and 20th centuries. The author classifies the syntactic structures of these quantifiers and analyses their meaning and formal vacillations: apocopated form (without ‑n) vs. non-apocopated form (with ‑n). Although hesitations tend to disappear gradually during the period under analysis, the uses of these quantifiers change in Catalan dialects. In fact, distinct geographical areas adopt different distributions of form and function. These linguistic changes are explained, highlighting the mutual influences and interactions between phono-syntactic, phonological, analogical and pragmatic factors.