Prosody and analogy in variation and language change. Lexical diphthongisation in Catalan and Spanish.

Derivational and rule-based models in phonology resort to mechanisms such as addition, reordering and deletion of rules to explain variation and linguistic change. While these mechanisms can easily account for parametric variation among languages, they also contribute to view synchronic language systems as static linguistic stages and language change as a sudden shift from one linguistic stage to another. Most of the changes occurring in natural languages, though, involve gradual and non-radical modifications of linguistic features. From the perspective of constraint-based approaches such as OT (Prince & Smolensky, 1993), linguistic variation and change can be conceived as a gradual reranking of particular constraints hat become increasingly prominent. This theory can easily capture, for example, the competition between a new developing tendency and antagonic forces which tend to keep old linguistic identities; moreover, it also allows for the expression of variation within the data by resorting to differences between individual speakers in the establishment of analogical relationships between lexical items. The paper shows that the gradual process of glide formation in rising sonority sequence