OPTIONALITY, LEXICALITY AND SOUND CHANGE

This paper investigates the relationship between variability and lexic ality on the one hand and sound change on the other within the theory of Lexical Phonology. The former leads to the proposal of the Optional ity Constraint (OC), which prohibits the application of optional rules in the lexical module. The constraint is found to be violated at the word level. The violation of OC as well as of other lexical modular pr inciples is accounted for by the help of a new licensing principle, ca lled the Polarity Principle. This allows for interacting modules to ha ve different properties of representation and rule application at thei r opposite ends. The OC leads to a resolution of the Neogrammarian Con troversy, that is consonant with the standard assumption concerning so und change, namely, the inherent relation between the latter and varia bility.