Lexical phonology and sound change: the case of the Scottish vowel length rule

The key assumption in the standard generative approach to historical linguistics (King, 1969) is that each sound change is incorporated directly into the native speaker's grammar as the final phonological rule, moving up gradually into the grammar as further changes are implemented. Restructuring of underlying representations by later generations during acquisition is theoretically permitted, but infrequently invoked, with the result that the historical phonology of a language will be almost directly mirrored in the order of its phonological rules. The only extractable generalizations are then that the ‘highest’ rules will correspond to the oldest changes, and that a sound change and the rule into which it is converted will tend to be identical or at least show a high degree of similarity in formulation. This approach casts no light at all on the problem of the implementation of sound change.