Gradient morphophonology: Evidence from Uyghur vowel harmony

For the Structuralists and early Generativists (e.g. Bloomfield 1933; Chomsky & Halle 1968), all grammatical knowledge was by definition discrete and categorical. Since phonetic patterns are gradient, early work argued that phonetics was extra-grammatical. However, a significant body of work has since shown that phonetic patterns are language-specific and must constitute part of a speaker\u27s knowledge about their language (e.g. Keating 1985). As a result, linguistic knowledge is not ontologically categorical. For other areas of the grammar, though, much work continues to assume that linguistic knowledge is categorical. In this paper, I investigate the categoricality of phonological patterns using acoustic vowel harmony data from Uyghur. By comparing subphonemic variation in Uyghur with attested patterns of phonetic reduction and interpolation, I demonstrate that gradience is not always derivable from phonetic forces. On these grounds I argue that vowel harmony, and by extension phonology, may be gradient. Furthermore, the claim that gradience plays a larger role in linguistic representations is also supported by a number of descriptive works, which suggest that gradient harmony may occur in a wide range of languages. Building on experimental, and typological evidence, I thus contend that gradience isn\u27t restricted to phonetics, but pervades both the phonological and phonetic modules of the grammar