Until now, a number of researches on language variation and change have been conducted from various perspectives, however, the approaches have not cooperated and have not shared their insights: sociolinguistic approaches have focused on a variety of factors that govern language variation and change by quantitative methods; formal approaches have focused on the qualitative analysis of human language competence as their research subject, accordingly the language usage has been overlooked. This book presents an exhaustive research about the ongoing language change in Japanese voice system, bridging between an empirical work based on a huge amount of spontaneous speech data on the one hand, and a formal account based on the grammatical theory on the other. The analysis identifies dynamic interactions of internal and external factors that govern the language variation and change, and provides a model of grammar that accommodates the inherent variability. This book should help shed some light on the driving force behind and the mechanism of language variation and change, and should be especially useful to scholars and students in sociolinguistics as well as formal linguistics.
