The Search for Structural Constraints
Most research on CS in the 1970s and 1980s was fuelled by the recognition that CS properly should be considered as a type of skilled performance with social motivations (cf. Gumperz, 1982; Heller, 1988; Myers-Scotton, 1993). However, it soon occurred to researchers that quite another aspect of CS also might not be an accidental matter: where in an utterance a speaker might switch might well not be simply a whim of individual speakers or even a matter of habit for a specific speech community. This chapter surveys earlier answers to the constraints question: what are the limits on where the speaker may codeswitch within a sentence, and what motivates these limits? (Note that only intrasentential CS is relevant to the constraints question, as it has been addressed to date.)
Three general approaches are apparent in the attempts to formulate constraints on CS. First, researchers articulated constraints on switching from the surface (e.g. largely using linear ordering, form class, or size of switched material). Second, some researchers proposed that constraints were driven by the same principles or rules formulated under current syntactic theories to explain syntactic structures within a single language. Third, simultaneously and then more recently as well, others suggested that a major linguistic constraint on CS is related to clashes in subcategorization restrictions between the languages involved.
In Chapters 4 and 5, I will argue instead that the source of constraints on CS is both more abstract and more specific: it lies at an even more non-representational level in message construction, within an even more hierarchical system of constituents than such dominant syntactic theories