Acquisition Based and Usage Based Explanations of Grammaticalisation. An Integrative Approach
This paper compares and discusses two mainstream explanations of grammaticalisation processes: Generative accounts regarding them as reflections of structural reanalysis through parametric change during language acquisition, resulting in recategorisation of lexical elements as functional heads in syntactic structure and functionalist approaches that focus on performance, arguing that speakers tend to either improve expressiveness or economise speech production by varying the application of the rules of grammar, which may result in conventionalisation and finally even change the rules of grammar or create new functional elements. Our aim is to integrate the advantages of both approaches. Basically, it is argued that performance-based conventionalisation plays a central role for grammaticalisation by providing the linguistic preconditions for recategorisation of lexical elements as functional ones, or semi-functional elements as fully functional ones. However, changes of the basic rule system of grammar, which includes the parametric representation of functional heads in syntactic structure, cannot be changed except through structural reanalysis during language acquisition. On the other hand, the input for language acquisition is speech, which is shaped by application and, to a certain degree, modification of the functional rules of the grammatical system by the speaker. The part of grammar that is accessible to manipulation by the speaker is called ‘fringe-grammar’ in generative theory. Thus the central claim will be: <i>in processes of grammaticalisation, change of the core grammar is often initialised by functional variation at the fringe.</i> The whole process may include several steps of alternate usage-based and acquisition-based changes. This model will be exemplified by its application to the analysis of the development of analytic tenses.