Some emergent discourse connectives in English : grammaticalization via rhetorical patterns
Discourse connectives are metatextual comments that signal discourse coherence relations. They can be realized by sentence adverbials that have their roots in verb phrase adverbials and have followed a path of development that is well attested both for English and cross-linguistically. This study investigates how and why it occurs. It claims that the development belongs to a wider phenomenon of unidirectional internal semantic change, that this change involves context-induced reinterpretation, and that both the immediate discourse context and the wider rhetorical context can be instrumental in bringing it about. Using diachronic and synchronic data in a corpus-linguistic approach, the frequency and distribution of the adverbials after all, in fact, at least and of course are investigated. These are found to follow similar paths of development at different rates and to varying extents. Each undergoes some increase in frequency, subjectification and abstraction, shift of discourse plane and categorial reanalysis. Each acquires at least one connective function to express rhetorical relations such as concession, contrast, justification or elaboration. These relations are defined using the framework of Rhetorical Structure Theory. The analysis identifies, in the history of the expressions, contexts of co-occurrence with particular relations that are argued to generate connective implicatures which later crystallize. During long periods the expressions may have stable but defeasible implicatures in the relevant contexts. These contexts include rhetorical structures spanning two or more clause complexes and often consisting of quasi-conventional sequences of rhetorical relations typical of argumentation. They may be described as incipient discourse constructions or rhetorical idioms. The emergence of new discourse connectives is seen to share many of the features attested in the grammaticalization of lexical material. It is argued that these phenomena are best accounted for in a single, usage-based theory of internal semantic change.