Dialogue Modelling and the Remit of Core Grammar

In confronting the challenge of providing formal models of dialogue, with its plethora of fragments and rich variation in modes of context-dependent construal, it might seem that linguists face two types of methodological choice: either (a) conversation employs dialogue-specific mechanisms, for which a grammar specific to such activity must be constructed; or (b) variation arises due to independent parsing/production systems which invoke a process-neutral grammar. However, as dialogue research continues to develop, there are intermediate possibilities, and in this paper we discuss the approach developed within Dynamic Syntax (DS, Kempson et al. 2001, Cann et al. 2005), a grammar framework within which, not only the parser, but indeed “syntax” itself are just a single mechanism allowing the progressive construction of semantic representations in context. Here we take as a case study the set of phenomena classifiable as clarifications, reformulations, fragment requests and corrections accompanied by extensions, and argue that though these may seem to be uniquely constitutive of dialogue, they are grounded in the mechanisms of apposition equivalently usable in monologue for presenting reformulations, extensions, self-corrections etc

Completability vs (In)completeness

In everyday conversation, no notion of “complete sentence” is required for syntactic licensing. However, so-called “fragmentary”, “incomplete”, and abandoned utterances are problematic for standard formalisms. When contextualised, such data show that (a) non-sentential utterances are adequate to underpin agent coordination, while (b) all linguistic dependencies can be systematically distributed across participants and turns. Standard models have problems accounting for such data because their notions of ‘constituency’ and ‘syntactic domain’ are independent of performance considerations. Concomitantly, we argue that no notion of “full proposition” or encoded speech act is necessary for successful interaction: strings, contents, and joint actions emerge in conversation without any single participant having envisaged in advance the outcome of their own or their interlocutors’ actions. Nonetheless, morphosyntactic and semantic licensing mechanisms need to apply incrementally and subsententially. We argue that, while a representational level of abstract syntax, divorced from conceptual structure and physical action, impedes natural accounts of subsentential coordination phenomena, a view of grammar as a “skill” employing domain-general mechanisms, rather than fixed form-meaning mappings, is needed instead. We provide a sketch of a predictive and incremental architecture (Dynamic Syntax) within which underspecification and time-relative update of meanings and utterances constitute the sole concept of “syntax”