Grammaticalisation of verbs into temporal and modal markers in Australian languages

In this paper I present some speculative stories about the development from verbs of some TAM markers in Australian languages. The verbs in question are basic and high frequency ones, including ‘say, do’, which can appear as a marker of inceptive aspect; telic, accomplishment, or activity Aktionsart; desiderative and possibly irrealis and imperative moods; and future tense. Rather than focussing on what particular lexical verbs might grammaticalise into, I take a construction-based approach, and examine possible grammaticalisalisations of three verbal constructions: the compound verb construction, complement constructions, and auxiliary constructions. This approach imposes some degree of control on the speculations about possible grammaticalisation pathways, and permits explanation of the rather different outcomes in the development of a single verb. To conclude the paper I turn to the question of motivation, and suggest that at least some of the grammaticalisations do not lend themselves to cognitive explanations in terms of conceptual similarity of source and target domains. Instead, I argue the need for a more complex cognitive explanation in which the linguistic sign plays a central role.