This paper presents a formal account of how to determine the discourse relations between propositions introduced in a text, and the relations between the events they describe. The distinct natural interpretations of texts with similar syntax are explained in terms of defeasible rules. These characterise the effects of causal knowledge and knowledge of language use on interpretation. Patterns of defeasible entailment that are supported by the logic in which the theory is expressed are shown to underly temporal interpretation.

I might summarize this section by saying that the English tenses, according to this analysis, form quite a motley group. PAST, PRES and FUT serve to relate reference time to speech time, while WOULD and USED-TO behave like Priorian operators, shifting the point of evaluation away from the reference time. HAVE also shifts the point of evaluation away from the reference time, but in a more complicated way. And FUT, in contrast to PRES and PAST, is a substitution operator, putting (...) the reference time of its clause in the plate of the speech time of subordinate clauses. (shrink)