Modelling discourse relations by topics and implicatures

This paper develops a theoretical approach that derives the semantic effects of discourse relations from the general pragmatic default priciples of exhaustivity—a kind of Gricean Quantity implicature—and topic continuity. In particular, these defaults lead to the inference of relations such as Elaboration, while other discourse relations, e.g. Narration and List are predicted to be ‘non-default’ and must be signalled, which contrasts with common assumptions in discourse theory. The present paper discusses some observations on the use of connectives and intonation in spontaneous speech which suggest that at least intonational signalling of such relations is obligatory.