Discourse topic

away from the logical structure of the constituents they are topics of. For a variety of purposes they are also needed as constituents in the discourse structure. The discourse relation of Alternation, for which the presence of disjunction is a good but defeasible indication, also requires a particular notion of topic for its semantics, and it is one that’s di¤erent from that for Narration. Developping a formal theory of discourse topic has proved di‰cult. One reason is that, as I’ll demonstrate here, the notion of topic is not a homogeneous one but varies depending on the discourse relations used – viz., on the discourse context. But even for a particular notion of discourse topic like that for Narration, it has proved di‰cult to develop an account in which a coherent discourse features a topic that we can construct as interpretation proceeds incrementally. We don’t have a satisfactory account of such a process, which may indeed be very complicated – clearly more complicated than recognizing whether some extant segment functions as a discourse topic to another discourse constituent. The problem for a theory of discourse interpretation even like SDRT in which discourse topics play a limited role is that if there isn’t any e¤ective way of constructing such topics or recognizing them, then there isn’t any e¤ective way of fully specifying a logical form for a discourse. Although SDRT limits the relevance of discourse topic and allows underspecification in descriptions of logical form (topics thus might often remain underspecified), it’s still an embarrassment not to have any way of making sense of topic construction and a fortiori the phenomena that the introduction of discourse topic was designed to deal with. In order to get a better grip on discourse topics, we need to understand better the information sources in language that a¤ect discourse topic. There are intriguing connections between the notion of contrastive topic, sentence topic and discourse topic. In this paper I’ll concentrate largely on contrastive topic’s contribution to discourse topic. Though not always present, contrastive topic as part of the information structure given by intonation furnishes an important source of information about discourse topic, as Beyssade and Marandin (2002) and Grabski (2002) have argued (see also von Heusinger 2001). I want first to pursue this line of thinking by beginning with Büring’s influential work in this area. Combining van Kuppevelt’s notion of discourse topic as a question and Büring’s work on contrastive topic leads to an attractive theory of the interaction 164 Nicholas Asher