Explaining reversible discourse marker sequences: A case study of and and so

When discourse markers (DMs) occur in sequences of multiple markers, their linear order is generally quite rigid. Still, there are clear cases of reversible DM sequences. This article examines the reasons for DM reversibility and explores its implications for theories of DM sequencing. A corpus analysis of the English DMs so and and suggests that one reason for their reversibility is that the different orders achieve different effects. When so follows and (And so…) it more often marks the upcoming utterance as a result or conclusion (‘therefore’). When so precedes and (So and…) it is more often used to change the discourse topic. Crucially, both of these functions are part of so's known functional spectrum. This shows that functional accounts of DM syntax must be sensitive to DM polyfunctionality. Moreover, a close analysis of each marker's individual contribution to their cumulative effect as a sequence points to a general ordering principle: In DM sequences, the earlier DM constrains the interpretation of the later DM by providing a particular interpretive context for it. This explains why alternative sequence positions may go along with different functions. In this way, the temporality of spoken language acts as a general constraint on DM sequencing.