Title: Topics in Counterfactual Semantics

Abstract: This paper develops a 2-component update semantics for counterfactual conditionals. It does so by taking basic update semantics and giving it two twists, one   mereotopicological and one more structural in flavor. This framework, in conjunction with ideas from rhetorical structure theory RST and segmented discourse representation theory SDRT is interesting in that it can help explain a variety of phenomena associated with counterfactual discourse, that more basic update semantics struggle with. On this account, meanings are understood as ways of updating the cognitive states of individuals who want to incorporate the information and subject matter conveyed by them. Counterfactuals (and conditionalities more broadly) are then analyzed compositionally through this lens. One biproduct of this theory, other than a more fine-grained notion of meaning than in traditional update semantics, is an attractive account of modal subordination which is modelled as a form of dynamic topic sensitivity.