Manfred Krifka (Leibniz-ZAS Berlin / HU Berlin)

In spite of mainstream semantic modeling, there is evidence that conditional sentences do not express conditional propositions, but conditional speech acts. I will propose a model for conditional speech acts using the notion of commitment spaces (Krifka 2015, SALT 25), a way of modeling the common ground in a conversation that does not only include the propositions that are assumed to be shared by the interlocutors, but also the possible continuations of this set of propositions in the further conversational development. The essential idea is that a conditional like If John was at the party, the party was fun states that for every continuation in which it gets established  that John is at the party, the speaker is committed to the truth that the party was fun. 

I will show how this model can be extended to accommodate counterfactual conditionals. The idea is that counterfactuals reduce the set of assumed propositions so that the antecedent propositions can be entertained, followed by a restriction for continuations from that set. A conditional like If John had been at the party, the party would have been fun states that whenever the propositions that rule out that John was at the party are removed from the common ground, all continuations from that modfied common ground in which it gets established that John was at the party are such that the speaker is committed to the truth that the party was fun. I argue that past tense phenomena in counterfactuals can be understood as indicating a stepping back from assumptions that have already been established in the common ground.