Tractatus 2.0211 and Stalnaker’s Assertions

In the Tractatus (Prop. 2.0211) Wittgenstein claims that a sentence expresses the same proposition in every possible world and, hence, which proposition is expressed cannot depend on how each world is (otherwise we have different propositions in each world). In this paper, I shall explore the interpretation of this thesis under the perspective of Stalnaker’s (1978) theory of assertions as the reduction of the context set, i.e., the set of possible worlds compatible with the information gathered at a conversation. In Stalnaker’s version, this principle follows from the explication of assertions as having the illocutionary point of excluding some possible worlds from the context set. If there is no unique instruction to exclude some worlds, then it is not clear which reduction is meant by the speaker. This might lead to a better understanding of (and motivation for) Wittgenstein’s own version.