One commonly stated reason for thinking that there are abstract entities such as propositions is that they are needed to account for undeniable facts about propositional attitudes and the sentences reporting such attitudes. According to the propositional theory, belief, doubt, assertion and other attitudes are relations between individuals and propositions. In sentences reporting these relations the words in the content-sentence refer to concepts or other abstract things and the entire ‘that-clause’ refers to a proposition. According to a common rival account, (...) propositional attitudes are complex relations between individuals and sentences and each that-clause refers to the content-sentence it contains. The words in the content-sentence either fail to refer or refer to themselves. A striking implication of both the propositional theory and the sentential theory is that the words and phrases in the content-sentence of a sentence expressing a propositional attitude fail to refer to the familiar things to which they ordinarily refer. (shrink)

Frege famously claimed that variations in the sense of a proper name can sometimes be ‘tolerated’. In this paper, we offer a novel explanation of this puzzling claim. Frege, we argue, follows Trendelenburg in holding that we think in language—sometimes individually and sometimes together. Variations in sense can be tolerated in just those cases where we are using language to coordinate our actions but are not engaged in thinking together about an issue.

The main chapters of this thesis develop and defend a version of two-dimensional semantics that provides an account of Kripkean a posteriori necessity.