Propositional attitudes, like believing and asserting, are relations between agents and propositions. Agents are individuals who do the believing and asserting; propositions are things that are believed and asserted. Propositional attitude ascriptions are sentences that ascribe propositional attitudes to agents. For example, a propositional attitude ascription α believes, or asserts, that S is true iff the referent of a bears the relation of believing, or asserting, to the proposition expressed by s. The questions I will address have to do with (...) the precise nature of propositions, and the attitudes, like belief, that we bear to them.I will assume both that propositions are the semantic contents of sentences, and that the proposition expressed by a sentence is a structured complex made up of the semantic contents of the parts of the sentences that express it. (shrink)