This doctoral dissertation is on the semantics of propositional attitude ascriptions. To be more precise, it is mainly concerned with various kinds of analyses of singular propositional attitude ascriptions. These are sentences of the general form 'X Øs that a is F', where 'X' can be replaced by the name of the person who is in the particular mental state, 'Ø' can be replaced by a propositional attitude verb, like 'believe', 'doubt', 'hope', 'desire', etc., 'a' can be replaced by the name of the individual/object about whom/which the particular attitude is held, and 'F' can be replaced by the name of the property that the individual/object is said to have. The dissertation takes belief to be a paradigmatic example of a propositional attitud...