The analysis of belief is concerned with what Russell calls 'prepositional attitudes' which are expressed by, e.g., 'Othello believes that Desdemona loves Gassio', or 'A knows that P,' 'A wishes that P', etc. The logical difficulties involved are many. Thus in 'A believes that P', what does 'that P' correspond to if it is false? It cannot be a fact. Since 'believes' is a two-place predicate, then it expresses a relation between two singular terms and 'that must be an entity. But philosophers disagree about whether 'that 'P is a proposition, a sentence, or a statement, and whether there is any difference between them. Other problems are posed by the rules of elementary logic - those of quantification, truth-functions, and identity. 'A believ...