 Frege held that correct propositional attitude attributions must indicate the way that individuals are represented by the agent (the agent’s mode of presentation of the referent) and that an occurrence of a referential expression within the scope of a propositional attitude verb refers to a way of representing an object rather than to the expression’s ordinary referent. ‘Superman’ and ‘Clark’ as they occur in (5) and (6) refer to the same man, known under these two different names. (5) and (6) share common referents but express different propositions or thoughts. Those same expressions as they occur in (1) and (4), however, refer to different ways that Lois has of representing the man Superman. According to Frege, this difference in reference explains the difference in truth-value of (1) and (4). The ordinary sense of an expression – the way that the expression indicates its referent – becomes a part of the truth-conditions for a sentence in which the expression occurs, if that expression is used within a belief context. Within this linguistic environment, expressions refer to their customary senses.