are true.  The first member of each pair is true, but ‘die Königin der Adria’ has a different sense from ‘Venice,’ because it is a descriptive phrase and has an internal syntactic and semantic complexity that the proper name ‘Venice’ does not.  Sellars guarantees the extensionality of reference by introducing a quantifier into his analysis of ‘refers’ statements.  He takes reference statements to quantify implicitly over senses, that is, functions of expressions, and then defines an extensional relation of material or extensional equivalence between senses (see SM III §63: 84).  Our example sentences are then analyzed, where ‘S’ is variable over senses (so that ‘S’ is a higher-order substitutional variable whose substituends are sortals such as •Venice•), as 