 The difference in sense between ‘Superman’ and ‘Clark’ also explains the difference in cognitive value between (5) and (6). Although both sentences have the same truth-value, because the constituents are co-referential, they express different senses, because the names ‘Clark Kent’ and ‘Superman’ express different senses, according to Frege. Although the truth-value of a sentence depends on the referents of terms, the cognitive value depends on the senses attached to the terms.