 Frege also made a different kind of contribution, which would prove important, to the study of propositions. In early work, he spoke as though propositional constituents were the relevant functions and (ordered n-tuples of) entities that such functions map to truth-values. But he later refined this view in light of his distinction between Sinn and Bedeutung; see the entry on  Frege.  The Sinn of an expression was said to be a “way of presenting” the corresponding Bedeutung, which might be an entity (with truth-values as special cases of entities) or a function from (ordered n-tuples of) entities to truth-values. The basic idea is that two names, like ‘Hesperus’ and ‘Phosphorus’, can present the same Bedeutung in different ways; in which case, the Sinn of the first name differs from the Sinn of the second. Given this distinction, we can think of ‘Hesperus’ as an expression that presents Venus as the evening star, while ‘Phosphorus’ presents Venus as the morning star. Likewise, we can think of ‘is bright’ as an expression that presents a certain function in a certain way, and ‘Hesperus is bright’ as a sentence that presents its truth-value in a certain way—i.e., as the value of the function in question given the argument in question. From this perspective, propositions are sentential ways of presenting truth-values, and proposition-parts are subsentential ways of presenting functions and arguments. Frege could thus distinguish the proposition that Hesperus is bright from the proposition that Phosphorus is bright, even though the two propositions are alike with regard to the relevant function and argument. Likewise, he could distinguish the trivial proposition Hesperus is Hesperus from the (apparently nontrivial) proposition Hesperus is Phosphorus. This is an attractive view. For intuitively, the inference ‘Hesperus is Hesperus, so Hesperus is Phosphorus’ is not an instance of the following obviously valid schema: A, so A. But this raised questions about what the Sinn of an expression really is, what “presentation” could amount to, and what to say about a name with no Bedeutung.