the proposition that Bono knows a good rhyme; and that sentence is true in a derivative sense just in case that proposition is true.4 While not identical to declarative sentences, then, propositions are nonetheless closely related to such sentences. In short, those sentences express propositions. But propositions and the sentences that express them cannot be placed in a one-to-one correlation. For consider the English sentence, “I think therefore I am,” and its Latin equivalent, “Cogito ergo sum.”