It is widely held that propositions perform a plethora of theoretical roles. They are believed to be the semantic values of sentences in contexts, the objects of attitudes, the contents of illocutionary acts, the referents of ‘that’-clauses, and the primary bearers of truth. This assumption is often combined with the claim that propositions have their truth-values eternally. Following Kaplan’s and Lewis’s Operator Argument, I argue that the compositional semantic values of sentences do not correspond to eternal propositions. Therefore, we cannot hold on to both assumptions at the same time: either we regard the non-eternal entities that realize the compositional role of propositions as fulfilling the remaining theoretical roles, or we abandon the assumption that there is a unique realizer. The Operator Argument has recently come under attack, mainly for its intensional assumptions. However, rejecting these assumptions is not a sufficient defense of eternal propositions as compositional semantic values of sentences. Firstly, we can give a generalized version of the Operator Argument that seems independent of the contested assumptions. Secondly, the extensional alternative to the intensional framework does not allow us to retain eternal propositions as unique semantic values either.