The slingshot argument: An improved version

In the paper I exploit Frege's notions of sense and synonymity in order to amend the slingshot argument. The main emendation is to replace the assumption about logical equivalence by an assumption about synonymity. While the replaced assumption begs the question about the reference of sentences, the replacing assumption has much more theoretical support from Frege's general conception of sense and reference and the relation between them. In the paper I use a specific notion of synonymity which I believe is faithful to Frege's discussion of the subject. I notice that if a stronger (and to my mind implausible) notion of synonymity is used, my version of the argument fails. The failure is explained by showing that this stronger notion of synonymity enables the assignment of facts, and not truth values, as the references of sentences.