 The view also seems to have all of the problems that face the neo-Russellianism. Because Superman is Clark Kent, and assuming that identity is necessary, the set of worlds in which Superman is strong is exactly the set of worlds in which Clark Kent is strong. But then (5) and (6) express the same proposition. But, as the Frege case shows, there is a strong intuition, and a pair of powerful arguments to back it up, that an agent can believe the one without believing the other. Proponents of unstructured-propositionalism are well aware of these problems. Stalnaker 1984, 1987, and 1988 contain extremely ingenious attempts to solve them.