   Given that ‘Hesperus’ and ‘Phosphorus’ are just names of the same object, how can Ava believe one thing and disbelieve the other? Given that ‘Hesperus’ and ‘Phosphorus’ apply to the same object, it would seem that ‘Hesperus is shining’ is true if and only if ‘Phosphorus is shining’ is true and that these two sentences express one and the same proposition. If what is essential to the proposition that Ava believes is that it is about Hesperus and the property of shining, how can she believe one thing and fail to believe the other since both are about Hesperus?