In Defence of Fictionalism about Possible Worlds

If you utter the sentence 'There were blue swans on the lake' in telling a story, you are not understood as committing yourself to the existence of blue swans. Rather your utterance is considered as an elliptical expression of the sentence 'In the story, there were blue swans on the lake'. Clearly, quantification within the scope of such a story operator does not carry serious ontological commitment. By analogy, Gideon Rosen [9] suggests that talk about possible worlds should be understood as talk within the scope of a story operator. Thus, if you assert 'There are possible worlds at which blue swans exist', Rosen holds that your assertion is best understood along the lines of 'According to the fiction of many possible worlds, there are worlds at which blue swans exist'.