Truth at a Fictional World
A sentence is true in a fiction iff it is true at certain worlds, say, at the closest worlds where the pretense which the narrator and the audience engage in is not only pretense. But to evaluate whether the sentence is true at a world, do we treat the world as actual or as counterfactual?
It seems that there could easily be stories in which water isn't H20, and Hesperus isn't Phosphorus. This suggests that the worlds must be treated as actual. However, it isn't clear that these terms ("water" etc.) are sufficiently rigid, and if not, there are also worlds as counterfactual where the identities fail. Could there be a story in which the stuff that actually is water isn't the stuff that actually is H2O? I'm not sure.
Another (sort of wacky) argument for evaluating fictional sentences by their A-intension is that engaging in a fiction seems to work like hypothtically conditionalizing on the fictional truths. That is, when we engage in a fiction F, the subjective probability we pretend to assign to a statement S more or less equals our conditional subjective probability of S given the relevant F-facts established by the pretense. Which equals the intutive subjective probability of the indicative "if [F-facts] then S". But indicative conditionals are often put forward as heuristics to determine A-intensions, rather than C-intensions.
(If one analyses truth in fiction in terms of indicative conditionals and holds that indicative conditionals are truth-functional one gets the funny result that for almost all F and S, "in fiction F, S" is true, though usually unassertable.)
On the other hand, consider a story in which Oswald doesn't kill Kennedy, and in which Kennedy is never even mentioned. Does someone else kill Kennedy in that story? Presumably not.
If fictional worlds were to be considered as actual, the impossibility solution to imaginative resistance would be in trouble. For I'm inclined to believe that false normative statements have a contingent A-intension.