vague fictional predicates

I have been thinking about the possibility of vague fictional predicates. I have no thesis yet, but I have some ideas that I thought I could post.

Let's assume that a predicate is vague iff it is unclear whether it applies in some cases. This might be slightly non-standard. It is far more common to say that a sentence is vague iff it is unclear whether or not it is true. But, I think we commonly trace the vagueness of a sentence to the vagueness of the predicate and I think that we believe something like the principle stated above.

Now, suppose that we have a fiction, F1, in which two predicates are introduced. The first predicate is a kind of quantity, 'quaps'. Objects of certain kinds, according to the fiction, can have various numbers of quaps. The other predicate is 'quapful'. According to F1, when an object has lots and lots of quaps, it is quapful. However, when it only has a few quaps it is not quapful. It seems that the situation just descibed is one in which the predicate 'quapful' is vague, according to the fiction. However, is it really vague?

Here is a reason to think that the answer to that last question is 'no'. It is not unclear whether anything is quapful because it is clear that nothing is quapful. That is, it is clear in the sense relavent here. There is some sense in which it is unclear whether anything is quapful. But this is the unclarity that results from fictional discourse and that leads to the vexing metaphysical questions about fiction that we all know and love. But this is not the kind of unclarity that is relavant to vagueness. it is not unclear of any object that it is quapful because it is clear that every object is not quapful. So, 'quapful' is not vague.

You might think that we should revise our analysis of vague predicates to say that a predicate is vague iff either it is unclear whether it applies to something or according to some story, it is unclear whether it applies to something. But this will result in the unwanted consequence that necessarily, every predicate is vague. But surely it is possible that some predicate is non-vague. Consider a ladigodian language in which everything is a name for itself and every property is a predicate that picks itself out. This language is perfectly precise. But, on the above view, it cannot be.

So, what should we say about the vagueness of 'quapul'? I am not exactly sure. It looks like, perhaps a good thing to say is that 'quapful' is not vague, but rather 'according to fiction F1' is vague. But this seems strange. Why is the vagueness rooted in that expression? Moreover, there is some reason to believe that the that expression can be non-vague. Perhaps the best account of truth in fiction has the following consequence. It is possible to tell a fiction, perhaps F1, in such a way that makes it that for every name n either 'according to fiction F1, n is quapful' is determinately true, or determinately false. Moreover, if it is determinately false because the fiction is simply silent about whether the predicate applies or not. But in this situation, all else being equal, 'according to fiction F1' is non-vague even though we still have an intuition that there is vagueness somewhere.

I guess I am thinking that the best solution is the following. 'quapful' is not vague. Moreover, 'according to fiction F1' is not vague (at least given the right kind of circumstances). However, the following is a truth: according to fiction F1, 'quapful' is vague. It is this truth that makes us mistakenly feel that there is a genuinely vague predicate.

Vagueness and Supervaluationism

One of the standard objections to supervaluationist views concerning vagueness is that if they are true, then there are true existential generalizations that lack true instances and true disjunctions none of whose disjuncts are true. However, I wonder if this is an essential feature of supervaluationist views. In particular, mightn't a supervaluationist say the following:

a. An atomic sentence S is true iff it is true under all precisifications, and
b. A non-atomic sentence S is true iff there are some true atomic sentences that entail it?

Anyway, I know this isn't worked out very well or anything, but it does seem to me that making this move allows the supervaluationist to avoid one of the major objections to his view. What do the rest of you think? And do you know if a move like this has been made by any supervaluationists in the literature?