The recent discussion of fictional worlds at Fake Barn Country (fast becoming my favourite blog) has brought to my attention several aspects of my initial semantic contextualism theory which are in need of improvement.
The basic problem is this: I had conceived of fictional worlds as being simply reducible to real-world objects (such as ink on paper) - a sort of 'naive account'. But this is clearly inadequate once you realise all the implicit assumptions that we seem justified in making about fictional worlds, e.g. that Grisham's world has the same US Constitution as ours (where did I see this example? Please mention the link in the 'comments' if you know!).
Apparently David Lewis has a theory relating fictional worlds to possible worlds, which solves this problem. As Joshua explained it: The rough version of Lewis' theory is that a statement S is true in a fiction F iff S is true in all those worlds where F is told as known fact.
Surely that "all" is far too restrictive though, since it would allow us to only make explicit, rather than implicit, inferences from the text. (There is some distant possible world where all the facts of Grisham's stories are true, and told as such, except that Aliens have invaded Earth and rescinded the US Constitution.) More likely it is supposed to be "in all those closest possible worlds where F is told as fact".
I wonder if we can generalise this? To put it into the terminology of my previous posts, let us say that a proposition P is true of a 'sub-world' SW (eg a fiction story, a dream, whatever) iff P is true in the closest possible world (talking about OWs here) consistent with the set of facts S [all the explicit (i.e. 'reduced') facts of the SW].
(I've effectively replaced "where F is told as fact" with "where the set (S) of facts which are told of F, are all true. I wouldn't think this should cause any problems, but do let me know if you disagree!)
Now this is getting a bit mangled, since I'm using the terminology 'sub-world' to refer to some - possibly very indirect - aspect of reality (such as "the world described by fictional story X"), whereas counterfactual "possible worlds" do not refer to anything real, but rather, to different ways the OW (objective world) could, possibly, have been. So this is merging two very different concepts (though both have been discussed in - different - recent posts), with unfortunately similar vocabulary.
Simple example: John Grisham's books are all based on Earth as we know it, where various non-factual events occur (big trials, runaway juries, and whatnot). The closest possible worlds consistent with S, then, will be the worlds most identical to reality in all other respects, except for those (relatively few) facts which must be altered to make all his counterfactual propositions (S1, S2, ... Sn) true and consistent. So the US does indeed have just the same constitution as it does in reality, unless something in the stories (explicitly or implicitly) contradicts this.
I'm not sure whether the generalisation beyond fiction works at all. It may be that the sorts of inferences appropriate to fictional stories are totally inappropriate to various other sub-worlds, such as dreams. I'm really not sure.
I'm not even sure this works for all fiction... what about fantasy worlds, which are entirely divorced from reality? You presumably could have a world "closer" to reality consistent with S, which nevertheless seems less true to the spirit of the story? I feel that an important factor here is reader expectations, shared cultural backgrounds (especially mythologies, etc). This seems a very serious point, and I think it must be from me misinterpreting Lewis' theory (perhaps I shouldn't have added in all that "closest possible worlds" stuff after all? But it does seem necessary in the Grisham case!)
A further problem concerns what the "close possible OWs" are close to. You see, if we are really Brains in Vats, then the possible OWs closest to our own OW consistent with story S would be entirely different from the OWs closest to the world of our common experience (CW) consistent with story S. But we want the latter, rather than the former - our understanding of [stories, dreams, etc] is based on our undersanding of the CW as we know it, rather than the abstract OW, whatever it may be. So we should clarify that by "closest possible OW", we mean the OW which is closest to our CW (i.e. the OW which is closest to [the OW where our CW is fact]). But I guess that's a somewhat pedantic point, and can be avoided if you're happy to assume that we're really not BIVs (or any other similar skeptical hypothesis).
I'm gonna have to think about all this a bit more... it certainly seems no easy task to reconcile the problem of background/implicit assumptions into my previously proposed theory of 'semantic contextualism' with its fully reducible sub-worlds. Bugger.
Update: See the "comments" for a very helpful explanation from Joshua.
I should also clarify that the basic ideas of semantic contextualism (that truth is relative to the 'world of reference', and that what world is relevant will vary according to context) aren't really affected by any of this - the whole 'reducibility' idea helped to keep the theory nice and simple, but it isn't in any way essential to it. But I plan to write a follow-up post sometime soon, which will discuss these matters further.