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10. Modality / E. Possible worlds / 2. Nature of Possible Worlds / b. Worlds as fictions

[possible worlds as complete consistent fictions]

8 ideas
Possible worlds are world-stories, maximal descriptions of whole non-existent worlds [Adams,RM, by Molnar]
     Full Idea: According to a theory proposed by Adams, possible worlds are world-stories, that is maximally complete consistent sets of propositions which between them describe non-existent whole worlds.
     From: report of Robert Merrihew Adams (Primitive Thisness and Primitive Identity [1979]) by George Molnar - Powers 12.2.2
     A reaction: Presumably this places an additional constraint on the view that a world is just a maximal set of propositions. It seems to require coherence as well as consistency. Suppose an object destroys all others objects. Is that a world?
A possible world can be seen as a complete and consistent novel [Jeffrey]
     Full Idea: A novel describes a possible world in as much detail as is possible without exceeding the resources of the agent's language. But if talk of possible worlds seems dangerously metaphysical, focus on the novels themselves, when complete and consistent.
     From: Richard Jeffrey (The Logic of Decision [1965], 12.8), quoted by David Lewis - On the Plurality of Worlds
     A reaction: Lewis seems to cite this remark from Jeffrey as the source of the idea that ersatz linguistic worlds are like novels. Why won't a novel with one tiny inconsistency count as a possible world? People seem to live in it.
Not every story corresponds to a possible world [Wiggins]
     Full Idea: It is perfectly notorious that not every story corresponds to a possible world.
     From: David Wiggins (Sameness and Substance Renewed [2001], 2.4)
     A reaction: Thus a fantasy castle might be decorated with 'beautiful circular squares', or be threatened by a lump of enriched uranium twenty feet in diameter. Wiggins is replying to the claim that a possible world represents a 'story'.
Linguistic possible worlds need a complete supply of unique names for each thing [Lewis]
     Full Idea: There are two difficulties with Carnap's taking possible worlds as linguistic. Everything must have a name, or our state-descriptions will be silent about nameless things, and nothing may have two names, or we may affirm and deny a predicate of one thing.
     From: David Lewis (On the Plurality of Worlds [1986], 3.2)
     A reaction: The idea of possible worlds as linguistic has no appeal for me, so this problem doesn't surprise or bother me, but it sounds fairly terminal for the project.
Maximal consistency for a world seems a modal distinction, concerning what could be true together [Lewis]
     Full Idea: An ersatz world must be maximally consistent (hence destroyed by an additional sentences), …but that is prima facie a modal distinction: a set of sentences is consistent iff those sentences, as interpreted, could all be true together.
     From: David Lewis (On the Plurality of Worlds [1986], 3.2)
     A reaction: This is indicative of Lewis's motivation for his project, which is to eliminate modal facts from the world. Only a vast multitude of non-modal concrete worlds can satisfy all the contraints. Cf many-worlds quantum mechanics for non-locality.
Linguistic possible worlds have problems of inconsistencies, no indiscernibles, and vocabulary [Lewis]
     Full Idea: Linguistic representations of possible worlds have three problems: some descriptions are inconsistent (which worlds cannot be); we cannot have indiscernible descriptions (though some worlds might be so); and descriptions are limited by vocabulary.
     From: David Lewis (On the Plurality of Worlds [1986], 3.2)
     A reaction: Lewis is wonderful at getting problems clearly on the table. I take the idea of possible worlds as linguistic entities to be a non-starter, because (as usual) animals do it too, when they think of possibilities, which even the dimmest ones must do.
Governing possible worlds theory is the fiction that if something is possible, it happens in a world [Yablo]
     Full Idea: The governing fiction of possible worlds theory says that whenever something is possible, there is a world where it happens.
     From: Stephen Yablo (Go Figure: a Path through Fictionalism [2001], 05)
     A reaction: This sounds like the only sensible attitude to possible worlds I can think of.
The truth of propositions at possible worlds are implied by the world, just as in books [Melia]
     Full Idea: Propositions are true at possible worlds in much the same way as they are true at books: by being implied by the book.
     From: Joseph Melia (Modality [2003], Ch.7)
     A reaction: An intriguing way to introduce the view that possible worlds should be seen as like books. The truth-makers of propositions about the actual world are items in it, but the truth-makers in novels (say) are the conditions of the whole work as united.