Combining Philosophers

Ideas for Lynch,MP/Glasgow,JM, David Lewis and Mulligan/Simons/Smith

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4 ideas

19. Language / D. Propositions / 2. Abstract Propositions / b. Propositions as possible worlds
A proposition is a set of possible worlds where it is true [Lewis]
     Full Idea: I identify a proposition with the set of possible worlds where it is true.
     From: David Lewis (Causation [1973], p.193)
     A reaction: As it stands, I'm baffled by this. How can 'it is raining' be a set of possible worlds? I assume it expands to refer to the truth-conditions, among possibilities as well as actualities. 'It is raining' fits all worlds where it is raining.
A proposition is a set of entire possible worlds which instantiate a particular property [Lewis]
     Full Idea: I identify propositions with certain properties - namely, with those that are instantiated only by entire possible worlds. Then if properties generally are the sets of their instances, a proposition is a set of possible worlds.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: I don't get this. How can the proposition that tomatoes are edible be an entire set of possible worlds? The proposition seems to be about tomatoes, and nothing else. Should we talk of 'possibilities', rather than of 'possible worlds'?
A proposition is the property of being a possible world where it holds true [Lewis]
     Full Idea: I identify propositions with properties that are instantiated only by entire possible worlds. If properties are the sets of their instances, a proposition is a set of possible worlds. A proposition is the property of being a world where it holds.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: This is so far away from my concept of a proposition (as a truth-evaluable representational mental event) that I struggle to compute it. So the proposition that I am sitting here is the property of 'being the actual world'. Eh?
Propositions can't have syntactic structure if they are just sets of worlds [Lewis]
     Full Idea: If it is central to 'proposition' that there be quasi-syntactic structure, so that there are subject-predicate, or negative, or conjunctive, or quantified propositions, then sets of possible worlds will not do.
     From: David Lewis (On the Plurality of Worlds [1986], 1.5)
     A reaction: He proposes 'more complicated set-theoretic constructions out of possibilia' instead. I am very much committed to propositions having quasi-syntactic structure.