| 23486 | Pictures are possible situations in logical space [Wittgenstein] |
| Full Idea: A picture represents a possible situation in logical space. | |
| From: Ludwig Wittgenstein (Tractatus Logico-Philosophicus [1921], 2.202) | |
| A reaction: This seems pretty close to the idea that propositions are sets of possible worlds (though that seems to add unnecessary extra baggage). If they just picture situations, why does he mention logical space? Within the limits of possible picturing? |
| 4897 | A proposition is a set of possible worlds for which its intension delivers truth [Perry] |
| Full Idea: The proposition expressed by a sentence can be thought of as a set of possible worlds, the worlds for which its intension delivers truth. | |
| From: John Perry (Knowledge, Possibility and Consciousness [2001], §8.1) | |
| A reaction: It has always struck me as important to hang on to the concept of a 'proposition' (over and above sentences). This idea gives a metaphysics for the concept, and the 'language of thought' offers appropriate brain structures. A neat picture. |
| 8420 | 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. |
| 9654 | 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'? |
| 15736 | 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? |
| 15738 | 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. |
| 7002 | If propositions are states of affairs or sets of possible worlds, these lack truth values [Heil] |
| Full Idea: When pressed, philosophers will describe propositions as states of affairs or sets of possible worlds. But wait! Neither sets of possible worlds nor states of affairs - electrons being negatively charged, for instance - have truth values. | |
| From: John Heil (From an Ontological Point of View [2003], Intro) | |
| A reaction: I'm not sure that I see a problem. A pure proposition, expressed as, say "there is a giraffe on the roof" only acquires a truth value at the point where you assert it or believe it. There IS a possible world where there is a giraffe on the roof. |
| 21624 | It is known that there is a cognitive loss in identifying propositions with possible worlds [Williamson] |
| Full Idea: It is well known that when a proposition is identified with the set of possible worlds at which it is true, a region in the space of possible worlds, cognitively significant distinctions are lost. | |
| From: Timothy Williamson (Vagueness [1994], 7.6) | |
| A reaction: Alas, he doesn't specify which distinctions get lost, so this is just a pointer. It would seem likely that two propositions could have identical sets of possible worlds, while not actually saying the same thing. Equilateral/equiangular. |
| 18001 | Are there partial propositions, lacking truth value in some possible worlds? [Magidor] |
| Full Idea: Are there such things as 'partial propositions', which are truth-valueless relative to some possible worlds? | |
| From: Ofra Magidor (Category Mistakes [2013], 1.1) | |
| A reaction: Presumably this could be expressed without possible worlds. Are there propositions meaningful in New Guinea, and meaningless in England? Do some propositions require the contingent existence of certain objects to be meaningful? |