Full Idea
I identify a proposition with the set of possible worlds where it is true.
Gist of Idea
A proposition is a set of possible worlds where it is true
Source
David Lewis (Causation [1973], p.193)
Book Reference
'Causation', ed/tr. Sosa,E. /Tooley,M. [OUP 1993], 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.