Full Idea
There are four models of the ontological status of possible worlds: conceptualist (mental constructions), combinatorial (all combinations of the actual world), abstract worlds (conjunction of propositions), and concrete worlds (collections of concreta).
Gist of Idea
Four theories of possible worlds: conceptualist, combinatorial, abstract, or concrete
Source
J Hoffman/G Rosenkrantz (Platonistic Theories of Universals [2003], 4)
Book Reference
'The Oxford Handbook of Metaphysics', ed/tr. Loux,M /Zimmerman,D [OUP 2005], p.66
A Reaction
[the proponents cited are, in order, Rescher, Cresswell, Plantinga and Lewis] They dismiss Rescher and Cresswell, both of whom seem to me more plausible than Plantinga or Lewis. 'Possible' can't figure in the definition. Possible to us, or in reality?