Full Idea
Possible worlds are just not the sorts of things that could ground modality; they are not suitable truthmakers.
Gist of Idea
Possible worlds are just not suitable truthmakers for modality
Source
Jonathan D. Jacobs (A Powers Theory of Modality [2010], §3)
Book Reference
-: 'Philosophical Studies' [-], p.6
A Reaction
Are possible world theorists actually claiming that the worlds 'ground' modality? Maybe Lewis is, since all those concrete worlds had better do some hard work, but for the ersatzist they just provide a kind of formal semantics, leaving ontology to others.