Editing David Lewis (philosopher) (section)

=== Criticisms ===
This theory has faced a number of criticisms. In particular, it is not clear how we could know what goes on in other worlds. After all, they are causally disconnected from ours; we can't look into them to see what is going on there.<ref>[[Robert Stalnaker]], ''Inquiry'', MIT Press, 1984, p. 49: "But if other possible worlds are causally disconnected from us, how do we know anything about them?"</ref> A related objection is that, while people are concerned with what they could have done, they are not concerned with what people in other worlds, no matter how similar to them, do. As [[Saul Kripke]] once put it, a presidential candidate could not care less whether someone else, in another world, wins an election, but does care whether he himself could have won it (Kripke 1980, p.&nbsp;45).{{citation needed|date=May 2021}}

Another criticism of the realist approach to possible worlds is that it has an inflated [[ontology]]—by extending the property of concreteness to more than the singular actual world it multiplies theoretical entities beyond what should be necessary to its explanatory aims, thereby violating the principle of parsimony, [[Occam's razor]]. But the opposite position could be taken on the view that the modal realist reduces the categories of possible worlds by eliminating the special case of the actual world as the exception to possible worlds as simple abstractions.

Possible worlds are employed in the work of Kripke<ref>"[[Naming and Necessity]]". In ''Semantics of Natural Language'', edited by D. Davidson and G. Harman. Reidel, 1980 (1972), pp. 253–355.</ref> and many others, but not in the concrete sense Lewis propounded. While none of these alternative approaches has found anything near universal acceptance, very few philosophers accept Lewis's brand of modal realism.