[1] Contemporary research in semantics typically uses possible worlds as formal tools without committing to a particular theory of their metaphysical status.
[2] Possible worlds are often regarded with suspicion, which is why their proponents have struggled to find arguments in their favor.
Quine himself restricted his method to scientific theories, but others have applied it also to natural language, for example, Amie L. Thomasson in her paper entitled Ontology Made Easy.
Finally, he argued that they could not be reduced to more "ontologically respectable" entities such as maximally consistent sets of propositions without rendering theories of modality circular.
(He referred to these theories as "ersatz modal realism" which try to get the benefits of possible worlds semantics "on the cheap".
Stalnaker argues that even if the English word "actual" is an indexical, that doesn't mean that other worlds exist.
[12] Some philosophers instead endorse the view of possible worlds as maximally consistent sets of propositions or descriptions, while others such as Saul Kripke treat them as purely formal (i.e. mathematical) devices.
[13] At least since Aristotle, philosophers have been greatly concerned with the logical statuses of propositions, e.g. necessity, contingency, and impossibility.
Thus, equivalences like the following have been proposed: Possible worlds play a central role in many other debates in philosophy.
[15] Scholars have found implicit earlier traces of the idea of possible worlds in the works of René Descartes,[16] a major influence on Leibniz, Al-Ghazali (The Incoherence of the Philosophers), Averroes (The Incoherence of the Incoherence),[17] Fakhr al-Din al-Razi (Matalib al-'Aliya),[18] John Duns Scotus[17] and Antonio Rubio (Commentarii in libros Aristotelis Stagiritae de Coelo).