 Impossible worlds have also been employed to give theories of a range of hyperintensional phenomena in metaphysics. One early application was in the theory of de re necessity, in offering a theory of how it could be necessarily true that an artifact could be made of slightly different material, but not too different, without succumbing to Chisolm’s paradox (Salmon 1984). Impossible worlds can be used to give a hyperintensional theory of properties as sets of possible and impossible instances (Nolan 2013: 8). They can be used to offer a theory of metaphysical explanation (Kment 2014), or in a theory of essence (Brogaard &amp; Salerno 2013: 646–8). They can play a central role in a theory of omissions of impossibilities (Bernstein 2016).