  One solution to this is to embrace a version of Modal Realism, for instance David Lewis', according to which other possible worlds exist and contain things of the same kinds as the things in the actual world (see Lewis 1986a). Then properties get identified with classes whose members need not belong to the same possible world. Thus the property of scarlet things is the class of things that are scarlet in any possible   world.[15]  And even if every actual F is a G and vice versa, since not every possible F is a G or vice versa, what makes something F, namely belonging to the class of actual and possible Fs, is not the same as what makes it G. The theory denies that there are and there could be necessarily coextensive properties.