 However, if one thinks that such conclusions are intolerable, how are they to be avoided? The obvious answer is that what is needed, in the Adam-Noah case, is that the roles played by Adam and Noah in the actual world include some properties that are essential to their bearers’ being Adam and Noah respectively: that Adam and Noah differ non-trivially in their essential properties as well as in their accidental properties: more precisely, that Adam has some essential property that Noah essentially lacks, or vice versa. For if ‘the Adam role’ includes some property that Noah essentially lacks, then, of course, there is no possible world in which Noah has that property, in which case the Adam role (in all its detail) is not a possible role for Noah, and the danger of a role-switching world such as the one described above is avoided.