 So Wiggins deals with objections mainly by two distinctions. One is between sortals that apply to objects through the whole of their existence, and sortals appropriate only to a phase of their existence: the other is between the ‘is’ of identity and the ‘is’ of constitution. Correspondingly, criticism centres on whether the concepts under which we pick things out behave in as regimented a way as Wiggins requires, and on whether the ‘is’ of constitution is sufficiently different from the ‘is’ of identity to perform the task he wants of it.