Metaphysically indeterminate existence

Sider (Four-dimensionalism 2001; Philos Stud 114:135-146, 2003; Nous 43:557-567, 2009) has developed an influential argument against indeterminacy in existence. In what follows, I argue that the defender of metaphysical forms of indeterminate existence has a unique way of responding to Sider's argument. The response I'll offer is interesting not only for its applicability to Sider's argument, but also for its broader implications; responding to Sider helps to show both how we should think about precisification in the context of metaphysical indeterminacy and how we should understand commitment to metaphysically indeterminate existence. And if I'm right that metaphysical indeterminacy can allow for indeterminate existence in a way that semantic indeterminacy can't, indeterminate existence might actually give us a reason to accept metaphysical indeterminacy (rather than a reason to reject it, as is commonly assumed).