(In considering whether a domain makes the theory true, the interpretation of the predicates occurring in the theory is restricted to the domain if need be.) This account is purely extensional: if a theory is committed to a kind K, and K′ has exactly the same members as K, then the theory is also committed to kind K′. And that will be its downfall. For, as above, ‘∃x Centaur(x)’ and ‘∃x Unicorn(x)’ will have the same ontological commitments. The only difference is that, because the condition is universal rather than existential, the criterion will have both of these sentences be (vacuously) committed to every kind of entity.  No improvement there.[6]