 Even if Lewis is right, however, the perdurance theory may still be found wanting, since it does not secure the most commonsensical position: that fatness is a property of a cat (Haslanger 2003). According to perdurance theory, rather, it is a property of a (temporal) cat part. Those known as stage theorists (Hawley 2001, Sider 2001), accepting the ontology of perdurance theory, but modifying its semantics, offer a way to secure this desirable result. Every temporal part of a cat is a cat, they say, so Tabby-on-Monday (which is what we refer to by “Tabby”, on Monday) is a cat and is fat, just as we would like. Stage theorists have to pay a price for this advantage over perdurance theory, however. For they must accept either that our reports of the cross-temporal number of cats are not always reports of the counting of cats (as when I say, truly, that I have only ever owned three cats) or that two cat-stages (cats) may be counted as one and the same cat, so that counting cats is not always counting in accordance with absolute identity.