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Full Idea
Identity across possible worlds makes sense only with respect to a sortal
Clarification
A 'sortal' says what sort of thing it is
Gist of Idea
Possible worlds identity needs a sortal
Source
Allan Gibbard (Contingent Identity [1975], IV)
Book Ref
-: 'Journal of Symbolic Logic' [-], p.198
A Reaction
See Gibbard's other ideas from this paper. I fear that the sortal invoked is too uncertain and slippery to do any useful job, and I can't see any principled difficulty with naming something before you can think of a sortal for it.
| 14064 | If a statue is identical with the clay of which it is made, that identity is contingent [Gibbard] |
| 14066 | A 'piece' of clay begins when its parts stick together, separately from other clay [Gibbard] |
| 14067 | Clay and statue are two objects, which can be named and reasoned about [Gibbard] |
| 14065 | Two identical things must share properties - including creation and destruction times [Gibbard] |
| 14070 | A particular statue has sortal persistence conditions, so its origin defines it [Gibbard] |
| 14069 | We can only investigate the identity once we have designated it as 'statue' or as 'clay' [Gibbard] |
| 14071 | Naming a thing in the actual world also invokes some persistence criteria [Gibbard] |
| 14072 | Possible worlds identity needs a sortal [Gibbard] |
| 14073 | Claims on contingent identity seem to violate Leibniz's Law [Gibbard] |
| 14074 | Leibniz's Law isn't just about substitutivity, because it must involve properties and relations [Gibbard] |
| 14076 | Essentialism is the existence of a definite answer as to whether an entity fulfils a condition [Gibbard] |
| 14077 | Essentialism for concreta is false, since they can come apart under two concepts [Gibbard] |
| 14078 | Only concepts, not individuals, can be the same across possible worlds [Gibbard] |
| 14079 | Kripke's semantics needs lots of intuitions about which properties are essential [Gibbard] |