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9. Objects / F. Identity among Objects / 8. Leibniz's Law

[identical objects must have identical features or truths]

18 ideas
Only if two things are identical do they have the same attributes [Aristotle]
Two things are different if something is true of one and not of the other [Duns Scotus]
Two bodies differ when (at some time) you can say something of one you can't say of the other [Hobbes]
Two substances can't be the same if they have different attributes [Spinoza]
Leibniz's Law is incomplete, since it includes a non-relativized identity predicate [Wasserman on Geach]
The indiscernibility of identicals is as self-evident as the law of contradiction [Kripke]
Do both 'same f as' and '=' support Leibniz's Law? [Wiggins]
Substitutivity, and hence most reasoning, needs Leibniz's Law [Wiggins]
Two identical things must share properties - including creation and destruction times [Gibbard]
Leibniz's Law isn't just about substitutivity, because it must involve properties and relations [Gibbard]
Indiscernibility is basic to our understanding of identity and distinctness [Noonan]
Leibniz's Law must be kept separate from the substitutivity principle [Noonan]
Leibniz's Law says 'x = y iff for all P, Px iff Py' [McGinn]
Leibniz's Law presupposes the notion of property identity [McGinn]
Leibniz's Law is so fundamental that it almost defines the concept of identity [McGinn]
Leibniz's Law is an essentialist truth [Oderberg]
If you say Leibniz's Law doesn't apply to 'timebound' properties, you are no longer discussing identity [Sider]
If two things might be identical, there can't be something true of one and false of the other [Hawley]