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Single Idea 16224

[filed under theme 9. Objects / F. Identity among Objects / 6. Identity between Objects ]

Full Idea

Two things can't be vaguely identical, because then a would have an indeterminacy which b lacks (namely, being perfectly identical to b), so by Leibniz's Law they can't be identical.

Gist of Idea

There can't be vague identity; a and b must differ, since a, unlike b, is only vaguely the same as b

Source

report of Gareth Evans (Can there be Vague Objects? [1978], 4.7) by PG - Db (ideas)

Book Ref

Hawley,Katherine: 'How Things Persist' [OUP 2004], p.118


A Reaction

[my summary of Katherine Hawley's summary (2001:118) of Evans] Hawley considers the argument to be valid. I have grave doubts about whether b's identity with b is the sort of property needed for an application of Liebniz's Law.


The 20 ideas with the same theme [two objects turning out to be one object]:

Two things relate either as same or different, or part of a whole, or the whole of the part [Plato]
Carneades denied the transitivity of identity [Carneades, by Chisholm]
Identity between objects is not a consequence of identity, but part of what 'identity' means [Frege, by Dummett]
Identity of physical objects is just being coextensive [Quine]
If Hesperus and Phosophorus are the same, they can't possibly be different [Kripke]
Identity statements can be contingent if they rely on descriptions [Kripke]
Identity statements make sense only if there are possible individuating conditions [Benacerraf]
There can't be vague identity; a and b must differ, since a, unlike b, is only vaguely the same as b [Evans, by PG]
A is necessarily A, so if B is A, then B is also necessarily A [Wiggins]
Claims on contingent identity seem to violate Leibniz's Law [Gibbard]
Two things can never be identical, so there is no problem [Lewis]
All identity is necessary, though identity statements can be contingently true [McGinn]
'Lightning is electric discharge' and 'Phosphorus is Venus' are synthetic a posteriori identities [Lycan]
We would understand identity between objects, even if their existence was impossible [Fine,K]
If two things are equal, each side involves a necessity, so the equality is necessary [Gallois]
Occasional Identity: two objects can be identical at one time, and different at others [Gallois, by Hawley]
Identities can be true despite indeterminate reference, if true under all interpretations [Schaffer,J]
Identity statements are informative if they link separate mental files [Recanati]
Identical entities must be of the same category, and meet the criteria for the category [Thomasson]
Identity claims between objects are only well-formed if the categories are specified [Thomasson]