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Single Idea 12004
[filed under theme 10. Modality / E. Possible worlds / 3. Transworld Objects / c. Counterparts
]
Full Idea
The outstanding technical objection to counterpart-theoretic semantics concerns its handling of the logic of identity. In quantified S5 (the orthodox semantics) a = b → □(a = b) is valid, but 'a' must not attach to two objects.
Gist of Idea
Counterpart theory is not good at handling the logic of identity
Source
Graeme Forbes (The Metaphysics of Modality [1985], 3.5)
Book Ref
Forbes,Graeme: 'The Metaphysics of Modality' [OUP 1985], p.66
The
25 ideas
from 'The Metaphysics of Modality'
11885
|
Only individual essences will ground identities across worlds in other properties
[Forbes,G, by Mackie,P]
|
11888
|
Identities must hold because of other facts, which must be instrinsic
[Forbes,G, by Mackie,P]
|
12003
|
De re modal formulae, unlike de dicto, are sensitive to transworld identities
[Forbes,G]
|
12004
|
Counterpart theory is not good at handling the logic of identity
[Forbes,G]
|
12005
|
The symbol 'ι' forms definite descriptions; (ιx)F(x) says 'the x which is such that F(x)'
[Forbes,G]
|
12008
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Unlike places and times, we cannot separate possible worlds from what is true at them
[Forbes,G]
|
12009
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The problem with possible worlds realism is epistemological; we can't know properties of possible objects
[Forbes,G]
|
12007
|
Possible worlds are points of logical space, rather like other times than our own
[Forbes,G]
|
12010
|
Is the meaning of 'and' given by its truth table, or by its introduction and elimination rules?
[Forbes,G]
|
12014
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An individual essence is a set of essential properties which only that object can have
[Forbes,G]
|
12015
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Non-trivial individual essence is properties other than de dicto, or universal, or relational
[Forbes,G]
|
12013
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Essential properties depend on a category, and perhaps also on particular facts
[Forbes,G]
|
12012
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Essential properties are those without which an object could not exist
[Forbes,G]
|
12011
|
Transworld identity concerns the limits of possibility for ordinary things
[Forbes,G]
|
12016
|
The problem of transworld identity can be solved by individual essences
[Forbes,G]
|
12017
|
In all instances of identity, there must be some facts to ensure the identity
[Forbes,G]
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12020
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An individual might change their sex in a world, but couldn't have differed in sex at origin
[Forbes,G]
|
12021
|
Haecceitism attributes to each individual a primitive identity or thisness
[Forbes,G]
|
12022
|
Same parts does not ensure same artefact, if those parts could constitute a different artefact
[Forbes,G]
|
12023
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Vagueness problems arise from applying sharp semantics to vague languages
[Forbes,G]
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12024
|
If we combined two clocks, it seems that two clocks may have become one clock.
[Forbes,G]
|
12025
|
Artefacts have fuzzy essences
[Forbes,G]
|
12027
|
There must be a plausible epistemological theory alongside any metaphysical theory
[Forbes,G]
|
12028
|
De re necessity is a form of conceptual necessity, just as de dicto necessity is
[Forbes,G]
|
12029
|
We believe in thisnesses, because we reject bizarre possibilities as not being about that individual
[Forbes,G]
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