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Single Idea 14969
[filed under theme 5. Theory of Logic / L. Paradox / 6. Paradoxes in Language / a. The Liar paradox
]
Full Idea
An example of the Strengthened Liar is the following statement SL: 'Either SL is neither-true-nor-false or it is not true'. This raises a serious problem for any theory that assesses the paradoxes to be neither true nor false.
Gist of Idea
Strengthened Liar: either this sentence is neither-true-nor-false, or it is not true
Source
Anil Gupta (Truth [2001], 5.4.2)
Book Ref
'Blackwell Guide to Philosophical Logic', ed/tr. Goble,Lou [Blackwell 2001], p.109
A Reaction
If the sentence is either true or false it reduces to the ordinary Liar. If it is neither true nor false, then it is true.
The
16 ideas
from Anil Gupta
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11215
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Notable definitions have been of piety (Plato), God (Anselm), number (Frege), and truth (Tarski)
[Gupta]
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11216
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If definitions aim at different ideals, then defining essence is not a unitary activity
[Gupta]
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11217
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Chemists aim at real definition of things; lexicographers aim at nominal definition of usage
[Gupta]
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11220
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Ostensive definitions look simple, but are complex and barely explicable
[Gupta]
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11218
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Stipulative definition assigns meaning to a term, ignoring prior meanings
[Gupta]
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11221
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A definition can be 'extensionally', 'intensionally' or 'sense' adequate
[Gupta]
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11222
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The ordered pair <x,y> is defined as the set {{x},{x,y}}, capturing function, not meaning
[Gupta]
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11223
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Definitions usually have a term, a 'definiendum' containing the term, and a defining 'definiens'
[Gupta]
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11224
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Traditional definitions are general identities, which are sentential and reductive
[Gupta]
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11226
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Traditional definitions need: same category, mention of the term, and conservativeness and eliminability
[Gupta]
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11225
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A definition needs to apply to the same object across possible worlds
[Gupta]
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11227
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The 'revision theory' says that definitions are rules for improving output
[Gupta]
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14965
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Truth rests on Elimination ('A' is true → A) and Introduction (A → 'A' is true)
[Gupta]
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14964
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The Liar reappears, even if one insists on propositions instead of sentences
[Gupta]
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14968
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A weakened classical language can contain its own truth predicate
[Gupta]
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14969
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Strengthened Liar: either this sentence is neither-true-nor-false, or it is not true
[Gupta]
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