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Single Idea 14968

[filed under theme 3. Truth / F. Semantic Truth / 2. Semantic Truth ]

Full Idea

If a classical language is expressively weakened - for example, by dispensing with negation - then it can contain its own truth predicate.

Gist of Idea

A weakened classical language can contain its own truth predicate

Source

Anil Gupta (Truth [2001], 5.2)

Book Ref

'Blackwell Guide to Philosophical Logic', ed/tr. Goble,Lou [Blackwell 2001], p.101


A Reaction

Thus the Tarskian requirement to move to a metalanguage for truth is only a requirement of a reasonably strong language. Gupta uses this to criticise theories that dispense with the metalanguage.

Related Ideas

Idea 16295 Tarski proved that truth cannot be defined from within a given theory [Tarski, by Halbach]

Idea 14796 Independent truth (if there is any) is the ultimate result of sufficient enquiry [Peirce]


The 4 ideas from 'Truth'

Truth rests on Elimination ('A' is true → A) and Introduction (A → 'A' is true) [Gupta]
The Liar reappears, even if one insists on propositions instead of sentences [Gupta]
A weakened classical language can contain its own truth predicate [Gupta]
Strengthened Liar: either this sentence is neither-true-nor-false, or it is not true [Gupta]