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Single Idea 8940

[filed under theme 5. Theory of Logic / L. Paradox / 6. Paradoxes in Language / a. The Liar paradox ]

Full Idea

In Tarski's account of truth, self-reference (as found in the Liar Paradox) is prevented because the truth predicate for any given object language is never a part of that object language, and so a sentence can never predicate truth of itself.

Clarification

'This sentence is false' is a Liar sentence

Gist of Idea

Tarski avoids the Liar Paradox, because truth cannot be asserted within the object language

Source

report of Alfred Tarski (The Concept of Truth for Formalized Languages [1933]) by Jennifer Fisher - On the Philosophy of Logic 03.I

Book Ref

Fisher,Jennifer: 'On the Philosophy of Logic' [Thomson Wadsworth 2008], p.38

A Reaction

Thus we solve the Liar Paradox by ruling that 'you are not allowed to say that'. Hm. The slightly odd result is that in any conversation about whether p is true, we end up using (logically speaking) two different languages simultaneously. Hm.

The 19 ideas with the same theme [problem when liars refer to themselves]:

6006 If you say truly that you are lying, you are lying [Eubulides, by Dancy,R]
9464 One of their own prophets said that Cretans are always liars [Anon (Titus)]
21564 Vicious Circle: what involves ALL must not be one of those ALL [Russell]
21567 'All judgements made by Epimenedes are true' needs the judgements to be of the same type [Russell]
19187 The Liar makes us assert a false sentence, so it must be taken seriously [Tarski]
8940 Tarski avoids the Liar Paradox, because truth cannot be asserted within the object language [Tarski, by Fisher]
6569 'This sentence is false' sends us in a looping search for its proposition [Wittgenstein, by Fogelin]
21692 If we write it as '"this sentence is false" is false', there is no paradox [Quine]
14964 The Liar reappears, even if one insists on propositions instead of sentences [Gupta]
14969 Strengthened Liar: either this sentence is neither-true-nor-false, or it is not true [Gupta]
13507 The machinery used to solve the Liar can be rejigged to produce a new Liar [Hart,WD]
9138 An infinite series of sentences asserting falsehood produces the paradox without self-reference [Yablo, by Sorensen]
15428 The Liar seems like a truth-value 'gap', but dialethists see it as a 'glut' [Burgess]
13371 If you know that a sentence is not one of the known sentences, you know its truth [Priest,G]
13372 There are Liar Pairs, and Liar Chains, which fit the same pattern as the basic Liar [Priest,G]
11014 Self-reference paradoxes seem to arise only when falsity is involved [Read]
9137 Banning self-reference would outlaw 'This very sentence is in English' [Sorensen]
15355 Strengthened Liar: 'this sentence is not true in any context' - in no context can this be evaluated [Horsten]
16336 The liar paradox applies truth to a negated truth (but the conditional will serve equally) [Halbach]