Liar Paradox
Updated 2026-09-10
INTRODUCTION
English translation pending.
CORE DEFINITION
What is odd about this sentence is false was already known to the ancients. Every lie is untrue, so is that sentence true? If true, it is a lie and so not true; if not true, then in asserting it the speaker lies, so it is true. The paradox turns on self-reference interacting with a truth predicate, and many-valued and dialetheic logics respond to it.
SCAFFOLDING EFFECT
Reduce cognitive load
- Screen for self-reference: check whether a sentence refers to itself, identifying paradox risk in advance. - Stratify the language: use the object language and metalanguage distinction to cut the self-referential loop. - Test the truth rules: examine the scope of the disquotational principle and keep the truth predicate from running wild.
Anchor fast decisions
The paradox arises from the interaction of self-reference with a truth predicate. As long as a language can construct a sentence referring to itself, and we accept the disquotational principle that a sentence is true if and only if what it says holds, a sentence equivalent to the claim that it is false can be produced, yielding a contradiction in classical logic.
MINIMUM ACTION
In progress 0/1Practice this model in one real situation:
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Source support: Explicit
- plato.stanford.eduhttps://plato.stanford.edu/entries/liar-paradox/verified
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