Liar paradox

related topics
{theory, work, human}
{language, word, form}
{law, state, case}
{math, number, function}

In philosophy and logic, the liar paradox or liar's paradox (pseudomenon in Ancient Greek), is the statement "This sentence is false". Trying to assign to this statement a classical binary truth value leads to a contradiction (see Paradox).

If "This sentence is false" is true, then it is false, which would in turn mean that it is actually true, but this would mean that it is false, and so on ad infinitum.

Similarly, if "This sentence is false" is false, then it is true, which would in turn mean that it is actually false, but this would mean that it is true, and so on ad infinitum.

Contents

History

The Epimenides paradox (circa 600 BC) has been suggested as an example of the liar paradox, but they are not logically equivalent. The fictional speaker Epimenides, a Cretan, reportedly stated that "The Cretans are always liars." However Epimenides' statement that all Cretans are liars can be resolved as false, given that he knows of at least one other Cretan who does not lie.

It is unlikely that Epimenides intended his words to be understood as a kind of liar paradox, and they were probably only understood as such much later in history.[citation needed]

The oldest known version of the actual liar paradox is attributed to the Greek philosopher Eubulides of Miletus who lived in the fourth century BC. It is very unlikely that he knew of Epimenides's words, even if they were intended as a paradox.[citation needed] Eubulides reportedly asked:

Full article ▸

related documents
Derek Parfit
Begging the question
Tractatus Logico-Philosophicus
Ethnography
Omniscience
Alvin Plantinga
Embodied philosophy
Stanley Fish
Saul Kripke
Individualism
Extrasensory perception
Id, ego, and super-ego
Complex systems
Green anarchism
Social anthropology
Jeremy Bentham
Literary criticism
Consensus reality
John Polkinghorne
Natural science
Omnipotence
Dystopia
Platonic realism
Natural theology
Psychological egoism
Abstraction
Ontology (information science)
The Mismeasure of Man
George Berkeley
Language acquisition