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The Gettier problem
1963· Idea or argument· Knowledge, logic & science
Well documentedSolid records, texts or physical evidence.
Edmund Gettier's three-page 1963 paper showing that a justified true belief can still fall short of knowledge.
See it on the Philosophy map →The idea
Idea: you can have a justified, true belief and still not know. Gettier's example: Smith has strong evidence that Jones will get the job and that Jones has ten coins in his pocket, so he concludes 'the man who gets the job has ten coins.' In fact Smith himself gets the job, and unknowingly has ten coins too. His belief is justified and true, but true by luck. Main objection: few reject the cases; the fight is over what fourth condition would fix the definition.
Why it matters
It overturned the standard definition of knowledge traced to Plato's Theaetetus and launched decades of searching for the missing ingredient.
Think of it like
Like believing a unit is leased because you saw a signed lease, when that deal fell through but another tenant happened to sign the same day.
Where it comes from
'Is Justified True Belief Knowledge?', Analysis (1963), three pages long. Gettier, at Wayne State University in Detroit, reportedly wrote it under pressure to publish, and published little else.
Still debated
No proposed fix, such as 'no false lemmas' or 'reliable process', has won consensus; Timothy Williamson argues knowledge cannot be defined in simpler terms at all.
Connections (2)
▸The Gettier problem refuted the classic answer to What can we know?Well documented
The connection
Many philosophers had taken knowledge to be justified true belief, a definition often traced to Plato's Theaetetus. Gettier's cases showed all three conditions can be met while a belief is right only by luck, so the three are not enough. The question of what knowledge is reopened.
When and how
Wayne State University, Detroit, 1963; Gettier targeted versions of the definition in A. J. Ayer (1956) and Roderick Chisholm (1957).
How we know
Nearly all philosophers accept the counterexamples; a 2017 study found the intuition across many cultures, though an earlier 2001 study had claimed differences.
Debates and open questions
Historians question whether anyone, even Plato, actually held the 'classic' definition in the neat form Gettier attacked.
▸Bertrand Russell anticipated, with his stopped clock, The Gettier problemWell documented
The connection
Russell's example: a man looks at a clock that has stopped, without knowing it, and happens to read the correct time. His belief is true and reasonably based, yet he does not know the time. That is a Gettier case fifteen years early, though Russell used it to make a different point.
When and how
Russell, Human Knowledge: Its Scope and Limits (1948). Around 770, the Indian Buddhist philosopher Dharmottara gave a similar case of a mirage over hidden water.
How we know
The passage is in Human Knowledge (1948); Gettier did not cite Russell, and the parallel was pointed out by later epistemologists.
Debates and open questions
Russell was arguing that knowledge is a vague concept, not refuting a definition; whether he truly anticipated Gettier or just used a similar example is debated.