A compact entry for students, philosophers-in-training, and anyone who has ever been certain about something and later found their certainty was borrowed from luck.
Definition: The Gettier problem is an epistemological challenge to the traditional definition of knowledge as justified true belief (JTB). It consists of counterexamples in which a person holds a belief that is (1) true, (2) supported by strong evidence, yet (3) not knowledge because the evidence points to the wrong explanatory path, while the truth of the belief is an accident or coincidence.
Core Concept
The problem originates from Edmund Gettier's 1963 paper, "Is Justified True Belief Knowledge?" Gettier constructed two scenarios involving a character named Smith. In both, Smith's conclusion is true and his premise is well-justified, but the justification does not actually connect to the truth in the right way. The term "epistemic luck" captures the central phenomenon: the believer happens to be right, but not because of their reasons.
Two Classic Cases
The Ten Coins Case. Smith is told by the company president that Jones will get the job. Smith also counts ten coins in Jones's pocket. From this, Smith concludes: "The person who will get the job has ten coins in his pocket." In fact, Smith gets the job, and Smith also has ten coins in his own pocket. The conclusion is true and justified by the evidence, but Smith does not know it.
The Ford in Barcelona Case. Smith has strong evidence for "Jones owns a Ford" based on rentals and past rides. He disjunctively adds "or Brown is in Barcelona" to create "Jones owns a Ford or Brown is in Barcelona." It turns out Jones does not own the Ford, but Brown is in Barcelona. Again, the belief is justified and true, but not known.
Why It Matters
The Gettier problem forced epistemologists to refine the analysis of knowledge. It exposed that the JTB account is insufficient—knowledge requires some fourth condition, perhaps a causal connection, sensitivity, safety, or virtue‑based reliability. The problem also has practical implications: it highlights how confident beliefs in daily life, fed by compelling but misleading evidence, can be accidentally true without constituting genuine knowledge.
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Join NowRelated Terms
- Epistemic luck: when a belief is true by chance or good fortune rather than through a reliable method.
- Reliabilism: the theory that knowledge is true belief produced by a reliable cognitive process—a response to Gettier cases.
- Post-Gettier epistemology: the research program attempting to fix the JTB definition or replace it.
Referenced Works & Texts
- Edmund L. Gettier, "Is Justified True Belief Knowledge?", Analysis 23, no. 6 (1963).
- Alvin I. Goldman, "Discrimination and Perceptual Knowledge", The Journal of Philosophy 73 (1976). Reliabilist response.
- Duncan Pritchard, Epistemic Luck (2005). The role of luck in knowledge.