Gettier Wrote Three Pages and Broke Plato's Definition of Knowledge

Edmund Gettier was an instructor at Wayne State in the late 1950s with no published work and a tenure clock running. His colleagues Alvin Plantinga and Hector-Neri Castaneda were prolific; he was not. So he wrote up something he had been turning over in conversation, sent it to Analysis, and in June 1963 three pages appeared under the title "Is Justified True Belief Knowledge?"

The target was old. In the Theaetetus, Plato had floated that knowing is having a true belief plus an account of why. By the twentieth century this had hardened into a formula: knowledge is justified true belief.

Gettier ran two short cases against it. Smith has strong evidence that Jones will get a job and has ten coins in his pocket. He validly infers that the man who will get the job has ten coins in his pocket. Smith turns out to be the one hired, and he also has ten coins. The conclusion is true. The belief is justified. He did not know it.

The second case uses disjunction. Smith justifiably believes Jones owns a Ford and adds, by logic alone, "or Brown is in Barcelona." Jones does not own a Ford. Brown happens to be in Barcelona. Justified, true, not knowledge.

Russell had described a man reading a stopped clock that showed the right time by accident. Gettier stripped the structure to its bones and presented a clean refutation epistemologists could not wave off.

Duncan Pritchard reports Gettier wrote the paper to satisfy a tenure requirement and had little interest in epistemology. He never published in the field again. His complete bibliography is the 1963 article, a 1965 book review, and 1967 comments on A. J. Ayer. When UMass marked fifty years of the paper with a conference in 2013, Gettier declined to attend. The patches keep coming. The crack is still there.