The Gettier Problem: Is Justified True Knowledge?

The Gettier problem is a philosophical question about whether a piece of information that happens to be true but that someone believes for invalid reasons, such as a faulty premise, counts as knowledge. It is named after American philosopher Edmund Gettier, who wrote about the problem in a three-page paper published in 1963, called "Is Justified True Belief Knowledge?". The paper refers to the concept of knowledge as justified true belief, credited to Plato, though Plato argued against this very account of knowledge in the Theaetetus . In the paper, Gettier proposed two scenarios where the three criteria seemed to be met, but where the majority of readers would not have felt that the result was knowledge due to the element of luck involved.
The term is sometimes used to cover any one of a category of thought experiments in
The more specific problem Gettier raises was also raised by Bertrand Russell in Human knowledge: Its scope and limits. In Russell’s stopped clock case, as modified by Israel Scheffler, Alice sees a clock that reads two o’clock. She believes it’s two o’clock, and that is true. However, unknown to Alice, the clock she’s looking at stopped twelve hours ago. So, she has an accidentally true, justified belief. Russell provides an answer of his own to the problem. Edmund Gettier's formulation of the problem was important as it coincided with the rise of the sort of philosophical naturalism promoted by W.V.O. Quine and others, and was used as a justification for a shift towards externalist theories of justification. John L. Pollock and Joseph Cruz have stated that the Gettier problem has "fundamentally altered the character of contemporary epistemology" and has become "a central problem of epistemology since it poses a clear barrier to analyzing