Gettier's Counterexamples and the Post-Gettier Debate

In 1963 the American philosopher Edmund Gettier published "Is Justified True Belief Knowledge?" in the journal Analysis, volume 23, issue 6, pages 121-123, a paper barely three pages long that is nonetheless routinely cited as among the most consequential in twentieth-century philosophy. Gettier opens by explicitly formulating the tripartite analysis as it had been stated by Chisholm and Ayer, then argues that he can describe cases in which all three conditions, truth, belief, and justification, are satisfied, yet in which competent judges would deny that the subject has knowledge. If such cases are genuine, the tripartite analysis fails to state sufficient conditions for knowledge, however secure its necessity claims about truth, belief, and justification individually might remain.