Edmund Gettier is Professor Emeritus at the University of Massachusetts,
Amherst. This short piece, published in 1963, seemed to many decisively to
refute an otherwise attractive analysis of knowledge. It stimulated a renewed
effort, still ongoing, to clarify exactly what knowledge comprises.
The Gettier problem, in the field of epistemology, is a landmark philosophical problem with our understanding of knowledge. Attributed to American philosopher Edmund Gettier, Gettier-type counterexamples (called “Gettier-cases”) overturned the long-held justified true belief (or JTB) account of knowledge. On the JTB account, knowledge is equivalent to justified true belief, and if all three conditions (justification, truth, and belief) are met of a given claim, then we have knowledge of that proposition. In his three-page 1963 paper, titled Is Justified True Belief Knowledge?, Gettier showed, by means of two counterexamples, that there were cases where individuals had justified true belief of a claim, but still failed to know it. Thus, Gettier showed that the JTB account was inadequate—it could not account for all of knowledge. The JTB account was first credited to Plato, though Plato argued against this very account of knowledge in the Theaetetus (210a).
The term “Gettier problem”, or “Gettier case”, or even the verb Gettiered is sometimes used to describe any case in epistemology that purports to repudiate the JTB account.
Responses to Gettier’s paper have been numerous. Some rejected Gettier’s examples, while others sought to adjust the JTB account to blunt the force of counterexamples. Gettier problems have even found their way into experiments, where the intuitive responses of people of varying demographics to Gettier cases have been studied.