Introduction

• The Gettier problem is a landmark issue in epistemology concerning the nature of descriptive knowledge.

• Named after American philosopher Edmund Gettier, who challenged the classical justified true belief (JTB) account of knowledge.

• The JTB account states knowledge equals a belief that is justified, true, and held.

• In his 1963 paper, “Is Justified True Belief Knowledge?”, Gettier presents two counterexamples where individuals have justified true belief but still fail to have knowledge.

• These cases show that the justification for belief, though seeming valid, is actually based on false reasons or luck, undermining true knowledge.

• Gettier concludes that the JTB account is inadequate as it lacks necessary and sufficient conditions to fully define knowledge.

• The terms “Gettier problem,” “Gettier case,” or “Gettiered” refer broadly to any epistemological case that challenges the JTB account.

• Responses vary: some reject Gettier’s examples as poor justification, others try to modify the JTB theory to address these problems.

• Gettier problems have been incorporated into sociological experiments studying intuitive human responses to these cases across diverse populations.

History

• The question of what constitutes knowledge dates back to early philosophy, notably in Plato’s dialogues Meno and Theaetetus.

• Gettier was not the first to raise the problem; it was recognized earlier by Alexius Meinong and Bertrand Russell, who discussed it in Human Knowledge: Its Scope and Limits.

• The problem has been known since the Middle Ages, with examples from Indian philosopher Dharmottara and scholastic logician Peter of Mantua.

• Dharmottara’s examples (c. 770 AD):

  • An observer mistakes a cloud of insects for smoke over a fire that has just been lit. Does the observer know there is a fire?

  • A traveller sees a mirage of water but actual water is hidden nearby. Did the traveller know water was there despite the hallucination?

• Indo-Tibetan epistemologists debated various theories of knowledge, including causal theories advanced by Gaṅgeśa in the 14th century.

• Russell’s stopped clock case: Alice sees a clock reading two o’clock and believes it is two o’clock, which is true; however, the clock stopped 12 hours earlier, so her belief is accidentally true but justified.

• Gettier’s formulation coincided with the rise of philosophical naturalism (e.g., W. V. O. Quine) and justified a shift toward externalist theories of justification.

• John L. Pollock and Joseph Cruz state the Gettier problem has fundamentally altered contemporary epistemology and remains a central barrier to analyzing knowledge.

• Alvin Plantinga critiques the historical view that JTB was the orthodox theory before Gettier, arguing that explicit JTB accounts before Gettier are rare.

• Plantinga acknowledges that some philosophers, like C. I. Lewis and A. J. Ayer, did advance a JTB account before Gettier.

Knowledge as justified true belief (JTB)

• The JTB (Justified True Belief) account of knowledge claims that knowledge can be analyzed as a belief that is both justified and true.

• According to JTB, a subject S knows a proposition P if and only if:

  • P is true,

  • S believes that P is true, and

  • S is justified in believing that P is true.

• The JTB account was first credited to Plato, although he argued against this account in his dialogue Theaetetus (210a).

• Gettier’s criticism challenged the adequacy of the JTB account as a full explanation of knowledge.