What is knowledge?
For some time, the answer to this perennial question was thought by many to be "justified true belief". If I believe X to be true, I have good reason for believing X to be true, and X really is true, then I know X. In 1963, Edmund Gettier published a now legendary three-page paper titled "Is Justified True Belief Knowledge?" in which he gave two examples of justified true belief that did not constitute knowledge. Since then, epistemologists have mostly agreed that there's some extra ingredient requisite for knowledge but have disagreed about what it is. After drawing out Gettier's examples, Peter Klein explains that there are two major camps. The first he calls etiology of belief: theories in which the extra ingredient has to do with how the belief was attained. Reliabilists, for example, argue that a justified true belief counts as knowledge if the belief is arrived at via a method that reliably delivers accurate beliefs. Klein belongs to the second camp: quality of evidence theories, which have to do with the strength of the justification, not the cause of the belief. Klein defends his own preferred quality of evidence theory: defeasibility theory, which involves the existence or absence of "defeaters" for the justification.
Next week: David Papineau: Physicalism
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Interested in knowledge? You may be interested in Alvin Plantinga's epistemology, which I discussed with professor Jim Slagle.
Explaining Knowledge: New Essays on the Gettier Problem (ed. Claudio de Almedia, Rodrigo Borges, Peter Klein)
"Is Justified True Belief Knowledge?" (Edmund Gettier)
0:53 - Introducing the Gettier problem (fallibilism and closure)
5:14 - Gettier's first example: Smith and Jones
8:43 - Gettier's second example: Jones and Brown
13:18 - Warrant
15:37 - Etiology of belief solutions: tracking, virtue, reliabilism
20:52 - Causes of belief
28:52 - Peter Unger on psychological certainty
33:22 - Defeasibility theory
46:41 - Argument against closure