Khan Academy: Analyzing Knowledge #2 (No False Lemma and No Defeater Approaches)

If we can't analyze knowledge simply as justified true belief, can we add one more ingredient to produce a successful analysis? In this Wireless Philosophy video, Jennifer Nagel examines two 'extra ingredient' analyses of knowledge: Michael Clark's 'no false lemma' analysis, and the fancier 'no undefeated defeaters' analysis of Keith Lehrer and Thomas Paxson.