Philosophical
Gettier Problem
Justified true belief is not sufficient for knowledge
Overview
Cases showing that justified true belief doesn't always constitute knowledge.
You justifiably believe Smith will get the job (boss told you) and Smith has 10 coins in his pocket (you counted). You infer: 'The person who gets the job has 10 coins.' This is true (you get the job and you have 10 coins), but your belief seems lucky, not knowledge.