justified true belief

Description
Often used to define "knowledge". Also referred to simply as justification or epistemic justification.
There are three essential features of JTB:
S knows that p if and only if (1)p is true, (2)S believes that p, and (3) this belief is ^[1]justiified.

Most philosophers agree that 1 and 2 are correct or valid, but 3 leaves a lot of room for ambiguity. Thus posited by the Gettier’s problem which reveals how all 3 criterion can be met and still have no mean when it comes to "having" or "gained" knowledge.