The traditional "definition of propositional knowledge," emerging from Plato's Meno and Theaetetus, proposes that such knowledge—knowledge that something is the case—has three essential components. These components are identified by the view that knowledge is justified true belief. Knowledge, according to the traditional definition, is belief of a special kind, belief that satisfies two necessary conditions: (1) the truth of what is believed and (2) the justification of what is believed. While offering various accounts of the belief condition, the truth condition, and the justification condition for knowledge, many philosophers have held that those three conditions are individually necessary and jointly sufficient for propositional knowledge.

The belief condition requires that one accept, in some manner, any proposition one genuinely knows. This condition thus relates one psychologically to what one knows. It precludes that one knows a proposition while failing to accept that proposition...