Tutorial # 16. Epistemology: What is Knowledge? Classical Analysis

Traditionally, knowledge was defined as justified true belief.

A knows that X meant that:
- X is true;
- A believes that X;
- A is justified in believing that X.

There must be three conditions satisfied if person A is to know X.
Firstly, person A must believe that X is the case.
Secondly, X must be true; it must be the case that X is true.
Thirdly, person A must be justified in believing that X is the case.

Edmund Gettier saw a flaw in this argument of justified true belief. In his paper he presented two counterexamples to the classical theory of knowledge.
He argued that the three conditions were satisfied, but person A really did not know X. Therefore, if Gettier is right, the three conditions are not sufficient to define what knowledge is: Knowledge is not justified true belief.