Final answer:
Edmund Gettier challenged the traditional definition of knowledge, showing that a proposition must be true, believed, and justified, but these are not sufficient due to the Gettier problem. Hence, philosophers propose adding a fourth condition to or revising the justification condition in the justified true belief framework.
Step-by-step explanation:
Edmund Gettier challenged the traditional definition of knowledge, showing that a proposition must be true, believed, and justified, but these are not sufficient due to the Gettier problem. Hence, philosophers propose adding a fourth condition to or revising the justification condition in the justified true belief framework.
According to Gettier, the standard definition of knowledge requires that a proposition, to be known, must be true, and the individual claiming to know the proposition must have justification for the belief. However, the Gettier problem illustrates that these conditions are not sufficient for knowledge because they do not preclude the possibility of a belief being true by accident or coincidence. To address these issues, philosophers have either looked to replace the justification condition with something more robust, or add a fourth condition to the justified true belief (JTB) framework.