Abstract

Knowledge is considered to be justified true belief. This analysis has its own historical background, starting from Plato's Theaetetus with the concept of Logos and continues in the history of philosophy.In contemporary epistemology three conditions of knowledge have been criticized by Gettier and this gave rise to three responses as follows; one group tried to defend the traditional defenition of knowledge and refuted Gettier's views. The second group tried to amend the three conditions of knowledge and the third group proposed the fourth condition. But all of them were at least unanimous that "justification" is the necessary condition of knowledge.How is a belief justified? In this regard foundationalists hold that non-basic beliefs obtain their epistemological validity from basic beliefs and basic beliefs are self-evident, while coherentists hold that the justification of a belief depends on its harmony and consistency with a person's set of the beliefs.Most of the foundationalists and coherentists are introverts, so they try to find those factors and elements for the justification of belief introspectively. But the extroverts hold that justification is a kind of harmony among a person's rational and internal actions and environment.