Epistemology is a branch of philosophy that deals with what we can know and the nature of our knowledge. The Greek term episteme means “knowledge.” Therefore, epistemology is the study of knowledge, or how we know what we know.
Since the time of Plato and Aristotle, JTB (justified true belief) has been the standard understanding of knowledge. A person p knows x if and only if p believes x, and p’s belief in x is justified and x is true. A belief is something we hold to be true. However, believing something does not ensure this belief is true. Therefore, offering justification for a belief supports believing something, but the mere presence of justification still does not ensure this belief is true. For any statement x to count as knowledge, a person must have belief and justification, and finally, the statement must be true.
But in 1963, the traditional definition of knowledge was challenged when the philosopher Edmund Gettier published the short article “Is Justified True Belief Knowledge?” In his article, Gettier sets forth two cases in which all three criteria are met but knowledge does not result. And whether by adding to JTB or by making some alterations to it, philosophers today are still making efforts to best resolve the Gettier problem. Nevertheless, JTB continues to play a decisive role in how we think about knowledge without fully defining everything about the nature of knowledge.
For example, although JTB is not a sufficient condition for knowledge, JTB is a necessary condition for knowledge. A sufficient condition is a condition that, if met, will guarantee that something will be the case. A necessary condition is a condition required for something to be the case but may not itself ensure that something will be the case.
For more information, please see chapter two “What is Knowledge?” in How Do We Know? An Introduction to Epistemology by James Dew and Mark Foreman.
~ Boethius ~