Justified true belief is a definition of knowledge that is most frequently credited to Plato and his dialogues. The concept of justified true belief states that in order to know that a given proposition is true, one must not only believe the relevant true proposition, but one must also have justification for doing so. In more formal terms, a subject S knows that a proposition P is true if and only if:
- P is true
- S believes that P is true, and
- S is justified in believing that P is true
This theory of knowledge suffered a significant setback with the discovery of Gettier problems, situations in which the above conditions were seemingly met but that many philosophers disagree that anything is known. Robert Nozick suggested a clarification of "justification" which he believed eliminates the problem: the justification has to be such that were the justification false, the knowledge would be false.
Famous quotes containing the words justified, true and/or belief:
“We are justified in enforcing good morals, for they belong to all mankind; but we are not justified in enforcing good manners, for good manners always mean our own manners.”
—Gilbert Keith Chesterton (1874–1936)
“People believe that photographs are true and therefore cannot be art.”
—Mason Cooley (b. 1927)
“A man may be a heretic in the truth; and if he believe things only because his pastor says so, or the assembly so determines, without knowing other reason, though his belief be true, yet the very truth he holds becomes his heresy.”
—John Milton (1608–1674)