Justified True Belief

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:

  1. P is true
  2. S believes that P is true, and
  3. 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:

    You who want to be justified by the law have cut yourselves off from Christ; you have fallen away from grace.
    Bible: New Testament, Galatians 5:4.

    ... women learned one important lesson—namely, that it is impossible for the best of men to understand women’s feelings or the humiliation of their position. When they asked us to be silent on our question during the War, and labor for the emancipation of the slave, we did so, and gave five years to his emancipation and enfranchisement.... I was convinced, at the time, that it was the true policy. I am now equally sure that it was a blunder.
    Elizabeth Cady Stanton (1815–1902)

    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)