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:
“If all mankind minus one, were of one opinion, and only one person were of the contrary opinion, mankind would be no more justified in silencing that one person, than he, if he had the power, would be justified in silencing mankind.”
—John Stuart Mill (1806–1873)
“A majority, held in restraint by constitutional checks, and limitations, and always changing easily, with deliberate changes of popular opinions and sentiments, is the only true sovereign of a free people.”
—Abraham Lincoln (1809–1865)
“It is impossible to calculate the moral mischief, if I may so express it, that mental lying has produced in society. When a man has so far corrupted and prostituted the chastity of his mind as to subscribe his professional belief to things he does not believe he has prepared himself for the commission of every other crime.”
—Thomas Paine (1737–1809)