In his three-page 1963 paper, titled "Is Justified True Belief Knowledge?", Gettier showed, by means of counterexamples, that there were cases where individuals had justified true belief of a proposition, but failed to know it.
In his three-page 1963 paper titled "Is Justified True Belief Knowledge?", Gettier showed that the JTB account was insufficient to account for knowledge. He did so by use of counterexamples, where individuals had justified true belief of a proposition, but failed to know it.