"How do we know what knowledge is? In his remarkable 1963 article, Gettier proves that Plato\'s 2000-year-old definition of knowledge is flawed-in just 930 words.. "How do we know what knowledge is? In his remarkable 1963 article, Gettier proves that Plato\'s 2000-year-old definition of knowledge is flawed-in just 930 words.