adj. Someone who doesn't know what you have just learned.
Against logic there is no armor like ignorance.
— Laurence J. Peter
Beware of the man who works hard to learn something, learns it, and finds himself no wiser than before. He is full of murderous resentment of people who are ignorant without having come by their ignorance the hard way.
Men are born ignorant, not stupid; they are made stupid by education.
— Bertrand Russell
It is impossible to defeat an ignorant man in argument.
— William G. McAdoo