Someone who believes that they are always right, no matter what. They posses an absurdly narcissistic view that in any conversation they always see the whole picture while no one else does, therefore they posses an inability to engage in rational, meaningful and open debate.
Never openly accept an invitation into discussion with these people, as circular conversation will ensue, and you will most likely end up feeling like a paddle ball, going back and forth, back and forth, back and forth, ad infinitum.
"I don't bother saying anything unless I know what I'm saying is factually correct. If no one can offer me an outlook I haven't already considered, then no, there is no reason not to dismiss another's arguments. A Deuce is always right, no matter what other viewpoints are presented."