You know you're winning the argument when that's the only thing the other side can throw out.
Actually,it happens because the debater on one side of the argument continues to restate a conviction. He is not really debating and he cannot make any compromises or moderate a conviction. Nobody can! It is the nature of a conviction.
At some point, the argument or actually a lack of true debate causes ulterior motives to be tossed into the mix.