One of the commonly used futile questions that often makes me laugh is: “Are you a liar?” or “Are you lying?”
Anyone with even the most rudimentary knowledge of logic would know this question leads nowhere.
When asked of a truthful person: It is truthfully answered: “NO”
And when asked of a liar: It is untruthfully answered: “NO”!
May I propose, that instead of asking such questions, we just make a declaration when addressing suspected deceivers by simply saying “you sir/mam are a liar”! Or if in a hurry we may just opt for the abbreviated “Liar”, preferably at a raised voice for a more forceful delivery!