noun
quibbler; argumentative person; logic-chopper
Refers to someone who habitually argues for the sake of arguing, often using overly logical or pedantic reasoning. Can be mildly derogatory.
彼は理屈屋だから、何を言っても言い負かそうとする。
He's such a quibbler that he tries to argue you down no matter what you say.
あの理屈屋と議論しても無駄だよ。
It's pointless to argue with that logic-chopper.
Compound of 理屈 (logic, reasoning) and 屋 (suffix for a person with a certain trait or occupation).