Reasoning or theoretical logic; the line of argument or rationale used to explain something.
彼の説明には理屈が通っているが、感情面では問題が残る。
His explanation is logically sound, but there are remaining emotional issues.
理屈では分かるが、実際にやるのは難しい。
I understand it in theory, but it's hard to do in practice.
この理屈に基づいて実験を行った。
We conducted the experiment based on this reasoning.
An (often strained or unreasonable) argument, excuse, or pretext; a contrived justification that may not be convincing.
彼の言い分は理屈に過ぎず、誰も納得しなかった。
His claims were just excuses; nobody was convinced.
理屈をこねて責任を逃れようとしているようだ。
It seems like he's trying to dodge responsibility by making excuses.
そんな理屈は通用しないよ。具体的な証拠を見せてください。
That excuse won't do. Please show concrete evidence.