論理

ろんり · ronri · JLPT N1 · noun

logic

論 = argument + 理 = reason: 論理 = argument + reason, i.e. logic

論 means discussion or argument, and 理 means reason or principle. Together they name the rules that make an argument sound, which is logic.

理 — jade radical 玉/王 + village 里 (phonetic)
理 is a semantic-phonetic compound: the jade radical 王 (玉) on the left signals meaning, while 里 on the right gives the sound. It originally meant the natural veins or grain in a piece of jade, then extended to 'pattern,' 'order,' 'principle,' and finally the modern senses 'reason' and 'to manage.'

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