noun
reason; logic of things; propriety
A formal, somewhat literary term referring to the inherent reason or principle behind matters, or the proper way things should be. Often used in contexts of moral or rational justification. Rare in casual speech.
彼の主張には事理をわきまえた説得力がある。
His argument has a persuasiveness that shows he understands the logic of things.
事理にかなった行動をとるべきだ。
You should act in accordance with reason and propriety.
道理 is the common word for 'reason' or 'logic' in everyday Japanese. 事理 is more formal and literary, emphasizing the inherent principle of things rather than general reasonableness.
理屈 refers to theoretical reasoning or argument, sometimes with a negative nuance of sophistry. 事理 is more about the natural order or propriety of things.
Compound of 事 (things, matters) and 理 (reason, principle). The exact historical derivation is uncertain; it is a Sino-Japanese word (kango) that appears in classical Chinese texts and was adopted into literary Japanese.