also: りをもちてひにおちる
expression
lose an argument despite being in the right; have right on one's side yet succumb
Proverb-like expression meaning that even when one's position is logically or morally correct, one may still lose the dispute or be defeated. Rare and somewhat literary.
理をもって非に落ちることもあるから、議論では戦略も必要だ。
Sometimes you can lose an argument even when you're in the right, so strategy is also necessary in debates.
A set phrase combining 理 (reason, right) + をもって (with, by means of) + 非 (wrong, injustice) + に落ちる (fall into). The exact origin is uncertain, but it reflects a classical Chinese-influenced construction.