N1 Role, Status, and Evaluation

~でなくてなんだろう: meaning, usage and examples

~でなくてなんだろう means: what could it be but... / it must be...

Updated 9 November 2026 · By the My Senpai team · Spotted a mistake? Tell us

Examples

1. 彼かれのこの行動こうどうが、愛あいでなくてなんだろう。

   What could this act of his be, if not love?

2. 一度いちど聞きいただけで全すべてを覚おぼえてしまう。これが天才てんさいでなくてなんだろう。

   Remembering everything after hearing it just once. If that is not genius, what is?

3. 戦争せんそうで多おおくの子こどもが命いのちを落おとす。これが悲劇ひげきでなくてなんだろう。

   Many children lose their lives in war. If that is not a tragedy, what is?

4. 見みず知しらずの人ひとのために命いのちをかける。これが勇気ゆうきでなくてなんだろう。

   Risking one's life for a total stranger. If that is not courage, what is?

When to use it

A rhetorical question meaning "if this is not X, what is?": the speaker insists that something is X in the fullest sense. It usually follows a description of a striking act or situation, then names it with a strong noun such as 愛あい, 奇跡きせき, 悲劇ひげき, 勇気ゆうき: これが奇跡きせきでなくてなんだろう (if this is not a miracle, what is?).

Nuance

Literary and emotional, used in essays, novels, speeches and editorials, not in conversation. The noun is an abstract, emotionally loaded word. The speaker is moved or indignant. なんであろう is even more formal. It states a conviction, not a real question.

Compare

にほかならない states the same conclusion flatly: 成功せいこうは努力どりょくの結果けっかにほかならない (success is nothing but the result of effort). でなくてなんだろう says it with emotion as a rhetorical question: これが努力どりょくの結果けっかでなくてなんだろう. Compare に違ちがいない, a guess: 彼かれが犯人はんにんに違ちがいない.

Tip: Typical shape: describe the act, then これが / それが + [big abstract noun] + でなくてなんだろう.