Grammar of なんで+verb in potential form+ようか

Question

ダドリーの誕生日———なんで忘れられようか。
Dudley's birthday — how could he have forgotten? (original English version)

The nuance of the English version is that he did forget the birthday, but based on some previous experience (in this case, unpleasantness) it seems unlikely that he would have forgotten and he feels foolish for forgetting.

I'm struggling with the Japanese meaning, In particular, why the volitional form? My literal translation would be "How would he be able to forget?", suggesting that he wants to forget but cannot (I'm assuming this is potential rather than passive. That's not clear to me either).

In summary, what is the actual nuance behind the Japanese sentence and how does that arise from the grammar?

Answer 1

「ダドリーの誕生日{たんじょうび}———なんで忘{わす}れられようか。」

The grammar pattern used here is:

「なぜ/なんで/どうして + Verb in Potential-Imperfective Form + か」

This is a 反語表現{はんごひょうげん} ("rhetorical question"); therefore, 「なんで忘れられようか」 actually means:

"One would never forget." or in Japanese, 「決{けっ}して忘れないだろう。」

rather than the literal translation:

"How would he be able to forget?" (to borrow your TL)

Thus, this is a statement disguised as a question.

why the volitional form?

What Japanese-learners call the "volitional form" is called 「未然形{みぜんけい}」 in Japanese and 未然形 basically expresses two things -- volition and conjecture. In the phrase in question, the 未然形 is used to express conjecture, which is represented by the 「だろう」part of my TL 「決して忘れないだろう。」 above.

Hope this helps.