Grammar of なんで+verb in potential form+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?

> {}——— **{}**

The grammar pattern used here is:

> // + Verb in **Potential-Imperfective** Form +

This is a {} ("rhetorical question"); therefore, actually means:

> "One would never forget." or in Japanese, {}

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 {} in Japanese and basically expresses two things -- **volition and conjecture**. In the phrase in question, the is used to express **conjecture** , which is represented by the part of my TL above.

Hope this helps.