Grammar
N2 verb-grammar

Cannot possibly 〜わけにはいかない

Meaning

"I cannot ~ (for social or moral reasons)"; with a ない form, "I have to ~".

Formation

Notes

Not physical inability — that is 〜られない — but a block imposed by duty, ethics or circumstance. Attached to a ない form it flips into obligation: 行かないわけにはいかない means "I have to go".

Examples

It is an important meeting, so I cannot take the day off.

Breakdown
important meeting take off cannot possibly

I cannot not return what I borrowed. (ない form = obligation)

Breakdown
borrowed thing not return cannot possibly

I drove here, so I cannot very well drink.

Breakdown
car came alcohol cannot drink

I promised, so I can hardly refuse.

Breakdown
promised refuse cannot possibly

Everyone is waiting, so I cannot just leave.

Breakdown
everyone is waiting go home cannot possibly

⚠️ Often confused with

Have no choice but 〜ざるを得ない

"Have no choice but to ~", "cannot help but ~".

Nothing for it but 〜よりほかない

"There is nothing for it but to ~".

Unable to 〜かねる

"Cannot ~", "am not in a position to ~" — a polite refusal.