Japatan
Formation
- V辞書形 + わけにはいかない
- Vない形 + ない + わけにはいかない
Explanation
This means "I can't do ~ because of common sense, my position, or the situation." It is not about ability; it means the speaker feels it would be wrong to do it. With the ない form, 〜ないわけにはいかない means "I can't not do ~," that is, "I have to do ~ (even if I don't want to)."
Examples
明日は大切な試験があるので、学校を 休むわけにはいかない。
I have an important exam tomorrow, so I can't miss school.
車で来たので、お酒を 飲むわけにはいきません。
I came by car, so I can't drink alcohol.
友だちとの約束だから、雨でも 行かないわけにはいかない。
It's a promise with a friend, so I have to go even if it rains.
先輩が仕事を手伝ってくれたのだから、お礼を 言わないわけにはいかない。
My senior helped me with my work, so I must thank them.
Notes
Do not use it for ability. For ability, use the potential form (泳げない, "I can't swim").
Related grammar
Mini quiz
1少し熱があるが、今日は大事な会議があるので、会社を休む（ ）。
Answer and explanation
Answer: 4 わけにはいかない
"I have a slight fever, but there's an important meeting today, so I can't take the day off." The situation prevents it, so わけにはいかない fits. わけがない is a strong guess ("there's no way"), not a decision about one's own action.
2部長に頼まれた仕事だから、（ ）わけにはいかない。
Answer and explanation
Answer: 2 やらない
"It's work my manager asked me to do, so I have to do it." 〜ないわけにはいかない means "must." The correct form is やらない; the other forms cannot come before わけ.
3A「もう一杯どう？」
B「ありがとう。でも、車を運転して帰るから、飲む（ ）。」
Answer and explanation
Answer: 1 わけにはいかないんだ
A: "How about another glass?" B: "Thanks, but I'm driving home, so I can't drink." Driving makes drinking unacceptable, so わけにはいかない fits. The other choices do not express refusing for that reason.
