I think they both mean that you have to do something because there is a social pression like なければならい、but I'm not certain that I can use them interchangeably. Could somebody confirm it?

  • Great question! Sadly I could only give 1 upvote ;-( I have feeling we both say "of course, should have known" when someone comes with a good pair of sample sentences where they are not interchangeable)
    – Tuomo
    Jul 11, 2019 at 13:29

1 Answer 1


Come one natives! My best guess (yes, please downvote, as this site is not for guesses, but I hope @Alex16 and I at least get someone to answer ;-) )

ないわけにはいかない has more of of the social pressure aspect (you are supposed to do X) while ずにすまない more likely means that there are some more "rational" (*) reasons for why failing to do X would cause problems.

(*) While it is "rational" to consider the other people when adjusting your message, here, by "rational", I meant simply a statement made without considering the "public opinion"

  • 3
    Please don't post a guess as an answer simply to motivate others to post answers. This is designed to happen naturally: unanswered questions are listed in the "Unanswered" tab where unanswered questions with the most votes rise to the top, so if you don't know an answer, the best you can do to support a question is to give it an upvote and make sure it is clearly presented (for example, tag it appropriately, suggest improvements in comments, etc.).
    – Earthliŋ
    Jul 13, 2019 at 15:56

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