〜ずにはすまない (social obligation — cannot avoid doing)

〜ずにはすまない

Formality Level: Semi-formal — formal writing, formal speech, analytical commentary

Classical Origin: ずに is the classical negative gerundive (see Lesson 1: 〜ず). すまない derives from 済む (sumu, to be settled/complete) in its negative form: "it does not settle/complete." The full pattern means: "without doing X, the situation cannot be settled/completed" → social or moral compulsion requires X.

Structure

Form	Example
V-neg stem + ずにはすまない	謝らずにはすまない
Suru → せずにはすまない	対応せずにはすまない

Note: する→せず (not するず). This is the classical irregular negative stem.

Meaning

"Cannot avoid doing X / Social/moral obligation compels X / Without doing X, the matter cannot be settled"

The obligation comes from external social norms, moral expectations, or situational necessity — not from the speaker's personal desire. The speaker may or may not want to do X, but the situation demands it.

Example Sentences

Japanese	English
これだけの失礼を働いたのだから、謝らずにはすまないだろう。	Having behaved so rudely, one cannot avoid offering an apology.
重大な規則違反が明らかになった以上、責任者が説明責任を果たさずにはすまない。	Now that a serious violation has come to light, those responsible cannot avoid fulfilling their obligation to explain.
公金の不正使用が判明した以上、調査委員会を設置せずにはすまない状況だ。	Given that misuse of public funds has come to light, the situation is such that an investigative committee cannot be avoided.
これほどの被害が出た以上、会社は補償を払わずにはすまない。	With damage to this extent having occurred, the company cannot avoid paying compensation.
彼の誤解を解くためには、真実を話さずにはすまない。	To resolve his misunderstanding, I cannot avoid telling the truth.

Pattern	Obligation Source	Key Difference
〜ずにはすまない	External social/moral compulsion	Society/morality requires X; speaker may not want to
〜ないではすまない	Same as above	Modern variant; slightly more casual
〜なければならない	Logical/functional necessity	Personal obligation; can be self-imposed
〜ざるを得ない	Reluctant necessity (no other choice)	Speaker has no other option; resignation nuance

Key distinction from 〜ざるを得ない:

〜ずにはすまない = social/moral world demands X; the speaker acknowledges the external necessity
〜ざるを得ない = speaker has no practical choice; situational compulsion with a resigned nuance

When NOT to Use

Do not use for personal preferences or desires: ×食べずにはすまない (wanting to eat is desire; this pattern requires external social/moral compulsion)
Do not confuse with 〜ずにはいられない (cannot help but do): 〜ずにはいられない = internal emotional compulsion; 〜ずにはすまない = external social compulsion.

〜ずにはすまない (social obligation — cannot avoid doing)