When a Japanese speaker wants to agree, but only barely — to leave the door open a crack without committing — they reach for a double negative that stops just short of "yes": 〜ないこともない ("it's not that I don't …"). The two negatives here do not snap back to a clean positive. Arithmetic would give you "X"; the language gives you something weaker and more careful: "X, I suppose — with reservations." It is a hedge, a politeness cushion, a way to admit a faint possibility while distancing yourself from a confident promise. English speakers routinely misread it as a firm yes; it is anything but.
The construction
Take a verb (or adjective) in its plain negative, then append こともない — literally "there is also not the case that [not-X]." The variant 〜ないでもない works the same way and sounds a touch more casual and offhand.
| Base | Plain negative | Hedged double negative |
|---|---|---|
| 行く | 行かない | 行かないこともない / 行かないでもない |
| 分かる | 分からない | 分からないこともない / 分からないでもない |
| できる | できない | できないこともない |
| おいしい | おいしくない | おいしくないこともない |
時間があれば、行かないこともない。
jikan ga areba, ikanai koto mo nai
If I've got the time, it's not like I wouldn't go.
気持ちは分からないでもない。
kimochi wa wakaranai demo nai
It's not that I don't understand how you feel.
Both land as a reluctant, qualified admission: I might go (but I'm not promising); I sort of get it (but only sort of).
Why the negatives don't fully cancel
Logically, "not (not X)" is X. Pragmatically, Japanese uses the double wrapper precisely to avoid saying the bare X. Each negative is a small step back from commitment, and two of them stack into a stance that is affirmative in direction but minimal in force. Think of it as the difference between "I'll do it" and "It's not as though I wouldn't do it" — the second grudgingly concedes the possibility while withholding enthusiasm.
やればできないこともないが、かなり時間がかかると思う。
yareba dekinai koto mo nai ga, kanari jikan ga kakaru to omou
It's not that I couldn't do it if I tried, but I think it'd take quite a while.
この値段なら、買わないこともないけど…。
kono nedan nara, kawanai koto mo nai kedo…
At this price it's not like I wouldn't buy it, but…
Notice how naturally が and けど ("but…") trail after it. That trailing "but" is the form's native habitat: it signals reservations, and the listener understands the "yes" is conditional and half-hearted. Ending on a bare 〜ないこともない, with the "but" merely implied by a trailing off, is itself a polite way to hedge.
With adjectives: faint praise, faint blame
Feed an い-adjective's negative in and you get lukewarm evaluation — the linguistic shrug.
このラーメン、おいしくないこともないよ。まあ普通かな。
kono rāmen, oishiku nai koto mo nai yo. mā futsū kana
This ramen's not bad, I guess — pretty middle-of-the-road, really.
おいしくないこともない is deliberately faint: not a compliment, not a complaint, just "it clears the bar." A confident おいしい would over-promise; this hedges the praise down to honest lukewarmness.
The distinguishing insight: a politeness hedge, not a strong claim
This is the heart of the form, and the reason it exists alongside a plain "yes." 〜ないこともない is a hedging and politeness device — its job is to soften. A speaker who could say はい chooses this instead exactly when they want to avoid the bluntness of a clear affirmative: to agree reluctantly, to concede a point grudgingly, to leave themselves an exit. So it reliably signals limited willingness or faint possibility, never eager assent.
「手伝ってくれない？」「うーん、忙しいけど、手伝わないこともないよ。」
tetsudatte kurenai — ūn, isogashii kedo, tetsudawanai koto mo nai yo
'Could you help me out?' 'Hmm, I'm busy, but it's not like I won't help.'
Keep it apart from 〜ないわけにはいかない
Two negative-heavy N2 forms sit close on the page but mean opposite things in force, and confusing them is the classic slip. Fix the contrast now.
| Form | Force | Feel |
|---|---|---|
| 行かないこともない | weak — faint possibility | "I might go, I suppose" |
| 行かないわけにはいかない | strong — inescapable duty | "I have no choice but to go" |
One is a hedge — a wobbly maybe. The other is an obligation — an iron must. They share the 行かない stem, but 〜こともない dials the commitment down to almost nothing, while 〜ないわけにはいかない cranks it up to compulsion. If you catch yourself unsure which you mean, ask: am I hedging (こともない) or am I compelled (わけにはいかない)?
Register and a close cousin
- Register: conversational and neutral; common in speech and in writing when a careful, non-committal tone is wanted. Frequent in negotiations, reviews, and polite refusals-that-aren't-quite-refusals.
- A near-synonym is the contracted 〜なくもない (行かなくもない, 分からなくもない), which is a hair more colloquial and clipped but means the same grudging "not not-X." For the wider toolkit of hedged and partial negation — adverbs like なかなか / 別に / めったに that tune the strength of a denial — see the partial-negation page.
一人で行けないこともないが、誰かいてくれた方が安心だ。
hitori de ikenai koto mo nai ga, dareka ite kureta hō ga anshin da
It's not that I can't go alone, but I'd feel safer with someone along.
Common mistakes
❌「明日、来られる？」「うん、行かないこともないよ！」（張り切って）
Tone clash — 〜ないこともない is a grudging maybe, so pairing it with eager enthusiasm sounds contradictory. For a keen yes, say 行くよ／もちろん行く.
✅「明日、来られる？」「行かないこともないけど、まだ分からない。」
ashita, korareru — ikanai koto mo nai kedo, mada wakaranai
'Can you come tomorrow?' 'It's not that I won't, but I don't know yet.'
❌ 気持ちは分からないこともない。（＝全然分からない、という意味で使う）
Misread as a plain negative — 分からないこともない actually means you DO sort of understand, not that you don't understand at all.
✅ 気持ちは分からないでもないが、賛成はできない。
kimochi wa wakaranai demo nai ga, sansei wa dekinai
I do sort of get how you feel, but I can't agree.
❌ 頼まれたので、やらないこともない。
Wrong form for obligation — a request compelling you gives 〜ないわけにはいかない ('I must do it'), not the weak hedge 〜ないこともない ('I might do it').
✅ 頼まれたので、やらないわけにはいかない。
tanomareta node, yaranai wake ni wa ikanai
I was asked, so I have no choice but to do it.
❌ この料理は食べないことない。
Incorrect — the も is not optional here; the set form is 〜ないこともない (or the contracted 〜なくもない).
✅ この料理は食べないこともない。
kono ryōri wa tabenai koto mo nai
It's not that I wouldn't eat this dish.
Key takeaways
- 〜ないこともない / 〜ないでもない = a hedged double negative: a grudging, qualified "yes, I suppose," not a full affirmative.
- The negatives don't cancel to plain X — they leave a weak, reluctant X, usually trailing into a "but…" (が / けど).
- It is a politeness and hedging device — reach for it to concede a faint possibility or limited willingness without the bluntness of はい.
- Don't confuse it with 〜ないわけにはいかない: that is strong obligation ("must"); this is weak possibility ("might, I guess").
- The contracted 〜なくもない means the same thing, slightly more casual.
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- 〜ないわけにはいかない: Cannot Not / MustN2 — The double negative that means felt obligation — 'the situation leaves me no choice but to' — and why it is near-opposite to the positive 〜わけにはいかない.
- なかなか / 別に / めったに 〜ないN3 — Three more adverbs that demand a following 〜ない — and each colours the negation with a specific attitude: なかなか (thwarted expectation), 別に (indifference / deflection), めったに (rarity).