なくもない details

write + it's not that one doesn't

kaka naku mo nai

it's not that one doesn't; sort of, up to a point

meaning: it's not that I don't write

彼かれの言いい分ぶんも、分からわからなくもない。

kare no iibun mo, wakara naku mo nai.

As for his side of it, it's not that I don't understand. neutral

面倒めんどうだけど、頼たのまれれば手伝てつだわなくもないよ。

mendou da kedo, tanomarereba tetsudawanaku mo nai yo.

It's a hassle, but if you ask me, it's not like I wouldn't help. casual

Examples

it's not that one doesn't — a hedged, partial yes reached by cancelling a negative

彼かれの言いい分ぶんも、分わからなくもない。

kare no iibun mo, wakaranakumonai.

As for his side of it, it's not that I don't understand. neutral

面倒めんどうだけど、頼たのまれれば手伝てつだわなくもないよ。

mendou da kedo, tanomarereba tetsudawanaku mo nai yo.

It's a hassle, but if you ask me, it's not like I wouldn't help. casual

ご提案ていあんの趣旨しゅしは理解りかいできなくもありませんが、時期尚早じきしょうそうかと存ぞんじます。

go teian no shushi wa rikai dekinaku mo arimasen ga, jikishousou ka to zonjimasu.

It is not that I fail to see the point of your proposal, but I believe it premature. formal

なくはない — は for も drops the hedging a notch — 行いかなくはない concedes the fact, 行いかなくもない keeps its distance from it; neither is the more spoken of the two.
ないでもない — the same litotes on the plain ない, stiffer and mostly written — 考かんがえられないでもない.
ないものでもない — stiffer again, with ものだ's air of general truth; almost confined to written argument and negotiation.

The two negatives cancel to a YES, never a no: 行いかなくもない means the
speaker might well go. The hedge is in how far — never in whether.

ないことはない
Both are double negatives conceding a grudging yes, but they answer different questions — ないことはない concedes FEASIBILITY ("can you?" — "well, I can"), while なくもない concedes DEGREE, hedging how far the speaker agrees or is willing.

なくてもいい
One て apart and both opening 〜なく — なくてもいい releases you from the act (行いかなくてもいい, you needn't go), なくもない half-commits you to it (行いかなくもない, I might well go after all).

Pattern	Attaches to
ないことはない