Difference between negative forms {-ず} and {-ぬ}

Question

{-ず} and {-ぬ} are two alternatives to the negative form {-ない} / {-ません}. But I noticed that depending on the word, it's either {-ず} or {-ぬ}, although it seems like some words can take both suffixes. Some examples I have encountered:

-ず

知らず (lyric in song "touch" by Younha)
わからず (lyric in song "aisuru mono" by Angela Aki)
せず (song title: "yudan sezu ni ikou")
なれず (lyric in song "mirae he" by Kiroro)

-ぬ

気づかぬ (lyric in song "arigatou" by Kokia)
届かぬ (song title: "todokanu omoi")
ならぬ (lyric in song "shunrai" by Yellow Generation)

both {-ず} and {-ぬ}

とらず / とらぬ
できず / できぬ

So are there rules for choosing between {-ず} and {-ぬ}?

Answer 1

In the modern form, ず is only used as an adverbial (食べずに出る leave without eating). ぬ can replace ない. In 文語, the the grammar used in writing until the reformations after WWII and still in many forms of poetry, songs, and very formal documents, the use of ず and ぬ was/is grammatically constrained in a manner no longer present in modern Japanese. ぬ was used with the　連体形 form of a word, meaning that it connected with a following noun (and it still does that). ず, on the other hand, connected with the 未然形　and was used for negative assertions.　It had conjugations, too, but those are really really rare now (ざら、ざり、ざる、ざれ、ざれ).

Just remember this: ず can end a sentence, but ぬ　can't; ぬ　modifies nouns, but ず doesn't:　知らぬ人、人知らず

Of course they've snuck into idioms and 慣用語: 我知らず (despite oneself)、暑さ知らずの所 (a place that knows no heat), 知らぬ顔 (pretend ignorance)、知らぬ存ぜぬで押し通す (persist in asserting one's innocence). (新和英大辞典)

Answer 2

-ぬ is an archaic form of -ない. I suspect its use in song lyrics has more to do with fitting the word into the right number of syllables; as far as I know, there is no difference in meaning.

-ず, on the other hand, indicates that one action took place without or in the absence of another action (the one with -ず). For example, 待たずに先に行く: to go on ahead without waiting.

Answer 3

This is an excellent question. I always think of this and don't know why I didn't think to post it.

Anyway, -zu seems to usually be an adverbial, connective form (often as -zu or -zu ni), whereas -nu seems to be a modifier.

誰も知らずに家に入った　- I entered the house without anyone (else) knowing

誰も知らぬ秘密　- A secret that no one knows.

That's just my perception of them up to this point. I actually have a theory about -nu that I really want to research into more.

Answer 4

There is a distinction between 'ず' and 'ぬ'　as in the other answers, but for the combination with the verbs, there is no limitation, despite your description. I do not understand why you came up with that limitation.

知らず / 知らぬ

分からず / 分からぬ

せず / せぬ

なれず / なれぬ

気づかず　/ 気づかぬ

届かず　/ 届かぬ

ならず　/ ならぬ

とらず / とらぬ

できず / できぬ

Answer 5

Both ず and ぬ came from the archaic negator ず in Heian period. The ず had conjugations ず (未然), ず (連用), ず (終止), ぬ (連体) and ね (仮定), as every Japanese learns in high school today. The ぬ was originally the 連体形 (noun modifying form) of ず.

After that, spoken Japanese lost the distinction between 連体形 and 終止形 in almost all cases. So, now we use ぬ or its variant ん as a sentence terminal form, and the word is officially called ぬ instead of ず. You might know that ん is heavily used in Kansai dialects.

The modern ぬ(ん) is conjugated as ぬ/ん, ×, ず, ぬ(ん), ぬ(ん) and ね. The noun modifying form is still used commonly, and the forms ず and ね are remaining in some fixed expressions such as 〜ず、 (中止法), 〜ずに (=〜ないで) and 〜ねば (=〜なければ).

The archaic ず and its conjugations are, however, still used in poetry and proverbs with the classical grammar. 親の心子知らず and 弘法は筆を選ばす are examples. Anyway, you don't need to use the archaic ず, nor even the modern ぬ, when you speak.

Answer 6

So are there rules for choosing between {-ず} and {-ぬ}?

Well, yes. Just look at how they are used, it should be obvious! It's probably something as below:

proposition-verbず(に), proposition.
親に挨拶をせずに、部屋に入ちゃった。
He rushed into his room without saying hello to his parents.

proposition-verbぬ
こういう行為を許さぬ！ I won't tolerate such behaviour! (draw out your sword, and slash your opponent for he danced on the table)

Proposition-verbぬ-nominalgroup…
言ってはいけぬ言葉は許さない! (draw out your sword, and slash your opponent for he said "sh*t")

You'll see that it's no more that old-fashioned¹ "〜ないで" and "ない".

¹: I don't like the qualification "archaic" for terms/words/conjugations I happen to use :P PS: the two last examples may not be very natural…

Answer 7

I came across the ぬ form in this proverb 触らぬ神に祟りなし which was loosely correlated with the english "Let sleeping dogs lie" I hear and use the {-ず} suffix all the time however, so in my limited experience it's more common.