Origin of ~なければ ならない

Question

The expression ~なければ ならない if I learned correctly means "must not not do ..." as in:

日本語を勉強しなければなりません。 You must not not learn Japanese. (i.e. you need to learn Japanese)

However, taken on face value it doesn't really make sense. しなければなりません translates into "if (you) don't do, doesn't become (what?)". The confusing part is that a direct translation into modern colloquial Chinese makes sense: 你不学日语的话，不成 = "If you don't learn Japanese, not become" = "You must learn Japanese".

This seems like a Japanese borrowing from a common Chinese phrase; 不...的话 acts like ～なければ, and of course なる is sometimes written 成る. However, the expression does not exist in Classical Chinese, which I presume Japanese borrowed the most (including all the un-Mandarin-y readings). Classical Chinese would use 不可～. I'm suspecting this might be a Chinese loan from Japanese, just like how 不不不不 is a syntactical English loan of "no no no no" and not really parseable (Chinese has no word for "no", only 不 = not = ～ない). Putting something like "must not" in a verb at the end is very un-Chinesey. Modern Mandarin-based Standard Chinese has also borrowed lots of 和製漢語 such as 民主, 共和国, 歌姫, 写真, カラオケ, and pretty much all the vocabulary related to biology and political science, curiously.

So when did this expression start in Japanese? Does any equivalent to ~なければ ならない exist in, say, Classical Japanese or Old Japanese? If so, it'd probably be the Chinese borrowing from Japanese, not the other way around.

Answer 1

One of the definitions of なる (成る) is to be completed (完成する), or to succeed (成功する), and thus carries the implication of "good". Consequently, ならない then means not completed; not successful; "it won't become (good)". Consider in English, if you say "That won't do", it begs the question: won't do what? But it has been ingrained in your mind to know that "that won't do" = "that's no good".

So to break it down into parts, 〜なければ means "if you don't 〜", and as we just said, ならない by itself means "no good" or "that won't do", you get "That won't do/be good if you don't 〜". Thus implying that you must do it.

This is why there are multiple ways to express having to do something. Instead of ならない, you can substitute いけない or だめ, both of which also express "no good"/"bad". And instead of 〜なければ, you can substitute 〜なくては. The translation changes slightly from "If you don't 〜", to "Not doing 〜", but gives the same overall semantics. Compare

• 全部食べなければならない　→　It's no good if you don't eat all of it
• 全部食べなくてはならない　→　Not eating all of it is/would be no good

So I know this doesn't exactly answer your question of when this expression came into Japanese, but you can more easily see how the structure makes sense.

Answer 2

なければならない is a double negation - something found in many languages. Other older expressions (in the sense that when they are used now they sound archaic) include -ざるべからず and -ねばならぬ.

Scholars seem to agree that at least partially the kanbun kundoku (漢文訓読) of the Chinese expression 不可不 contributed to the establishment of Japanese expressions such as ずはあるべからず and ざるべからず. (Source) It looks like these expressions appeared earlier than なければならない and なくてはならない as long as we are talking about auxiliary verbs - so including Xしなくてはならない, but not including Xがなくてはならない.

I think this can be considered a calque, or something close to it.

Now, as to how 不可不 might or might not be related to -なければならない, through -ざるべからず or otherwise, I couldn't find much evidence either way. However, I note that -なければならない used auxiliary verbs, seems fairly absent in the texts from the Edo period and earlier. I'm inclined to imagine it became popular more recently and dwarved the other expressions that had played the same role, considering its widespread usage in the Meiji period through the Reiwa period. It seems possible that someone re-translated -ざるべからず into -なければならない and it got traction. (Again, this is mostly my guess, and I don't have direct evidence to support the last part. I'm happy to be proven wrong.)