grammar - Origin of ~なければ ならない

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

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)". As in English, if you say "That won't do", it has the same 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.