Conjugating into なければ


To create ～なければいけません or similar forms, I've been having trouble finding the
exact method for conjugating into ～なければ.

I imagine (but also greatly doubt) that it's something like this: 食べる -> 食べない
-> 食べなく -> 食べなける -> 食べければ. However, even if it was like that I still wouldn't
really understand why. Can anyone explain the exact process to get from ～ない to
～なければ?




## A modern perspective

`〜ければ` is the conditional ending for adjectives. Since the `〜ない` form of verbs
is shaped like an adjective, it uses adjective endings like `〜い` and `〜ければ`.
That's it! From a modern perspective, there are no steps in-between.

However, some grammars do take it one step further: they divide `〜ければ` into
`〜けれ` (the hypothetical form of an adjective), plus `ば` (a conditional
particle). This explanation is attractive because `ば` appears elsewhere with
conditional meaning, as in `ならば`.

But either way, it's pretty simple. `〜なければ` is the negative conditional form.

* * *

## A historical perspective

Historically speaking, `〜ければ` was presumably formed by a contraction of some
sort. But what sort? The explanation @istrasci gives is a common one and can
be found elsewhere on this site, that`〜ければ` was a contraction of `〜く+あれば`. In
turn, we can say `あれば` was a form of `ある` with the conditional `〜ば` attached.†

However, this leaves us wondering why the first vowel is /e/ rather than /a/.
Sansom, on page 205 of his 1928 [_Historical Grammar of
Japanese_](https://archive.org/stream/historicalgramma00sansuoft#page/205/mode/2up),
gives an explanation:

> This change is easy to understand, for the final _e_ of _kare_ influences
> the preceding vowel _a_ , by a tendency which is common in Japanese.

In contrast, Frellesvig, in his 2010 _History of the Japanese Language_ ,
suggests that the `〜けれ` stem comes from a contraction of _*ki-are_ into
_kyere_ , giving way to modern _kere_. Either way, it's a contraction of some
sort of adjectival form plus `あれば`.

* * *

## What is ある doing there?

The presence of `ある` is most likely purely grammatical, inserted so that
endings like `〜ば` can attach to adjectives. We shouldn't really translate it
as "exists" in English. Instead, we should describe `〜なければ` as the conditional
form of the negative `〜ない`.

This sort of grammatical use of `ある` is common and can be seen in all sorts of
places in Japanese, including in other adjectival inflections:

> 〜な **く** ＋ **あ** った ＞ 〜な **か** った

I trust you understand that `〜なかった` is simply a negative past form, and that
you don't attempt to translate it as though it has "exists" in it. You can
apply the same sort of logic here.

* * *

## Historical versus modern

Why look at it from a modern perspective? Well, let me ask you this: when you
say **_goodbye_** in English, do you always think [**_God be with
ye_**](http://www.etymonline.com/index.php?allowed_in_frame=0&search=goodbye&searchmode=none)?
Of course not! Historically speaking, it's a contraction of that phrase, but
today speakers use **_goodbye_** as a pre-formed unit. It's simply part of
their vocabulary. In that sense, the word is no longer a contraction.

Likewise, when you say `〜なければ`, please don't think something like "if it's
such that you don't", as @istrasci wrote. It's simply a negative conditional
form.

* * *

† _For simplicity's sake, I'm referring to this verb as_ ある, _which is its
modern citation form. Its historical citation form was_ あり.

