「です」, what is it really? Is my analysis correct?


At an elementary level, often, Japanese learners are taught that です is
equivalent to the verb "to be" in English. Typical example:

> 私は学生です, I am a student.

That's fine, after all, it works. And to be honest, most people probably
wouldn't really need a different explanation for the rest of their life.

With this question I'd like to go a little deeper. Can we really call です（or だ)
an auxiliary verb?

To start with, if you look だ up on
[goo](https://dictionary.goo.ne.jp/thsrs/17293/meaning/m0u/%E3%81%A0/), it is
grouped together with です, である, and のだ.

Right off the bat, you get this explanation:

> 断定を表わす。 expresses a conclusion/decision

So here is not really mentioning the word "verb" or "auxiliary verb" at all.
Shortly after you can see:

> 「です」は、「でございます」が変化したもの,

So, we can start by saying that actually です is an alteration/contraction of
でございます.

Continuing to read the definition we get:

> 「である」は、「で」に補助動詞「ある」が接続したもので、同様のものに「であります」「でございます」がある。

Hence, 「である」 is formed by attaching to「で」the subsidiary/auxiliary verb「ある」.
Because actually:

> 「で」は「だ」の連用形。 「で」is the conjunctive/continuative form of 「だ」

Therefore, if I'm not wrong, we can do the following passages:

> 「で」+「あります」＝「であります」＝ 「でございます」 ＝ 「です」

Does the above make sense? In particular I'm a bit doubtful about the second
equality.

To sum it up, 「です」 is a variation of 「だ」(its polite form). It is also a
contraction of 「でございます」, which in turn is the same as 「であります」(forgetting here
about the differences in usage), that is formed by attaching 「で」 to the
verb「あります」.

So, after this long trip, we arrive to the conclusion that the "hidden verb"
behind 「です」, is in fact
[ある](https://dictionary.goo.ne.jp/thsrs/15900/meaning/m0u/%E3%81%82%E3%82%8B/),
which is actually (or at least more close to) the sought after "to be".

Is this a correct explanation? How can it be improved? Or, if it's wrong,
where and why?




Your collection of questions conflate a few things: 1) what is だ・です in modern
Japanese, and 2) how did だ・です derive historically.

Because of #2, #1 is a bit ... messy. :) So let's start with the history.

> 「です」は、「でございます」が変化したもの,

This isn't an explanation of what です is now, so much as an explanation of the
historical derivation. Shogakukan's 国語大辞典 provides this description:

> 「でござります」→「でござんす」→「であんす」→「でえす」→「です」の経路で生じたものという

Meanwhile, the modern plain form だ derives as:

> 「にてあり」から出た「である」が、〔dea〕→〔da〕と変化したものという。→であ・じゃ・である

Modern で (which actually appears from around the 1300s-1500s) is understood to
have evolved from earlier にて (which is still used in formal writing).
Classical copular ("is") verb あり equates to modern verb ある.

Looking now at the particular parts of your post:

> 「で」は「だ」の連用形。 「で」is the conjunctive/continuative form of 「だ」

Well, yes, in the modern language. But historically, だ derives from で + ある --
so this is not a regular kind of conjugation paradigm.

> To sum it up, 「です」 is a variation of 「だ」(its polite form).

Yes. Though I might not use the term "variation" so much as "polite form".

> It is also a contraction of 「でございます」,

It _derives_ from a contraction of でございます, but I don't believe it's considered
to be such a contraction in modern regular usage.

> which in turn is the same as 「であります」(forgetting here about the differences
> in usage)

It's not quite the same as であります. Note that ございます is the humble version of
あります. That difference in usage is important. :)

> that is formed by attaching 「で」 to the verb「あります」.

Yes -- but note also that であります is **not** a verb unto itself, but simply the
particle で plus the verb あります.

> So, after this long trip, we arrive to the conclusion that the "hidden verb"
> behind 「です」, is in fact ある, which is actually (or at least more close to)
> the sought after "to be".

Historically, yes. And if you dig around in classical Japanese and older
stages of the language, you'll find just that -- あり serves as the primary
copular verb.

In modern Japanese, however, だ・です is the primary copular verb: it closes a
predicate, and (optionally) supplies social register information
("politeness"). One no longer says things like 綺麗にあり, one says instead 綺麗だ.
Similarly, instead of 本にてあり, one says 本だ.

Related thread touching upon social register:

  * [Why can't だ be used after an I-adjective?](https://japanese.stackexchange.com/questions/43244/why-cant-%E3%81%A0-be-used-after-an-i-adjective)

I hope the above covers the bases for you. If not, please comment and I can
edit the post accordingly.

### Addendum

I missed a question of yours that I'd meant to answer.

> Can we really call です（or だ) an auxiliary verb?

Depends. :) "Auxiliary verb" (助動詞) is a kind of loose category in Japanese
school grammars. The [article on the Japanese
Wiktionary](https://ja.wikipedia.org/wiki/%E5%8A%A9%E5%8B%95%E8%A9%9E_\(%E5%9B%BD%E6%96%87%E6%B3%95\))
provides a table showing the various things that get this label. Some of them
I really don't agree with: そうだ and ようだ are listed here, and those are clearly
そう or よう + copular だ・です -- and だ・です is right there in the table as it's own
pair of rows at the bottom. Others like らしい, ない, and たい are adjectival in form
and function. Many, like させる or たがる, have full conjugation paradigms (i.e.
they have forms for all conjugation slots), whereas others like negative
supposition まい or positive supposition う are defective (i.e. have incomplete
conjugation paradigms; see [Defective
verb](https://en.wikipedia.org/wiki/Defective_verb) at Wikipedia).

Basically, it's a grab-bag of odds and ends that get stuck on the ends of
other things (often, but not always, verbs). This category was also previously
called simply 助け言葉 ("helping words"), and this vague moniker is a clue to the
vagueness of the category itself.

So, _"can we really call です（or だ) an auxiliary verb?"_ Sure. So long as we're
clear on what we mean by "auxiliary verb". :)




Your collection of questions conflate a few things: 1) what is だ・です in modern
Japanese, and 2) how did だ・です derive historically.

Because of #2, #1 is a bit ... messy. :) So let's start with the history.

> 「です」は、「でございます」が変化したもの,

This isn't an explanation of what です is now, so much as an explanation of the
historical derivation. Shogakukan's 国語大辞典 provides this description:

> 「でござります」→「でござんす」→「であんす」→「でえす」→「です」の経路で生じたものという

Meanwhile, the modern plain form だ derives as:

> 「にてあり」から出た「である」が、〔dea〕→〔da〕と変化したものという。→であ・じゃ・である

Modern で (which actually appears from around the 1300s-1500s) is understood to
have evolved from earlier にて (which is still used in formal writing).
Classical copular ("is") verb あり equates to modern verb ある.

Looking now at the particular parts of your post:

> 「で」は「だ」の連用形。 「で」is the conjunctive/continuative form of 「だ」

Well, yes, in the modern language. But historically, だ derives from で + ある --
so this is not a regular kind of conjugation paradigm.

> To sum it up, 「です」 is a variation of 「だ」(its polite form).

Yes. Though I might not use the term "variation" so much as "polite form".

> It is also a contraction of 「でございます」,

It _derives_ from a contraction of でございます, but I don't believe it's considered
to be such a contraction in modern regular usage.

> which in turn is the same as 「であります」(forgetting here about the differences
> in usage)

It's not quite the same as であります. Note that ございます is the humble version of
あります. That difference in usage is important. :)

> that is formed by attaching 「で」 to the verb「あります」.

Yes -- but note also that であります is **not** a verb unto itself, but simply the
particle で plus the verb あります.

> So, after this long trip, we arrive to the conclusion that the "hidden verb"
> behind 「です」, is in fact ある, which is actually (or at least more close to)
> the sought after "to be".

Historically, yes. And if you dig around in classical Japanese and older
stages of the language, you'll find just that -- あり serves as the primary
copular verb.

In modern Japanese, however, だ・です is the primary copular verb: it closes a
predicate, and (optionally) supplies social register information
("politeness"). One no longer says things like 綺麗にあり, one says instead 綺麗だ.
Similarly, instead of 本にてあり, one says 本だ.

Related thread touching upon social register:

  * [Why can't だ be used after an I-adjective?](https://japanese.stackexchange.com/questions/43244/why-cant-%E3%81%A0-be-used-after-an-i-adjective)

I hope the above covers the bases for you. If not, please comment and I can
edit the post accordingly.

### Addendum

I missed a question of yours that I'd meant to answer.

> Can we really call です（or だ) an auxiliary verb?

Depends. :) "Auxiliary verb" (助動詞) is a kind of loose category in Japanese
school grammars. The [article on the Japanese
Wiktionary](https://ja.wikipedia.org/wiki/%E5%8A%A9%E5%8B%95%E8%A9%9E_\(%E5%9B%BD%E6%96%87%E6%B3%95\))
provides a table showing the various things that get this label. Some of them
I really don't agree with: そうだ and ようだ are listed here, and those are clearly
そう or よう + copular だ・です -- and だ・です is right there in the table as it's own
pair of rows at the bottom. Others like らしい, ない, and たい are adjectival in form
and function. Many, like させる or たがる, have full conjugation paradigms (i.e.
they have forms for all conjugation slots), whereas others like negative
supposition まい or positive supposition う are defective (i.e. have incomplete
conjugation paradigms; see [Defective
verb](https://en.wikipedia.org/wiki/Defective_verb) at Wikipedia).

Basically, it's a grab-bag of odds and ends that get stuck on the ends of
other things (often, but not always, verbs). This category was also previously
called simply 助け言葉 ("helping words"), and this vague moniker is a clue to the
vagueness of the category itself.

So, _"can we really call です（or だ) an auxiliary verb?"_ Sure. So long as we're
clear on what we mean by "auxiliary verb". :)

