What is the difference between しない and じゃない?


So as the title says,

**What is the difference between しない and じゃない?**

**And is じゃない even a verb?**

* * *

I know that しない comes from する. It's in the negative form. (It should be
mizenkei)

But when I tried to conjugate it in the plain negative:

`s• + -a + -nai`

It was more like sanai. And it would make more sense if they changed the sound
to janai(じゃ) . But for somehow it's (し).

-

I know it's irregular verb.

But how did the (root s•) become (shi し) in the plain negative?

It makes perfect sense to be (shi し) in the polite form (shimasuします) with the
(base -i)




I may be jumping in a bit early, as your post in its current state is a bit
confused. However, I think I understand enough of what you're trying to ask to
attempt an answer.

I'll restate your core question as I understand it.

# How does する conjugate into the negative form しない?

As you note, する is an irregular verb. So things get a bit messy.

## Conjugation types: regular "consonant-stem" verbs

In your approach, it looks like you're applying the simplified rules for so-
called "consonant-stem" verbs, verbs where the stem (the part that never
changes) ends in a consonant. These are verbs like [書く]{kaku} ("to write") or
[流す]{nagasu} ("to flush something, to make something flow"). In a lot of
English-language materials for learning Japanese, the conjugation patterns for
these are described a bit like the following:

[code]

    Plain form:       kak-u   nagas-u
    "-masu" stem:     kak-i-  nagash-i-
    "-nai" stem:      kak-a-  nagas-a-
    "-ba" stem:       kak-e-  nagas-e-
    Command form:     kak-e   nagas-e
    Volitional form:  kak-ō   nagas-ō
    
[/code]

In Japanese-language materials, verb stems aren't classed as "consonant stems"
or "vowel stems", but instead they're classed by the number of different
vowels that happen. In the above, there are five vowels, so these verbs are
called [五段]{ごだん}[活用]{かつよう} ("five-step conjugation") verbs.

## Conjugation types: the irregular _sa_ verb

> But how did the (root s•) become (shi し) in the plain negative?

Again, する is an irregular verb: it has no "root s●".

The Japanese-language name for this specific verb, which has its very own
unique conjugation pattern, is サ[行]{ぎょう}[変格]{へんかく}[活用]{かつよう}, or " _sa_
-column irregular conjugation", often abbreviated as サ[変]{へん}. It's the only
verb with this conjugation pattern, so you just have to memorize it. It
behaves a bit more like a so-called "vowel-stem" verb, only a bit wonky (more
on that further below). Here's the pattern for modern verb する.

[code]

    Plain form:       suru
    "-masu" stem:     shi-
    "-nai" stem:      shi-
    "-ba" stem:       sure-
    Command form:     seyo (Western / Kansai), shiro (Eastern / Kantō)
    Volitional form:  shiyō
    
[/code]

So the negative of する is that stem ''shi-'' plus the negative ending ''-nai''
= しない.

## History

In both modern and Classical Japanese, the verb する is classed as
サ[行]{ぎょう}[変格]{へんかく}[活用]{かつよう}, or " _sa_ -column irregular conjugation". In
Classical Japanese, the verb had the following verb stems (the part before any
conjugation suffixes like ～ない or ～ます). For comparison, I've added the _s_
-column endings for the Classical [二段]{にだん}[活用]{かつよう} ("two-step conjugation")
verb, one of the patterns that evolved into the modern "vowel-stem" verbs, as
well as the _s_ -column endings for a Classical [四段]{よだん}[活用]{かつよう} ("four-
step conjugation") verb, the precursor to our modern regular
[五段]{ごだん}[活用]{かつよう} ("five-step conjugation") verbs. I'm also including the
Japanese names for each conjugated stem form. (Note that the "attributive"
replaced the "conclusive" in modern Japanese.)

  * [活用]{かつよう}: サ変 二段 四段
  * [未然形]{みぜんけい}： せ せ さ _mizenkei_ , "irrealis" ("hasn't happened yet"): _-nai_ stem
  * [連用形]{れんようけい}： し せ し _ren'yōkei_ , "infinitive": _-masu_ stem
  * [終止形]{しゅうしけい}： す す す _shūshikei_ , "conclusive": plain form
  * [連体形]{れんたいけい}： する する す _rentaikei_ , "attributive" (used to modify a noun, like an adjective)
  * [已然形]{いぜんけい}： すれ すれ せ _izenkei_ , "realis" ("assuming it has happened"): _-ba_ stem
  * [命令形]{めいれいけい}： せよ せよ せ _meireikei_ , "imperative": command form

You can see how する behaves much more like a Classical vowel-stem verb: only
the [連用形]{れんようけい} or _-masu_ stem is different.

### Classical negative

In Classical Japanese, the negative form of する was せぬ. This is the _-nai_ stem
せ + negative suffix ぬ.

Beginners of Japanese usually don't encounter negative ぬ, since Eastern
Japanese (Tokyo Japanese, also called Kantō Japanese) is the "standard", and
this ぬ isn't part of everyday Eastern Japanese. It's still used to some extent
in Western Japanese (Kansai Japanese, as spoken in places like Kyōto and
Ōsaka).

### Shift to the modern negative

The shift from Classical negative form せぬ to modern しない included two changes
-- 1) the Western and older negative suffix ぬ was replaced by the Eastern
negative suffix ない, and 2) the せ shifted to し.

#1 is pretty straightforward, but #2 may require looking at the phonetics
(sounds).

In modern Japanese, we're taught that the _i_ vowel is special for the _s-_
kana -- the consonant part of し is pronounced not like _s-_ , but like _sh-_ ,
as _shi_. This kind of fiction-y consonant sound is called an "affricate" in
phonetics studies. In older times, up through at least the 1600s and possibly
later, せ was also pronounced as an affricate, as _she_ , instead of the modern
_se_.

Beginning materials for Japanese often omit any discussion of pitch accent.
For する, the negative form in Eastern Japanese has a so-called "flat" or low-
high pitch, shown in some dictionaries as pitch type "0" (zero, meaning no
[downstep](https://en.wikipedia.org/wiki/Downstep)) or by marking the word
like [しない]{LHH}. This means that the first mora (the し) has a low pitch, then
the な and the い have a high pitch. As compared to a word in the English
language, it's a bit like the し is unstressed. When し is unstressed in a
Japanese word, it's often pronounced without the vowel value, more like just
_sh_ without the _i_. You might have already noticed that して is pronounced
more like _shte_.

I haven't read any academic studies about this change, but I suspect these two
factors may have combined: after the shift to Eastern Japanese, せぬ or せない
would have been pronounced more like _shnu_ or _shnai_ , making the initial
sound ambiguous as to whether it should be spelled せ or し.

# Is じゃない even a verb?

This is more of a phrase than a verb.

じゃ is a contraction of では.

  * で is sometimes explained as the conjunctive form of plain-form だ and polite-form です, the copular ("to be") verb.
  * The は is the same as the topic particle, used here in what is sometimes called the "contrastive は" construction -- "contrastive" because you're actually negating the statement.

ない is the basic negative in the plain form, same as the suffix ～ない in しない,
only used independently to negate nouns and ～な adjectives. This ない conjugates
the same as any ～い adjective, with adverb form なく, past tense なかった, etc. The
polite form for this independent use is ありません, and you might even see ～ではありません
in some of your materials as the polite way to say "it is not ～".




I may be jumping in a bit early, as your post in its current state is a bit
confused. However, I think I understand enough of what you're trying to ask to
attempt an answer.

I'll restate your core question as I understand it.

# How does する conjugate into the negative form しない?

As you note, する is an irregular verb. So things get a bit messy.

## Conjugation types: regular "consonant-stem" verbs

In your approach, it looks like you're applying the simplified rules for so-
called "consonant-stem" verbs, verbs where the stem (the part that never
changes) ends in a consonant. These are verbs like [書く]{kaku} ("to write") or
[流す]{nagasu} ("to flush something, to make something flow"). In a lot of
English-language materials for learning Japanese, the conjugation patterns for
these are described a bit like the following:

[code]

    Plain form:       kak-u   nagas-u
    "-masu" stem:     kak-i-  nagash-i-
    "-nai" stem:      kak-a-  nagas-a-
    "-ba" stem:       kak-e-  nagas-e-
    Command form:     kak-e   nagas-e
    Volitional form:  kak-ō   nagas-ō
    
[/code]

In Japanese-language materials, verb stems aren't classed as "consonant stems"
or "vowel stems", but instead they're classed by the number of different
vowels that happen. In the above, there are five vowels, so these verbs are
called [五段]{ごだん}[活用]{かつよう} ("five-step conjugation") verbs.

## Conjugation types: the irregular _sa_ verb

> But how did the (root s•) become (shi し) in the plain negative?

Again, する is an irregular verb: it has no "root s●".

The Japanese-language name for this specific verb, which has its very own
unique conjugation pattern, is サ[行]{ぎょう}[変格]{へんかく}[活用]{かつよう}, or " _sa_
-column irregular conjugation", often abbreviated as サ[変]{へん}. It's the only
verb with this conjugation pattern, so you just have to memorize it. It
behaves a bit more like a so-called "vowel-stem" verb, only a bit wonky (more
on that further below). Here's the pattern for modern verb する.

[code]

    Plain form:       suru
    "-masu" stem:     shi-
    "-nai" stem:      shi-
    "-ba" stem:       sure-
    Command form:     seyo (Western / Kansai), shiro (Eastern / Kantō)
    Volitional form:  shiyō
    
[/code]

So the negative of する is that stem ''shi-'' plus the negative ending ''-nai''
= しない.

## History

In both modern and Classical Japanese, the verb する is classed as
サ[行]{ぎょう}[変格]{へんかく}[活用]{かつよう}, or " _sa_ -column irregular conjugation". In
Classical Japanese, the verb had the following verb stems (the part before any
conjugation suffixes like ～ない or ～ます). For comparison, I've added the _s_
-column endings for the Classical [二段]{にだん}[活用]{かつよう} ("two-step conjugation")
verb, one of the patterns that evolved into the modern "vowel-stem" verbs, as
well as the _s_ -column endings for a Classical [四段]{よだん}[活用]{かつよう} ("four-
step conjugation") verb, the precursor to our modern regular
[五段]{ごだん}[活用]{かつよう} ("five-step conjugation") verbs. I'm also including the
Japanese names for each conjugated stem form. (Note that the "attributive"
replaced the "conclusive" in modern Japanese.)

  * [活用]{かつよう}: サ変 二段 四段
  * [未然形]{みぜんけい}： せ せ さ _mizenkei_ , "irrealis" ("hasn't happened yet"): _-nai_ stem
  * [連用形]{れんようけい}： し せ し _ren'yōkei_ , "infinitive": _-masu_ stem
  * [終止形]{しゅうしけい}： す す す _shūshikei_ , "conclusive": plain form
  * [連体形]{れんたいけい}： する する す _rentaikei_ , "attributive" (used to modify a noun, like an adjective)
  * [已然形]{いぜんけい}： すれ すれ せ _izenkei_ , "realis" ("assuming it has happened"): _-ba_ stem
  * [命令形]{めいれいけい}： せよ せよ せ _meireikei_ , "imperative": command form

You can see how する behaves much more like a Classical vowel-stem verb: only
the [連用形]{れんようけい} or _-masu_ stem is different.

### Classical negative

In Classical Japanese, the negative form of する was せぬ. This is the _-nai_ stem
せ + negative suffix ぬ.

Beginners of Japanese usually don't encounter negative ぬ, since Eastern
Japanese (Tokyo Japanese, also called Kantō Japanese) is the "standard", and
this ぬ isn't part of everyday Eastern Japanese. It's still used to some extent
in Western Japanese (Kansai Japanese, as spoken in places like Kyōto and
Ōsaka).

### Shift to the modern negative

The shift from Classical negative form せぬ to modern しない included two changes
-- 1) the Western and older negative suffix ぬ was replaced by the Eastern
negative suffix ない, and 2) the せ shifted to し.

#1 is pretty straightforward, but #2 may require looking at the phonetics
(sounds).

In modern Japanese, we're taught that the _i_ vowel is special for the _s-_
kana -- the consonant part of し is pronounced not like _s-_ , but like _sh-_ ,
as _shi_. This kind of fiction-y consonant sound is called an "affricate" in
phonetics studies. In older times, up through at least the 1600s and possibly
later, せ was also pronounced as an affricate, as _she_ , instead of the modern
_se_.

Beginning materials for Japanese often omit any discussion of pitch accent.
For する, the negative form in Eastern Japanese has a so-called "flat" or low-
high pitch, shown in some dictionaries as pitch type "0" (zero, meaning no
[downstep](https://en.wikipedia.org/wiki/Downstep)) or by marking the word
like [しない]{LHH}. This means that the first mora (the し) has a low pitch, then
the な and the い have a high pitch. As compared to a word in the English
language, it's a bit like the し is unstressed. When し is unstressed in a
Japanese word, it's often pronounced without the vowel value, more like just
_sh_ without the _i_. You might have already noticed that して is pronounced
more like _shte_.

I haven't read any academic studies about this change, but I suspect these two
factors may have combined: after the shift to Eastern Japanese, せぬ or せない
would have been pronounced more like _shnu_ or _shnai_ , making the initial
sound ambiguous as to whether it should be spelled せ or し.

# Is じゃない even a verb?

This is more of a phrase than a verb.

じゃ is a contraction of では.

  * で is sometimes explained as the conjunctive form of plain-form だ and polite-form です, the copular ("to be") verb.
  * The は is the same as the topic particle, used here in what is sometimes called the "contrastive は" construction -- "contrastive" because you're actually negating the statement.

ない is the basic negative in the plain form, same as the suffix ～ない in しない,
only used independently to negate nouns and ～な adjectives. This ない conjugates
the same as any ～い adjective, with adverb form なく, past tense なかった, etc. The
polite form for this independent use is ありません, and you might even see ～ではありません
in some of your materials as the polite way to say "it is not ～".

