みぜんけい or れんようけい form for ない conjugation of i-adjectives


It appears that nai conjugates onto the renyoukei (.ku) form of i-adjectives
instead of the mizenkei (.karo) form, as it does with verbs. Is this correct?
Every source I've found shows the .kunai result without ever explaining what
form is used.




> It appears that 「ない」 conjugates onto the 連用形{れんようけい} (～～く) form of
> i-adjectives instead of the 未然形{みぜんけい} (～～かろ) form, as it does with verbs.
> Is this correct?

Yes, it is correct. As a Japanese-learner, I suppose you would just have to
memorize the rule in forming the negative forms. Keep making mistakes and
eventually, only the correct forms will sound good in your own ear.

Why does this difference exist, then?

In short, because we are, strictly speaking, talking about two different
「ない's」 here -- two different words with the same spelling, that is, at least
historically.

「ない」 attached to verbs is an **_auxiliary verb_** while 「ない」 attached to
adjectives is an **_adjective_**.

**_Tips on how to tell the two 「ない's」 apart:_**

Try replacing the 「ない」 with 「ぬ」 in phrases containing 「ない」. If it still makes
sense, it is the auxiliary verb 「ない」.

「かわいく **ない** 」⇒「かわいく **ぬ** 」 Makes no sense; Must be the adjective 「ない」.

「話{はな}さ **ない** 」⇒「話さ **ぬ** 」 Makes perfect sense; Must be the auxiliary verb
「ない」.




> It appears that 「ない」 conjugates onto the 連用形{れんようけい} (～～く) form of
> i-adjectives instead of the 未然形{みぜんけい} (～～かろ) form, as it does with verbs.
> Is this correct?

Yes, it is correct. As a Japanese-learner, I suppose you would just have to
memorize the rule in forming the negative forms. Keep making mistakes and
eventually, only the correct forms will sound good in your own ear.

Why does this difference exist, then?

In short, because we are, strictly speaking, talking about two different
「ない's」 here -- two different words with the same spelling, that is, at least
historically.

「ない」 attached to verbs is an **_auxiliary verb_** while 「ない」 attached to
adjectives is an **_adjective_**.

**_Tips on how to tell the two 「ない's」 apart:_**

Try replacing the 「ない」 with 「ぬ」 in phrases containing 「ない」. If it still makes
sense, it is the auxiliary verb 「ない」.

「かわいく **ない** 」⇒「かわいく **ぬ** 」 Makes no sense; Must be the adjective 「ない」.

「話{はな}さ **ない** 」⇒「話さ **ぬ** 」 Makes perfect sense; Must be the auxiliary verb
「ない」.

