In a recent comment I claimed that ない was a verb which was the negative form of ある. I was surprised by the reply that "ない is an adjective (or adjective-like auxiliary) anyway, not a form of ある".

Obviously I know that ない behaves like an adjective, but my confusion lies in how Japanese people think about verb negation. Is ある->ない just a special case? For example, does Japanese grammar think of 食べない as a verb which is the negation of 食べる, or does it think of it as an adjective? Maybe I'm just trying to apply western principles to Japanese grammar and my question doesn't even make sense. I'm not sure.


3 Answers 3


That is confusing ない as adjective and ない as auxiliary verb.

The standalone ない is an adjective, but ない in 食べない is an auxiliary verb. This is basically similar to negations in other languages in the sense that negation is expressed by a functional word that is not used by itself. (Or maybe Japanese grammarians stipulated so that it looks that way.)

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    Arguably, there is one ない, and it happens to appear in both roles (standalone, and as a verb suffix). The entire grammatical category of 助動詞【じょどうし】 ("auxiliary verb") is a grab-bag of things that grammarians haven't known how to class cleanly, with functions and inflection paradigms that are all over the place -- as we can see in the tables in the Japanese Wikipedia article on this subject. Commented Jul 7, 2023 at 17:29
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    Looking specifically at the verbal suffix, ~ない inflects pretty much the same way as any other ~い adjective (the one corner case is when adding the "seems like / heard that" suffix ~そう, where a ~さ~ gets stuck in the middle). Syntactically, morphophonemically, what solid grounds are there for classing this as a "verb"? Commented Jul 7, 2023 at 17:31
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    @EiríkrÚtlendi - 助形容詞 ("auxiliary adjective") might have been about right. That さ is shared with one adjective, namely いい (or よい).
    – aguijonazo
    Commented Jul 7, 2023 at 20:11
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    @EiríkrÚtlendi OP asked about how Japanese grammar thinks about this, and this answer is correct in that respect. At least until high school, every teacher teaches ない in 食べない as a 助動詞 that inflects like an adjective.
    – naruto
    Commented Jul 8, 2023 at 21:43
  • @naruto, good point about the context of the OP question. A concern I was trying to address with my comment is the way that some learners glom onto the idea that there are "different" ないs (standalone, suffix) or "different" とs (conditional, quotative, adverbial), etc., when instead what we see is that there is one ない and one と that simply happen to play different roles -- much like the word "get" in English can be used in multiple different ways (to receive, to have happen to oneself, to make someone else do, to become, etc.), yet it's all still the same word "get". Commented Jul 10, 2023 at 17:28

In addition to what was said in other answers, I will mention that ある in some other modern dialects and in Old/Middle/Classical Japanese has negative form created in the same ways as other verbs.

In Kansai dialects (Ōsaka, Kōbe, Kyōto cities etc.), suffix へん (or ひん for -i-vowel stem verbs) is used after 未然形 (see 1, 2):

Affirmative Negative
ある あらへん
帰る(かえる) 帰らへん(かえらへん)

(About adjectives in Kansai, see 3, 4.)

In Middle/Classical Japanese, suffix / is used after 未然形:

Affirmative Conclusive Affirmative Attributive Negative Conclusive Negative Attributive
あり / ある ある あらず あらぬ
歸る(かへる) 歸る(かへる) 歸らず(かへらず) 歸らぬ(かへらぬ)

Maybe I'm just trying to apply western principles to Japanese grammar and my question doesn't even make sense. I'm not sure.

Let's explore that possibility. I agree that the grammatical terms used to describe English (along with most European languages, etc.) don't fit well to describe Japanese.

The terms "noun" and "verb" are fairly universal, but even "noun" has complications (there are many grammatical properties you might conceivably expect a "noun" to have, and multiple overlapping classes of words in Japanese that have some but not all of those properties). By the time you get to "adjective" there is already no clear agreement.

What we call "i-adjectives", i.e. what are natively called [形]{けい}[容]{よう}[詞]{し} (literally "description words"), function in most respects the same way as verbs ([動]{どう}[詞]{し} "motion words", even though this includes completely stative and intransitive verbs). In particular, they are both predicates, and they both can be used attributively.

Here by "predicate" I mean that by combining with just a grammatical subject (and we can even omit this contextually in Japanese), we get a grammatically complete (even if semantically vague) utterance. In English, we cannot say "the cat cute"; we require a copula in order to turn the adjective "cute" into a proper completion for the sentence. But in Japanese, 猫が可愛い is fine. The particle が is not a copula, but only a case marker. We do not require です; and if we add it then it is functioning as a politeness marker, not as a copula, which is why we can't substitute だ. The copular function - the part represented by "is" in English (although this has many other uses in English) - is already contained within 可愛い.

On the flip side, English does not allow us to use verbs to describe nouns directly (attributively): we cannot say "a walks person", but instead "a person who walks" - the verb needs to get pushed into an explicitly marked relative clause using a relativizing pronoun. But in Japanese, 歩く人 is fine, in the same way that 可愛い猫 is fine.

Mainly where these predicates differ is that 動詞 generally accept a full set of case-marked participants in the "action" - が-marked grammatical subject, を-marked grammatical direct object, as well as に- and で- marked participants for which analogues are not as clear-cut. When used attributively, this implies that something that would be a complex sentence by itself can then be used to describe a noun by just dropping the noun after it (meaning something like "the (noun) for/in which (complex description of event or premise) occurs/is the case"). 形容詞 on the other hand, as far as I can recall seeing, only accept a が-marked subject; and when used attributively, such a subject is generally part of a fixed expression (e.g. 背が高い).

Is ある->ない just a special case?

There are many ways to analyze this. My view is: yes, but it's an irregularity of the conjugation of ある - not a separate kind of ない. In Japanese, the negations of 動詞 simply are 形容詞 that are formed using ない.

Whether the [未]{み}[然]{ぜん}[形]{けい} ("a-stem" for godan verbs) to which ない is attached counts as a "word", let alone a "separate" word from the ない itself, is a matter of definitions, and not a fruitful debate; but ない by itself does negate ある, and it is the same thing as ない attached to a 動詞 in 未然形 form. It just happens that ある is irregular, such that its "a-stem" is null when attached to ない (although the volitional, ある -> あら+い -> あろう (via ウ音便), seems to be regular). Alternately, we could say that ある is "defective", and the verb ない is substituted as its negative form, in the same way that できる is substituted as the potential of する.

Describing ない in English as an "auxiliary verb" doesn't make sense if we're going to use the word "adjective" at all. Verbs conjugated with ない end with... い, i.e., not a う-row kana; and they don't accept a を-marked direct object etc.

The remaining question is why the conjugation works this way. To my understanding, the mental model is that only the underlying "action" itself is being negated, not the entire proposition. In English, it's natural to say something like "I didn't tell the story", and "the story" is still a direct object. But in the Japanese mindset, if you didn't speak, then the unsaid-thing no longer merits the grammatical privilege of being marked with を. So either the former direct object has to become a topic, or else the entire proposition can be nominalized and its existence (although this doesn't feel like quite the right word in English) then denied.

  • I flagged the question as a duplicate of In what way is the negative form of a verb an adjective?, but I don't know if people will agree. If they do, I'll move my answer there and adapt it appropriately. Commented Jul 8, 2023 at 16:25
  • Your duplicate link was helpful, but I think we should leave it as is. A lot of useful material in your answer and the link but I think sundowner's answer is definitive. Commented Jul 9, 2023 at 8:52
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    Some adjectives, such as 必要 and 優しい, take a に-argument.
    – aguijonazo
    Commented Jul 9, 2023 at 10:17

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