Generally, in all Japanese language classes, the rule you're taught is that です does not follow い adjectives. Instead, い adjectives can act like stative verbs, and as such terminate a sentence by themselves. However, I have heard this usage frequently. I don't necessarily have a specific example in mind that I've heard, because it doesn't seem all that rare.

However, recently I got into a discussion with someone who suggested that い adjective + です is dangerous, and has the potential to be offensive and/or rude when used incorrectly so foreigners should avoid it. One specific example given was 美しいです sounding vulgar. They also said that い adjective + だ is flat out ungrammatical in all situations. When I've posed this same question to other Japanese speakers, they take no issue with 美しいです and they say it sounds fine.

My question is, there seems to be some disagreement. Does anyone have a definitive answer about why such a disagreement might exist, and how I should go about knowing whether or not it's safe to use い adjective + です in normal usage? Or maybe people here also have no issue with it, and think that the original person I spoke to was perhaps mistaken.

If it's not safe, then what do I do if I want to end a sentence with an い adjective politely? Follow it with ~のです perhaps?


Following an い-adjective with です is perfectly acceptable, as in the following examples:

  • あの人はひどいです。
  • 昨日は楽しかったです。

I don't see any vulgar aspect to 美しいです failing contextual clues that could make nearly any description vulgar.

Something that may be getting confused in all of this is that while the polite form of an い-adjective is followed by です -- e.g. さむいです -- the plain form is not followed by だ. So the plain form of さむい is just さむい. The examples above would be, in plain form, as follow:

  • あの人はひどい。
  • 昨日は楽しかった。

のです is different again, and while polite, adds an air of explaining something.

  • Right. That asymmetry (presence vs. absence of copula depending on the politeness) is an interesting fact when you think about the grammar. – user458 Jul 10 '11 at 8:36
  • @sawa That's a good point. I hadn't thought about it quite like that before. Seems like a similar phenomenon to do-insertion in English... I wonder if they're actually at all related. – rintaun Jul 10 '11 at 8:50
  • Not strictly, but in a broad sense they are. Pleonastic elements like 'do' or the copula are inserted only to satisfy some requirements such as to add politeness (in Japanese), or host an affix (in English), etc. – user458 Jul 10 '11 at 9:03

'です' does follow i-adjectives. It's purpose is to add politeness. I see no problem with it, but maybe I am missing something. Was there a particular example that was discussed when the person said it is dangerous? The only thing I can think of is that the expression can be made milder by adding the sentence final particle , which indicates addresser's expectation of the addressee's agreement.

美しいです 'It is beautiful.'

美しいですね 'It is beautiful, isn't it?'

'のです' will change the meaning. It implies that it is an explanation to or expansion on something mentioned in the previous context.

美しいのです 'It is the case that it is beautiful' (Perhaps following a context: 'I like this place'. Then, it would be imply: 'The reason for it is because')

i-adjective + だ is ungrammatical in standard Japanese, but it may be used in some Tohoku dialects.

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    Interesting! I never knew about い-adjective + だ being standard in Tohoku dialect. – rintaun Jul 10 '11 at 8:30
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    @sawa: no, "ちゃ" does not embed a "だ". We commonly say "んだちゃ" to say "そうですね". But the Tohoku dialects have a very loose grammar, so I think that deciding whether or not to put だ after い-adjectives is a matter of person, usage and situation. – Axioplase Jul 10 '11 at 9:26
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    i think the idea is that nouns and な-adj have な at the end, and in plain form this is what changes to だ. い-adj doesn't have that so no だ – Mark Hosang Jul 10 '11 at 13:57
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    @Pacerier 'だ' is the plain form copula. 'です' is the polite form copula. 'です' has a clear purpose of adding politeness, and that makes it possible to use it after i-adjective. 'だ' does not contribute to the meaning, and that makes it tricker for 'だ'. – user458 Jul 10 '11 at 14:52
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    @Mark That is how it is explained in traditional grammar. (By the way, ending a noun with 'な’ is not what traditional grammar tells, but is actually done, and you have correctly pointed this out.) But to see it from a modern perspective, 'な' is something that heads a relative clause, comparable to the English 'that' in 'the picture that is beautiful'. On the other hand, 'だ' is the copula, comparable to the English 'be'. – user458 Jul 10 '11 at 14:55

Err, I don't agree with your initial statement. I think that generally you are taught that い adjectives are followed by です.

I think that it is never dangerous to say "美しいです" and that you should put a です all the time, until you reach enough confidence to know when you may drop it, and just say 美しい.

However, い-adj + だ is basically just wrong. There are situations where this can be heard, but it's mostly when talking to farmer in a deserted rural area (to express how harsh and uneducated it may sound).

  • That's kind of how I felt too I guess, it just sounds better to me instinctively, but it just caught me off guard when I heard that it was strange, so I thought I'd ask. – Zach Jul 10 '11 at 17:27

い adjective + です was originally a slang used by people who were not familiar with standard Japanese and only recently (1952) officially accepted. Still now, it's not considered really sophisticated, in my oppinion. Only おいしゅうございます etc were correct until then.

And there is a comment that says it's standard in Tohoku dialect, but that is not true at all. That's actually a common misconception that many speakers of other regions hold. He obviously is mixing it with dialects of north-east Kanto. (Note that Miyagi is linguistically not Tohoku but north-east Kanto) Or, he may have misheard sentence-ending particle でゃ of Tohoku dialects. あと、吉幾三の「おら東京さ行ぐだ」はいわゆるネタですから。

  • I'm not sure I agree with the assessment of 形容詞+です as slang, and also as non-standard. Not accepted in academic Japanese at the time? Certainly, that is true, and well documented - and it did become accepted in academic Japanese in 1952. However, as speakers of English likely know, the actual language we speak (where split infinitives, dangling participles, and the like are both common and standard) is different in many ways from the language which is taught to be "correct" in schools (where those constructions are not considered standard). – rintaun Oct 24 '13 at 8:02
  • I'm curious what you think is "sophisticated", if い adjective + です isn't. – Darius Jahandarie Oct 24 '13 at 16:16
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    >rintaun:Not accepted in academic Japanese at the time? I'm not sure what do you mean by "academic", but "Only recenyly officially accepted" means that Ministry of Education had instructed people to avoid that form until 1952 and later they stoped to bother to instruct it. >Darius (First, it won'be a problem in casual conversations.) For example, the current prime minister keeps avoiding it in his speech by various means like ・・わけであります. I personally find these ways pleasant. すばらしいです → すばらしい すばらしいですね → すばらしいですね すばらしいですよ → すばらしいですよ – user4092 Oct 25 '13 at 5:38

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