Hallo.
Just started with –na and –i adjectives, and I have read that you can omit the verb with –i adjetives in order to make the sentence informal.
However, I have found that です is omitted with –na adjetives as well, instead of being replaced with だ.
さくらいろがきれい
Page5:
Why is this? Can anybody help me?
Thank you
The informal copula is だ, which you’ve probably seen before.
So さくらいろがきれいだ would be a grammatically complete sentence.
However, ending sentences with だ is considered quite blunt and forceful, and so it usually isn’t done unless one intends to be blunt and forceful. So it’s normal to omit the copula in informal sentences that end with nouns and な adjectives.
BTW, I’m not quite sure what you mean by “I have read that you can omit the verb with –i adjetives in order to make the sentence informal”
Are you still talking about です there? です is not usually referred to as a verb, so that’s why I’m just checking.
And in the case of an い adjective, the です is actually not a copula either. It’s actually only there to express politeness.
You are right, I’m having problems translating です。 Maybe I shouldn’t translate it at all and focus on the adjective itself, it would probably be clearer.
Thanks for your help!
Besides, what Leebo 先輩 said, I suggest to not think of i-adjectives as adjectives in English since they conjugate (present/past) etc…
So, you think of them as verbs? Is that what you mean?
As something that is quite similar to verbs.
形容詞 are still more comparable to English adjectives than Japanese verbs in my opinion. English happens to only conjugate verbs. Japanese happens to conjugate both verbs and い-adjectives. But how English adjectives and 形容詞 are used in sentences match up pretty well in terms of their grammatical role. (e.g. “the car is blue” → 車が青い and “the blue car” → 青い車)
Perhaps this is a matter of starting with the wrong assumptions because most Japanese textbooks teach formal Japanese first: not all adjectives in Japanese ‘need’ to be followed by another verb. い-adjectives can end sentences on their own (or be complete sentences alone), whereas な-adjectives need だ to make a grammatically complete sentence. For that matter, just for your information, apparently ‘い-adjective + です’ used to be considered a mistake, with しい→しゅうございます, あい→おうございます and so on being the only correct forms. (Here’s a discussion of the other possibilities for other い-adjective verbs.) It was only approved at some time in the 1950s by the Japanese education ministry.
But yes, so, you can drop だ after な-adjectives (or even after nouns) in a casual context because it’s still clear what the sentence means and because… I guess you could say that だ is sort of attached to the stem of the な-adjective and conjugates on its own, whereas for an い-adjective, い is an integral part of the adjective and can’t simply be dropped. The other considerations linked to using だ have already been mentioned by Leebo above.
I think they thought です was a verb.
I tend to think of it as a verb too because it does conjugate (not that that’s the only criterion for something to be a verb), and I mean, these things are all fundamentally forms of で＋ある, right? ある is a verb. But regardless of the grammatical nature of the copula, yeah, it’s true that here especially, です has no grammatical function, only a role as a politeness marker.
です is missing a lot of conjugations that verbs normally have, so I have trouble treating them as the same thing.
I usually consider it similar to a defective verb, which is a term for portuguese verbs that lack conjulgations. です would be a bit more extreme than what we have in portuguese, but the principle stands.
Edit: I said that, but the verb to ache lacks almost 50% of its conjulgation table, so I think “this verb doesnt conjulgate all the time” isn’t a problem for me
French has these too, so I had a similar idea in mind.
I personally just see it as a specialised form of である, which has all the usual forms, I believe. In any case, etymologically, I’m pretty sure である comes from にてある, which is to say にある, which was にあり・なり in Classical Japanese. です is just a shortening of であります or something similar, unless I’m quite mistaken, which would make it a verb form, or at least something that evolved from で followed by a verb form. (です is labelled as a 助動詞 by 大辞林, for what it’s worth, which would put it in the same category as ない、れる and other things resembling suffixes for an English speaker.)
Do not think of です as something to be “omitted” tbh, it really only has 2 usages - it replaces だ in polite speech and the weird part - it also is used after keiyoushi (i-adjectives but really the only real adjectives) in polite speech but only as a politeness marker - no grammatical function
Textbooks starting absolute beginners with 丁寧語 has always been a pet peeve of mine because です and ます are some of the few zombie verbs that retain older and exceptional grammar that is completely absent in the rest of japanese - it would be like starting people off in English with the sentence “How may I be of use to you?” instead of “How can I help you?”
What an amazing amount of information you’ve given me!!! 
Thank you sooo much!! 
I really need to sum up everything that you all are telling me:
Although –na adjectives technically require “だ” for a complete sentence, they can be omitted informally to avoid a strong effect.
As -i adjectives are very strange, in order to use them easily I should think of them as verbs when they conjugate, but as adjectives when they relate to other words within the sentence.
These adjectives (-i) do not need verbs, and when です is used with them, it is only for politeness.
Whether or not です is a verb is a matter for discussion, but it could be useful to use it as if it were a “special case”, such as a Portuguese or French defective verb. Very nice, because in Spanish the verb “to rain” works that way, too. Easy!
It would be more useful to think, not of what です is, but of how to use it: politeness marker o replacement for だ
It may be easier to start studying informal Japanese, rather than formal.
I hope these guides will help me a lot, thank you!
The だ and です distinction is a little more complicated, from my understanding of it. Here’s a Tofugu article about it that goes into a lot of detail about why one or the other might be used.
Thank you, a lot of complementary information. I’ll keep it in mind.
