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  5. Grammar: 食べないんです vs. 食べません


Grammar: 食べないんです vs. 食べません

The Feeling module has the sentence

どうして あさごはんを 食べないんですか

which is translated as "Why aren't you eating breakfast?" I have not encountered the nai-form + です before: why would one use it, rather than たべません?

Also, is translating this as present progressive really appropriate? Wouldn't one need the te-form + いる for that?

June 17, 2017



Hi Faisane, a native speaker here.

Hopefully this page can give you an answer to your query. https://www.thoughtco.com/what-is-n-desu-2027871

The present progressive tense is fine to me as it is relating to someone’s intention (future action).


Thank you - that article is really helpful. There's even a very similar sentence in there!

I'm still not sure on the use of present progressive; even the sentence in the article is translated as "why don't you eat" but that's a minor quibble. Thanks again!


食べない and 食べません mean exactly the same thing, except the former is the informal dictionary form and the latter is the polite ます/です form that's more appropriate for strangers and people situated above you socially (e.g. your teacher, your boss, etc.)

The real difference here isn't ない vs ません. The difference is that tiny little ん between ない and です you probably didn't even notice. The んです is actually a contraction of の+です. When placed after a verb in dictionary form, の nominalizes the verb and its clauses, meaning you can treat the relative clause headed by the verb before の as a noun phase in the surrounding sentence. This has many uses, some of which you will see later on in the skill tree.

Now, this hasn't exactly answered your question. Why on earth is it useful to turn 食べない into a noun with ん/の just to end it with です? It creates emphasis that the statement is a fact or the current situation. 食べません is a fairly neutral statement, simply meaning "(you) do not eat", whereas 食べないんです is more pointed, meaning something more like "it is the case that (you) are not eating".

Therefore the full sentence in the provided example 「どうして あさごはんを 食べないですか」 could be translated a bit more accurately as "why is it that you are not eating your breakfast", which makes a slightly more pointed question than the neutral 「どうしてあさごはんを食べませんか」 ("why aren't you eating breakfast"). I'm not sure I can properly explain the intonation it adds in every case, but in this situation it shows interest in the lack of apetite of the person you're talking to.


Oh. I see the question has already been answered by a native speaker, lol. Well, my explanation and the article posted above doesn't completely overlap, so I'll leave it and hopefully someone finds it helpful.


It's very helpful, thank you! The whole ん issue is something I haven't yet understood completely, so I keep having to revisit it. (And you were right - even though I noticed it, I wasn't really aware of the significance.)


Re: ですか

it shows interest in the lack of apetite of the person you're talking to.

Yes, you've hit the nail on the head. :)


I think the "n" desu is more emphatic. It's a fact that I don't eat.

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