70451
I've just heard the phrase [失礼]{しつれい}しなければならないんです (shitsurei shinakereba
naranaindesu) used as _Excuse me, I have to leave_. The explanation said it
literally translates to _If I don't leave, it won't do_ , but I need help on
breaking it down precisely.

What does each word mean and how does the grammar work here?
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2019-08-30T11:39:51.260
70447
2020-02-22T08:20:27.577
2020-02-22T08:20:27.577
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question
grammar conjugations phrases
Break down the phrase "[失礼]{しつれい}しなければならないんです"
> 失礼{しつれい}しなければならない

失礼 (shitsurei) is "rudeness".

失礼する (shitsurei suru) is "to be rude"

失礼しない (shitsurei shinai) is the negation "to not be rude".

失礼しなければ (shitsurei shinakereba) is a conditional form of the above "If I am
not rude"

失礼しなければならない (shitsurei shinakereba naranai) I'm now sure how to break down
ならない meaningfully but in this context it kind of means "It's no good".

So literally the whole thing means "If I'm not rude then it's no good". Really
you should think of なければならない (nakerebanaranai) as a unit in its own right.
This attaches to the negative form of the predicate and means "must do"/"have
to do" etc, which is the logical implication of the expansion "If I don't do,
then it's no good".

Overall then, the sentence means "I have to be rude", which is what you might
say if you were leaving.
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2019-08-30T14:01:15.937
70451
2019-08-30T14:01:15.937
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answer
**① Grammar pattern**

The grammar pattern used here is:

> V(ない form, and drop the い) + なければならない

which means "must V", where V is any verb in the plain negative form (ending
in ない) . First drop the い and then add なけらばならない

> 食【た】べない → 食【た】べな →食【た】べなけらばならない。"Must eat".
>
> 行【い】かない → 行【い】かな → 行【い】かなければならない。"Must go".
>
> 散歩【さんぽ】しない→ 散歩【さんぽ】しな → 散歩【さんぽ】しなければならない。"Must stroll".

* * *

**② The meaning of 失礼【しつれい】する**

失礼【しつれい】する means "to be rude", but in some situations it also means "goodbye"
or "to leave". For sure, this meaning comes from the fact that leaving someone
may be considered rude, no doubt here, but I would think of it as a set phrase
to say goodbye. In fact, when Japanese people end a phone call in a formal
situation, they use 失礼【いつれい】します as a farewell word.

* * *

**③ 〜んです**

Just for the sake of completeness, this grammar attached at the end of the
sentences has several usages, in this sentence it adds the nuance of "the fact
is...". There are many explanations in this in this site, for example [this
one](https://japanese.stackexchange.com/a/44012/32952).

* * *

Therefore, according to the points ① , ② and ③, the original sentence can be
translated as

> Excuse me, the fact is that I have to leave.

as you pointed out. Breaking it down:

a) The "have to" part corresponds to the conjugation なければならない as explained at
①.

b) The "leave" part corresponds to the meaning of 失礼【しつれい】 as explained at ②.

c) The "Excuse me" part, though not appearing explicitly, is present in the
fact that "to excuse oneself" is an idiom that can convey "to leave" in a
polite way, both in English and in Japanese, as
[desseim](https://japanese.stackexchange.com/users/4533/desseim) pointed out
in a [comment](https://japanese.stackexchange.com/questions/70447/break-down-
the-phrase-shitsurei-shinakereba-naranaindesu#comment118778_70453).

d) The "the fact is" part corresponds to the final 〜んです (see ③).

As a conclusion, I agree with [user3856370's
answer](https://japanese.stackexchange.com/a/70451/32952) that

> Really you should think of なければならない (nakerebanaranai) as a unit in its own
> right.

It will make it easier to wrap your head around this grammar point.

Hope it helps!
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2019-08-30T15:29:47.053
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2019-09-01T14:33:38.547
2020-06-17T08:18:27.500
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answer