15803
> …あの犯行予告、俺がやったんじゃないんだけどな。  
>  I wasn't the one who issued that threat, but no matter. (English subs)

What's the difference between んじゃない and んだ as they're used here?

One would ordinarily expect んじゃない to be the negative of んだ. If that were true,
then the above sentence would be invoking the _explanation modality_ twice.
But it seems that instead んじゃない has an entirely unrelated meaning.

I'm looking for their definitions in relation to each other (to the extent
that they can be related). And how does this difference enable them to be used
together as in the above sentence?
CC BY-SA 4.0
2014-05-07T22:39:16.420
15800
2022-07-11T21:28:46.293
2022-07-11T21:28:46.293
30454
4481
question
word-choice words usage nuances modality
What is the difference between んじゃない and んだ?
のだ at the end of a sentence is usually what you called “explanation modality”.
(whether it's explanation or not.)

のではない is often used to make a **partial negative** statement. This may be a
over-simplification, but I can't think of a good explanation of its function.
The の works like a nominalizer or a quote mark.

If you say 俺はやらなかった, it means I didn't do it.  
If you say 俺がやったんじゃない, it means the thing happened, but it's not done by me.

It may be worth mentioning that, **both のではない and のだ** can sometimes be used
to **correct an existing proposition.** e.g.

> **俺が** やった **んじゃない** 。 **あいつ** がやった **んだ** 。

Sometimes you want to empathize “you are thinking wrong”, so you use both
のではない (to correct the proposition before it) and のだ (to correct the listener's
thought).

> **俺が** やった **んじゃない** **んだ**

Although I don't think the last んだ means the same as the んだけどな in your
question, it's still a modality のだ, because without んだ it's still a valid
sentence.

* * *

It seems that you can read Japanese tutorials, so I added some Japanese
resources.

庭{には}三郎{さぶろう} mentioned のではない in his book [日本語文法概説{にほんごぶんぽうがいせつ} 43.1.3
部分否定](http://www.geocities.jp/niwasaburoo/43hitei.html#43.1):

> 「～のではない／わけではない」は、「部分否定」とは違いますが、全面的な否定ではない、という意味では近い用法です。
```

>     １　資料を全部見たの／わけ　ではない。
>     ２　この事典を調べたのではない。
>         cf.　この事典は調べなかった。
>  
```

>
> 例１では、部分否定になっていますが、例２では他の何かと対比しているように感じます。
>
> 複文で理由などを表す節があると、「～のではない」の否定はその節を焦点 とします。
```

>     金が欲しいから行ったのではない。
>  
```

>
> 「行った」のですが、その理由は「金が欲しいから」ではない、ということになります。

He says のではない or わけではない is not the same as **partial negation** but similar to
it. It may sound like the part being negated **contrasts** with something
else. It can also be used to negate reason or purpose clauses.

[中上級を教える人のための日本語文法ハンドブック](http://books.google.com/books?id=0eprLex8sr0C&lpg=PA303&ots=4JMrwWxAty&pg=PA301#v=onepage&q&f=false)
has a more detailed explanation at p.301

> なお、「のではない」のあとには否定した要素に対応する「正解」[...]が続くのが普通です。

It says **のではない is usually followed by a correction**.

工藤{くどう}真由美{まゆみ} 's
[～のではないの意味と機能](http://kamome.lib.ynu.ac.jp/dspace/bitstream/10131/2850/1/KJ00004463679.pdf)
is a more exhaustive study. After reading it, you will know why I say “partial
negation” is over-simplification. I quickly went through it. Its explanation
might be different from mine (e.g. whether のではない is the negative form of the
modality のだ), but it definitely contains valuable information.
CC BY-SA 3.0
2014-05-08T07:08:19.047
15803
2014-05-09T03:14:01.717
2014-05-09T03:14:01.717
4833
4833
15800
answer
**_Comment_**

In my experience, once you get to this level it is sometimes easier to
understand these intuitively because you can understand a lot from the context
and the way the person says the phrase.

Breaking them down can get quite complicated because grammatically there is a
lot going on: I have given two ways to analyse 〜たんじゃない but I think they both
have merit.

**_Analysis_**

My take on

> 「…あの犯行予告、俺がやったんじゃないんだけどな。」  
>  "I wasn't the one who issued that threat, but no matter."

is:

> 「・・・」

ー＞ Spoken Japanese, might even contain colloquialisms that seem contradictory
just as they do in English ("I haven't eaten none of them.")

> "but no matter..."

ー＞ Spoken English also leaves some things unsaid and that seems to be case
here. I have not seen the film so I don't know what happens next or before but
I guess you will understand from the context.

> あの犯行予告、

ー＞ The topic of conversation. あの indicates both parties know what they are
talking about.

> 俺がやった

ー＞ I did it

> 俺がやった **ん**

ー＞ Something that I did. ん＝の which is a nominaliser like こと. Generally used
for things closer to speaker.

> じゃない

ー＞ Negates what comes before it ie: 俺がやったんじゃない= Not something that I did.

> 〜たんじゃない

ー＞ result of putting (やっ)た＋ん＋じゃない together:

In Japanese: 〜たんじゃない＝〜のではない＝わけではない＝〜というわけではない  
In English: ＝"it is not that ~ but rather that," ; only the ~part of the
statement is negated

> んだ

ー＞ Means same as のです, the sentence ending used for explaining something, and
also often to show emotional importance of what comes before it. (So for
example, you would tell a doctor: 頭が痛いんです because you want to communicate that
it matters.)

> けど

ー＞ Equivalent to "but" (like が) and in spoken Japanese the following phrase is
often left unsaid because it is obvious from context. It is performing a
similar function to the "but, no matter..." in the English translation. (Or to
take another example; 「先生、頭が痛いんですが・・」＝ "Doctor, my head really hurts [, please
can you give me something for it?]")

> な

ー＞ Means same as ね、〜 "know what I mean?". な is a harsher more masculine
version. It is often used to emphasise the importance of what comes before it
and to seek empathy from the listener.

If you put all these together you end up with something close to the
translation.

_References_

I expect you already have references for all the basic components but possibly
not 〜たんじゃない because it colloquial? Since writing this I noticed it is covered
in the detail of item 3 in 新完全マスターN３、文法, p38.

Understanding this kind of colloquialism is tested at JLPT N1 (聴解). If you
want to wok on this you could try one the text books for that exam.
CC BY-SA 3.0
2014-05-09T00:26:00.300
15823
2014-05-12T23:14:39.017
2014-05-12T23:14:39.017
1556
15800
answer
んだ According to my lecturer's explanation, many sources refer to んだ as
explanation modality, and it is true many times, you can come across んだ when
the sppeaker is giving explanation. However according to his explanation the
real function of んだ is to soften up the question and statement.

I myself also try to deepen my skills regarding this topic, I just wanted to
add my experience about it.
CC BY-SA 3.0
2015-05-31T04:32:54.073
24662
2015-05-31T04:32:54.073
5392
15800
answer