重要な科目じゃないの

[eeky]

Hi,

「これまでの科目は全部続くんだ。そうじゃなきや、僕 は『闇の魔術に対する防衛術』を捨てるよ」
「だってとっても重要な科目じゃないの！」ハーマイオニーが衝撃を受けたような声を出した。

I completely misunderstood this when I read it. I thought Hermione says "That's because it's not an important subject at all".

Apparently, though, she is saying that it *is* an important subject. How on earth do we figure that?

 

[Toritoribe]

I can only say, as usual, from the context.
Indeed "noun/na-adjective + じゃない" is most ambiguous, but the context including, for instance, だって is used to deny what the addressee said, と（っ）ても is not used with the negative of an adjective (全然/まったく is used for "not~at all"), the sentence final particle （わ）よ is used to express the speaker's strong recommendation/opinion against the addresse when with じゃない(の is used to express the things about the speaker themselves), etc., etc... shows that it's not simple negative.
In conclusion, if Hermione said "That's because it's not an important subject at all", it would be something like そうね、全然重要な科目じゃないしね. She wouldn't say this words with 衝撃を受けたような声 in this case, though. So, this tone of voice is also another key you should be aware of.

 

[eeky]

Obviously not the case here, but だって at the start of a sentence does often means "because", right?

 

[eeky]

Sorry, another question, maybe repetitive. I know I have had difficulties before with じゃない etc.

I can get my head around じゃないか suggesting an affirmative, because it is a bit like English tag questions "isn't it?", etc.

However, I have the greatest difficulty in comprehending how a non-questioning じゃない can be an affirmative and not a negative, no matter how much the context suggests that it ought to be. It seems to me that we have to arbitrarily understand the exact opposite of what the words actually say. How can I understand this?

 

[Toritoribe]

Yes, だって means "because", but this "because" connotes "I deny what you said, because~". especially when the speaker heard something from the one they are talking to and said だって at the top of the answer. It's close to でも, as in the dictionary I linked below.

だって
［接］《助詞「だって」の接続詞化したもの》相手に反論したり、相手の反対を予想しつつ理由や言い訳を述べる場合に用いる。そうはいっても。でも。なぜかというと。「とても間に合いません。―人手が足りません」

だって［接］の意味 - 国語辞書 - goo辞書

You can think じゃないの is a female or soft version of じゃないか.
じゃないか doesn't always have questioning tone. It can be strong affirmative, similar to ～だろう？ vs. ～だろう！. Probably I wrote this somewhere in this forum, じゃない is treated almost as a sentence final particle. It can be attached directly to a noun, verb or adjective. In fact, Hermione can say だってとっても重要な科目よ！ in almost the same meaning/nuance.

 

[eeky]

Could Hermione have said 「だってとっても重要な科目じゃない！」 (i.e. without の)?

Also, when you interpret じゃない as a non-questioning affirmative, do you feel that it is an idiomatic pattern that has lost all connection with the actual words じゃ（では）ない? Or, if you feel a connection, how do you reconcile the fact the meaning is apparently reversed?

 

[Toritoribe]

Yes. The meaning is the same.

It's the former, since it can't be replaced with ではない or ではありません. 重要な科目ではない/ありません can be "It is an important subject, isn't it/don't you think so?" with a rising intonation, but can never be a strong affirmative even with any intonation/tone. Further, this じゃない never conjugates. For instance, じゃなかった is not used as the past form, instead, ～たじゃない (e.g. 重要な科目だったじゃない) is used.

 

[eeky]

Right, that's useful for my understanding.

Thank you for your continued patience in explaining these patterns.