Does this double negative make a positive or negative sentence?

Question

Is that sentence saying that you will worry, or that you won't worry?

最初からユニコーンを見つけるくらい大変だって知っていれば心配しないじゃないですか

I'm pretty sure it's saying that you will worry, since she said that a unicorn is something you don't find right before this. But even without knowing that can Japanese people grammatically tell that it is "will worry", or is it implied based on context?

Or is it "won't worry" anyway? The double negative is confusing >.<

Answer 1

The sentence sounds like double negative, but it is not. To understand what じゃないですか mean, simply replace it with です. But じゃないですか more sounds like you are not sure about what you've said, and you want the listener to agree with you.

Here are some examples:

• 心配しないです: I won't worry.

• 心配しないじゃないですか: I won't worry.(and I want you to agree with it.)

• これはとても難しい問題です: This is a very difficult problem.

• これはとても難しい問題じゃないですか: This is a very difficult problem. (and I want you to agree with this)

• そうです。: It is.

• そうじゃないですか : It probably is.

Answer 2

The phrase じゃないですか in Japanese works in a similar way to the phrase n'est-ce pas in French. The speaker seeks some kind of approval from the listener. It is close to isn't or right at the end of a sentence in English.

心配しない : You do not worry

心配しないじゃないですか : You do not worry, right?

最初からユニコーンを見つけるくらい大変だって知っていれば心配しない : You do not worry although you knew from the start it may be as difficult as trying to find unicorns.

最初からユニコーンを見つけるくらい大変だって知っていれば心配しないじゃないですか : You do not worry although you knew from the start it may be as difficult as trying to find unicorns, right?

Answer 3

〜じゃないですか can often be translated along the lines of:

• Isn't (it the case that) ~ ?
• ~, right?

So in your case it would be something like "if ... one wouldn't worry, right?"

Related: Meaning of ありじゃないかなぁ.