Grammarians, is "isn't" by definition rhetorical?

"is it not the third door on the left?" Taken literally, the speaker presumes that the door on the left is not the correct door, yet anyway asks the question. In common use, we know that the question is earnest, so it is not intended to be rhetorical.

So it's either rhetorical or superfluous.

(xpost)

It is by definition rhetorical. The question "Is" is just that. To add the word "not", as in "is not", makes it rhetorical.

This seems to make even less sense than I originally thought! He is saying "Is" is a question, but "Is not" is by definition rhetorical. Apparently, any question that adds "not" is rhetorical, by this rule. If so, this must be some very old rule of grammar that is no longer accurate.

And yet... that's not really what you're doing. You're asking for confirmation. It's a question that begs an answer, no matter how you slice it.

No, you are asking someone to confirm if you BELIEVE to be false. All you are really doing is combining two thoughts into one question: "I think this is not true" and "Am I right in this belief?"

In short, "Is it not?" is the same as "Is it false?"

"Is it" implies "Is it true?" and "Is it not" implies "Is it false?"

"Is it false?" is not a rhetorical question.

Right?

Only for the purposes of tone. It means the same thing.

But that's the practical use, not the definition. As I said upthread, we believe the question to be earnest, so it's not actually rhetorical. But the wording itself is rhetorical.. again I say, because you already believe/presume/know/guess the answer.

So, is the question "Is it false?" a rhetorical question? Because "is it not true" is the same thing as "is it false?"

As I said earlier, the word "not" implies that the speaker knows (or presumes to know) to answer. The "not true" = "false" thing needs clarification .. "Is it false/true?" either means that there is an understanding about what "it" is, or else the speaker is speaking nonsense. So clarify that for me.. Is this what you mean?:

"I think Madame is French for shoe. Isn't that true?"
.. So why are you doubting yourself? Why not ask "Is that true?" Because you're already presuming that your previous statement is untrue, and you're looking for confirmation.

I mean, just because you're implying an assertion in the course of the question (the assertion being something along the lines of "I thought"), that doesn't nullify the genuine interrogative nature of the question itself! There seems to be something of a spectrum, between pure-rhetorical ("are we not men") to a mostly-rhetorical suggestion ("couldn't we do it that way?") to the kind of stuff we're talking about ("didn't you already say that?") to some kind of example of ... I dunno, I feel like there must be some kind of question that you couldn't ask except in the negative, even though I can't think of any good examples. (Something that functions, grammatically, a bit like "Is this non-allergenic," where what you're asking about is the "not" exception itself.)