Why do positive and negative variants of the same question elicit the same answer? [duplicate]

In common American English usage, these two questions elicit the same response:

1. Do you have a ticket?
2. Don't you have a ticket?

These are the usual answers (I was going to say "possible answers" but I can think of a whole host of situations where one could get other answers, e.g. wake up someone in the middle of the night and ask it, the answer might easily be "I don't know" or "maybe" or "hey, just let me sleep!"... but that's neither here nor there... :-)

• Positive: "Yes" or "Yes, I do".
• Negative "No" or "No, I do not".

But consider this: the questions are logically equivalent to:

1. You have a ticket, right?
2. You do not have a ticket, right?

Here I am not so sure that a "Yes, that's right" response means the same thing to each question. (One could still, however, use "Yes, I do" as @F'x answer in How to answer a negative question without ambiguity? illustrates, to remain valid and unambiguous.)

(As a side note, it is interesting to compare the same question in Chinese, where one literally asks "Do you have/not have a ticket?" and the common answers are:

• "[I] have"
• "[I] not have"

...which also removes the ambiguity... while at the same time straying from my original question:-)

So why can I rewrite the questions so that they are essentially equivalent yet expect different answers?

As John Lawler says, below, “There is no asserted logical proposition in a question.” There is no ‘logical’ difference between Do you have a ticket? and Don’t you have a ticket? to be taken into consideration: both amount to the same thing, Do you … ?. The same is true of a third variant, You do have a ticket, don’t you?

The difference between them lies in the context which prompts the question and the answer which is expected. The answer to any of them, yes or no, depends on my possession of a ticket, not your expectation.

ME: Can I join you guys for the show?
YOU: Do you have a ticket? … a neutral question: you have no idea whether I have a ticket.
ME: Oh, yeah. … OR
ME: No, but I just checked at the box office and there are lots of tickets left.

ME: It looks like I’m not going to be able to join you guys for the show after all.
YOU: Don’t you have a ticket? … the context prompts you to expect the answer ‘No’
ME: Oh, yeah, but I just got called in to work. … OR
ME: No, and I just checked the box office and they’re sold out.

ME: You guys go ahead, I’ll meet you there.
YOU: You do have a ticket, don’t you? … You told me the show would sell out, and knowing my dilatory habits you suspect I’m going to try to buy one at the last minute.
ME: Oh, yeah, but I’ve got some errands to run first. … OR
ME: No, but I’m meeting up with a guy who’s selling me his one.

Your ‘Right?’ questions, on the other hand, literally ask a different question: Not Do you have a ticket? but Am I right in my assumption that you do/don’t have a ticket? And if I am literal-minded I will answer that question:

YOU: You have a ticket, right?
ME: Yeah, you’re right. … OR
YOU: No, you’re wrong.

YOU: You don’t have a ticket, right?
ME: Yeah, you’re right. … OR
ME: No, you’re wrong.

More likely, however, I will provide the relevant facts which justify the answer and eliminate ambiguity:

YOU: You have a ticket, right?
ME: Yeah, I have a ticket. … OR
ME: No, I have a ticket.

YOU: You don’t have a ticket, right?
ME: Yeah, I don’t have a ticket. … OR
ME: No, I have a ticket.