This question already has an answer here:
In common American English usage, these two questions elicit the same response:
- Do you have a ticket?
- 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:
- You have a ticket, right?
- 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?