[1] In many cases it may be intended to start a discourse, as a means of displaying or emphasizing the speaker's or author's opinion on a topic.
(Monty Python's Life of Brian) the question functions as a negative assertion.
(Julius Caesar, Act 3, scene 2, 257) Negative assertions may function as positives in sarcastic contexts.
For example, in response to being informed that smoking can increase the possibility of developing lung cancer, someone could respond with the question, "Who knew?"
The question functions as an assertion that the truth of the statement should have been utterly obvious.
is repeatedly answered with other questions: "How do you catch a cloud and pin it down?
This can moreover be a manifestation of an epiphrase, as Daisy had personally asserted her own opinion on her question.