The purpose of a rhetorical question is to assert or deny a point, gain agreement from an audience or person in a subtle manner or to create effect. Rhetorical questions do not require an answer. An example of a rhetorical question is, "Can't you do anything right?"
One type of rhetorical question is a hypophora, which is used to control a discussion by asking and answering a question. This type of rhetorical question is often used in political debates to imply a position or to challenge an opponent with a negative assertion. An example of a hypophora is, " What has my opponent ever done for us? Nothing." The question is not posed to ask what good deeds the opponent has done, but it insinuates that the opponent has done nothing.
Rhetorical questions are also used in academic writing for multiple purposes. A rhetorical question presents the writer's main purpose and involves the reader. It also ensures that the reader is following the same line of thought as the writer.
When used sarcastically, negative rhetorical questions are used for a comedic effect, as are rhetorical affirmations. Rhetorical questions are also used to finalize a debate or show that a decision has been made. An example of this is, "Well, why not?"