There are also rhetorical questions. These don't need an answer, as they are designed to answer themselves.
Eg. "What responsible person would drive a car when drunk?" = silly question: no responsible person would drive when drunk. So the actual meaning is, only irresponsible people drive drunk.
The idea of a rhetorical question is to play on the emotions and senses of the listener, and not the logic.
What kind of an answer is this anyway?! ;)