“Rhetorical Question: A question that expects no answer. The answer may be self-evident (If she doesn’t like me why should I care what she thinks?) or immediately provided by the questioner (What should be done? Well, first we should…). The question is often asked for dramatic effect. Rhetorical questions are sometimes announced with such a phrase as I ask you (when nothing is in fact being asked): ‘Garn! I ask you, what kind of a word is that? / It’s Ow and Garn that keep her in her place / Not her wretched clothes and dirty face’ (Alan Jay Lerner, My Fair Lady, 1956).”
Excerpted from: McArthur, Tom. The Oxford Concise Companion to the English Language. New York: Oxford University Press, 2005.