WhitmanO'Niell thinks "Can I ask you a question?" is a particular waste of linguistic breath.
I agree that on paper, this phrase does look absurd. In fact, in real life, it is strange to hear that and really think about it. That it is a waste of breath? Hmmm.
I'm a big fan of H. P. Grice and his maxims for successfuly negoiating discourse. English speakers typically avoid confrontation and over-directness by saying things like "It's cold in here" to prompt us to close the door. Following Grice's maxim of relevance, we link the two together and understand the implicit request.
"Can I ask you a question" gives the listener an opportunity to signal that he is not currently interested in talking. I consider it a polite introduction rather than a waste of breath. Now let me ask you a question...Oh, you are leaving. I guess you must be busy...
