Rhetorical question

Rhetorical questions are "Questions that do not require an answer, but are only put in the form of a question in order to produce a greater effect" (Bradley's Aids to Latin Prose, cited OED). Rhetorical, indeed, is the adjective from rhetoric, the art of making speeches, and speeches are where you may expect to find rhetorical speeches most often, if not always wisely. A politician who says, in a speech, "Are we to approve of this monstrous proposal?" is not expecting to hear a response. It is to be expected that the mood of the audience will follow the implication of the speech - that this 'monstrous' idea cannot possibly meet with approval.

There is always the danger in the speech that the audience - or one heckler in it - will react in a way contrary to the speaker's intention. Whether to ask the question is to an extent a amtter of the speaker's judgement of the mood in the audience. If the audience is hostile, the speaker is wise not to ask the rhetorical question, but to form it as a statement.

What is true of a speech is even truer of the written word. You are advised not to use rhetorical questions in academic writing. They are a weak from of argument; and you cannot assume that all raders of your work will agree with you. Consider the response if a reader thinks the 'wrong' answer to the question. Indeed, questions in written English are usually a mistake.