If I went to a doctor and said “Tell me how to diagnose a patient,” or I went to a judge and said “Tell me how to interpret the law,” or I went to an artist and said “Tell me how to be creative,” do you think they would be able give me a few sentences that completely answer my question and prepare me for professional work as a doctor, judge, or artist? If they had spent years as students learning their subject matter, and additional years teaching or writing a textbook on their specialty, they might be very good in their professions but I’d bet they’d all find it tough to answer such a question in any meaningful way.
The thesis statement should reflect the essay's purpose. Whether your purpose is to give readers some sort of information, to entertain readers, or to persuade readers to agree with you, the thesis statement should be written to fit the purpose. While all thesis statements should be debatable rather than a sweeping statement, the purpose for your writing will dictate the tone and word choice of the statement, which should then be carried out throughout the entire essay. While some instructors may say thesis statements should never be a question, if this is not a requirement from your instructor, sometimes the purpose calls for a question as a thesis statement, especially when trying to persuade your readers, but it is never necessary to announce when you are about to ask a question by “begging the question;” just ask it.