Persuasion
When a speaker has conclusively proven what he has stated in his proposition, is his speech ended? In some cases, yes; in many cases, no. Mere proof appeals to the intellect only; it settles matters perhaps, but leaves the hearer cold and humanly inactive. He may feel like saying, "Well, even if what you say is true, what are you going to do about it?" Mathematical and scientific proofs exist for mere information, but most arguments delivered before audiences have a purpose.
They try to make people do something. A group of people should be aroused to some determination of purposeful thought if not to a registered act at the time. In days of great stress the appeal to action brought the immediate response in military enlistments; in enrollment for war work; in pledges of service; in signing membership blanks and subscription blanks; in spontaneous giving.