+197.  Necessity of Persuasion.+—­It is frequently not enough to convince our hearer of the truth of a proposition.  Often a person believes a proposition, yet does not act.  If we wish action, persuasion must be added to argument.  If we always acted at the time we were convinced, and in accordance with our convictions, there would be no need of persuasion.  Strange as it seems, we often believe one thing and do just the opposite, or we are indifferent and do nothing at all.  We all know that disobedience to the laws of health brings its punishment—­yet how many of us act as if we did not believe it at all!  The indifferent pupil is positive that he will fail if he does not study.  He knows that he ought to apply himself diligently to his work.  There is no excuse for doing otherwise, yet he neglects to act and failure is the result.

+198.  Motive in Persuasion.+—­The motive of persuasion depends upon the nature of the question.  The motives that we have in mind may be selfish, or, on the other hand, they may be supremely unselfish.  We may urge others to act in order to bring about our own pleasure or profit; we may urge them to act for their own self-interest or for the interest of others.  We may appeal to private or public interest, to social or religious duty.  When a boy urges his father to buy him a bicycle, he has his own pleasure in mind.  When we urge people to take care of their health, we have their interest in view; and when we urge city improvements or reforms in politics, we are thinking of the welfare of people in general.

+199.  The Material of Persuasion.+—­Persuasion aims to produce action and may make use of any of the forms of discourse that will fit that purpose.  We may describe the beauty of the Adirondacks or narrate our experiences there in order to persuade a friend to accompany us on a camping trip.  We may explain the workings of a new invention in order to persuade a capitalist to invest money in its manufacture.  Or we may by argument demonstrate that there is a great opportunity for young men in New Orleans, hoping to persuade an acquaintance to move there.  When thus used, description, narration, exposition, and argument may become persuasion; but their effectiveness depends upon their appeal to some fundamental belief or feeling in the person addressed.  Our description and narration would not bring to the Adirondacks a man who cared nothing for scenery and who disliked camp life.  The explanation of our invention would not interest a capitalist unless he was seeking a profitable investment.  Our argument would not induce a man to move to New Orleans if his prejudice against the South was greater than his desire for profit and position.  In each case there has been an appeal to some belief or sentiment or desire of the person whom we seek to persuade.