The art of putting together arguments and expressing them effectively is called rhetoric. This involves two separate steps: determining what to say and determining how to say it. When modern people talk about rhetoric, they usually are only talking about the second part, the form of the argument. Classically, though, the first part -- the content of the argument -- was just as important to this art. Invention is the first step in assembling the content of your rhetorical argument.
The first step to constructing a rhetorical argument is invention. This is the process of figuring out what you want to say. Aristotle, a great classical authority on rhetoric, divided invention into specific "topics," or ways to find ideas to help build your argument. The topics of invention include definition ("I am human, therefore I eat"); comparison ("I like food, and you're a lot like me, so you probably like food too"); cause and effect relationship ("If you do not eat, you will die"); and testimony ("Most doctors agree that not eating results in death").
Stasis theory is a useful way to approach rhetorical invention when there is a disagreement over the issue being discussed. "Stasis" means "strife" in Greek, and here it refers to the thing people are disagreeing about. Before you can compose your rhetorical argument to make your point, you must understand exactly what the disagreement is, so you know what you're trying to prove. The process of stasis involves asking questions to determine what people believe and where they disagree.
There are four types of stasis questions used in rhetorical invention: conjectural, definitional, qualitative and procedural. A conjectural question addresses the facts or truth of the situation ("Did you take the cookies?"); a definitional question addresses the nature of the situation ("What did you take?"); a qualitative question addresses the importance or morality of the situation ("Did you have permission to take the cookies?"); a procedural question addresses what should happen next ("Should you be grounded because you took the cookies?").
When the process of invention is complete and you have found all your points, there are four more steps to the art of making a rhetorical argument. After invention comes arrangement, in which you line up your points in a logical order. Then comes style, in which you plan the figures of speech and rhythms you will use to make your argument as effectively as possible. The next step is memory, in which you memorize not only your speech as you have written it but also any other points you may wish to add and stylistic elements you may wish to improvise. The final step in rhetoric is delivery, in which you plan the performance of your speech. Delivery includes things like when to talk faster or louder, when to pause for effect, and what to do with your hands.