The ancient Greek philosopher Aristotle, who lived from 384 to 322 B.C., defines rhetoric as “the faculty of observing, in any given case, the available means of persuasion.” In the classical world, rhetoric was a formal branch of learning that dealt with the techniques and devices used to convince or persuade an audience. The ancient philosophers Aristotle, Cicero and Quintilian, in particular, developed theories concerning speech-making and persuasive writing. Aristotle’s Rhetoric is one of the most influential treatises on the subject, and Aristotle and rhetoric have been inexorably linked for more than 2,000 years.
A persuasive speech consists of three things: the speech itself, the subject of the speech and the listener to whom the speech is addressed. For Aristotle, effective rhetoric takes the speaker, the speech and the hearer equally into account. The three means of persuasion available to the speech-maker, according to Aristotle and rhetoric, are ethos, or "character;" logos, or "argument;" and pathos, or "suffering." Ethos is an appeal that is made based on the speaker's character; logos is an appeal that is based on logic or reason; and pathos is an appeal that is based on the hearer's emotions.
For a speaker to achieve Aristotelian ethos, he or she must appear to be credible. If the speaker is credible, he or she will have a better chance of persuading an audience that his or her argument is valid. Aristotle suggests that credibility can be established by displaying practical intelligence, a virtuous character and good will.
To persuade with logic, according to Aristotle and rhetoric, the argument must demonstrate, or at least seem to demonstrate, that something is the case. For Aristotle, there are two kinds of logical arguments: inductions and deductions, popularly referred to as inductive or deductive reasoning. An inductive argument proceeds from the particulars to the universal. A deductive argument in which certain things have been supposed proceeds from one particular case to a similar particular case, provided that both particulars are closely related and logically connected.
From the viewpoint of Aristotle and rhetoric, the success of persuasive efforts depends to a large extent on pathos, or the emotional disposition of the listening audience. Emotions have the capacity to alter a hearer’s judgments, no matter the character of the speaker or the logic of his or her argument. In Rhetoric, Aristotle suggests that it is necessary to arouse in the listener an emotion that particularly favors the argument being presented. To achieve this, Aristotle proposes that it is necessary to possess the knowledge and definition of every significant emotion and to be aware of the likely existing emotions already present in the listeners.
For example, by definition, an Aristotelian rhetorician would be able to deduce the circumstances in which his or her audience would most likely become angered by an opposing viewpoint. Simply by knowing whom the listener is angry with, and for what reason, the speaker can emphasize aspects of his or her argument that will arouse further anger and will naturally sway the listener to the speaker’s side. Although to some people this might smack of manipulation, the arousal of emotions is an accepted — and necessary — rhetorical device.