In his treatise on rhetoric, written in the fourth century B.C.E., Aristotle explained that persuasion could be brought about by the speaker’s use of three types of persuasive appeals or proofs—termed logos, pathos, and ethos. The first appeal uses reasoned arguments, the second targets listeners’ emotions, and the third enlists speaker credibility to further the persuasive aims (see Table 24.1). According to Aristotle, and generations who followed him to the present day, you can build an effective persuasive speech with any one or a combination of these appeals or proofs, but the most effective persuasive speeches generally make use of all three.

Logos: Appeals to Reason

Many persuasive speeches focus on issues that require considerable thought. Aristotle used the term logos to refer to persuasive appeals directed at the audience’s rational thinking, or reasoning, on a topic. Should the United States enact stricter immigration laws? Does the U.S. government endanger our privacy with its surveillance programs? When you ask audience members to make an important decision or reach a conclusion regarding a complicated issue, they will look to you to provide solid reasons and evidence—to offer appeals to logos. Appeals based on logical reasoning use arguments as a framework for the appeal. An argument is a stated position, with support, for or against an idea or issue (see Chapter 25, on “Developing Arguments for the Persuasive Speech”).

Bear in mind that reason—logos—is never divorced from emotion. Emotion always informs our judgments, and appeals to logos contain elements of pathos, just as appeals to pathos contain elements of logos.⁷

Appeals to Logos Using the Syllogism

Consider that you are addressing your classmates about starting a local chapter of the Campus Kitchens Project, an organization that enlists student volunteers to recover food from school cafeterias and coordinate its distribution in their communities. To gain their support, you might begin by posing a general statement about hunger with which the audience will likely agree on principle, such as “No one here wants children to go hungry.” Next, you claim that “Two out of five children in our community depend on food banks” and then suggest that “The Campus Kitchens Project will help to alleviate hunger in our community.”

A rational argument of this sort is actually a syllogism, a set of propositions, or statements to be proved, that lead to a conclusion. The first proposition states a general case (also called a major premise). The second proposition states a specific case (minor premise) (e.g., an example of the general case). The conclusion is a necessary consequence of the general and specific cases. The classic example is this:

Syllogisms are a classic form of deductive reasoning, or reasoning from a general condition to a specific instance to a conclusion. Reversing direction, inductive reasoning moves from specific cases to a general conclusion about them. Note that a syllogism can be valid or invalid and true or false. Syllogisms are valid (but not necessarily true) if and only if the conclusion necessarily follows the premises.

A well-developed syllogism will lead listeners to a clearer understanding of an issue; one that is poorly thought through will lead them to unfounded conclusions. Here is an example of a contemporary syllogism that is effectively developed (i.e., is both valid and true):

And here is one that is poorly developed (i.e., valid but untrue):

The preceding example is valid because the conclusion of necessity follows from the premises. However, the conclusion is false because the general case is unfounded—in this instance, there is a hasty generalization, or an assertion that a particular piece of evidence (an isolated case) is true for all individuals or conditions concerned. (See the section on fallacies in reasoning in Chapter 25.)

Aristotle pointed to another form of syllogism, one that we use far more frequently, both in everyday communication and in speeches. An informal syllogism (also called an enthymeme) states either a general case or a specific case but not both. The case not stated is assumed to be understood because speaker and audience share knowledge of it, either through common sense, shared values, or universal principles.

The syllogism about regular aerobic exercise above can be restated as an informal syllogism as follows:

Regular aerobic exercise improves heart health . . . so swimming regularly should improve your cardiovascular health.

Note that the statement includes the general case and the conclusion seen in the formal syllogism above, but omits mention of a specific case:

According to Aristotle, informal syllogisms formed the heart of persuasive speeches, because audiences are most persuaded by having something we already know demonstrated to us.⁸ The missing premise represents that knowledge. However, as persuasive appeals, informal syllogisms work only when the audience understands and agrees upon the premise left unsaid. Ethically, whether stated or merely implied, the premises that form any logical appeals you offer to the audience must be both valid and true.

Chapter 25 expands on the uses of logical appeals in a persuasive speech and addresses lines of reasoning.

Pathos: Appeals to Emotion

A second powerful means of persuasion first described by classical theorists is appealing to listeners’ emotions. The term Aristotle used for this is pathos. It requires “creating a certain disposition in the audience.”⁹ Feelings such as pride, love, compassion, anger, shame, and fear underlie many of our actions and motivate us to think and feel as we do. Appealing to these emotions—that is, using pathos in a speech—helps establish a personal connection with the audience and makes issues more relatable and arguments more compelling.

You can evoke emotion in a speech by using vivid imagery and emotionally charged words, telling compelling stories (especially ones that touch upon shared values such as patriotism, selflessness, faith, and hope), and using repetition and parallelism to create drama and rhythm (see Chapter 16 for guidelines on using these and other techniques of language in a speech). Visual images woven into a speech can also be a powerful means of appealing to the audience’s emotion.

Consider the following example from a speech by Winston Churchill, delivered to the British House of Commons, in June of 1940 following the mass retreat by British and Allied forces from northern France. Here Churchill seeks to fortify the nation for the battles ahead with vivid imagery and emotionally charged words (“odious apparatus of Nazi rule”) and the cadenced repetition of similar phrases (“We shall . . . ”):

Even though large tracts of Europe and many old and famous states have fallen or may fall into the grip of the Gestapo and all the odious apparatus of Nazi rule, we shall not flag or fail. We shall go on to the end, we shall fight in France, we shall fight on the seas and oceans, we shall fight with growing confidence and growing strength in the air, we shall defend our island, whatever the cost may be, we shall fight on the beaches, we shall fight on the landing grounds, we shall fight in the fields and in the streets, we shall fight in the hills; we shall never surrender . . . ¹⁰

Although emotion is a powerful means of moving an audience, relying solely on naked emotion to persuade will fail most of the time. What actually persuades is the interplay between emotion and logic. As Aristotle stressed, pathos functions as a means to persuasion not by any persuasive power inherent in emotions per se but by the interplay of emotions—or desire—and sound reasoning. Emotion gets the audience’s attention and stimulates a desire to act on the emotion; reason is then presented as justification for the action. For example, a popular television advertisement depicts a grandfatherly man in a series of activities with family members. An announcer makes the logical appeal that people with high blood pressure should maintain their prescribed regimen of medication; this is followed by the emotional appeal “If not for yourself, do it for them.”

Appealing to an audience’s emotions on the basis of sound reasoning ensures that your speech is ethical. However, as seen in the accompanying Ethically Speaking box, there are a host of ways in which emotions can be used unethically.

Ethos: Appeals Based on the Speaker’s Character

Imagine how you would respond if the president of your country presented him-or herself as seeming not to care about the country’s citizens, as untrustworthy and even unkempt? No matter how well reasoned a message is or which strong emotions its words target, if audience members have little or no regard for the speaker they will not respond positively to his or her persuasive appeals. Aristotle recognized that the nature of the speaker’s character and personality also plays an important role in how well the audience listens to and accepts the message. He referred to this effect of the speaker as ethos, or moral character.

What does a persuasive appeal based on ethos include? The first element is competence, or the speaker’s mastery of the subject matter. Skillfully preparing the speech at all stages, from research to delivery, as well as emphasizing your own expertise, evokes this quality.

The second element of an ethos-based appeal is moral character, as reflected in a straightforward and honest presentation of the message. The speaker’s own ethical standards are central to this element. Current research suggests, for example, that a brief disclosure of personal moral standards relevant to the speech or the occasion made in the introduction of a speech will boost audience regard for the speaker.¹¹

The final element is goodwill toward the audience. A strong ethos-based appeal demonstrates an interest in and a concern for the welfare of your audience. Speakers who understand the concerns of their listeners and who address their needs and expectations relative to the speech exhibit this aspect of the ethos-based appeal.