A rhetorical appeal is the formal way of talking about how you use different methods to persuade someone. Let's imagine you're ten years old and you really want a new video game for your birthday. You approach three people: your dad, your mom, and your grandma.
For your dad, you point out that you have been a very good student this year, you have done all of your chores, and you are a very responsible youngster who deserves to have a new video game.
For your mom, you argue that video games improve hand-eye coordination and studies have shown that video games improve problem-solving ability and critical thinking.
For your grandmother, you point out that you are very cute and her favorite grandchild, and that you love her very much.
You just used three methods of persuasion: appealing to your own character, appealing to logic, and appealing to emotions. In formal rhetoric, this is called ethos, logos, and pathos. No one type is better than the other; usually the most effective arguments - the ones most likely to persuade someone of something - use all three. However, some may be more appropriate for one audience over another. A team of scientists is more likely to be persuaded by studies, research, and logical thinking, so it may be better to use logos. A prestigious university may be more likely to be persuaded by your character and credibility as a person, meaning it may be better to use ethos. And, like your grandmother, your family may be more likely to be swayed by emotions, using pathos.
Advertisements, academic papers, and even tweets may use these three appeals. A car advertisement may point out the safety record of its vehicle (logos), mention how long its brand has been around and its reputation (ethos), as well as have humor to help persuade you to buy the car (pathos). All of them work together to persuade you to do something, whether that's to buy something, do something, or feel something.
Rhetorical appeals are methods of persuading someone in an argument, as defined by Aristotle. Artistotle identified three methods:
Ethos: The credibility or trustworthiness of the source. Example of ethos: "Noted Harvard professor John Smith says..."
Logos: The use of reasoning and logic to convey a particular message. Example of logos: "According to a study performed by John Smith..."
Pathos: The use of emotions to provoke a response. Example of pathos: "Poor John Smith, who never got to see his puppy again...."
We often think of "pathos" to mean "pathetic," but pathos does not have to mean just negative emotions like sadness or pity! Humor is another emotion that can be effective when persuading an audience of something. Positive emotions - inspirational, joy, or humor - are equally as valid when using pathos.
Understanding rhetorical appeals can help writers to build a stronger argument and be more persuasive in their writing. By identifying rhetorical appeals, writers can begin to understand when it is more appropriate to use one method over another.
For instance, we talk about "knowing your audience". But why is that important? Because knowing your audience allows you to know what will be the most effective method of persuasion for them.
Most effective methods of argument use all three rhetorical appeals to support their point.
Knowing what rhetorical appeals are and how they work also allows you to spot when someone is trying to persuade you of something.
We tend to think of rhetorical appeals in a very formal setting, such as an essay, but we see rhetorical appeals everywhere.
You may remember this commercial, which uses pathos to persuade the viewer to donate to the SPCA:
You may be wondering whether or not to try a new diet when your friend says he tried it and it worked. You trust your friend, so you decide to try the diet based on ethos.
Or you want to buy a new car, so you do research to find which has the best gas mileage based on studies. You just used logos to make a decision.