Ethos is a means of convincing the audience of the credibility of the speaker. It is most commonly used in persuasive writing, such as Jonathan Swift's "A Modest Proposal" or Abraham Lincoln's "Gettysburg Address."
Aristotle named ethos as one of the three main methods of persuasion. He theorized that people are most likely to believe someone with expertise, or someone who is worthy of respect. Jonathan Swift uses this device in his satire, "A Modest Proposal," as he presents an argument for eating babies in order to help with poverty. He cites various experts, including a "knowing American" and a French physician, to validate his plan.
Ethos is used in political speeches such as the Gettysburg Address and many other presidential addresses throughout history. Powerful political figures can establish their own credibility through the use of sincere presentation, articulation and careful language. The willingness to acknowledge both sides of the argument also lends credibility to the speaker and is a form of ethos. Often, this type of rhetoric is used in combination with pathos and logos.
In modern times, ethos is often used in persuasive advertising. "Doctors agree you should accept this treatment" or "The effectiveness of this product was verified by scientists" are examples of ethos in business.