Definition
Ethos is the rhetorical appeal grounded in the speaker's credibility. An audience is more willing to accept a claim from someone they perceive as knowledgeable, honest, and fair, so establishing ethos is often the first work a persuasive speech does, before the logical argument even begins.
Example
A debater opens by acknowledging a point their own side is weaker on, before making their case: "I'll be upfront that the cost estimates here are contested, and I'll explain why our side's case still holds even under the higher estimate." That kind of visible fairness builds credibility with the judge before the substantive argument starts.
Common mistakes
Ethos is not the same as simply asserting your own credentials or repeating that you are right. Real ethos is earned through demonstrated fairness, accurate representation of the other side's argument, and consistency, not through claiming authority. A debater who misrepresents an opponent's position or overstates evidence loses ethos immediately, even if the judge cannot articulate exactly why the speech feels less trustworthy afterward.