In rhetoric, ethos is one of the three artistic proofs (pistis (πίστις)) or modes of persuasion (other principles being logos and pathos ) discussed by Aristotle in 'Rhetoric' as a component of argument. Speakers must establish ethos from the start. This can involve "moral competence" only; Aristotle however broadens the concept to include expertise and knowledge. Ethos is limited, in his view, by what the speaker says. Others however contend that a speaker's ethos extends to and is shaped by the overall moral character and history of the speaker—that is, what people think of his or her character before the speech is even begun (cf Isocrates).
According to Nedra Reynolds, Professor of Writing & Rhetoric, "ethos, like postmodern subjectivity, shifts and changes over time, across texts, and around competing spaces"(Reynolds, 336). However, Reynolds additionally discusses how one might clarify the meaning of ethos within rhetoric as expressing inherently communal roots. This stands in direct opposition to what she describes as the claim "that ethos can be faked or 'manipulated'" because individuals would be formed by the values of their culture and not the other way around (Reynolds, 336). While its meaning and application within literature might differ over time, this classical interpretation persists.
There are three categories of ethos.
- phronesis - practical skills & wisdom
- arete - virtue, goodness
- eunoia - goodwill towards the audience
In a sense, ethos does not belong to the speaker but to the audience. Thus, it is the audience that determines whether a speaker is a high- or a low-ethos speaker. Violations of ethos include:
- The speaker has a direct interest in the outcome of the debate (e.g. a person pleading innocence of a crime);
- The speaker has a vested interest or ulterior motive in the outcome of the debate;
- The speaker has no expertise (e.g. a lawyer giving a speech on space flight is less convincing than an astronaut giving the same speech).
Completely dismissing an argument based on any of the above violations of ethos is a formal fallacy, rendering the dismissal of the argument invalid.
The term "source credibility" has been used as the construct examined in the social sciences. Though recent work has found support for the existence of the three dimensions identified above, work from the 1950s through the 1980s consistently revealed two dimensions (competence and character) with other dimensions such as dynamism found only when broad approaches equating credibility with "person perception" were taken.