These are two of Aristotle's three modes of persuasion. Ethos persuades through the character and credibility of the speaker — why you should trust them. Logos persuades through reasoning and evidence — why the argument holds. The third is pathos, which persuades through emotion. Most effective arguments use all three.
The core difference
- ethos — credibility. "As a surgeon of thirty years…" The audience is being given a reason to trust the speaker.
- logos — reasoning. Evidence, data, logical structure. The argument stands on its own merits.
- pathos — emotion, included here because the pair only makes sense as part of the trio.
The everyday meaning of ethos
Outside rhetoric, ethos has taken on a second life meaning the characteristic spirit of a group — "the ethos of the school". That sense is entirely standard and is far more common in ordinary use than the rhetorical one, which is worth knowing before assuming a writer means Aristotle.
Logos elsewhere
Logos is Greek for word, reason or account, and carries theological weight in Christian usage. It is also the root of logic and of the -logy ending in every field name from biology to etymology. It is not the plural of logo, which is logos by coincidence of spelling only.
Frequently asked questions
What are the three modes of persuasion?
Ethos (credibility), logos (reasoning) and pathos (emotion), as set out by Aristotle. Strong arguments generally use all three.
Is logos the plural of logo?
The spelling coincides, but they are unrelated. The rhetorical logos is Greek for word or reason; logos meaning brand marks is simply the plural of logo.
Does ethos only mean credibility?
No. In everyday English it usually means the characteristic spirit of a group or institution, as in "the ethos of the company".