The rhetorical triangle is a theory of formal argumentation based on ideas first proposed by Aristotle. An argument is mapped on a triangle in which each of the three points are represented by three elements of argumentation: ethos, logos and pathos. Ethos represents the form or manner of the argument, logos represents the central message or idea, while pathos is the emotive force.
Aristotle identified each of the elements as common appeals used in arguments. A perfectly balanced argument depicts a triangle with sides of equal length. As the argument skews more towards one element, the sides of the triangle likewise lengthen or shorten to reflect it.
When breaking down the categories even further, ethos is the ethical component and represents the competence and character of the speaker and the language and formalities used to present the argument. Logos is the rational component of the argument, the use of facts, statistics and reasoning. Pathos represents an appeal to emotions and spiritual or cultural beliefs.
A version of the triangle developed by Robert Scholes is often taught in schools and links ethos with the speaker, pathos with the audience and logos with the message itself. This version is found in the book "Writing Arguments" first published in 1992.