For our purposes, 'logos' is the appeal to a reader or listener's sense of logic. 'How do your arguments convince me to take action?' This is the kind of question that an audience asks when listening to a speech or reading a text. This definition comes from the tradition of analyzing rhetoric, as founded by the Greek philosopher Aristotle. In this tradition, logos is one of three main rhetorical appeals, together with pathos and ethos, which are appeals to the sense of emotion and authority respectively. Appealing to a sense of logic usually involves arguments, syllogisms, and reasoning. This means that a persuasive speaker will present several premises before coming to a conclusion.

Here is an example of logos, as found in a speech by Ben Bernanke, chairman of the Federal Reserve.