When deciding how to support an argument, the writer needs to understand pathos, ethos, and logos. Chapter 11 of "The Purposeful Argument: A Practical Guide" defines each word: Pathos is an "emotional appeal that comes from support such as stories, illustrations, charts, or photos"(281). Ethos "is a term that refers to one's authority or expertise on a topic, one's credibility"(281). Logos is "support based on facts"(281).
Logos, Ethos and Pathos Described - a handout from Harvard University
Logos, Ethos, Pathos by David McMurrey, Kalani Pattison, and Nicole Hagstrom-Schmidt - a chapter of "Howdy or Hello? Technical and Professional Communication." This is an OER book from Texas A&M University.
Aristotle's Rhetorical Situation - a webpage on OWL Purdue that discusses Pathos, Ethos, and Logos. It also mentions Kairos.
Logos, Ethos, and Pathos in Persuasive Writing - a webpage from Marquette University's law school describing how to use Logos, Ethos, and Pathos in legal writing.
Aristotle's Appeals: Incorporating Ethos, Pathos, Logos in Your Persuasive Writing - a webpage from George Mason University