Aristotle, and W. Rhys Roberts. Rhetoric. Mineola, NY: Dover, 2004. Kindle Electronic Edition.
Book II, chapter 22.
After having spent considerable time working with different elements of an argument, Aristotle begins to discuss Enthymemes, previously introduced as syllogisms. Aristotle urges the speaker to avoid making obscure arguments. Simplicity is almost always more accepted (Aristotle II.22, B. 1395b). “The first thing we have to remember is this. Whether our argument concerns public affairs or some other subject, we must know some, if not all, of the facts about the subject on which we are to speak and argue” (Aristotle II.22, B. 1396a). Facts which are specific to a case are superior to generalizations.
Aristotle then moves into classes of enthymemes, which he considers first to be either those which prove or those which disprove a proposition (Aristotle II.22, B. 1396b). “The demonstrative enthymeme is formed by the conjunction of compatible propositions; the refutative, by the conjunction of incompatible propositions” (Aristotle II.22, B. 1396b).