Quintilian, and J.S. Watson. Institutes of Oratory.Edited by Lee Honeycutt, 2010. Kindle Electronic Edition. Book IV Chapter 4.
In an argument it is necessary to state a proposition. Different authors take different approaches in arrangement. Quintilian here says, “In my opinion the commencement of any proof is a proposition, which may be advanced not only in stating the principal question, but sometimes even to introduce particular arguments…” (Quintilian IV.4.1). Yet in some questions the question requires no proposition, as it is adequately clear (Quintilian IV.4.2). The proposition may, however, be used to make an idea more clear or striking to the listener (Quintilian IV.4.4). On either side of a debate the propositions may be either simple or complex, having one idea or multiple ideas (Quintilian IV.4.5-7). Some propositions are very simple, such as, “I accuse you of murder.” (Quintilian IV.4.8). There may also be propositions which are more like suggestions, “It is upon these points that you are to decide” (Quintilian IV.4.9).