Dispositio is the system used for the organization of arguments in Western classical rhetoric. The word is Latin, and can be translated as "organization" or "arrangement."
It is the second of five canons of classical rhetoric (the first being inventio, and the remaining being elocutio, memoria, and pronuntiatio) that concern the crafting and delivery of speeches and writing.
The first part of any rhetorical exercise was to discover the proper arguments to use, which was done under the formalized methods of inventio. The next problem facing the orator or writer was to select various arguments and organize them into an effective discourse.
Aristotle defined two essential parts of a discourse: the statement of the case and the proof of the case. For example, in a legal argument, a prosecutor must first declare the charges against the defendant and provide the relevant facts; then he must present the evidence that proves guilt. Aristotle allowed that in practice most discourse also requires an introduction and a conclusion.
Later writers on rhetoric, such as Cicero and Quintilian refined this organizational scheme even further, so that there were eventually six parts:
While this structure might appear to be highly rigid (and certainly some writers on the subject were overly pedantic), it was in practice a flexible model. Cicero and Quintilian, for example, encouraged writers to rearrange the structure when it strengthened their case: for instance, if the opposing arguments were known to be powerful, it might be better to place the refutation before the proof.
Within each major part, there were additional tactics that might be employed. For instance, a prosecutor might sum up his case with forceful repetition of his main points using a technique known as accumulatio. The defense attorney in the same case might use a different approach in his summation.
Finally, dispositio was also seen as an iterative process, particularly in conjunction with inventio. The very process of organizing arguments might lead to the need to discover and research new ones. An orator would refine his arguments and their organization until they were properly arranged. He would then proceed to those areas that we generally associate with rhetoric today — the development of the style and delivery of the arguments.