The Topics is the name given to one of Aristotle's six works on logic collectively known as the Organon. The treatise presents the art of dialectic — the invention and discovery of arguments in which the propositions rest upon commonly held opinions or endoxa. Topoi are "places" from which such arguments can be discovered or invented.
What is a "topic"?
In his treatise Topics, Aristotle does not explicitly define a topos, though it is "at least primarily a strategy for argument not infrequently justified or explained by a principle." He characterises it in the Rhetoric thus: "I call the same thing element and topos; for an element or a topos is a heading under which many enthymemes fall." By element, he means a general form under which enthymemes of the same type can be included. Thus, the topos is a general argument source, from which the individual arguments are instances and is a sort of template from which many individual arguments can be constructed. The word τόπος is also related to the ancient memory method of "loci", by which things to be remembered are recollected by mentally connecting them with successive real or imagined places.
Though the Topics, as a whole, does not deal directly with the "forms of syllogism", clearly Aristotle contemplates the use of topics as places from which dialectical syllogisms may be derived. This is evidenced by the fact that the introduction to the Topics contains and relies upon his definition of reasoning : a verbal expressionin which, certain things having been laid down, other things necessarily follow from these.. Dialectical reasoning is thereafter divided by Aristotle into inductive and deductive parts. The endoxa themselves are sometimes, but not always, set out in a propositional form, i.e. an express major or minor proposition, from which the complete syllogism may be constructed. Often, such propositional construction is left as a task to the practitioner of the dialectic art; in these instances Aristotle gives only the general strategy for argument, leaving the "provision of propositions" to the ingenuity of the disputant.
Division of the text
Book I of the Topics is introductory, laying down a number of preliminary principles upon which dialectical argumentation proceeds. After defining dialectical reasoning and distinguishing it from demonstrative, contentious, and "pseudo-scientific" syllogism, Aristotle notes the utility of the art of dialectic, then sets out four bases from which invention of such reasoning proceeds. He next elucidates various senses of "sameness", as bearing directly upon the usual character of such arguments. Dialectical propositions and dialectical problems are characterized. Then, the ὄργανα or means by which arguments may be obtained are described, in a four-fold summary, as:
Methods and rationale for attaining each of these ends are briefly illustrated and explained. Book II is devoted to an explication of topics relating to arguments where an "accident" is predicated of a subject. Book III concerns commonplaces from which things can be discussed with respect to whether they are "better" or "worse". Book IV deals with "genus"—how it is discovered and what are the sources of argument for and against attribution of a genus. Book V discusses the base of "property"—that which is attributable only to a particular subject and is not an essential attribute. Property is subdivided into essential and permanent, versus relative and temporary. Book VI describes "definition" and the numerous means that may be used to attack and defend a definition. Book VII is a short recapitulation of "definition" and "sameness", and compares the various difficulties involved in forming arguments, both pro and con, about the other bases of dialectical disputation. Book VIII is a lengthy survey containing suggestions, hints, and some tricks about the technique of organizing and delivering one or the other side of verbal disputation.
The ''Topics'' as related to the treatise on sophistical refutations
The Sophistical Refutations is viewed by some as an appendix to the Topics, inasmuch as its final section appears to form an epilogue to both treatises.