Given the above picture of dialectical argument, the dialectical art will consist of two elements.
– One will be a method for discovering premises from which a given conclusion follows, while the other will be
– a method for determining which premises a given interlocutor will be likely to concede.
The first task is accomplished by developing a system for classifying premises according to their logical structure.
We might expect Aristotle to avail himself here of the syllogistic, but in fact he develops quite another approach, one that seems less systematic and rests on various “common” terms.
The second task is accomplished by developing lists of the premises which are acceptable to various types of interlocutor.
Then, once one knows what sort of person one is dealing with, one can choose premises accordingly.
Aristotle stresses that, as in all arts, the dialectician must study, not what is acceptable to this or that specific person, but what is acceptable to this or that type of person, just as the doctor studies what is healthful for different types of person: “art is of the universal”.
1. The “Logical System” of the Topics
The method presented in the Topics for classifying arguments relies on the presence in the conclusion of certain “common” terms (koina) — common in the sense that they are not peculiar to any subject matter but may play a role in arguments about anything whatever.
We find enumerations of arguments involving these terms in a similar order several times. Typically, they include:
- Opposites (antikeimena, antitheseis)
1.1. Contraries (enantia)
1.2. Contradictories (apophaseis)
1.3. Possession and Privation (hexis kai sterêsis)
1.4. Relatives (pros ti)
- Cases (ptôseis)
- “More and Less and Likewise”
– The four types of opposites are the best represented.
Each designates a type of term pair, i.e., a way two terms can be opposed to one another.
– Contraries are polar opposites or opposed extremes such as hot and cold, dry and wet, good and bad.
– A pair of contradictories consists of a term and its negation: good, not good.
– A possession (or condition) and privation are illustrated by sight and blindness.
– Relatives are relative terms in the modern sense: a pair consists of a term and its correlative, e.g. large and small, parent and child.
– The argumentative patterns Aristotle associated with cases generally involve inferring a sentence contaning adverbial or declined forms from another sentence containing different forms of the same word stem:
– “if what is useful is good, then what is done usefully is done well and the useful person is good”.
In Hellenistic grammatical usage, ptôsis meant “case” (e.g. nominative, dative, accusative); Aristotle’s use here is obviously an early form of that.
– Under the heading more and less and likewise, Aristotle groups a somewhat motley assortment of argument patterns all involving, in some way or other, the terms “more”, “less”, and “likewise”.
“If whatever is A is B, then whatever is more (less) A is more (less) B”;
“If A is more likely B than C is, and A is not B, then neither is C”;
“If A is more likely than B and B is the case, then A is the case”.
2. The Topoi
At the heart of the Topics is a collection of what Aristotle calls topoi, “places” or “locations”.
Unfortunately, though it is clear that he intends most of the Topics (Books II-VI) as a collection of these, he never explicitly defines this term.
Interpreters have consequently disagreed considerably about just what a topos is.
Discussions may be found in Brunschwig 1967, Slomkowski 1996, Primavesi 1997, and Smith 1997.