Douglas Walton proposed returning to Aristotle's dialectic as a way to look at arguments:
This new way of viewing an argument is frequently called informal logic, suggesting a contrast with formal logic (the dominant type of logic in western intellectual tradition). But it could also be called communicative logic, or pragmatic logic perhaps, in that it is expressly directed to judging particular aspects of how an argument was used for some communicative purpose, well or badly, in a given case.
Formal logic evaluates an argument by its form. The form has to be valid. Walton claims this is different for an informal argument:
The form is not, by itself, sufficient to enable one to arrive at an evaluation of the argument as weak or strong, reasonable or fallacious....
In informal logic, an argument is evaluated with respect to how it has been used in that particular case, within the framework of what is called a type of dialogue. A dialogue is a goal-directed, collaborative conversational exchange, of various types, between two parties.
If one looks at deductive logic as formal logic and non-deductive logic as informal logic one may be able to use Walton's dialogue types as a way to list the different types of non-deductive arguments. This may not present a fixed list of non-overlapping items that agrees with other lists, but it would provide a basis upon which one could say whether or not an argument, or dialogue, should be placed somewhere in one's grouping of informal, non-deductive arguments.
Walton offers seven dialogue types in the paper:
- The "critical discussion" occurs where the goal is to resolve a conflict of opinions.
- The "persuasion dialogue", broader than the critical discussion, occurs where one side attempts to prove a thesis using premises accepted by the other side.
- The "negotiation type of dialogue" occurs where the goal is to make a deal.
- The "quarrel" occurs where the goal is a better personal relationship between the parties.
- The "information seeking type of dialogue" occurs where the goal is to transfer information from one party to another.
- The "deliberation" occurs where two parties are trying to decide what action to take when prompted by a practical problem.
- The "inquiry" occurs where the goal is to prove something to a high standard.
This list looks different from a list of informal fallacies of relevance or ambiguity or a discussion on analogy, probability and scientific hypothesis as a contrast with deduction that one finds in logic textbooks such as Irving Copi's Introduction to Logic. Here informal logic is based on its own foundation of dialogue rather than on how it contrasts with deduction's emphasis on valid form.
Copi, I. M. Introduction to Logic. Sixth Edition. Macmillian. 1982.
Walton, D. New Methods for Evaluating Arguments. Inquiry: Critical Thinking Across the Disciplines. Summer. 1996. https://www.dougwalton.ca/papers%20in%20pdf/96NewMethod.pdf