This paper argues for a reinterpretation of Aristotle's concept of an enthymeme and also his wider informal logic in terms of arguments that are defeasible. They are represented by forms of argument that are called argumentation schemes, considered to be similar to forms of argument found in deductive logic, but different from the foregoing in virtue of their being defeasible. Indeed, the most interesting schemes have been put forward as a helpful way of characterizing structures of human reasoning that have (...) proved troublesome to model deductively. The paper sheds new light on Aristotle's topics and how to dene `enthymeme'. If the traditional denition of an enthymeme in logic accepted for over two thousand years is a misnomer, the question is raised whether we ought to redene it as a defeasible argumentations scheme or leave things as they are. (shrink)

The contribution critically discusses Walton's argumentation scheme approach. On the one hand, its enormous richness and closeness to the empirical argumentation material is appreciated, but, on the other, fundamental conceptual weaknesses are revealed. Although the approach more recently has been declared to strive for “true beliefs and correct choices” it has not systematically developed the proposed schemes in a way that these goals are reached. Accordingly, many proposed schemes are fallacious from an epistemological standpoint.

The existing classifications of arguments are unsatisfying in a number of ways. This paper proposes an alternative in the form of a Periodic Table of Arguments. The newly developed table can be used as a systematic and comprehensive point of reference for the analysis, evaluation and production of argumentative discourse as well as for various kinds of empirical and computational research in the field of argumentation theory.

This paper uses the language of formal dialectics to explore how argumentation schemes and their critical questions can be characterized as an extension to traditional dialectical systems. The aim is to construct a dialectical system in which the set of locutions is extended to include scheme-based moves the set of structural rules describes the roles that critical questioning can play; and the set of commitment rules distinguishes between exceptions and assumptions.

Computer tools are increasingly used to support the analysis of argumentative texts. Generic support for argumentation analysis is helpful, but catering to the requirements of specific theoretical approaches has additional advantages. Although the pragma-dialectical method of analyzing argumentative texts is widely used, no dedicated computational support tools exist. An outline is presented for the development of such tools, that starts with the formal approximation of the pragma-dialectical ideal model of a critical discussion.