Defeasible Classifications and Inferences from Definitions

Abstract

This paper shows how classifications and definitions can be used to construct different patterns of logical reasoning called defeasible argumentation schemes, often identified with heuristics, or short-cut solutions to a problem. We show how it is possible to argue reasonably for and against arguments from classifications and definitions provided the arguments are seen as defeasible. We examine a variety of arguments of this sort, including argument from abductive classification, argument from causal classification, argument from analogy-based classification and arguments from classification based on generalizations.

Defining Marriage: Classification, Interpretation, and Definitional Disputes

“…The force of this locus depends on the force of the definition, and on whether the definition admits for possible exceptions or defaults. The argument can be based on various definitional criteria (Sorensen 1991;Walton and Macagno 2010;Macagno and Walton 2014) which include definition and other descriptions of meaning that only metaphorically can be considered as definitions, such as descriptions, metaphorical definitions, etymological definitions, etc. The strength of the maxim depends on the convertibility of the terms of the definition, which in turn depends on the type of definition chosen (Walton and Macagno 2009).…”

“…56, 168), namely a second-order rule governing the interpretation of the legal statements and the application of the legal rules (Macagno and Damele 2016). In both cases, the classification is an intentional, deliberative act justified by a pattern of defeasible reasoning called "argument from classification," in which a new property (or a name) is attributed to an entity on the basis of other properties detected (Hastings 1963;Zarefsky 1998;Schiappa 2003;Zarefsky 2006;Walton and Macagno 2009;Walton and Macagno 2010). This argument can be represented as follows (Walton, Reed & Macagno 2008, p. 319…”

Evidential Modals at the Semantic-Argumentative Interface: Appearance Verbs as Indicators of Defeasible Argumentation

“…In this regard, dealing with arguments from classification, Walton and Macagno (2010) state that the "Argument from Criteria to Verbal Classification" (which fits the kind of 442. 430 reasoning exploited in our case of study) is defeasible due to the generalization made in the major premise:…”

“…As noted by Walton and Macagno (2010), in our everyday experience we have to rely on defeasible evidence and limited knowledge in order to categorize what we perceive. When we visit an exhibition our reasoning in approaching works of art functions as a heuristic, a temporary way to solve problems of categorization.…”

Classifying the Patterns of Natural Arguments

“…Classification broadly understood as the use of a particular word to denote a fragment of reality (Walton and Macagno 2010) can be based on different definitional or quasidefinitional material relations, which hide deeper forms of reasoning. The convertibility of the definiens and definiendum is a semantic (or rather metasemantic) relation, and for this reason it depends on the nature of the specific definition.…”