Defeasible classifications andinferences from definitions

Douglas Walton, Fabrizio Macagno

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)34-61
Number of pages28
JournalInformal Logic
Issue number1
Publication statusPublished - 2010


  • Abductive reasoning
  • Argument from analogy
  • Argument fromcriteria to a verbal classification
  • Defeasible modus ponens
  • Heuristicclassifications types of definitions


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