Reasoning by Cases in Structured Argumentation
This work addresses formalization challenges in defeasible reasoning with disjunctive information for researchers in computational argumentation and non-monotonic logic, representing an incremental extension to an existing framework.
The paper extends the ASPIC+ framework for structured argumentation to incorporate reasoning by cases for defeasible arguments, allowing construction of arguments with conclusions from disjunctive premises, and shows that this approach yields different results compared to existing non-monotonic logic methods like disjunctive default theory or the OR-rule.
We extend the $ASPIC^+$ framework for structured argumentation so as to allow applications of the reasoning by cases inference scheme for defeasible arguments. Given an argument with conclusion `$A$ or $B$', an argument based on $A$ with conclusion $C$, and an argument based on $B$ with conclusion $C$, we allow the construction of an argument with conclusion $C$. We show how our framework leads to different results than other approaches in non-monotonic logic for dealing with disjunctive information, such as disjunctive default theory or approaches based on the OR-rule (which allows to derive a defeasible rule `If ($A$ or $B$) then $C$', given two defeasible rules `If $A$ then $C$' and `If $B$ then $C$'). We raise new questions regarding the subtleties of reasoning defeasibly with disjunctive information, and show that its formalization is more intricate than one would presume.