Deontic Explanations via Logical Argumentation
Inhalt
In many normative reasoning contexts, one is not merely interested in knowing whether an obligation holds, but also in why it holds despite other norms to the contrary. Answers to such why questions are deontic explanations. They not only lead to a better understanding of normative reasoning, they also motivate compliance and collaboration. The importance of such explanations increases with the development of AI systems that need to comply with normative codes. The study of explanation is growing rapidly but, so far, little to no formal work has been done in the intersection of explanation and normative reasoning. What is more, existing approaches in deontic logic do not make explicit the reasons why certain obligations do and do not hold given a normative system, and are, therefore, not yet suitable for deontic explanations. In collaboration with Christian Strasser, we developed Deontic Argumentation Calculi (DAC): Sequent-style proof systems tailored to the construction of deontic explanations. DAC generate transparent arguments that provide explicit reasons why certain obligations hold and why certain norms are inapplicable. We prove that Formal Argumentation (FA) frameworks instantiated with DAC arguments are sound and complete with respect to the nonmonotonic inference relation of the class of constrained Input/Output (I/O) logics, a renowned formalism for defeasible reasoning with norms and their conflicts. We demonstrate how to employ DAC to generate deontic explanations using general tools from the FA literature. In particular, we use these tools to generate deontic explanations as answers to contrastive questions of the form “Why am I obliged to ϕ, despite ψ?”
