Abstract
This paper provides an analysis of contrary-to-duty reasoning from the proof-theoretical perspective of category theory. While Chisholm’s paradox hints at the need of dyadic deontic logic by showing that monadic deontic logics are not able to adequately model conditional obligations and contrary-to-duties, other arguments can be objected to dyadic approaches in favor of non-monotonic foundations. We show that all these objections can be answered at one fell swoop by modeling conditional obligations within a deductive system defined as an instance of a symmetric monoidal closed category. Using category theory as a foundational framework for logic, we show that it is possible to model conditional normative reasoning and conflicting obligations within a monadic approach without adding further operators or considering deontic conditionals as primitive.
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I would like to thank the anonymous referees for their helpful comments on previous versions of this paper. A special thank you goes to Jean-Pierre Marquis for his constructive comments, encouragements, support and, more importantly, for his trust. I would also like to thank Andrew Irvine, François Lepage and Yvon Gauthier for their involvement in the project. This research was financially supported by the Social Sciences and Humanities Research Council of Canada.
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Peterson, C. Contrary-to-Duty Reasoning: A Categorical Approach. Log. Univers. 9, 47–92 (2015). https://doi.org/10.1007/s11787-014-0111-7
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DOI: https://doi.org/10.1007/s11787-014-0111-7