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. (shrink)

The crucial feature of obligation sentences to which the puzzles point is that such sentences, and evaluative sentences more generally, are defeasible. They may be warranted, given some information, only to be defeated by further information. A theory that recognizes this no longer needs to see conditional obligation as anything more than a simple combination of unary obligation and the conditional.

Standard dyadic deontic logic (as well as standard deontic logic) has recently come under attack by moral philosophers who maintain that the axioms of standard dyadic deontic logic are biased against moral theories which generate moral conflicts. Since moral theories which generate conflicts are at least logically tenable, it is argued, standard dyadic deontic logic should be modified so that the set of logically possible moral theories includes those which generate such conflicts. I argue that (1) there are only certain (...) types of moral conflicts which are interesting, and which have worried moral theorists, (2) the modification of standard dyadic deontic logic along the lines suggested by those who defend the possibility of moral conflicts makes possible only uninteresting types of moral conflicts, and (3) the general strategy of piecemeal modification standard dyadic deontic logic is misguided: the possibility of interesting moral conflicts cannot be achieved in that way. (shrink)