Modelling Ceteris Paribus Preferences with Deontic Logic

We present a formal semantics for deontic logic based on the concept of ceteris paribus preferences. We introduce notions of unconditional obligation and permission as well as conditional obligation and permission that are interpreted relative to this semantics. We show that these notions satisfy some intuitive properties and, at the same time, do not encounter some problems and paradoxes that have been extensively discussed in the deontic logic literature. We prove that the satisfiability problem for our logic is in NP. Finally, we show that the fragment of our logic in which the content of a deontic operator is a literal has an equivalent representation based on conditional preference networks (CP-nets).