Conflicting obligations in multi-agent deontic logic

Extending John Horty's multi-agent deontic logic to moral reasoning with subjective utilities, we provide a language and semantics to study moral reasoning with sentences like 'Group g of agents ought see to it that phi in the interest of group F'. We illustrate our deontic logic with a new formal analysis of the Prisoner's Dilemma, thereby showing that games can be studied fruitfully with our deontic logic. Finally, we prove a characterization theorem on conflicting obligations.