  Axiom \((D)\) guarantees the consistency of the system of obligations by insisting that when \(A\) is obligatory, \(A\) is permissible. A system which obligates us to bring about \(A\), but doesn’t permit us to do so, puts us in an inescapable bind. Although some will argue that such conflicts of obligation are at least possible, most deontic logicians accept \((D)\).