 As Mally’s words indicate, he was not primarily interested in deontic logic for its own sake: he mainly wanted to lay the foundation of “an exact system of pure ethics” (eine exakte reine Ethik). More than half of his book is devoted to the development of this exact system of ethics. In the following, we will, however, concentrate on the formal part of his book, both because it is its “hard core” and because it is the part that has attracted the most interest.