In practical reasoning of an informal sort, the concept of duty plays a limited, relatively unproblematic role. In thinking about what to do, reasonable people try to see their wants in relation to their interests and to the interests of others; they evaluate alternatives in the light of their previous commitments and bear in mind their obligations and responsibilities. Duty is one among other factors to be taken into account. The reason is obvious: A person's duties are the things he or she is expected to do by virtue of having taken on a job or assumed some definite office. One could say (although it sounds somewhat redundant) that believing that one's duties entail doing something or other is a reason, though not a conclusive one, for doing that thing, and believing that a possible line of action would count as a neglect of duty is a reason...