From Richard Posner’s The Problematics of Moral and Legal Theory (1999), pp. 67-68:

Every academic moralist believes implicitly that his is the right approach and everyone should follow it….But given the variety of necessary roles in a complex society, it is not a safe idea to have a morally uniform population.  On the one hand, we need soldiers, police, jailers, judges, spies, and other operators of society’s security apparatus; also politicians, entrepreneurs, managers of huge enterprises, and administrators of lunatic asylums.  On the other hand we need mothers, nurses, forest rangers, kindergarten teachers, zookeepers, and ministers of religion.  We need gentle, kind, and sensitive people, but we also need people who are willing to employ force, to lie, to posture, to break rules, to enforce rules, to rank people . . . . We need people who are empathetic and sympathetic but also people who are brave, tough, callous, and obedient–and others who are brave, tough, callous, and defiant . . . .

A related point, one that can be tied back to moralists’ inability to resolve moral dilemmas in a convincing fashion, is that they disvalue conflict and hence tragedy . . . . The law has to deal with these tragic situations somehow, but it does not have to yield to the moralist who believes that no moral dilemma is beyond the power of moral reasoning to resolve.  It is better for the law to adapt to the elements of ineradicable conflict in modern social life than to submerge them under a factitious intellectual harmony.