Politicians often appeal to moral principles as a least-cost method of enforcing their policy demands. To do so effectively, they must understand how such principles fit into ordinary people's decision functions. Here I distinguish three ways for formally representing moral principles. One reduces morality to enlightened self-interest, denying that morality has any special place in the decision calculus. Another, while acknowledging that people do internalize moral principles per se, enters them into utility functions as just another consumption good. Truly strong moral principles, however, are best represented by a third model of seriously held moral principles which must be kept formally apart from mundane considerations. Such principles are as precarious as they are powerful. Policy-makers who want to tap them must respect the formalisms that make them strong, most typically by shielding moral principles from contamination by egoistic impulses.