There can be no morality without law but there can be law without morality.
Law can create particular obligations but law cannot create a law that dictates an obligation to obey law. Law can punish but cannot create the general obligation to obey law. Such an obligation comes via moral character. “Morality must be distinguished from self-interest, although the two can often coincide…What is the rational ground for morality and its obligation?”
The rational ground for morality rests upon the need for mutual cooperation within a community. With mutual cooperation comes mutual dependence. Mutual cooperation demands trust, which relies upon honesty. Honesty implies obligation. Violence destroys cooperation.
Cooperation is essential for social life; only if we wish to withdraw into isolation can we afford to ignore cooperation. Empirically we can find cooperation within every community. Morality is about human relationships thus empirically we can find both the need and presence of morality in all communities.
Morality exists in all communities but it has many variables and much diversity. Three factors are important here: differences in religion, differences in politics, and differences in production and economic relations.
“Certain moral commitments with their attendant obligation are necessary for any kind of human co-operation whatever. These must first be acknowledged before there can be other values which vary. This is an a priori not an empirical thesis.” By definition, a group of individuals without human co-operation is no community at all.
A diversity of moral codes within a community can be accepted but primary loyalty to all within the community must be to the community and not to particular groups or classes within the community. Those values that unite must be more important than those that divide.
A community is a group committed to the rule of law, which entails three specific principles of law: the law is supreme with equality and freedom under the law. Legal rules are supreme and all members are subjected to and protected by those rules.
Public interest, when properly understood, forms the “rational basis of both government and politics”.