1. In some cases, the directions given by those in authority call attention to already-existing moral responsibilities. Thus criminal law forbids many acts which would be morally wrong even if the law did not forbid them. In other cases, however, authorities require something which would not otherwise be morally required.
2. Even when an authority is only calling attention to an already-existing obligation, the obligation’s backing by authority generates an additional moral duty, the duty to obey. This, furthermore, is the only moral duty generated when authority directs something which is not otherwise morally required. In other words, the only new moral responsibility arising in either case from the decision of an authority is the duty to obey. Thus the question comes down to this: Why should persons sometimes obey other persons? The obligation to obey is grounded in two distinct ways (see S.t., 1, q. 96, a. 4; 1–2, q. 95, a. 1; 2–2, q. 57, a. 4; q. 104, aa. 1–2).
3. First, if two or more people are morally obliged to cooperate but not all are capable of deciding what to do, fairness (the fifth mode of responsibility) requires that those in a better position to decide for the good of the whole community do so, and that all follow the directions to carry out such decisions. Thus, authority and obedience can have a moral grounding in the differing abilities of people who are morally bound to live in community and engage in common action.
4. Authority of this kind is present in a family, which is a natural society. Parental authority is not based on the children’s consent or on common commitment. But neither does it simply come down to the fact that parents were there first and are stronger. Rather, a family must live a common life; moral judgments and choices must be made; children are more or less incapable of making these judgments and choices. Even as children grow, decisions are often required about matters where no consensus can be obtained. Even then parents can judge and choose in a sense that children cannot, since they are responsible for the whole family and have scope for action which the children lack.
5. The second way in which the obligation to obey is grounded is found in societies created by a common commitment. In making such a commitment, people unite to cooperate for goods which they cannot pursue by themselves. The commitment must be implemented by an indefinite series of choices, and these choices must be carried out cooperatively for the sake of the common purpose.
6. The many diverse communities based on common commitment have no single locus of authority. In many friendships and purely voluntary associations, all the parties share authority and decide together what to do, then obediently carry out the common plan of action together. Although this might seem the ideal arrangement, it is not practical in a complex society, where not all can share authority on all matters because decision making itself is a full-time job. In such cases, the locus of authority is frequently part of the understanding on which the common commitment constituting the society is made.
7. In societies based on common commitment, the obligation to obey has a twofold moral basis. First, one is morally required to make commitments, for people must pursue goods and, as the second mode of responsibility makes clear, they should not do this in an altogether individualistic way. Moreover, once one has made commitments, they must be carried out despite obstacles. Second, once a person has entered into a community formed by mutual commitments, fairness (the fifth mode) requires one to carry out even those decisions one finds burdensome and personally unrewarding. This is so because one wants others to carry out decisions which benefit oneself. All should do their part; those who do not, impose on others.
8. Despite the real moral ground of authority, the duty to obey is nonabsolute (see S.t., 1–2, q. 96, a. 4; 2–2, q. 104, a. 5). First, a person convinced that what authority directs cannot be done without moral wrongdoing must not violate conscience out of obedience. Thus children should not obey when their parents tell them to act spitefully or tell lies. Second, cases arise in which duties conflict and it is impossible to carry out all of them at once. Third, there are cases in which legitimate decisions should be overridden. This happens when a member of the community is in a position to know that an exception to an authoritative rule is urgently required by the very goods to which members of the community have made their common commitment (see S.t., 1–2, q. 96, a. 6; 2–2, q. 120).