Today in Pacem in Terris:
53. (People), both as individuals and as intermediate groups, are required to make their own specific contributions to the general welfare. The main consequence of this is that they must harmonize their own interests with the needs of others, and offer their goods and services as their rulers shall direct—assuming, of course, that justice is maintained and the authorities are acting within the limits of their competence. Those who have authority in the State must exercise that authority in a way which is not only morally irreproachable, but also best calculated to ensure or promote the State’s welfare.
54. The attainment of the common good is the sole reason for the existence of civil authorities. In working for the common good, therefore, the authorities must obviously respect its nature, and at the same time adjust their legislation to meet the requirements of the given situation .( Cf. Pius XII’s broadcast message, Christmas 1942, AAS 35 (1943) 13, and Leo XIII’s encyclical epistle Immortale Dei, Acta Leonis XIII, V, 1885, p. 120)
Everything political: governments, methods of governance, rulers by “divine right,” or elections, or even drawing straws–all this exists only for the betterment of society and for the effort to find the common good. Individuals work toward this common good as well. But we have higher purposes, of course. Public authorities do not.