The president of the Pontifical Academy for Social Sciences, which is hosting a conference on Blessed John XXIII’s 1963 encyclical Pacem in Terris, has told Vatican Radio that “there is nothing in Catholic social thought that espouses a world government.”
Asked whether it is “possible to get to a global governance, or is it just an ideal which is not something we can realize in the real world,” Mary Ann Glendon, a law professor at Harvard University, distinguished between “world government” on the one hand and “transnational approaches” that are in accord with the principle of subsidiarity on the other hand:
"I think the great contribution of Catholic social thought on that point is that which we refer to as subsidiarity that there are certain things best done closest to the people affected by the decisions. So one has to be rather careful in speaking about global governance to keep in mind that we need to develop international approaches or transnational approaches to those kinds of problems that can’t be handled at a lower level of responsibility. There is nothing in Catholic social thought that espouses a world government."
In Pacem in Terris, Blessed John XXIII spoke of the need for a “general authority equipped with world-wide power”:
"Today the universal common good presents us with problems which are world-wide in their dimensions; problems, therefore, which cannot be solved except by a public authority with power, organization and means co-extensive with these problems, and with a world-wide sphere of activity. Consequently the moral order itself demands the establishment of some such general form of public authority.
But this general authority equipped with world-wide power and adequate means for achieving the universal common good cannot be imposed by force. It must be set up with the consent of all nations. If its work is to be effective, it must operate with fairness, absolute impartiality, and with dedication to the common good of all peoples. The forcible imposition by the more powerful nations of a universal authority of this kind would inevitably arouse fears of its being used as an instrument to serve the interests of the few or to take the side of a single nation, and thus the influence and effectiveness of its activity would be undermined. For even though nations may differ widely in material progress and military strength, they are very sensitive as regards their juridical equality and the excellence of their own way of life. They are right, therefore, in their reluctance to submit to an authority imposed by force, established without their co-operation, or not accepted of their own accord."
Citing Pacem in Terris, Pope Benedict likewise spoke in his 2009 encyclical Caritas in Veritate of an
"urgent need of a true world political authority, as my predecessor Blessed John XXIII indicated some years ago. Such an authority would need to be regulated by law, to observe consistently the principles of subsidiarity and solidarity, to seek to establish the common good, and to make a commitment to securing authentic integral human development inspired by the values of charity in truth. Furthermore, such an authority would need to be universally recognized and to be vested with the effective power to ensure security for all, regard for justice, and respect for rights. Obviously it would have to have the authority to ensure compliance with its decisions from all parties, and also with the coordinated measures adopted in various international forums."