174 Courage and generosity are needed in order freely to establish shared goals and to ensure the worldwide observance of certain essential norms. For this to be truly useful, it is essential to uphold “the need to be faithful to agreements undertaken ( pacta sunt servanda )”, and to avoid the “temptation to appeal to the law of force rather than to the force of law”. This means reinforcing the “normative instruments for the peaceful resolution of controversies... so as to strengthen their scope and binding force”. Among these normative instruments, preference should be given to multilateral agreements between states, because, more than bilateral agreements, they guarantee the promotion of a truly universal common good and the protection of weaker states.
Source: Fratelli Tutti (Vatican.va)