- Maintaining peace in the world:
For: Unrealistic to believe it could prevent all wars, but it has been successful in negotiating peacful resolutions to conflicts, and has authorized the defense of countries from unprovoked attacks, such as South Korea. The UN has also been instrumental in the development of the concept of human rights, which was virtually nonexistent beforehand. Failures to intervene in human rights affairs have not been failures of the UN, but rather failures by its member states, like the US in the case of Rwanda.
Against: UN peacekeepers usually only come into conflict after thousand of civilians have been killed, and are sometimes unable or too late to act in certain situations, such as the Rwandan Genocide or their inability to intervene in Syria because of the Vetos of China and Russia. Also, UN resolutions have often been used as justification for wars, such as the 2003 invasion of Iraq and the "responsibility to protect". Research actually shows a rise in armed conflicts from 1945 and a plateau after the end of the cold war. Despite their development of human rights, the UN has often failed to protect them, as it stood by during the terrible Rwandan massacre, and has tolerated some of the worst dictatorships as part of its mebers