Nigeria, Sept. 25 -- The most revealing thing about the United Nations in 2026 may be the distance between the world for which it was created and the world it is now expected to govern.

The Security Council was designed in the aftermath of the Second World War, when the distribution of military and political power looked very different from what it does today. Much of Africa was still under colonial rule. Many of the countries that now occupy the General Assembly as sovereign states did not yet exist as independent nations. The institutions of global governance reflected the priorities and power of that moment.

Eight decades later, the world has changed almost beyond recognition, but the central architecture of the Security Council has...