In a shockingly stupid decision, the British public have voted 52% to 48% to leave the European Union. In the short term this means an economic disruption that will blight people’s lives. In the long term this means that unless it is permitted to remain in the European Economic Area, Britain will no longer have EU regulations to protect its workers, consumers, and environment. Even if it stays in the EEA (and the EU has every reason to refuse to permit it to do so to deter other countries from leaving the EU), it will no longer be able to play a part in solving collective action problems like tax avoidance and climate change, and its non-involvement will undermine the solutions proposed by others in Europe. Brexit will also aid and abet other Euroskeptic movements throughout Europe and dump gasoline on the right nationalist fire that grips so much of the world today. Many people in Britain and elsewhere throughout the world will be harmed, some now, some later, many irretrievably so. No political outcome can be legitimate if it permanently and irretrievably harms so many people with no substantive advantages. For these reasons the next British government must refuse to invoke Article 50. Parliament is sovereign, and its sovereignty cannot be abrogated by a referendum. This is a controversial view–refusing to honor the referendum would make a lot of people very angry. But the long term harms of Brexit to Britain’s young people are too great for any government to morally justify invoking Article 50, irrespective of public opinion.