Last Monday at the American libertarian blog The Volokh Conspiracy, Ilya Somin made a post announcing his support for the thesis of the Open Borders NGO that migration should be as unhindered as possible. Linking to various authors' arguments in favour of this thesis, Somin makes the argument that the tendency worldwide should be not to raise barriers to migration but to lower them.
As the Open Borders Manifesto notes, and as I have said in the past, most open borders advocates do not claim that the right to free migration is absolute and always trumps opposing considerations. Just as I reject absolute property rights or absolute freedom of speech, so too I reject absolute rights to free migration. But we do believe there should be a strong presumption in favor of free migration that can only be overcome by strong evidence that restriction is the only way to prevent a harm great enough to outweigh the vast benefits of freedom to natives and migrants alike.
Many of the commenters at the Volokh Conspiracy are unconvinced, arguing that the author underestimates the costs involved. I myself am undecided about the thesis: There do seem to be great potential gains in GDP globally if there was a freer global market in labour alongside other global markets, but I'm also quite aware that there could be significant political costs if these associated migrations ever became problematic.
What do you, readers of Demography Matters, think of the argument?