Eric Posner and Glen Weyl have a provocative essay in the New Republic this month arguing that massive guest worker schemes could help facilitate large numbers of immigrants from poor countries to come and work in the developed world. Their model is the Gulf States, which have enormous numbers of workers—85% of the population of the United Arab Emirates, for instance, are guest workers:

If the OECD countries copied the migration policies of the GCC countries, they would reduce global inequality by much more than their welfare systems do within their borders. For example, if OECD countries welcomed migrants in proportion to their GDP at the same rate and from the same poor nations as Qatar does, this would reduce global inequality by about twice the amount that eliminating all internal inequality in the OECD countries would —and by twice the rate that taxes and transfers in these countries reduce global inequality. If they  adopted the same per-citizen rate at which the UAE takes migrants, they could accomplish much more. By taking in the 60 percent of the global population who make less than the bottom five percent in the United States and paying them $5,000 per year, the U.S. and Europe would reduce global inequality by roughly a third.

We citizens of OECD countries take pride in our political and civil rights, and our generous welfare systems. Yet we maintain our high standard of living by giving no rights and trivial money to people who live outside our arbitrary borders. While we fuss over whether we should raise or lower our marginal tax rates, we ignore the plight of the most desperate people in the world. And yet we are surprised that leaders of China and the GCC accuse us of hypocrisy when we criticize their records on human rights.

It's a controversial idea. These schemes seem to address most of the intractable problems that people have with immigration—these guest workers cannot vote, their children do not become citizens of the states they are born into, and they have to return home after a certain period of time, so they can't have the negative lasting impact on culture that some people say immigration will lead to.

But, as I and many other visitors to the Gulf have noted, the system feels almost like slavery. Indeed in cases where workers' passports are confiscated it essentially is slavery. Posner and Weyl are not suggesting this, but their plan would bring the reality of global poverty right up to our doorsteps—provided they know what their lives will be like, we can assume they would be made better off by this, but many people would find actually seeing this kind of deprivation on a daily basis to be unacceptable. But whether we could tolerate this and whether we should tolerate it are two very different questions.