Now economists calculate, and it's a back of the envelope calculation, that removing all immigration controls would double the size of the world economy and even a small relaxation of immigration controls would lead to disproportionately big gains. Now from an ethical point of view, it's hard to argue against a policy that would do so much to help people who are much poorer than ourselves. The famous Rand study reckons that the typical immigrant who arrives in the US ends up $20,000 a year better off. And it's not just the migrants themselves who gain, it's the countries that they come from. Already the migrants working from poor countries, working in rich countries send home around 200 billion dollars a year through formal channels, and perhaps twice that through informal channels. And that compares to the mere 100 billion dollars that Western governments give in aid. And those remittances? They're not wasted on weapons. They're not siphoned off into Swiss bank accounts. They go straight into the pockets of local people. They pay for food. They pay for clean medicine, clean water. They're paying for medicines. They help keep kids in school. They help start up new businesses.