Collier addresses the ethical and practical dilemmas of migration, questioning who should benefit from the productivity gains it generates. He questions the use of migrant-specific taxes, suggesting that while these taxes might provide compensation to home countries for lost human capital or to host nations for their infrastructure, they could create a second-class status for migrants and hinder integration efforts. 

Collier notes that host societies, whose social systems underpin these gains, have some basis for receiving a share of the benefits but warns against policies that foster inequality or social division. He compares the protectionist policies of host nations—intended to safeguard labor markets and maintain social cohesion—with universalist approaches that focus on reducing migration barriers to promote global welfare and economic opportunities on a large scale.

Diasporas accelerate migration by lowering financial and logistical barriers for new migrants. They provide crucial support, such as funding travel costs, offering housing, and helping migrants navigate legal systems. These networks also create pathways for family-based migration, which often overrides merit-based entry systems, leading to a shift in the composition of migrant populations. This system can prioritize relatives over highly skilled workers, potentially undermining policies designed to attract educated migrants.