Exodus: How Migration Is Changing Our World

Collier argues that while nations have a moral obligation to assist those in need, this responsibility does not justify open-border policies. He posits that effective migration policy must balance ethical considerations with the practical realities faced by host countries, as unrestricted migration can impact social cohesion and stability.

Migrants gain economically by moving from low-wage to high-wage countries, benefiting from the institutions and infrastructure built by host societies and raising questions about how they should share in the advantages provided by these systems. At the same time, these financial improvements often come with psychological and social costs. Higher incomes do not always lead to greater well-being, as many migrants experience cultural dislocation and family separation, which can reduce overall happiness.

Host countries face challenges balancing economic gains from migration with maintaining social cohesion. Family reunification policies can undermine merit-based systems, accelerating migration beyond what is economically optimal and creating tensions between economic needs and humanitarian goals. Debates around migrant-specific taxes reflect this balance: While intended to support origin countries, such taxes could discourage remittances, deepen financial strain, and hinder integration, making them counterproductive.

Migration also has profound effects on the countries of the “bottom billion” (See: Key Figures).