There are two extreme perspectives on the labour market impacts of migrants. At one end of the spectrum are those who assert that migrants and local workers are perfect substitutes, so that each migrant displaces a local worker, so that each migrant removed opens a job for a local worker. At the other end of the spectrum are those who argue that there is no relationship between migrant and local workers, because migrants fill jobs that local workers refuse, making migrants perfect complements for national workers.