Block 1 Around 40 per cent of the population of poor countries say that they would emigrate if they could. There is evidence that suggests this figure is not a wild exaggeration of how people would behave. If migration happened on anything approaching this scale, the host societies would suffer substantial reductions in living standards. Hence, in attractive countries, immigration controls are essential.Block 8 is partially incorrect, and even that quasi-error is mitigated by the fact that Collier points out that while the "widening of choices and horizons is a social gain", diversity itself is not. Block 7, of course, is completely wrong, as evidenced by American post-1973 wage stagnation.
Block 2 Diasporas accelerate migration. By “diasporas”, I mean those immigrants and their descendants who have retained strong links with their home societies, rather than cutting loose and integrating into their host societies. These links cut the costs of migration and so fuel it. As a result, while diasporas are growing, migration is accelerating. Diasporas continue to increase until immigration is matched by the rate at which immigrants and their offspring are absorbed into the general population. A crucial implication of this interconnection is that the policies for migration and diasporas must be compatible.
Block 3 Most immigrants prefer to retain their own culture and hence to cluster together. This reduces the speed at which diasporas are absorbed into the general population. The slower the rate at which they are absorbed, the lower the rate of immigration that is compatible with stable diasporas and migration. By design, absorption is slower with multicultural policies than with assimilative policies.
Block 4 Migration from poor countries to rich ones is driven by the wide gap in income between them. This gap is the moral horror story of our times. The difference in incomes is ultimately due to differences in political and social structures: poor countries have political and social systems that are less functional than those in rich ones. Their dysfunctional systems persist in part because they are embedded in the identities and narratives of local cultures. Migrants are escaping the consequences of their systems but usually bring their culture with them.
Block 5 In economic terms, migrants are the principal beneficiaries of migration but many suffer a wrenching psychological shock. As far as can be judged from the net effect on happiness, the economic gains and psychological costs broadly offset each other, although the evidence on this is currently sketchy.
Block 6 Because migration is costly, migrants are not among the poorest people in their home countries. The effect on those left behind depends ultimately on whether emigrants speed political and social change back home or slow it down. A modest rate of emigration, as experienced by China and India, helps, especially if many migrants return home. However, an exodus of the young and skilled – as suffered by Haiti, for example – causes a haemorrhage that traps the society in poverty.
Block 7 In high-income societies, the effect of immigration on the average incomes of the indigenous population is trivial. Economies are not damaged by immigration; nor do they need it. The distributional effects can be more substantial but they depend on the composition of immigration. In Australia, which permits only the immigration of the skilled, the working classes probably gain from having more skilled people to work with. In Europe, which attracts many low-skilled migrants, the indigenous poor probably lose out through competition for social housing, welfare, training and work. The clearest effect on the jobs market is that new migrants compete with existing migrants, who would consequently be substantial beneficiaries of tighter controls.
Block 8 The social effects of immigration outweigh the economic, so they should be the main criteria for policy. These effects come from diversity. Diversity increases variety and this widening of choices and horizons is a social gain. Yet diversity also potentially jeopardises co-operation and generosity. Co-operation rests on co-ordination games that support both the provision of public goods and myriad socially enforced conventions. Generosity rests on a widespread sense of mutual regard that supports welfare systems. Both public goods and welfare systems benefit the indigenous poor, which means they are the group most at risk of loss. As diversity increases, the additional benefits of variety get smaller, whereas the risks to co-operation and generosity get greater. Each host society has an ideal level of diversity and hence an ideal size of diasporas.
Block 9 The control of immigration is a human right. The group instinct to defend territory is common throughout the animal kingdom; it is likely to be even more fundamental than the individual right to property. The right to control immigration is asserted by all societies. You do not have the automatic right to move to Kuwait; nor do the Chinese have the automatic right to move to Angola, although millions would if they could. Nor do Bangladeshis have the automatic right to move to Britain and claim a share of its social and economic capital. It sometimes makes sense to grant the right to migrate on a reciprocal basis. Thousands of French people want to live in Britain, while thousands of Britons want to live in France. Yet if flows become too unbalanced, rights derived from mutual advantage can be withdrawn: Australia, for instance, withdrew them from Britain. The expansion of the EU has created these unbalanced situations and the original reciprocal right may therefore need modification.
Block 10 Migration is not an inevitable consequence of globalisation. The vast expansion in trade and capital flows among developed countries has coincided with a decline in migration between them.
The biggest falsehood concerning immigration is that it is good for the economy. I'll address this in a future post, but the TL;DR version can be understood by simply comparing GDP and immigration rates from 1900 to 2010.