The surprising thing about One Nation’s new immigration policy is not that it contains extreme ideas. It is that parts of it deserve serious discussion.

The best part is its pledge to regulate the size and composition of the temporary migrant population.

This is the right number to target because it links directly to problems people care about, including poor planning, obstacles to integration and migrant worker exploitation.

It is also feasible to contain. Its size is determined by two flows a government can control: the net intake of people on temporary visas, and the number who convert to permanent status.

If these flows are kept equal, the temporary population stabilises. This is not a theory or forecast. It is a mathematical fact.

By contrast, recent political debate has focused on net overseas migration (Nom): the difference between migrant arrivals and departures.

Nom provides a rough measure of all migration. So to claim Nom is the problem supports the false conclusion that all migration is problematic.

It is not. Some parts cannot and should not be regulated, such as movements of Australian citizens. Others, such as permanent migration, are already well regulated. Temporary migration, by........

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