Population-boosters have focused on two key arguments to convince us that we need a big Australia: ageing and skills.

Australia has an ''ageing crisis'', they say, and importing younger migrants is the way to deal with it. But the Productivity Commission dismissed this last year in Population and Migration: Understanding the Numbers, concluding that "realistic changes in migration levels … make little difference to the age structure of the population in the future, with any effect being temporary". Now attention has turned to the ''skills shortage'' and ''demand for labour'' arguments.

Apparently we need skilled migrants to fill all sorts of gaps - most notably to dig up and sell our finite, mineral assets. This is despite the fact mining is highly mechanised and, at a little more than 200,000 workers, makes up less than 2 per cent of Australia's workforce.