The economic case for rapid population growth though immigration is surprisingly weak, but a lot of economists are keen to give you the opposite impression. Fortunately, the Productivity Commission can't bring itself to join in the happy sales job.
I suspect that, since almost all economists are great believers in economic growth as the path to ever higher material living standards, they have a tendency to throw in population growth for good measure. There's no doubt a bigger population leads to a bigger economy; the question is whether it leads to higher real income per person, thereby raising average living standards.
Of course, business people can gain from selling to a bigger market, regardless of whether the punters are better off. So I'd be wary of advice coming from economists employed by business or providing consulting services to business.
In 2006 the Productivity Commission conducted a modelling exercise to assess the effect of a 50 per cent increase in our skilled immigrant intake. It found that, after 20 years, real gross domestic product was only about 4 per cent higher than otherwise.
And the increase in real income per person was minor. What's more, most of the gains accrued to the migrants themselves, with the existing population suffering a tiny net decline in income. Why this lack of benefit? You'd expect the extra skilled labour to raise the proportion of the population participating in the labour force, thus boosting production per person.
But most of the productiveness of workers are achieved by the physical capital they're given to work with. So unless your extra workers are given extra capital equipment - a process known as "capital widening" - their productivity is likely to decline, thus offsetting the gain from having more workers.
Note, too, that we have to increase the housing stock to accommodate the migrant workers and their families, as well as providing the extra public infrastructure for a bigger population. So the migrants are paid to supply their labour, but the rest of us have to provide the extra economic and social capital they need if standards aren't to fall.
Last week Tony Burke, the federal minister responsible for developing a "sustainable population strategy" next year, released an issues paper to encourage discussion. It was accompanied by the reports of three advisory panels, including one on the economic aspects, led by Heather Ridout of the Australian Industry Group.
Ridout's report sets out to talk up the economic case for high migration by dispelling "myths" and pointing to hard-to-quantify benefits "often ignored by low-growth advocates when they skim the literature" (that's what they call a professorial put-down).
The main hard-to-quantify benefits left out of the Productivity Commission's modelling are the economies of scale arising from a bigger market. But why after all these years have economists been unable to produce good empirical evidence of something as straightforward as scale economies?
And why wax lyrical about unmeasurable benefits without mentioning unmeasurable costs? In its recent booklet on population and immigration, the commission acknowledges that as well as economies of scale there could be diseconomies.
The Ridout report objects that the commission's modelling measured the benefit of increased immigration only over 20 years. Sorry, but if you have to wait more than 20 years for the payoff you're not talking about a powerful effect.
A relatively new argument in favour of high immigration is that it could foster economic growth by countering to some extent the decline in labour-force participation caused by the ageing of the population. But, since immigrants age too, all this can do is put off the evil hour (not a course of action usually promoted by economists). To continue postponing the crunch you have to keep upping the dose of immigration.
The Productivity Commission is blunt: "changes in migration flows are unlikely to have a significant and lasting effect on the ageing of Australia's population".
The Ridout report argues that a faster-growing, immigration-fuelled economy would require greater levels of investment by businesses and in public infrastructure. This greater capital spending would generally involve investment in more productive capital equipment, as recent technological improvements will be embedded in the newer stock. In this way, faster growth of the size of the economy would drive the productivity gains that are central to advances in material living standards, we're told.
Huh? The proposition is that by taking on a need for considerable investment in capital widening (to provide the extra workers with the equipment and infrastructure they need to be as productive as the existing workers) we're increasing the scope for capital deepening (giving each worker more and better capital equipment).
Am I missing something? This is a twist on a common economists' argument I've never managed to fathom: we need to grow more and do more damage to the natural environment because when we're richer we'll be able to afford to fix the damage we've done to the environment.
The Ridout report asserts that provided population growth is "balanced and managed well", living standards will rise. It needs to be "matched by greater commitments to education and skills development, more and better investments in infrastructure, greater attention to the development of our cities and regions and to our natural environment".
In other words, to give business the extra population it wants but prevent this from worsening all those things, governments at all levels will really need to lift their game as well as spend a lot more. Turn in a perfect performance and high immigration won't be a problem.
I prefer the commission's way of putting it: "population growth and immigration can magnify existing policy problems and amplify pressures on 'unpriced' entities, such as the environment, and urban and social amenity".
