In their responses to the global financial crisis, most world leaders — our own Kevin Rudd among them — have stressed the need to avoid lapsing into protectionism. Earlier this month, the head of the World Trade Organisation complimented Australia for having “been at the forefront of lobbying against protectionism measures over recent months.”

That’s not to say their practice has always followed suit; there’s been some tinkering with things like purchasing policy to appease protectionist sentiment. But in general, politicians have accepted the need to keep the world trading system open, and to avoid measures like the Smoot-Hawley tariff that helped prolong the great depression.

So observe the double standard that says we can let in foreigners’ goods, but keep out their labor — as seen in the government’s announcement yesterday of a 14% reduction in skilled migration.

Immigration Minister Chris Evans said he was just being “responsive to the economy”, even though study after study has shown immigration to have a positive or neutral effect on employment. The unions, of course, supported him strongly, while the opposition’s only complaint was that the government should have acted sooner.

James Jupp, in this morning’s Age, explains the economic facts but says that “economic argument here is less important than the political response to public opinion, which has never been very enthusiastic about bringing in potential rivals for jobs.”

He omits to point out, however, that public opinion has been consistently pandered to in that direction by politicians. Former Immigration Minister Philip Ruddock was a particular offender, but neither side of politics has been blameless. Indeed, the Howard government, despite its xenophobic rhetoric of “border protection”, boosted the skilled migrant intake considerably in response to the long period of economic expansion.

The idea that immigration adversely affects employment is the “big lie” of Australian politics: the statement that is never argued for directly, but treated as an uncontroversial certainty (compare “Iraq has weapons of mass destruction”), to the extent that most people never even think of questioning it. Yet the logic of it is every bit as fallacious as the corresponding argument for tariff barriers.

Over recent decades, the tariff debate has been revolutionised: whatever the prejudices of the electorate, and whatever their private feelings, our elected representatives evidently feel obliged to at least pay lip service to free trade.

But when it comes to keeping out actual human beings, protectionism suddenly becomes respectable. It’s a sad comment on our humanitarianism, our economic literacy, and our politicians’ backbone.