The tribes take up their standard positions and shout across the divide in a dialogue of the deaf.

The left cries that any questioning of the benefits of immigration amounts to racism.

And the right bellows back that immigrants bring problems - taking but not giving, diluting a culture, putting African gangs on our safe streets and plotting with foreigners (whether in Beijing or Beirut).

Kristina Keneally doesn't fit easily into either bunker when she calls for Australians to have a "first go" at jobs by cutting temporary migration.

But a cynic might say she is playing to the right, both within her own party's union section and to voters beyond.

Labor - like Labour and like the Democrats - is an increasingly uneasy partnership between its working-class and middle-class supporters, and there may be a bit of rightward foot-shuffling going on as the party realigns after defeat.

Labour in Britain is doing the same after its disastrous last campaign, when lifelong Labour voters deserted it. Maybe, too, the Democrats will rethink at the end of the year when Trump wins! Or should I say "if"?

In both Britain and the United States, immigration has been a driver of voters to the right.

But raising the issue invariably prompts the knee-jerkers.

Fixed positions are taken. "Immigrants don't take Australian jobs. They create jobs for others," shouts The Guardian from the left, while economists line up to say immigration benefits economies.

From the other side, "One Nation leader Pauline Hanson has claimed vindication for 'decades of being labelled racist'," according to one of Mr Murdoch's websites.

This kind of polarised debate helps nobody except politicians seeking cheap votes and politicised newspapers which thrive on fear.

In this poisoned environment, nuanced debate is barely possible, and that is a tragedy.

In Britain, debate was closed down because any mention of the costs of immigration was howled down as racist.

The eventual backlash was immense and destructive.

It turns out all those ignored citizens in towns where Poles and Czechs were doing the work the natives didn't want to do anyway - or not at Polish and Czech wages, at least - stuck two fingers up and voted to leave the European Union.

We in the British middle class had never imagined how it could happen. How could they be so stupid? After all, the benefits of immigration were obvious. The economists told us so.

We, the comfortable ones, had cleaners and painters and cheaper taxis and waiters and dog-walkers at a price we could suddenly afford.

What was there not to like?

Quite a lot, actually, if you were a British-born cleaner, painter, taxi driver, waiter or dog-walker.

The truth is that immigration is complex. Nobody but a fool wants a completely open door, but the great economies, from the United States down, were built on substantial immigration by hard-working people driven to succeed.

But there is a cost, too. Communities are disrupted by change. Wages are undercut - as Australian unions know. Low-wage workers benefit an economy, but not every worker in it.

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The Latin Americans, Africans, Asians and Pacific Islanders doing the dirtiest - and now the most dangerous - jobs in our hospitals and care homes keep the wage bill for our health services down, and so also our taxes.

Immigrants pick the fruit in California and Lincolnshire and Queensland which we eat so cheaply.

But immigration is not just about economics, despite the impression economists give.

There are cultural matters. In your mind, ask those who stood on the shore at Botany Bay in 1788 about the benefits brought by the immigrants who sailed in.

I speak Welsh and I have witnessed Welsh-speaking communities destroyed by English-speaking immigration.

It's true that the villages I once knew are materially better off, with their bistros and prosperous shops selling pottery knick-knacks - but I see mostly the ghosts of a culture.

Don't get me wrong. I am extremely pro-immigration.

But do not pretend it's a simple matter of right or wrong. There are complex costs and benefits which need weighing.

In Britain, the tribes shouted each other senseless.

Australia should not do the same.