Sunny draws my attention to the "awful" fact that the public are overwhelmingly hostile (pdf) to immigration. This raises the question: what if anything can be done to change this?

One possibility is to appeal not merely to the facts, but to the evidence of people's own eyes. A poll (pdf) by Ipsos Mori has found that although 76% of people think immigration is a big problem in Britain, only 18% think it a big problem in their own area, and twice as many say it is not a problem at all.

However, several things make me fear that an evidence-based approach won't suffice to change people's minds:

- Hostility to immigration does not come merely from the minority who lose out in the labour market. People from higher social classes and the retired are as opposed to immigration as others. And even in the 60s, when we had as full employment as we're likely to get, there was widespread anti-immigration feeling. This suggests we can't rely upon improving labour market conditions to improve attitudes to immigration.

- There's little hope of attitudes changing as older "bigots" die off. The Yougov poll found that 68% of 18-24 year-olds support the Tories' immigration cap.

- Antipathy to immigration has been pretty stable (in terms of polling if not the violence of its expression) since at least the 1960s. This suggests there are deep long-lasting motives for it; I'd call these cognitive biases such as the status quo and ingroup biases.

- There's an echo mechanism which helps stabilize opinion at a hostile level. Politicians and the media, knowing the public are opposed to immigration, tell them what they want to hear and - a few bromides aside - don't challenge their opinion; one of the many appalling features of "Duffygate" was Gordon Brown's abject failure to challenge Mrs Duffy's hostility to immigration. (The BBC is also guilty here: "impartial" debates about immigration often seem to consist of the two main parties arguing about how to control it.)

All this makes me ambivalent about "calls for a debate" about immigration. Part of me thinks: bring it on - let's talk about the facts. But another part of me thinks that rightists just want to raise the salience of an issue on which public opinion is on their side.

There is, though, a deeper issue here.The fact that public opinion is hugely and stably opposed to immigration suggests that there is a tension between liberty - immigration is an issue of freedom - and democracy.