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.
- 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.
- 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.
This, more than the economic arguments, is why the focus on "high-skilled immigration" is important.
After all, economically, immigration is good. One of the easiest shortcuts to growth is population growth, especially when that population growth comes in the form of people who arrive able to start working immediately. The canard about "benefit scrounging immigrants" is just that ; and given many migrants return home  long before retirement, even benefits which they may actually be eligible for aren't claimed.
Insofar as there are negative economic repercussions from such a policy, they would mainly limited to a potential downwards squeeze on low-skilled wages . But, as Dillow points out , we already have an answer for policies which help the nation overall while hurting those worst off: redistribution of wealth. And living wage policies, and stronger enforcement of them, would help too.
But, as Dillow bemoans, none of these points help win the argument. The record seems to show that talking about the facts doesn't change much, and immigration attitudes are remarkably set in stone.
Loosening the restrictions on high-skilled immigration, though, ought to be a much easier thing to implement. It would have much less of an effect on the overall figure, and would still result in large increases in welfare. But it remains a far more politically acceptable thing to push for. Even some of the attacks on high-skilled immigration – like the crackdown on student visas or the increased hurdles foreign graduates have to jump over to use their (still largely publicly funded) skills in the UK – only became popular once they were rephrased as attacks on low-skilled immigration. So the student visa discussion, for instance, was focused on "fraudulent" language colleges, rather than accredited universities which are also hit.
Hopefully there will still be a genuine change in attitude. I still look forward to a day where we accept that discrimination against someone based on where they were born is as unacceptable as discrimination against someone based on what gender they are. But until then, if we want more and better immigration, we may have to sneak it in under the radar.