Why are those so opposed to migration so blind to something that will cause it to increase so dramatically?

I’m not talking about the sheer barkingness and loose-cannonness of so many of UKIP's Councillors and MEPs; I’m not talking about how their plans to move to an American-style healthcare system (i.e. to dismantle the NHS) will doom them electorally once voters get to know about them; I’m not even talking about their barely-suppressed racism and anti-Muslim prejudice which will surely come back to bite them as Britain keeps becoming a more tolerant society. I’m talking about their outright climate-denial, and the consequences thereof, consequences that I think we are only just starting to understand.

Over the past 12 months, there have been repeated calls for a 'UKIP of the left'. Including from prominent voices such as John Harris in the Guardian, from the New Statesman, and more. The latest is Simon Jenkins, writing in the Guardian. His article (Jan 24) supportive of the Brighton Green administration's referendum on increasing Council Tax (to preserve vital services that government cuts are endlessly squeezing) is welcome. His claim that the Greens are 'the UKIP of the left' however requires further examination.

Last week in Parliament the new ‘Green House’ thinktank launched with a report I’ve authored on how to restructure our democratic institutions to take account of those who are not here yet: future people. The 30 page report prepared with the assistance of the new ‘Alliance for future generations’ umbrella-group of NGOs is called Guardians of the Future.

The starting point of my thinking on all this is this question: ‘Democracy’ means ‘government by the people’, but who are ‘the people’?

If you want a primer on Wilkinson and Pickett's joint book The Spirit Level, then the pieces here are worth a look (one by me). And for a comprehensive set of responses to their critics, including a pre-emptive strike against Gerry Hassan’s recent piece on OK this is all you need. (It is worth noting too that Wilkinson and Pickett’s work is peer-reviewed; that of their critics isn’t.)

For me as a philosopher, the thing about The Spirit Level that is most exciting is that as a study of the pervasive harms of inequality it strongly suggests that John Rawls's 'difference principle', which says that inequalities are OK provided that they materially benefit the worst off, a principle that has dominated political philosophy for 40 years, is simply wrong. Empirically wrong.

Many voters are 'against immigration' and against foreign aid (they say things to me on the doorstep along the lines of: "We should take care of our own; that's enough"); and yet they insist that they are not racists. This includes many Tories and the whole of UKIP – and many ordinary voters.

My reaction, perhaps like yours, is to suspect that, actually, in many cases they are racists. But it is hard to prove that; dangerous to say it (at least, to someone's face) – and, I increasingly suspect, not always true, not by any means.

It is no longer socially-acceptable to exhibit prejudice against ethnic minority people on grounds of their ethnicity, women on grounds of their gender, or working-class people on grounds of their class. The last bastions of discrimination are being overcome: such as prejudice against gay and lesbian people, and against disabled people.

But is there one crucial bastion of discrimination still strongly in place?