What function do, or should, left-wing parties serve? I ask this old question because of a paper which Jon has drawn my attention to.

Peter Taylor-Gooby points out that, as inequality has risen, attitudes towards the poor and benefit recipients have hardened.He suggests several longer-term reasons for this, among them the decline of class alignment and rise of individualism. I'd add three other factors:

- A mistaken factual base. The public under-estimate bosses' pay and over-estimate welfare benefits.

- Recessions usually make people more mean-spirited.

- Capitalism generates cognitive biases (ideologies) that result in hostility to welfare recipients.

As Taylor-Goody says, it doesn't need to be this way: "Alternative approaches that emphasise reciprocity, solidarity and inclusion are possible."

This poses the question: how do we get to such approaches from where we are? One possibility is to look to a leftist party to argue for them. But there are good reasons to expect the Labour party not to do this. Just as companies' marketing strategies rarely work by telling potential customers they are stupid, so political campaigns rarely do so. This is why Labour panders to some of the worst aspects of public opinion, on immigration or welfare, rather than outrightly opposes it. The Labour party is a managerialist marketing strategy, not a force for truth and justice.

But if Labour is not an agency for radical change, what is? Sure, there are a few bloggers and columnists who are trying to shift the Overton window, but these tend to preach to smallish groups of the already-converted.

This, of course, is not to deny that social attitudes can change. For example, during my lifetime, attitudes to gays has improved considerably. But I fear that this progress has been like Max Planck's view of scientific advance - it has happened one funeral at a time.

And herein lies a paradox of the left. Whilst we have spent decades advocating social change, we have remarkably few answers to the question: through what mechanisms, exactly, can it be achieved?