There's a good talk by Jonathan Haidt examining the differences in moral thinking between liberals and conservatives. This is American usage of course, but particularly focussing on social rather than economic issues, so it is not too inaccurate.
Haidt identifies what he calls the 5 foundations of morality by which he means 5 traits in evolutionary psychology (touched on here), connected with questions of moral behaviour. These are:
1. Harm/Care. We are disposed to bond with others and care for them, and have strong feelings about those who cause harm.
2. Fairness/reciprocity. This is associated with the golden rule ("Do unto others as you would be done by.") Also, I dare say, there is a fairness/reciprocity basis to both support for a social safety net, and for free trade. Both are reciprocal, but are often associated with opposing ideologies.
3. Ingroup/loyalty. We have a powerful instinct for forming tribes, mostly to oppose other tribes. More on this shortly.
4. Authority/respect. The anarchists' lament. Stop taking orders, they might say. Just listen to me and stop taking orders!
5. Purity/sanctity. Not just sex, but also attitudes to food for example.
So while we have the brain wiring to be guided by all of these consideration, there are differences of opinion as to which are moral. According to the video, conservatives tend to recognise all 5 as moral, and liberals just the first 2. In contrast to ingroup/loyalty we celebrate diversity; in contrast to deference to authority, we question it; in contrast to purity, we celebrate the freedom to be impure.
Haidt makes some sweet bipartisan point about the conservatives having a point, using all the tools in the toolbox to maintain order (yuk! stability, perhaps, please?) and that libs and cons therefore exist in some wonderful symbiotic dynamic harmony like yin and yang. But I will move swiftly on from there by looking more closely at the 5 foundations and British politics.
Disagreements here a generally over what constitutes harm, and the extent of our duty to care for our neighbour. Mill, in On Liberty, argues, for example, that there are duties of care - to throw a line to somebody drowning for example. I see little disagreement on this except from libertarians. Am I right?
But while I disagree with libertarians who say that the state should not seek to do good, I agree that it should not try to (and can't) make us good. Socialists on the other hand don't seem to see a problem with that. (Do other liberals agree with me?) Conservatives can be found in both camps, I guess.
Greens generally apply harm/care thinking to the natural world, which, it can be argued, means a failure to apply it properly to human beings.
Socialists believe that the poor deserve more, conservatives that the rich deserve more. Greens believe that everybody deserves less. I, frankly, don't know who deserves what, but I bet it isn't a function of class identity. Fairness in the sense of equal rights is still opposed by many Conservatives, but otherwise is largely agreed.
Both free trade/freedom of contract, and the social safety net and public services can be seen in terms of reciprocity. Socialists and greens are against half, and conservatives and libertarians against the other half; liberals support both halves.
I agree that liberals are not greatly moved by this (except obviously as political partisans, like everybody else). Socialists and conservatives represent ingroups based on social class.
Socialists have struggled politically from the numerical decline of the unionised working class. Labour, therefore has had to expand its ingroup suffering much pain in the process.
This has left the working class feeling justifiably aggrieved that nobody represents them, creating opportunities for the BNP. The BNP being of course the epitome of the evil of ingroup/outgroup thinking.
Having your ingroup taken away, or being betrayed by it, can be an utterly crushing experience. Politics would perhaps be much healthier if there were an old-fashioned working-class socialist party. As long as it never won any power. We may have the best policies for millions of poor people, but we don't represent their interests against those of the middle classes.
Clearly this issue separates liberals and libertarians from conservatives and fascists. Socialists appear in both camps and in the middle ground.
I think Greens have a complex relationship with this one. I know many would post them firmly in the authoritarian camp, but they also have a strong anarchist influence. In any case this is not so much about whether strong authority is necessary, or even helpful, in saving the planet - a question we will all have to face; but whether an attitude of deference to authority is a good thing, on which point I think they are largely with liberals.
This is not so clear as in the US with its big religious right, although the same trend is apparent.
However I think the biggest on purity/sanctity are the Greens. Organics, GM, alt meds, being close to nature. Support for such "natural" things, often out of proportion to the benefits (if any), seems to be a purity thing.
In Haidt's surveys everybody recognised Harm/Care and Fairness/Reciprocity as moral instincts, but conservatives did tend to rate them lower than liberals. Understandable: these different factors must be weighed against each other. And yet libertarians also seek to diminish the scope of considerations of harm/care and fairness, reducing them to "no initiation of force" and free trade. I think this explains why they are seen as right wing, with some justice, even though they don't agree with conservatives on foundations 3 to 5.
So this just illustrates yet again the error of lumping any of these ideologies with any other. A five dimensional compass would not sort these babies out. It is no good lumping greens with fascists or communists, or lumping libertarians with conservatives, as if this could end the debate. Both must be opposed for what they actually say, unless, of course, on occasion, they are right.