After some distressing experiences around bill sharing in restaurants, a friend identified a syndrome he called "I only had the prawn cocktail", which is probably self-explanatory. Current advice on this subject (Debrett's: niggling "will be embarrassing and look cheap") confirms that shared bill evasion remains a problem, maybe a growing one, as might be expected in hard times. It is still a surprise, however, to find "I only had the prawn cocktail" elevated into a political philosophy, one that actively cultivates resentment in individuals obliged to subsidise services from which they do not personally benefit.

Why, for example, should non-rail users help fund a railway system? I barely use network railways. Thus, as transport secretary, Patrick McLoughlin, agrees, in the context of crippling, above-inflation fare increases, I can hardly be expected to pay top dollar as a taxpayer for a transport system whose cost and quality concerns me roughly as much, on a daily basis, as donkey provision in Cleethorpes. In fact, as McLoughlin suggests, it is pretty gracious of those of us who get by without trains to chip in anything at all. "The taxpayer overall is contributing a lot," McLoughlin says. "And I am afraid that the passenger has to make his contribution. He does it as a taxpayer and as a passenger as well."

This concern for non-commuters has not, of course, put an end to divisiveness. The Tory MP Dominic Raab, who promises to be to the credo "I only had the prawn cocktail" what the US philosopher John Rawls was to the common good, says that southern passengers are being ripped off to bail out northerners. "Labour's warped franchise agreements with train operators left my constituents paying a massive subsidy for other lines," he told the Times, under the headline "South 'cheated' in fares hike".

It is not enough for Raab's personal tribe to question, quite rightly, the great railway scam supervised by the coalition; the Raabites' resentment must be converted into hostility against other users, in this case northern passengers who may still not be aware that, by patronising, say, the TransPennine Express, they are personally extorting cash from commuters on the 08.03 Esher to Waterloo. But in an era of southern triumphalism, the inhabitants of an area recently characterised by another Tory as so desolate, being "well away from anybody's residence", as to be ripe for merciless fracking, might well experience this as a small victory.

If the phrase "We're all in this together" is less often on George Osborne's lips nowadays, maybe that is not so much down to rhetoric-shame as the realisation that, as demonstrated by north v south, strivers v shirkers, baby-boomers v Generation Y, "We're all at each other's throats" is emerging as the more appealing rallying cry. When any social investment not personally advantageous is apt to be perceived as daylight robbery, there may be more traction in Raab's imputation of something actively warped about the common good, the idea of "certain general conditions that are ... equally to everyone's advantage", as Rawls defined it. Certainly, Labour did not surface from its torpor, as it might once have done, to contest McLoughlin's depiction of taxpayers' and rail passengers' interests as inimical, or to point out that an accessible system benefits everyone, in the first place by taking cars off the road.

The transition of the railways from a communal to a more niche service, very much for those with a private train habit, builds on the important work of Lord Browne in exposing outdated notions of collective benefit. It was Browne who argued in his review, Securing a Sustainable Future for Higher Education, that, since, to paraphrase, graduates would be the ones making shedloads out of their degrees, they should be made to buy them, regardless of progressive taxation and the advantages to their country of an educated population. One page was called: "How would it benefit me?" For the government, Browne's answer was: "Less involved, less regulation." Voters have duly been encouraged, following this switch to educational pay-as-you-go, to question whether the common good is not really a quaint term for a bunch of sectional bonuses, paid for, as Browne put it, by "people who may not have participated".

As the railway system drops off the list of civilised essentials, along with hundreds of libraries (irrelevant to anyone with an Amazon account), attention turns to other services dependent upon payments from non-beneficiaries. Flood defences, for instance, provided by people who live nowhere near a river. With stay-at-home parents already demanding to know what they have to gain from a childcare tax credit, and drivers challenging the right of cyclists to use space on "their" roads, child-free adults, at least, might want to ask: "How would it benefit me?", about fertility units, maternity leave, schools, playgrounds and all the related services in which they, like Browne's non-graduates, will never participate.

True, as he conceded with universities, there are some social benefits to be had from these endless children, but nothing to compare to the value their parents extract. By way of an example, the Tory-led Worcestershire county council is already wondering if the parents of children in care should not "contribute" to the soaring cost of vulnerable juveniles.

As much as Labour spluttered, in response to the last proposal, a concerted defence of the common good has become more difficult, if not impossible for the party, following Ed Miliband's U-turn on universal benefits. In January, in "one nation" mode, he explained that "universal benefits are an important bedrock of our society". By June, Ed Balls was regretting that "it can no longer be a priority to continue paying the winter fuel allowance to the wealthiest pensioners"; Miliband promptly confirmed that child benefit cuts would not be reversed.

So Labour also menaces, only from a different direction, social cohesion already vitiated by the coalition's attempts to sever taxpayers' supposed interests from those of students, train passengers, northerners, nimbys, families on income support, and any other social group with the potential to be distanced and redefined as a bunch of over-indulged leeches.

The problem of dumping universality, Peter Hain thinks, would be this: "If middle Britain ceased to benefit from the welfare state through at least some universal benefits, why would they still finance the lion's share of it?"

No less than the abject Raab, fomenting intra-service animosity in the quiet coach, Miliband may be correct to diagnose a growing public unwillingness, exceeding even that of the angry prawn cocktail consumer's, to subsidise the allegedly undeserving. But to exploit, rather than overcome, such resentment seems a curious way for Miliband to preserve Labour values that, according to another senior party figure, are "built on relationships, in practices that strengthen an ethical life. Practices such as solidarity, where we actively share our fate with other people".

That was David Miliband in the Keir Hardie lecture, delivered shortly before he lost to Ed.