What's worse: being feckless and rich, or being feckless and poor? In my view, it's an unhelpful, even a stupid question. But I ask it anyway, because this question, in some incarnation or other, seems to inform so much political debate in Britain.

A version of it has appeared in the outcry over comedian Jimmy Carr's tax avoidance, as it always does when a wealthy person is revealed as unwilling to fulfill their fiscal responsibilities to the society in which they thrive.

What's worse, people ask: tax avoiders or benefit cheats? The funny thing is, whichever side of the ideological fence you are on, you tend to think the question is rhetorical, the answer obvious.

A version of it featured in the wake of last summer's riots, with many people suggesting looting trainers was a tiny misdemeanour compared to the looting perpetrated by international corporations, particularly banks, whose own feckless behaviour created not just a few frightening nights in a few cities, but years of economic recession and austerity, damaging or destroying businesses around the world. Again, according to your lights, this view is either inherently empathetic or inherently repugnant.

Another version has appeared in the wake of research highlighting the fact that children, increasingly, are turning up at school hungry. Evidence from several respected organisations – the Trussel Trust, Kids Company, The Prince's Trust and the Association of Teachers and Lecturers – strongly suggests poverty is the animating factor here. But right-wing posturers insist that there is no excuse, ever, for such an egregious dereliction of parental duty.

Just as unhelpfully, many on the left are too eager to undermine the economic argument by insisting on framing their arguments in terms of class. Middle-class people are often neglectful parents as well, they insist, while the poorest of people can be excellent parents. David Cameron may leave his child in the pub, but a lot of working-class parents would never even dream of taking their child to a pub in the first place.

As a child of the latter sort of parents, and as an, ahem, less-than-perfect middle-class parent myself, I certainly don't disagree with this view. But I do find it at best facile, and at worst counter-productive. Wealth is not an antidote to human frailty, obviously. But the important point, one that this particular left-wing argument self-destructively tramples over is this: poverty can and does drive people to desperate measures, and render them less able to resist their own frailties and flaws.

When I was on the dole and hungry during the early 1980s recession, I stole food – from shops and from my parents' house. I'm not proud of it. But the point is that as soon as I was working, and not hungry, I became a person who wouldn't dream of doing such a thing.

Had I never experienced want of something basic to my survival, I'd only know the me who wouldn't dream of doing such a thing as stealing. (I did benefit cheating, too, by not declaring cash-in-hand work.) And yes, I know that there are far finer, far better people than me – rich and poor – who would never steal food, even if they were actually dying of malnutrition. But I still think comfortable people can be too self-righteous, and can make generous assumptions about how noble they would be in adversity, never having experienced it.

One could argue that stealing to feed yourself is bad, but not as bad as sending your kids to school hungry. I offer, not an excuse, but an explanation. You're on the dole. You're depressed. You're not even looking after yourself properly, by any means. You're living on fags, booze, spliffs, takeaways and telly, long into the night. You're tired and a bit hungover. Tomorrow you'll make the changes you need to make, stop squandering your tiny budget on rollups, white cider, skunk and chips … But today the kids can get themselves off to school. They've done it before. They don't complain. They've done it so many times that you're not even in the habit of checking there's milk and marge in the fridge, or bread in the cupboard. I'd like to think I wasn't capable of that, under any circumstances. Yet, I can't say with any certainty that such behaviour, under certain conditions, is so very far beyond the bounds of "normal" human psychology. Nor, by the way, is having no alternative but to trust the children to get their own breakfast, because you have to leave for work so early, and endlessly being disappointed because they're kids, and you just can't get them to grasp how important breakfast is.

A lot of this is beside the point. Rich or poor, humans can be feckless, selfish. But the smaller the material largesse you can marshal to indulge your selfishness, the more it's going to impact on your dependents. Affluent people who choose, for whatever reason, not to adequately prepare their kids for school, will get an au pair to do it, give them money to buy breakfast on the way, or maybe send them to boarding school. It's not ideal. Money doesn't transform people and make them lovely archetypes. But lack of money makes less-than-perfect situations worse. It's sentimental to idealise noble poverty. (It's also naive to expect noble wealth.) It demands more than many people are capable of. Unfortunately, however, there's a tendency to do it in the ideologies of both left and right.

When New Labour started banging on about "lifting children out of poverty", I knew in my heart that its "project" was a dud. Widespread deprivation – among the adults who have the children, not the children themselves – is a signal of a systemic failure, not an unfortunate by-product of an otherwise healthy economy. New Labour tried to cure smallpox by putting makeup over the rash. Now, the coalition is suggesting the problem is that people simply won't take responsibility for putting the makeup over the rash themselves.

Actually, it is all pretty simple. Capitalism is supposed to create wealth in which everyone can share – not equally, but at least to the acceptable benefit of all. When capitalist societies start featuring widespread unemployment (as happened in the 1970s), or widespread instances of wages that don't cover basic needs (which accelerated in the 1980s), or simply increasing inequality (which started galloping in the 1990s), then it isn't doing what its champions expect it to do, and the state has to step in.

But many defenders of capitalism, feckless themselves, won't acknowledge the fact that capitalism is not providing enough economic security to enough people (or enough kinds of people), and instead blame the state precisely because it is obliged to mop up the human wreckage of this failure. The way to "shrink the state" (and tackle "child poverty") is to provide decent private sector jobs.

But after the private sector failed to do this, during many years of boom, Britain has a government that subscribes to the supreme inversion that dictates that removing the symptom of our economy's failure – state dependency – will cure the malaise. The smallpox still rages. Slapping state makeup on it was silly enough. But insisting that the silly makeup was the actual problem is catastrophically deluded. Capitalism claims its redistributive function as its great virtue. Yet it resents and blames the state's attempts to subsidise this virtue's failure. No wonder people find politics irrelevant. It is.