Poor children are to be made poorer unless their mothers can prove that they were raped. Sometimes all it takes is one subclause of a single policy to show the true face of an administration, and this nasty little addendum to the Welfare Reform and Work Bill is shocking in its casual cruelty.

Almost as shocking is the lack of outcry – so far – as the Tories slice what remains of the welfare state into tiny decorative scraps to wrap the presents they’re giving to their upper-middle-class base. Among the flagship cuts announced in the Budget are swingeing cuts to tax credits. Families with more than two children will lose up to £2,780 per subsequent child from 2017, with an important exception: the government, in its beneficence, has decided not to withdraw support if these extra children, these gurgling drains on the coffers of state, were conceived as a result of rape.

Let’s sit with that one for a while. Let’s ponder that piece of political positioning. Let’s slow down and smell the squeaky leather and stale air of the conference rooms where politicians sat down to discuss which children they are going to impoverish this year. Let’s taste the Victoria sponge in the taxpayer-subsidised Whitehall cafés where advisers gathered to decide precisely how much violence needs to be done to a woman before her children can eat.

There are layers of monstrosity here. Let’s unwrap them one by one. The first is the question of child poverty. Hungry, shivering children are a moral quandary for this administration: conservative logic, after all, holds that individuals are to blame for their economic circumstances but it’s hard to tell someone it’s their own fault they’re poor when they’re not even out of nappies yet. Having failed to meet every national target on child poverty, the Conservatives have simply redefined poverty. Now, unable to blame impoverished toddlers for their lot in life, they have decided to blame their parents for having sex in the first place.

Child poverty is not only important as an indicator of global development. It is an indicator of the human decency of any state. This government has made a clear statement that it is prepared to let more children grow up in poverty to finance an economic recovery structured to benefit the super-rich and nobody has yet removed the mirrors from the washrooms of Westminster. George Osborne’s argument that “work is the best route out of poverty” is moral rather than factual, which is another way of saying it’s a stunning lie. Most families receiving welfare benefits have at least one employed adult.

That’s the first horror. The second is the rape exception itself. To understand why it is so abhorrent, it’s worth looking at where else a similar principle is applied. Liberal campaigners for abortion rights sometimes condemn nations for forbidding the practice “even in cases of rape”. This has always seemed to me a telling twist of logic. If you truly believe that abortion is murder, then surely it remains murder whatever the circumstances of conception. If, however, abortion restrictions are less about the ethics of life than they are about punishing women for having sex, it makes perfect sense to make an exception for rape. If you want to make an example of bad women who have consensual sex by forcing them to carry unwanted pregnancies to term, it makes perfect sense to separate off the good women who became pregnant through no “fault” of their own. That’s what any rape exception is about: it’s about punishing women for having agency.

The same logic is at play in the proposed rape exception to the welfare bill. Feckless “welfare mothers” have long been favourite ogres of conservatives, but either children deserve to grow up in poverty or they do not. This is not about fairness, nor even about saving money. It is about sin. It is about punishment for sin, and specifically the twin working-class sins of poverty and fertility. It is also about misogyny.

Attacks on welfare are always attacks on women. As long as the sexual double standard exists in employment and childcare, women will need welfare more than men do. Women battered by a patriarchal system that does not consider child-rearing and domestic tasks “real work” will need support to raise those children. Already plunged back into the old sexist bargain – depend on a partner or watch your children suffer – the women of Britain now face another appalling prospect. They face having to beg a jobcentre adviser for the money to raise their rapists’ children.

That is the underlying horror in this package of poison. It’s a woman in a sterile office some months from now having to explain the circumstances of her rape to a welfare adviser who is inclined, both by modern economic policy and by ancient sexist prejudice, not to believe a word she says. If “welfare claimant” is already synonymous with “fraudster” in the public imagination, thanks to a long and successful campaign on the part of the right-wing press, so is “rape victim”. Less than 10 per cent of rapists are convicted in court, and crisis centres for victims of sexual assault are already closing up and down the country. How does the government think this is going to work? By keeping poor women in their proper place: abject and terrified.

I am not suggesting that children conceived in rape should not receive public support. I am suggesting that all children should receive public support – whatever the pearl-clutchers in government happen to think of their parents’ sexual morality.

As the Chancellor continues the time-worn Tory tradition of shrinking the state until it is just small enough to fit into ­everyone’s bedroom, we are speaking in hypotheticals – but they are hypotheticals that lay bare the bloodless moral core of this government.