Cutting social security is easy, quipped one former minister tasked with doing just that, explaining that he could save anyone £1bn a year – just so long as they told him which million families to take £20 off every week. Sweeping rhetoric blasted the welfare reform bill through the Commons unscathed, but more forensic scrutiny in the Lords is exposing exactly who will be hit. The government suffered one important defeat just before Christmas and went on to lose three straight votes on Wednesday – and there's a way to go yet.

All three causes that triumphed were worthy winners: protections for disabled young people who could never work; for cancer patients; and for all of those with serious health problems who face having their entitlement cut off cold after just one year. Looming Lords divisions will address other flaws, including new charges on lone parents for chasing maintenance which they are owed, and the new cap on the benefits of larger families which will – as the children's commissioner has just pointed out – unfairly and perhaps unlawfully penalise youngsters from bigger broods.

Underlying all of these disparate problems, of course, is the drive to reduce the deficit with undue haste, as well as the deliberate decision to concentrate the pain on disability and family benefits, as opposed to sharing the suffering more evenly across pensions and certain other services. No government could create a good news story out of this unbalanced retrenchment, but this administration has compounded the difficulties by neglecting the details at every stage. Iain Duncan Smith speaks passionately about creating a simpler new universal credit for claimants, but the very principles which will govern the new system are not always thought through, which is why the rights of disabled young people were casually swept away for the sake of a few million pounds, prompting the first of Wednesday's defeats. Neglected, too, is the new credit's design – hence the ludicrous exemption of council tax rebates which could undermine the whole architecture. Last but not least, there is the small matter of delivery. New payment systems have, putting it mildly, not often worked happily. The warnings of the public accounts committee yesterday echoed the growing private concerns of officials.

Welfare minister Lord David Freud gave the saga a twist by moving to reverse his defeats in later votes, after most opposition peers had left for the night. A conspiracy to thwart the will of the house? It's hard to judge, given the intricacies of Lords procedure. But either way, a mix-up of this sort is hardly likely to encourage rebellious peers to relent. Slowly but surely, the ugly fact of vulnerable people losing out is coming to haunt this debate – because it is not spin but the truth that has power.