YOU don’t have to spend very long in politics to understand that it only takes a syllable or a hint of a fact to hand an opponent a golden opportunity. There will be thousands of people who still believe that Britain actually does send £350 million to Brussels every week despite clear and repeated proof that this was not the case.

But the fact that the total bill was £350m before the rebate, European payments and the benefit of being part of the single market were taken into account was enough for Boris Johnston to parade up and down the country in front of a bus proclaiming the “truth.”

Political communicators know the key has become not whether something is absolutely true, but whether there is a big enough kernel of truth to make something stick in the public mind.

It’s the same in journalism; one disputed claim can mean weeks and weeks of to-ing and fro-ing with the regulator over a story which is fundamentally true, and defamation cases have gone all the way to proof to establish that mistakes do not necessarily mean a story is damaging.

Proof is a very difficult word. A criminal case must be proved beyond all reasonable doubt but a civil case is judged only on the balance of probability, even though the impact on the individuals can be just as devastating. So footballer David Goodwillie was cleared of rape in a criminal trial but lost the civil case brought against him by his victim because the bar of proof was lower.

Which brings me to recent changes to UK child tax credit which limits payments to the first two children from this month onwards. As most people will now know there is a set of exemptions including multiple births, adoption and those children born as a result of coercion, the now-infamous rape clause.

Whether or not you agree with the two-child cap in principle depends on your attitude to welfare reform but I don’t know anyone who thinks a rape victim should be put through a further ordeal to claim a financial benefit to which the law says they are entitled. And so civil servants devised a system to ensure tax credits were paid for children born as a result of coercion; clumsy, awkward or whatever, it seems to me that the motivation for creating the exemption was undeniably well-meaning and I have little doubt (although no proof) that had there been no exemption there would now be a demand for one.

We have heard over the past few weeks, and in this week’s Holyrood debate, that women in these circumstances will have to prove their child was born as a result of rape and that they will have to fill in an eight-page form. Neither of these claims is true, but the impression opponents have created is that the process is effectively a repeat of a courtroom cross-examination and if this were the case I’d be as outraged as the First Minister.

The kernel of truth is that there is a process and there is a form, and yes with the explanation and instructions it runs to eight pages. But it is for health professionals to complete and nowhere is there any demand for proof, even if there have been no criminal proceedings. Yes, the mother has to sign the form, but by the very nature of the circumstances the mothers will already be in the healthcare system, getting help from GPs, midwifes and health visitors for all aspects of their well-being and meeting all the bureaucratic requirements that bringing a new person into the world involves.

It may be that the system doesn’t work as intended, but its simplicity is such that with the sympathy and sensitivity which has been spelt out as an essential part of it then it should.

But this is politics and that’s not what the First Minister or Kezia Dugdale want.