In the dealings of the Axeman and the Taxman we also need a Paxman – someone to tell us in fact what we remember we think we were told.
But we also need to know what everyone else thinks they were told. Nick Robinson's assembled audience of ordinary people – firefighter, businessman, consultant psychologist, low-paid worker, single mother – were there to tell us whether they were buying what the Government is selling.
Many had confident opinions about what the effect of the VAT rise would be. One wanted an admission that a pay freeze was a pay cut after inflation (Cameron gave it to her). Another valiant young woman said she worked like fury even though she was only £11 better off than "those who choose not to work".
It's a measure of the public mood that her moral structure seemed eccentric. Whereas the young woman who worked no more than 16 hours a week because there was "no point" in losing benefits by working more – she sounded a mainstream moderate.
Of such discrepancies are civil wars made.
Whoever wins this argument gets a generation's possession of the country's soul. Assuming we have one.
Harriet Harman is trying to shape the facts to start the argument on her preferred terms.
Are the rich, for instance, paying more in cash and as a proportion of their income than the poor?
It sounds straightforward but there are ways of presenting this so that you can choose an answer that matches your bag and shoes. It's yes and it's no and it's everything in between.
All right, something more black and white: how much money has been set aside to pay for restoring the index link to pensions?
She asked more than once. Cameron eventually replied with éclat: "One BILLION!"
Harriet looked through the Red Book ("or in her case the Unread Book", Cameron said by way of a passing smack) and went to the appointed page and read out: "Amount set aside: zero!"
But even that wasn't a secure point. Later briefing suggests it's been deferred, or referred, or offset. You know, it's a retrofisculated cross-payment.
Other questions were judged more inconvenient only by his replies: Will families with an income of less than £40,000 still have tax credits? Will there be fewer police officers at the end of the parliament than at the beginning?
The answers to these tended to start: "What we want to do is... " And, "What I am saying is this:" And then we didn't hear much for a few seconds while the shouts of angry laughter died down.
There are those looking for reasons to dislike David Cameron, and maybe they will find material there for their pastime. For others – it's funny how forgiving you are when you like someone.
He didn't answer the question? Oh, don't be priggish, no one ever does, and he did answer it, he answered it more than Tony Blair did, did you see how nice he was to the new members, he's so polite, he had some funny jokes, wasn't it good when he said, "the Unread Book"!
Hmmmm. It is suddenly possible to see how Gordon Brown's admirers could admire him; those who weren't disabled by animosity towards the fellow. It's quite shocking, this discovery of how subjective and irrational politics is.