There is a very good reason why the House of Commons speaker – as in most parliamentary democracies – will not tolerate use of “unparliamentary language”: however bitter and hostile parliamentary debates become, they should not degenerate into playground name-calling. For that reason, MPs do not call it each other “liars”.

David Elstein has apparently not learned these rules of civilised and dispassionate debate. In his recent blog, in response to a well-argued post by the BBC’s Director of Policy James Heath, he crossed that line and called James a liar - not just once, but forty times. In doing so, he has demeaned himself, this site, and one of the most important political debates of the 21st century.

For nearly 30 years David has denounced the licence fee system of funding the BBC, railed against what he believes to be an unjust compulsion, and passionately advocated its replacement by voluntary subscription (except for a brief few months when a new Director General was being appointed and his animus temporarily evaporated).

It will therefore come as no surprise that he found fault with James’ arguments, because he despises any justification for a licence-funded BBC. His intellectual position is a doctrinaire mixture of ideological puritanism and right-wing free market fanaticism which elevates the principle of consumer “choice” above all other collective social, economic and cultural benefit. It is a familiar refrain which I have previously rebutted for OpenDemocracy, and do not intent to revisit here.

He is perfectly entitled to his views. He and I have done frequent battle on platforms, in broadcast studios and in print. These are robust and civilised debates in which I tell him why his arguments are dangerous and entirely wrong-headed, using many of the arguments advance by James. He responds in kind. But never once, in all those years of heated exchanges, has he called me a liar.

I am certain that, if David’s vision were implemented, we would eventually lose an internationally admired and domestically effective cultural institution. But David is apparently not bothered if he’s wrong. In oral evidence to the Culture Media and Sport select committee Inquiry into the Future of the BBC, he made it clear that he was entirely unconcerned about the consequences of his own fallibility: "I am only recommending [subscription] because I think it would make the BBC better. I may be wrong; I am quite relaxed about that."

He is wrong, but that is his prerogative. What he is not entitled to do, when attempting to impose his ideology on the national conversation, is to call his opponents liars because he takes exception to their arguments. Many of his own points are tendentious and over-stated (precisely the accusations he levelled at James Heath), and couched in a now familiar combination of sophistry and intellectual pedantry. But they are not dishonest. He is not a liar. And to resort to that kind of juvenile invective is to debase the currency of proper intellectual debate.

Having been comprehensively out-argued by Claire Enders and Steve Hewlett during his select committee appearance, David at one point turned to Claire and said patronisingly: "Claire, you have to take the emotion out of this". I would offer him exactly the same advice. He is in danger of becoming as preposterous as the argument he recently advanced in a collection of essays that “the BBC might feel nervous about being one of the few public bodies with a vested interest in mass immigration….. ”. To which I can only reply: “Do calm down, dear”. And add that he might, on reflection, wish to offer a personal apology to James Heath for such an undignified personal attack.