We don't have an impartial, truth-seeking BBC. We've got a toothless, neutral BBC

Consider: "Profligate Labour, unlike the financially responsible Tories, amassed a huge debt prior to the financial crisis, which is the major cause of our current economic problems."

This thought is everywhere. Tory and Lib Dem spokespeople drop it into their every other conversation on radio and TV. It's been repeated in the Press, on the internet, etc. to the point where it's become a factoid - something everyone just "knows" to be true.

However, Labour reduced the national debt by 22%. It inherited a debt of 42% of GDP from the Tories in 1997. By the start of the banking crisis the debt was just 35%. Here's a Conservative commentator, Ramesh Patel, confirming this. Patel concludes, "The deficit myth is the grossest lie ever enforced upon the people and it has been sold by exploiting people's economic illiteracy".

Also remember that David Cameron pledged to match Labour's spending plans (so much for "profligate Labour, responsible Tories").

Now, this "profligate Labour, responsible Tories" debt myth, if that is what it is, is politically enormously consequential. It's an election changer. It's also providing much of the justification for the heaviest assault on the welfare state since its creation.

If this is indeed a myth, shouldn't a state-funded national broadcasting corporation have a duty to explode it?  Don't they have a duty to educate and inform the public, to "speak truth unto Nation", ensuring that, particularly when it comes to myths that are likely to be election-deciders, politicians and journalists don't get to pull the wool over the public's eyes?

Yet, as far as I can see, rarely, if ever, do the BBC challenge this myth, certainly not in any sort of sustained and determined way.

But perhaps that is the stance that a properly impartial, unbiased BBC should take? It shouldn't be taking sides, right?

Actually, neutrality - not taking sides - is not the same thing as impartiality - providing an unbiased and objective investigation and assessment.

A politically neutral broadcaster will simply provide a forum in which opposing voices are given equal airtime. A politically impartial broadcaster with a commitment to revealing the truth is something quite different. An impartial investigative broadcaster has teeth and may robustly criticise a view. A neutral broadcaster is toothless.

The BBC's failure to challenge the debt myth effectively, given its scale and importance in shaping the political landscape and election results, may demonstrate neutrality, but it does not demonstrate an impartial commitment to exposing the truth and educating and informing the public.

A BBC committed to  revealing impartially the truth on key issues, in a country in which public opinion is heavily influenced by a largely right-wing press, will inevitably have to spend more of its time countering right-wing myths and fibs than left-wing myths and fibs. This will undoubtedly provoke accusations of left-wing bias. But actually, it's what any genuinely impartial broadcaster with a commitment to revealing the truth would do.

However, I fear we don't have a courageous, impartial, truth-seeking BBC. We've got a toothless, neutral BBC instead.