In recent weeks a document alleging all manner of Russian chicanery involving Donald Trump has been circulating among American journalists. Written by a former intelligence official from the UK it includes lurid sexual allegations, alongside claims that Trump’s associates are effectively Russian agents or in cahoots with the Kremlin and FSB to target Trump’s opponents in the US.

If the allegations are true they are dynamite. But attempts to substantiate the substance of the document have so far failed, which is why it has gone unpublished‎. That is until now, or last night, when Buzzfeed (the emerging digital giant) published in full anyway, acknowledging that it had no idea what was true and what was not.

All journalistic‎ enterprises make mistakes, sins of omission or adding two and two and coming up with five. But Buzzfeed’s blunder is in a different category. They admit the allegations are unsubstantiated, but because they are interesting they are just putting it out there for readers to make their own minds up. This is prurience masquerading as public interest. The defence seems to be that this document was shown by the CIA to Trump last week. So what? That’s hardly a test of accuracy or reason to publish in full.

The publication of the document not only turns journalistic convention on its head in terms of truth. It probably helps Trump, because it drags his critics – who accuse him of being untruthful – down to his level. The charge against Trump is that he is a stranger to the truth and that he and his supporters deploy fake news to bolster their man.

Now, here are his critics – who rightly lament his post-truth approach – doing something rather similar in a bid to destroy him. Already several basic factual flaws have been highlighted in the document, which enables him to deny the whole lot. Here poor journalism has given him a get out, which means he can and will denounce anything from the intelligence community he does not like. The source of the latest report is described as credible, but then so were the sources that provided the information on WMD, Iraq and uraniam before the 2003 war.

Trump’s critics need to grow up. He won’t be defeated by playing him at his own game and abandoning standards just to get even. Time and again he has benefited from his critics descending from the moral high-ground, choosing to try to out Trump Trump. Remember the ruination of Marco Rubio, who humiliated himself in the primaries by talking about the size of Trump’s hands? Rubio lost his dignity and never recovered.

What is needed on Trump is painstaking work and a dedication by reporters to establishing the facts. If these claims are valid, let’s see the evidence and the Americans can take it one step at a time towards impeachment if it is true. Oh, and someone needs to establish whether the Trump tapes – video and audio – that are said to exist do exist.