This, mostly, is the story of one morning spent on the internet, and what I found out. But let me first tell you why I was searching at all.

Yesterday Sir Tim Berners-Lee, one of the genius originators of the World Wide Web, announced the setting up of a new foundation, rather artlessly called the “World Wide Web Foundation”, which body intends to research what has been happening on the internet, and make suggestions on how to improve it. Which is a very good idea.

Anyway, in the lead-up to the foundation of the foundation Sir Tim mentioned his worries about one aspect of weblife, the fact that, using the net, “a cult which was 12 people who had some deep personal issues suddenly find a formula which is very believable - a sort of conspiracy theory of sorts and which you can imagine spreading to thousands of people and being deeply damaging”.

Of course, the dissemination of stupid ideas, and their equation with sensible ones, didn't need the internet. There are books and academics. When I recently referred to the “barking” theories of an American theologian concerning President Bush's supposed complicity in the 9/11 attacks, a senior professional in the psychiatric business wrote to me saying that he had found the theologian's works meticulously researched and “scholarly”.

In fact what they were was “scholarish” in that they referenced dozens of sources and contained hundreds of footnotes. Once you chased down those references and sources you discovered that they were partial, distorted and, very often, referred back to the works of other conspiracy theorists. There was nothing scholarly about them.

The great MMR scare was, largely, a print panic caused by ignorant journalists and media folk who were unable to distinguish between an unsubstantiated theory on the one hand and a scientific consensus built around significant studies on the other. The result was an absolutely unnecessary loss of herd immunity from measles in some communities. Someone should be sued.

The MMR business, like aspects of the climate change debate, was aided by a boneheaded refusal to discriminate between better and worse arguments. On the one hand a scientist says X, on the other hand another one says Y, so X and Y are roughly to be accorded equal respect. You get this in the creationist versus evolution debate. For example one BBC News website item last week, “Who are the British creationists?”, concluded its even-handed coverage of the debate by quoting a creationist vicar saying: “Evolution is a worldview that leads to futility. It's no wonder people are dissatisfied with it.”

But “evolution” is simply not a worldview, It is, rather, the best scientific hypothesis we have, by miles, for how species develop. By contrast both creationism and its sly relative, intelligent design, are readily falsifiable by scientific method. Evolution stands up.

But you know, folks, why don't we just teach people what they want to hear? A bit of intelligent design next to evolution in biology, a bit of flat Earth versus round Earth in physics, a bit of anti-Semitism versus Judaism in RE. That'd be fair.

Speaking of which, here's my tale. At the weekend I was tidying up some footnotes for my book on conspiracy theories, which is to be published next spring. In one chapter I deal fleetingly with a dead American conspiracist called Harry Elmer Barnes, and mention his affinity with/for a French Holocaust denier called Paul Rassinier. I was after a date and found it after a quick Google, but not before noticing that the Rassinier biography on Wikipedia, the online encyclopaedia, was a little bit odd. I let it go. Then, yesterday, I read Berners-Lee's comments and returned to the site.

I was right - righter, in fact, than I had realised. The biography begins with what seems to be a neutral introduction, but is in fact a selective description of Rassinier as a pacifist, activist, as anti-Nazi, a former concentration camp prisoner, and then, at the end of the introduction, comments that Rassinier has “come to be remembered for his views on the Holocaust, which have caused some to call him the ‘father of Holocaust Denial'”. Note that “some”, as opposed to the positive things - pacifist, activist, prisoner - that Rassinier can be called without qualification.

What then happens is a process whereby the entry's authors suggest a scholarly neutrality while, at the same time, normalising Rassinier's easily refutable views on the Holocaust. For example, Rassinier believed there was no deliberate Nazi policy of extermination of the Jews and no gas chambers. And we find, in the text, some support for this view cited in the works of “Princeton historian, Arno J. Mayer”. There is a short extract from Mayer's own book, warning readers that “sources for the study of the gas chambers are at once rare and unreliable”, that “there is no denying the many contradictions, ambiguities, and errors in the existing sources” and that “most of what is known is based on the deposition of Nazi officials and executioners at postwar trials and on the memory of survivors and bystanders”.

It's pretty clear what you're supposed to take from this: that Rassinier's argument about there being no gas chambers should be taken seriously. So I then Googled Mayer. The first thing I discovered was that exactly this selection of quotes from Mayer's work appeared on Holocaust-denial and neo-Nazi websites. The next thing I found out was that Mayer himself is a deeply controversial historian of the period, having argued that more Jews died of diseases in the camps than were murdered, and that the extermination was more a consequence of Nazi anti-Bolshevism than of anti-Semitism. The first contention is unsupported, the second is ludicrous.

But even given that, the Mayer quote was doctored. Mayer certainly believed that the gas chambers were real and that untold thousands had been killed in the death camps, but the nature of Mayer's qualification was withheld from Wikipedia readers. As was the fact that Rassinier's biographer, Jean Plantin, whose work was used for much of the Wikipedia entry, was fined and given a suspended prison sentence in Lyons in 1999 for Holocaust denial. You have to go to the French edition of Wikipedia to find that out.

So it took me an instinct, one morning, three hours, and a background in this material, to realise that the Rassinier Wikipedia biography - the first item on Rassinier that appears when you search for his name - had probably been written by someone with sympathies for the Holocaust denial camp of David Irving. The uninitiated, however, would never know, for not once does this poisonous bias break cover.

One of Berners-Lee's ideas was for a kind of Kitemark - or series of Kitemarks - of website quality. This wouldn't be centrally administered, but, presumably, would be applied by organisations wanting their websites to satisfy certain standards. Certainly widely used sites such as Wikipedia should have some method for expert evaluation and certification or, where sites have not been evaluated, for adding a serious intellectual health warning. Of course people must learn to discriminate themselves, but it would be naive to suppose that they won't need some help. Yesterday's small trawl suggests to me that it can't come a moment too soon.

Times Recommends

• It’s the beginning of the affair
• Afghanistan: still a price worth paying
• Heroes of the downtrodden