(The opinions made some people seem wrong and other people seem right.)
One day a person writes a new article for the wikipedia. The article is about a historical event and the person has read everything he could find about the event. The thing is, there are not many historical documents about this event. Nonetheless, everything in the article has a citation, except for a few statements that are the author's own opinion. The opinions are not strong or implausible but, they made some people seem wrong and other people seem right. Really, one could not tell from the historical record who was right and who was wrong, but the guy who wrote the article found himself taking sides. In any case, since no one knows much about the event, none of the other editors in the wikipedia would catch the opinion slant in the article.
(She's smart enough to know that wikipedia can be wrong, so she spots checks some of the sources.)
In a few months a reporter for a local paper is looking to do a story about the historical event. She searches the web and skims the wikipedia article to get a base idea for her research. She's smart enough to know that wikipedia can be wrong, so she spots checks some of the sources and finds that the article seems to be pretty solid. She doesn't dig too deep, it's just a newspaper article after all. She notices that one of the interesting statements in the article isn't sourced, so she calls a local university and asks a historian about it.
But, she asks a leading question, since she really wants to include the opinion bit in her article, it's probably the most interesting thing about the historical event! The professor at the university responds to the leading question in a correct way "That would certainly be possible" he says. The article runs in the local paper with the slant that makes some of the people seem wrong and others seem right. The man who wrote the wikipedia article notices the paper. He uses the newspaper article as a source for the opinion parts of his write-up. Now it is perfectly sourced.*
(In 10 years time, the slant invented by a wikipedia editor is the accepted understanding of the event.)
In a year or two a grad student notices the article in the wikipedia and the quote from the professor that seems to support the slant. He decides to study the event more from that angle. He produces a scholarly article furthering the slant, since, as often happens, he finds more of what he was looking for becuase he was looking for it. His scholarly article becomes widely cited, and, in 10 years time, the slant invented by a wikipedia editor is the accepted understanding of the event.
There is no one alive from the event to contradict it, and maybe it is even correct, but it is ultimately based on an opinion of an individual who had a way of looking at the facts that seemed plausible enough others. A card-house of citations and sources was built up around the theory. It is an invented truth.
I don't think that this kind of development is anything new, this isn't an essay about "the perils of wikipedia," per se., but it is about how truth can be invented. It is a little scary, but only, I suppose if you take everything you read as gospel. I think it is important to be on the look-out for invented "facts."
Are there any "truths" that you regard as invented?
*Based on a true story. The rest is fictional... for now.