On the very first day at Fourth Street Fantasy convention (which as of this posting, is still in session for another half-day or so), Elizabeth Bear mentioned running into a writing myth I’d never heard myself before: Women can’t ride stallions, because stallions get aggressive around women. Geldings or mares only for female riders, please.
This particular bit of misinformation is officially categorized as an urban legend. I call it a writing myth as well, because, while it is not a myth about writing, it is typical of a particular class of background misinformation that gets some writers (and occasionally editors) in trouble.
Specifically, the class of things that one is so sure of that one is positive one doesn’t need to check them out. Things “everybody knows,” or things that one learned from some supposed expert or authority figure. So the writer doesn’t check, and the misinformation gets propagated further. If the writer is lucky, the copyeditor will fact-check the assertion and point out the problem. If the writer is unlucky, then either a) the copyeditor will not check, and the writer won’t find out about the mistake until the story is in print, at which point the writer will learn about it from the most obnoxious fan at the convention, at the worst possible time, or b) the writer will have based a key scene or plot point on the misinformation, necessitating rewriting large chunks of the story when the copyeditor catches the mistake.
And then there are the things you find out that are verifiably true, but you can’t use because “everybody knows” something different. When I was writing Mairelon the Magician, I discovered that the use of “pig” as a vulgar slang term for the cops dates back to the 17th century. I thought that was really interesting, but there was no possible way I could use it in a novel set in an alternate 1814 England. After all, “everybody knows” that calling cops “pigs” dates from the 1960s. Similarly, there’s no way I would use the term “gay” to describe something bright and cheerful in a book set in the 1890s, even though that was what the word meant then. The word has been very thoroughly repurposed since then, and it’s too difficult for most modern readers to make the mental shift.
Once in a while, it’s worth the effort to fight to correct a particularly egregious and common “everybody knows,” but most of the time, trying to make it clear within the story that this is neither an accidental mistake nor an ill-informed invention on the writer’s part just throws the whole story out of balance and puts far too much emphasis on a minor bit of information. What this means is that sooner or later, someone is going to come up to you after the story is published and explain that you have gotten things wrong – that the word “telegraph” was not in use until after Samuel Morse invented the electric telegraph in the mid-1840s; that women can’t ride stallions; and so on. Almost invariably, these people inspire a deep desire in the writer to commit violence; equally invariably, there is no point in arguing with them. Experience shows that even if one says “The Oxford English Dictionary has four citations of the use of telegraph in the 1790s,” (sorry; mine’s a paper copy, so I can’t post a link) the person will simply blink and reiterate, “Yes, but there were no telegraphs until the mid-1800s.”
In other words, getting the facts right will not protect you from the terminally misinformed. Every writer I know who’s been around for more than a book or two has run into someone like this, and none of us enjoy the experience. (Even worse are the people who have confused their personal convictions and opinions about the past with historical fact, and who are perfectly ready to go on for hours or pages about their pet topic, whether that is a JFK-assassination-conspiracy theory, what the primary cause of the American Civil War was, or whether Ares and Aphrodite were considered lovers by the Ancient Greeks.
This nearly always prompts someone to say, “Well, if people are going to think it’s wrong anyway, why bother with all that research?” And some writers do adopt this attitude. Me, I’d rather be criticized by people who are provably wrong in their claims (go look at the OED; there really are four cites for “telegraph”, from 1794 to 1798, and a bunch more in the early 1800s) than by the people who actually know what they are talking about. Especially if a plot-point depends on it.