Lately I’ve overheard people making offhand comments to the effect that “It was fiction, so [something like whether wyrms have two legs or four, or cyanide really tastes like bitter almonds, or why the sea is boiling hot, or whether pigs have wings] is just made up.” It’s the idea that because the events of the story never happened, or the people in it don’t exist, the things around them — descriptions of their surroundings, perhaps, if it’s historical fiction, or the tools they’re using, aren’t to be trusted as accurate depictions of reality.
First of all, there is no good reason to think this. Suppose someone in the future wrote something about, say, how Hillary Clinton won the 2016 election. And suppose a small scene or piece of description had to do with some small detail (unrelated to the election) that’s familiar to us now, but won’t even be in the history books written in a hundred years. Suppose the authour did a lot of careful research to make sure that part would be accurate, knowing the impression that good or slovenly research can make on an educated audience. Suppose they actually got it right. And then suppose that this future audience, reading the book, assumed that as Event A did not happen, Thing B did not exist. Why? I don’t know, but that’s what readers often do. There’s no real logical connection.
People don’t realize the amount of research writers do, even on seemingly insignificant things that only appear briefly. We want to create an air of reality. We want the atmosphere to be consistent. And because publishers and informed readers want stories to be as realistic as possible, we have to. (Only real life often doesn’t follow the same rules, but as it’s real life it’s hard to argue with it. Some people try to do so, and they usually end up insane.)
But there’s no point getting very angry, even as a writer who does a lot of research even when it isn’t historical fiction I’m working on, and would like people to notice that and not assume that because it’s in a (fictional) story it’s not true. Many of the same people who assume that everything written in a piece of fiction is itself fiction also read the newspaper, or listen to the news on the radio, or read things online, and swallow them whole. Authours do get a sort of poetic justice in the end.