It’s easy to laugh at the very wrong things that people once believed, but try not to feel too superior. My friend Susannah Gregg was living in South Korea and working there as an English teacher when she first learned about fan death, a common belief among people in that country that oscillating desk fans are among the most deadly inventions known to man. She was stepping out for a beer with a friend when he noticed, to his horror, she had left her fan running with her pet rabbit still inside her house. Her friend, a twenty-eight-year-old college graduate, refused to leave until she turned off the fan. He explained to her that everyone knows you can’t leave a fan running inside a room with the windows shut. That would mean certain death. It was shocking to him that she was unaware of something so simple and potentially life-threatening. Susannah thought he was kidding. It took several conversations to convince him it wasn’t true and that in her country, in most countries, no one believed such a thing. She successfully avoided absorbing the common belief not because she was smarter than her friend but because she had already done the experiments necessary to disprove the myth. She had slept in a house with a fan running many times and lived to tell about it. Since then, she has asked many friends and coworkers there about fans, and the response has been mixed. Some people think it is silly, and some think fan death is real. In 2013, despite the debunking power of a few Google searches, the belief that you shouldn’t fall asleep or spend too much time in a room with a running electric fan is so pervasive in South Korea that Susannah told me you can’t buy one within their borders without a safety device that turns it off after a set amount of time. The common belief is so deep and strong that fan manufacturers must include a safety switch to soothe the irrational fears of most consumers.

In Latin, it is argumentum ad populum, or “appeal to the people,” which should clue you in that this is something your species has worried about for a long time. The fallacy works like this: If most people believe something is true, you are more likely to believe it is true the first time you hear about it. You then pass along that mistaken belief, and on and on it goes.

Being a social creature, the first thing you do in a new job, new school, new country, or any other novel situation is ask people who are familiar with the environment to help you get acquainted with the best way to do things, the best places to eat, the hand gestures that might get you beheaded, etc. The problem, of course, is that your info is now based on opinions that are based on things such as conformity and emotions and norms and popularity, and if you’ve spent any time in a high school, on a dance floor, or at a rave, you know that what is popular is not always what is good or true. It isn’t exactly something we’ve overcome, but at least we now have a strategy for dealing with it.