It’s frustrating to propose an idea and have people dismiss it just because it’s weird. You’ve surely seen people ridicule ideas like worrying about wild animal suffering or computers becoming sentient or comets crashing into the planet. I’ve encountered some of this for claiming aspartame is likely harmless but ultrasonic humidifiers might not be.

The thing is, dismissing weird ideas is not wrong.

I have a relative who got the J&J vaccine for Covid, so as some people were getting their third shot, she still only had one. I claimed that it would be fine to go ahead and get a second shot of an mRNA vaccine since this was sure to be approved soon, and was already approved in some countries. She gently responded, “I will get another shot when my doctor tells me to.”

Was she wrong? In a narrow sense, maybe. Mixing-and-matching of vaccines was approved soon after, and I maintain that this was knowable in advance. But more broadly, she was following a good strategy: For most people, “just do what your doctor says” will give better results than, “take unsolicited medical advice from uppity relatives.”

From a Bayesian standpoint, it would arguably have been a mistake if she did listen to me. Skepticism of weird ideas is a kind of “immune system” to prevent us from believing in nonsense.

The problem, of course, is that weird ideas are sometimes right. For 200 years, most Western people thought that tomatoes were poisonous. Imagine you were one of the initial contrarians going around saying, “Well actually, tomatoes are fine!” and demonstrating that you could eat them. I bet you’d have had a rough time.

Especially because if you convinced someone and they went home and cooked some tomatoes, their cookware probably had lead in it which the acidity in the tomatoes would leach out, leading to lead poisoning. Your follow-up campaign of, “really tomatoes are ok, we just need to switch to non-leaded cookware!” would bomb even harder.

I’m glad people persevered so we aren’t covering our pizzas with mayonnaise. But how are we supposed to resolve this tension in general? Here are eight proposed rules.