We recently established a successful Useful Concepts Repository. It got me thinking about all the useless or actively harmful concepts I had carried around for in some cases most of my life before seeing them for what they were. Then it occurred to me that I probably still have some poisonous concepts lurking in my mind, and I thought creating this thread might be one way to discover what they are.
I'll start us off with one simple example: The Bohr model of the atom as it is taught in school is a dangerous thing to keep in your head for too long. I graduated from high school believing that it was basically a correct physical representation of atoms. (And I went to a *good* high school.) Some may say that the Bohr model serves a useful role as a lie-to-children to bridge understanding to the true physics, but if so, why do so many adults still think atoms look like concentric circular orbits of electrons around a nucleus?
There's one hallmark of truly bad concepts: they actively work against correct induction. Thinking in terms of the Bohr model actively prevents you from understanding molecular bonding and, really, everything about how an atom can serve as a functional piece of a real thing like a protein or a diamond.
Bad concepts don't have to be scientific. Religion is held to be a pretty harmful concept around here. There are certain political theories which might qualify, except I expect that one man's harmful political concept is another man's core value system, so as usual we should probably stay away from politics. But I welcome input as fuzzy as common folk advice you receive that turned out to be really costly.
The accusation of being bad concepts was not because they are vague, but because they lead to bad modes of thought (and because they are wrong concepts, in the manner of a wrong question). Being vague doesn't protect you from being wrong; you can talk all day about "is it ethical to steal this cookie" but you are wasting your time. Either you're actually referring to specific concepts that have names (will other people perceive of this as ethically justified?) or you're babbling nonsense. Just use basic consequentialist reasoning and skip the whole ethics part. You gain literally nothing from discussing "is this moral", unless what you're really asking is "What are the social consequences" or "will person x think this is immoral" or whatever. It's a dangerous habit epistemically and serves no instrumental purpose.