ELI5: Explain Like I'm 5

Definist fallacy

A definist fallacy is when someone gives an explanation or a definition of something that is circular, meaning it just repeats the same ideas without actually telling you anything new. Imagine you ask someone what a tree is, and they say “well, a tree is a tall, woody plant that has leaves and branches and grows in the ground, and it’s a tree because it’s a kind of plant that looks like a tree.” That’s not really telling you anything helpful, because you already know what a tree looks like if you’re asking what it is.

So, a definist fallacy is when someone tries to explain something by just restating the idea without actually giving any new information or insights. Kind of like if you ask why the sky is blue, and someone says “because it’s blue!” That might be true, but it doesn’t really explain why. So, if you want to understand something, it’s important to ask questions to get a real explanation, and not just accept circular answers that don’t really tell you anything new.