> nobody 30 years ago believed the earth was flat but they probably couldn’t articulate why they believed that

I'm not sure that this needs to be a requirement. Cultural axioms like this have value; there's a lot of knowledge to be had in the world, and not enough time or space in the mind to derive it all. I don't need to prove to myself from first principles every time I have a headache that aspirin will help.

There's danger, sure, if the wrong axioms take root, and we need to keep an open eye for new data that show we might be wrong. But it's unreasonable to expect that every individual person can cogently argue one side or the other of something with such overwhelming evidence that it has been accepted as a fact.