edit: didn’t see rule 1, but anyway I expect answers to be open ended. Just give your thoughts
We are fundamentally ignorant, and are tricked by our brains into thinking we fundamentally know.
Have a look at the book, “The Self Illusion” by Bruce Hood and “The Mind is Flat” by Nick Chater.
We all build models of the world based on the information we’re exposed to. Majority of the information we have about the world doesn’t come through direct experience, and that makes it difficult for us to evaluate the accuracy of the information we operate on. As long as our direct experience doesn’t contradict our model then we have no reason to question it.
What we can be said to know fundamentally is what we have genuine experience with. Somebody working in a particular domain or studying it for personal interest has fundamental understanding of the problems solved in that domain.
Very simplistic question demanding very simplistic answer on a subject with a history of 2000+ years of epistemology that should have been in a philosophy community instead of asklemmy.
One could get good answers from a philosophy community, I agree. My original motivation was getting answers from people in general further than philosophy-subscribed people, almost like trying to start a discussion with friends, you know? One can always do own research or ask an AI otherwise.