> But if the knowledge is in a book or comes from another other man-made source, it's some how infallible

Nobody who's ever done research believes that. Everything gets put along a spectrum of trust/accuracy.

You should be able to say what you believe, what you base that belief on, what it would take to disprove that belief, and how likely you think it is to be disproven.

That's why you do research from as many primary sources as you can, because yeah, otherwise you're reading someone else's interpretation. Sometimes you can't do that (you don't read the language, etc) and then you have to judge the quality of the interpretation.

It's an enormous amount of work to write a book, and making things up doesn't make that process a whole lot easier. So most people try to be accurate. Especially with editors and such doublechecking work. I still always judge the quality of the work as I'm reading it.

LLMs just flat out can't be trusted. They're endless fountains of words and aren't accurate by nature. They're fine if you already know the answer, and not fine if you don't.