Mark Earnest wrote on 1/12/2018 3:15 AM:

Snip

This comes from the premise of textbooks from the library and
Wikipedia being credible. They are usually credible anyway. We just
know that. That is why it is the ultimate premise. There is no real
way to explain ultimate premise except to say ultimate premise is
when we just know something without any way of saying how we know.
The chain of premises has to be rooted somewhere.

I would suggest that the "real way to explain ultimate premise" is to
call it *A GUESS* !!

--
Daniel