One of the precepts of Aletheia Quest with Alan Fahrner is that “you can know truth.” However, part of doing that successfully (and honestly, is understanding its limits). This famous quote from former Defense Secretary Donald Rumsfeld is worthy of pondering:
Because, as we know, there are known knowns. These are things we know we know. We also know there are known unknowns. That is to say, we know there are some things we know we do not know. But there are also unknown unknowns. The ones we don’t know we don’t know.
(Originally from my Aletheia Quest blog.)