When Pontius Pilate reportedly uttered “Quid est veritas?” (“What is truth?” in John 18:38) he was responding to Jesus’ claim that He came into this world to bear witness to the truth.
A modern American might have replied, “Hey, what do I know?” to the same effect – that “truth” is hard to pin down, especially what might well be only a subjective truth. Pilate’s problem was that what he saw as a subjective, perhaps even petty, issue was a very serious and objective one to those he governed.
A reference librarian, of course, might have asked Jesus if He had a citation for that.
Reference librarians are, sometimes, on the safe path of looking for what appears to be an objective truth. “How tall is Mt. Everest?” “How can I write to my senator?” What’s the atomic weight of Uranium?”
Other times, the “objective truth” comes on shifting sands. “How tall is Mt. Everest (using the latest measuring methods)?” “How can I write to my senator (so I can be most sure that he/she will read my letter)?” “What’s the atomic weight of Uranium (used in atom bombs)?”
Sometimes, they’re in a trackless desert where it’s hard to nail down, to objectify (as it were), the question in an answerable form. “What drugs interact with my medications?” (Let’s hope the person asking knows what they are!) “Who discovered the DNA helix?” (Watson and Crick probably don’t deserve all the credit for a team effort.) “My father might have been exposed to Agent Orange during the Vietnam War … what should I do about his symptoms?” (Finding out what the “might” means is best done through a referral … he might actually have spent the entire war in Philadelphia.)
At other times, they’re in quicksand.
“What version of the Bible shows that black people are supposed to be slaves?” (That was a real question at a real reference desk.) What was the cause of the War Between the States? (That’s a bit of a poser because that’s not how the American Civil War is generally regarded from the POV of the victors.) Who won the Korean War? (Nobody won, actually, since there’s never been a peace treaty … but the South Koreans seem to be doing pretty well lately.) “How big is the Loch Ness monster?” (Good luck with this one!)
There’s no “one right answer” for these questions.
The “nature of truth” is, in no small part, the world of the reference librarian.