'He has learned nothing,' Zuckerberg considers crowdsourcing news fact-checks for Facebook

What you seem to be hinting at is the correspondence theory of truth. The problem with that is that “facts” as we use them in political discussions don’t bear a one-to-one relationship to “facts” as a philosophical ideal. See also: The most pertinent objection to the Correspondence Theory of Truth. We do not have access to objective reality to check correspondence.