Another problem with some people is that they don’t consciously believe (or won’t openly admit) they have absolute certainty. In their speech, they say that they doubt this and that, that they "cannot know everything" but I guess that’s mostly a trick for them to say "and neither do you." With them, one first needs to convince them that they are lying to themselves before having a talk about certainty vs uncertainty.
It reminds me of how rich dialogue choices always constitute a part of great RPGs. You cannot pretend to have done good work on a role-playing game if dialogue options boil down to "Tell me more", "Yes", and "Not now".
The topics are fire. Will it be relevant to read The Network State?