We live in a world where one person's clear proof is another's insane hallucination. I work with someone, sane to all appearances, who believes that the 9/11 atrocity was masterminded by a U.S. University club that in order to provide a pretext to invade Afghanistan. There is at least one webmaster who is firmly convinced that I am personally controlling the Brazilian tourist industry. (Well, at least he WAS convinced, until he was found mysteriously dead, riddled with poisoned blowpipe needles.
) And so it goes. In any case, a perfect strangers "assurance of knowledge" is (and should be) worth nothing--nothing at all--without independently verifiable corroborating evidence.