you can’t reason someone out of an opinion or position that they didn’t reason themselves into.
Been trawling around the net a bit. This was interesting:
https://writersblik.wordpress.com/tag/r-m-hare/
Essentially, as other commenters have noted, belief in conspiracy theories, religion and ideological politics ar bliks, as defined by the philosopher RM Hare. The beliefs are unverifiable, and ultimately unfalsifiable, as in his parable of the Paranoid Man.
The Story of the Killer Dons (aka The Parable of the Paranoid Man)
“A certain lunatic is convinced that all dons want to murder him. His friends introduce him to all the mildest and most respectable dons that they can find, and after each of them has retired, they say, ‘You see, he doesn’t really want to murder you; he spoke to you in a most cordial manner; surely you are convinced now?’ But the lunatic replies, ‘Yes, but that was only his diabolical cunning; he’s really plotting against me the whole time, like the rest of them; I know it, I tell you.’ However many kindly dons are produced, the reaction is still the same.”
I think you really have to worry if you suffer from pronoia – the belief that people are conspiring to help you.