I was just listening to Today Explained on the train, and they brought up the little-known fact that what drove Roseanne Barr to the point where she was tweeting racist insults at a former Obama aide was that she's a strong believer in the latest iteration of the Satanic Panic conspiracy theory -- in this case, the belief that there really is a global conspiracy at the highest level of all the world's governments to cover up the fact that large numbers of the world's wealthiest and most powerful people collect child pornography and/or hire child prostitutes, and to protect their panderers, and that the reason that so much of the press spends all day looking for ways to smear Donald Trump is that he's leading a secretive counter-conspiracy that will expose the entire Clinton administration and all of their friends as child predators.
The evidence for this is slight, and believing in it is deranged. As it happens, I spent decades studying conspiracy theory and conspiracy theorists, and I have a strong opinion about how people get this way. It's based on a metaphor that the dean of all conspiracy theory fiction writers, the late Robert Anton Wilson, used in two of his books: Chapel Perilous and the Four Magical Weapons you need to escape it.
Because, you see, as James Loewen documented in his best seller /Lies My Teacher Told Me,/ there comes a point in almost every adult's life where they realize that their parents and their teachers lied to them. So once you can no longer trust what the schoolbooks told you, how do you decide what to believe? In Wilson's metaphor, you've walked through the doors of Chapel Perilous, the hall of illusions, where you can't tell friend from foe, where you can't tell the exits from the paths that lead deeper into the darkness. How do you get out?
After studying all of the ways that people who fall into conspiracy theory go insane, Wilson concluded that the poets got it right when the said that you'll never escape Chapel Perilous unless you carry four weapons in with you: the Sword of Intellect, the Wand of Intuition, the Cup of Compassion, and the Shield of Courage.
INTELLECT: A few of our high school students take classes in Plane Geometry. An even tinier percentage take Advanced Placement classes in logic or law or advanced history. So there are tons of madmen out there who dived into conspiracy theory to "prove" what's true, who have no idea what it means to "prove" anything. Without the formal education to recognize logical fallacies and the rigorous exercise of having your arguments analyzed for them until you reflexively do it to yourself, you'll join those madmen who ignore glaring evidence that their theories are wrong and cling desperately to evidence that doesn't even come close to proving what they want to believe.
INTUITION: I don't just mean common sense, here. The world is filling up with madmen who sincerely worry about what risk expert Bruce Schneier calls "movie-plot theories." If you dive into conspiracy theory without some ability to tell the difference between "the way people act in fiction" and "the way actual people act," you'll make up enemies with abilities that are completely unrealistic, like the ability to organize a multi-thousand person conspiracy that nobody has heard of, but, somehow, you have heard of it. It doesn't take a whole lot of mathematical or psychological intuition to realize that if you think that's plausible, you're a madman.
COMPASSION: Even before they decided to try to find out which of the myths they were told in grade school and high school were true and which were lies, even when they believed them all, the world is full of madmen who truly believe in Enemies. Not opponents, Enemies, with a capital-E: mustache-twirling sadists who hate you and everybody like you so much that they spend their every waking moment plotting and scheming and working hard to find ways to hurt you. How many such people do you know, personally? Is that kind of thing actually common in your family, in your social circle? Do such people go far in life, if you've ever met many of them, or (be honest) don't they usually end up homeless or living in somebody's basement, never having achieved anything in life. Then what makes you think that other people are nothing like the people you know? Sure, sometimes there really is an Us and a Them, but if you try to research conspiracy theories and you think that They aren't even the same species as Us, that their motivations are entirely different from our motivations? You will go mad.
COURAGE: See those madmen over there who lash out in all directions, who attack any thing they don't understand? They didn't know who to believe or what to believe, but, being cowards or adrenaline junkies, they decided to believe whatever they hear that scares them the most. They're easy marks for any monster who wants to use them as a weapon against the innocent; all that monster has to do is scare them.