At a dinner party last year, I was casually saying how silly I thought my brother-in-law was for believing in chemtrails when a couple, whom I considered to be very reasonable people, responded that the government really does use them for population control. To be fair, they were shocked that I, a person they thought to be very reasonable, refuse to set up Face ID on my iPhone because I’m pretty sure “they” will use it for surveillance, even though I’m not sure who “they” are.

Conspiracy theories have always fascinated me. When I was thirteen, I worshiped Blink-182 and nodded along to Tom DeLonge’s theories about Area 51. Now that I’m older and a psychologist, I’m much more interested in the psychology of how and why people believe in conspiracy theories.

What are conspiracy theories?

First, let’s define the term. A conspiracy theory is a non-mainstream explanation for something about the world that involves secret, powerful, and often sinister groups. It’s speculative, meaning it’s not based on verified facts. It’s often complex. (Just think of that meme of Charlie from It’s Always Sunny in Philadelphia madly gesturing at crisscrossing strings on a wall crammed with “evidence.”) It usually includes negative and distrustful beliefs about an “other.”

A conspiracy theory is a non-mainstream explanation for something about the world that involves secret, powerful, and often sinister groups.

And importantly, a conspiracy theory is not falsifiable—any evidence against the theory would be chalked up to a cover-up, paradoxically reinforcing the theory. When scientists try to reassure people that chemtrails consist only of normal water vapor, a hardcore chemtrail believer might conclude that scientists have been bought by the government to lie to the people.

This episode is not going to debunk (or bunk) any specific conspiracy theories. After all, I’m no expert on airplane contrails or moon landings. But it turns out that, whether they’re true or not, the psychology of conspiracy theories is fascinating. (Spoiler alert: Sleep disorders might be involved in alien abduction conspiracy theories!)

But let’s start with the basics.

Why do people believe in conspiracy theories?

Psychologists specializing in conspiracy theories believe that people have three main motivations…

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This content was originally published here.