The false, evidence-free conspiracy theory that a massive child sex abuse ring involving Hillary Clinton is being run out of a pizza restaurant in Washington, DC, has been debunked by every legitimate media outlet that has covered it.

That hasn't stopped "pizzagate" from crawling out of the darkest corners of the Internet and nearly causing a real-life tragedy. On Sunday, a gunman walked into the restaurant at the center of the fake controversy and fired at least one shot; he was reportedly "self-investigating" the conspiracy.

The logic of conspiracy theories is the opposite of that used for standard scientific discovery: the latter holds that a theory is false until it's proven true, but conspiracy theorists argue that their theories are true because they haven't been proven false — a logical fallacy known as the "argument from ignorance" that forces skeptics to debunk something that doesn't exist.

Social psychologist Dr. Sander van der Linden, director of the Social Decision-Making Lab at the University of Cambridge, has written extensively about conspiracy theories. He told ATTN: that the idea of something being true until proven false falls under what neuroscientists call "motivated reasoning" — a belief held not because of eliminating false hypotheses, but because of wanting to think it true.

"This person is motivated to confirm the conspiracy theory and deny the need for any evidence to the contrary," van der Linden said. "Often, belief in conspiracy theories is not about the evidence, but is linked to a higher-order ideological worldview that supports the underlying narrative, in this case, any information that puts Hillary Clinton in a bad light."

To an expert like van der Linden, belief in pizzagate likely isn't motivated by concern for children, but by a deep distrust of Hillary Clinton and other authority figures. "Because somebody already believes that Hillary Clinton cannot be trusted," he said, "the conspiracy must be true, rather than the other way around, which is based on flawed logic."

Cognitive neuroscientist Dr. Bobby Azarain, based at George Mason University, believes this as well, saying "The logic just makes no sense. You could similarly state that you are going to believe in fairies and unicorns until someone definitively proves that they don't exist—which is an impossible task."

So how does one debunk a self-perpetuating myth when every attempt to refute the conspiracy is seen as evidence that the conspiracy must be true?

According to van der Linden, the best solution is to not repeat the conspiracy theory in the first place, or to do so in a way that warns the listener what they're about to hear is false.

"Repeating the myth only strengthens people’s memory association with the myth and thus, inevitably fuels the spread of misinformation further," he said. "Provide a plausible and non-conspiratorial explanation that doesn't repeat the buzzwords associated with the myth."

And while the logic of conspiracy theories is tortured and fallacious, there's no requirement to engage with it. As Dr. Azarian puts it, "We should only accept that something may be true if there is sufficient evidence to support it. Otherwise, we would find ourselves spending all our time on disproving every absurd claim some nut or Internet troll decides to throw out there."