Conspiracy theories serve a useful social purpose, or they would not exist.

Their purpose is to reaffirm your prejudices. If you dislike a certain group of people or their political views, conspiracy theories can supply you with storylines that turn them into monsters.

It's a handy way to underline all the differences that exist between you, whilst affirming the rightness of your outlook.

During the rise of Nazism in Germany many conspiracy theories were spread about the Jewish people. They were powerful and rich not because of their education and abilities but because they were a race of scheming parasites who cheated the system and polluted the German people, the Nazis claimed.

Usually, this kind of rhetoric is confined to playgrounds and people grow out of it. No one is all good or all bad, we later learn. Understanding that in real life most people present a more complicated picture is an aspect of maturity. But that maturity is abandoned when scapegoats are being sought.

In America, we used to be more resistant to efforts to demonize an entire group of people. But in 2017 a new series of conspiracy theories, many of them with their roots in foreign government psychological operations or psych-ops, began to emerge on online right-wing forums like 4Chan.

The obviously made-up stories of QAnon provided people who were already angry and alienated from the wider nation with some dangerous new reasons to dig deeper into their own resentments. 

The timing was perfect. For the first time in American history, an authoritarian strong man was in the White House, a man around whom they could build a new American mythology. Trump didn't care a fig for their lunatic conspiracies but he understood their propaganda value and he played to them all shamelessly. 

Trump was not just another political leader the new QAnon conspiracy theory insisted, he was a kind of rat-catcher waging a secret war – so they convinced themselves – against a shadowy cabal of elite Hollywood players and top Democrats who were abusing children in a Washington Pizza Parlor.

It was bonkers, but all the most successful conspiracy theories often are. Take the worst crimes you can think of and attribute them to your opponents and before long you'll have tens of thousands of people, and then millions, buying right into it.

You can laugh at their credulity but a North Carolina man fired an assault rifle inside the Washington, DC pizzeria that QAnon falsely claimed had been the center of a child sex trafficking operation in December 2017.

Edgar Maddison Welch, 29, received 36 months of probation and was ordered to pay $5,744 in restitution for firing shots with his AR-15 rifle inside the named pizza shop.

He later told police he was attempting to find and rescue the child sex slaves that he had read about online, but on the day he found no evidence of child sex trafficking anywhere in the restaurant and eventually surrendered.

There's no point in chiding him for his utter stupidity. There's no point in scalding him for his willingness to risk his life and others for a made-up story on the internet. The fact is he could have killed someone over another online story created to attack Hillary Clinton and assist Donald Trump. 

A few years after this event Trump would start a cynical conspiracy theory of his own. He had won the election he lost, he told his credulous supporters. He was the rightful president who had been cynically cheated of his post.

His Vice President Mike Pence would step up and stop the certification of Joe Biden's presidency on January 6, he assured them all. His supporters would take America back, by force of arms if necessary. 

You saw what happened next. The point of conspiracy theories is always mass dehumanization. Dehumanization is the first step to prepare for mass violence.

This was true during the rise of Nazism in the 1930s and it's equally true of Trump's decision to promote conspiracy theories on his own Truth Social account last week.

On his site, Trump re-posted a picture of President Biden, Vice President Kamala Harris, and House Speaker Nancy Pelosi with the words “Your enemy is not in Russia” written in black bars over their eyes.

Your enemy is Russia, however. It's foolish and dangerous to believe otherwise. So ask yourself why Trump is playing games like this, turning his fellow Americans into monsters.

Why is he propping up cruel dictators like Vladimir Putin instead? What kind of violence is he preparing the ground for in America? And is your own name on his growing enemies list?