It’s happened before. It shouldn’t be shocking that it would happen again.

Elliot Rodger, who gunned down and stabbed 20 people, killing six, in Isla Vista, California, in 2014, wanted the world to know exactly why he did it.

“All you girls who rejected me and looked down upon me and treated me like scum, while you gave yourself to other men. And all of you men, for living a better life than me, all of you sexually active men, I hate you. I hate all of you. And I can’t wait to give you exactly what you deserve — utter annihilation.”

The unmitigated hatred that Rodger felt, and his subsequent murderous rampage, has resonated with thousands of other angry young men. These “incels” — short for “involuntarily celibate” — come together online, post memes, insult each other and fantasize about inflicting violence on the women to whose bodies they feel entitled.

Alek Minassian’s rampage through a busy Toronto street appears to be another instance of incel-inspired carnage, a terrorist attack committed in the name of a vile and violent misogynistic ideology.

For years, those who have delved into these sewers of hate have been trying to sound the alarm. These men idolize violence, despise women and want nothing more than to act out on their rage. But few listened.

While misogyny is one of the most eternal forms of hatred, the way these men organize and express it is something new. Not only do they fantasize about inflicting maximum harm, they hope to inspire others to do the same.

Incels are just one strand of the broader “manosphere,” a network of online subcultures dedicated to anti-feminism that have formed over the last two decades. Derided by the pick-up artists and red pillers as “betas,” and by the MGTOWs (men going their own way, who rival incels when it comes to misogyny) for requiring the approval of women, incels are at the most extreme end of the spectrum.

In the upcoming months and years, there will be many debates over whether Minassian was motivated solely by misogyny or whether mental illness played a part. But as with ISIS-inspired or white supremacist terrorists, people who are already vulnerable in one way or another are the most likely to be radicalized.

While it can often feel impossible to stem a tide of hatred so strong, we must act to try to disrupt the radicalization of young men and to address the root causes of their fury.

The first step is to take them seriously.

While their comical lingo — Chads, Stacys, femoids, white knights — may sounds ridiculous, it all serves the purpose of dehumanizing the people around them, a necessary precursor to violence. They are not just angry virgins — they are an extremist community, dedicated to hate, who encourage each other to inflict real-world violence.

Next, disrupt their networks and deprive them of platforms.

Before Charlottesville, many people ignored the alt-right as an online side-show, until hundreds of actual people showed up in the streets to march, to intimidate and to kill. We realized there are real people behind these screen names and they do actually believe what they say they believe.

It was only then that mass outrage prompted hate sites such as The Daily Stormer to be pushed to the dark web, for Spotify to remove hate music and for Apple Pay to deprive hate groups of payment services.

The same methods need to be applied to these misogynist groups.

Put their forums on the defensive by forcing web hosting services to drop them. Push Reddit to close down the copycat subreddits that have sprung up in recent months. Pressure Facebook to shut down groups and pages that glorify misogynistic violence and venerate Elliot Rodger and other killers.

It will be impossible to eradicate their spaces entirely — even The Daily Stormer has returned to the clear web — but we need to make it more difficult for them to organize and to inculcate new men into their nihilistic death cult.

There also needs to be a systematic effort at deradicalizing those who are already indoctrinated. Law enforcement and governments have programs aimed at countering other forms of emerging extremism. Incels and other radicalized misogynists should also be targeted.

But most importantly, we need to address the toxic masculinity that lies at the heart of their hatred.

These young men have been consistently fed lies their whole lives; women are things, men are entitled to their bodies and sexual conquest is the route to fulfillment.

Some are already professing that a pull-yourself-up-by-your-bootstraps approach — the sort advocated by Jordan Peterson — is the answer. And while Peterson, because of his anti-feminist views and his alt-light appeal, may be able to convince some of them out of their abject nihilism, he reinforces the toxic notions that underlie their misogyny. A less explicitly violent anti-feminism isn’t the antidote; it’s just a watered-down version of the very same poison.

Instead, boys and men need to be taught healthy forms of expressing masculinity. The extremist misogyny of incel culture is derived from the more casual and systemic misogyny of our broader societies. That needs to be fought in classrooms, in online spaces, in pop culture and within our institutions.

At the root of the nihilism of incel culture is a very real longing for human connection. There’s nothing wrong with feeling lonely or rejected or sexually unsatisfied. And when incel communities were first being formed online, people were attempting to express those feelings and work through them.

But that has now festered into a toxic subculture of people who dehumanize women, fetishize violence and push each other to enact that violence in real life, whether to themselves or to others.

Minassian’s act of terror was intended to inspire others to do the same. And unless we act, that’s exactly what will happen.