Yesterday’s headline writers took the afternoon off, it seems, and engaged the newsroom’s cliché machine: A van “plowed” into crowds on Toronto’s Yonge Street, killing at least 10 and wounding several. That many readers no longer blanch at this agricultural metaphor—indeed they expect it—is a mark of how far the technique of mass vehicular homicide has spread. The alleged driver does not appear to have anything to do with the Islamic State, with whom the technique is now most associated. But of course we all waited (or rather, some of us did) to discover whether his name was Muslim, and we were ready to deploy our opinions to the crime scene, depending on the result.

In fact the alleged driver turns out to be a Canadian of likely Armenian descent, and sympathetic not to ISIS but, according to a Facebook post the company confirmed to be from the suspect’s since-deleted account, to “incels,” short for “involuntarily celibate.” Incels, mostly male, want to have sex but find no willing partners. They often resent the sexually active for spurning them. In 2014, in Santa Barbara, a 22-year-old killed six people, two of them Tri Delta sorority women, as “retribution” (his word, in a manifesto) for his celibate misery. The Toronto police added that yesterday’s van suspect might be “mentally ill,” and by implication defective not in morals but in mind. The evidence we see now points to pure violent sexual frustration. That is most definitely a moral impairment.

It’s important to sympathize with the sexless, if not the sexless murderer. Like most things, sex is harder to appreciate when it’s available. In that way, for some, sexual fulfillment is a bit like nutritional fulfillment: A normal day of eating will keep you comfortable enough to think about other things, but fast for a day and your gut will soon become a permanent gnawing distraction. (Ramadan, the Muslim month of daytime fasting, starts next month. Part of the idea is to reacquaint oneself with hunger, and cultivate sympathy for those for whom it is not a choice.) Total long-term involuntary celibacy, because of physical disability or moral or physical repulsiveness or something else, is clearly a preoccupying annoyance, and worse for being the kind of thing you can expect to be mocked for admitting. To have a sex life of some sort seems to me a human right. It’s claiming the right to another person’s sex, or retribution if it is denied, that crosses from an exercise of one’s own humanity to an infringement on someone else’s, in a form of slavery.

And that is something the Toronto killer and his ISIS fellow killers seem to share: a belief that whole classes of people have no unalienable value of their own. (ISIS actually instituted sex slavery, modeled on the sex slavery practiced by the Prophet Muhammad. Estimates of the total number of ISIS sex slaves do not exceed the low thousands—mostly Yazidis, but possibly including the American aid worker Kayla Mueller.) These criminals have a common but not generic variety of wickedness, with many antecedents in history. Some might find consolation in noticing that we have seen this type of murder before. And there is undeniable solace in noting, as Steven Pinker has, that such episodes of cruelty and violence happen less than they used to, as the civilizing process has conditioned us to reject them in ourselves. The fact that the Toronto police officer who arrested the driver did so without shooting him is itself a sign of barbarism’s retreat.

To this optimism, however, we should add two notes of despair. The first is the virality of technique: Sexually undesirable losers have long taken out their frustration on others—mostly individual women; but now, after four years of Islamic State R&D, the menu of mayhem is greatly expanded. Many cruelties our modern sensibilities would never have considered are now easy to emulate and, more importantly, contemplate. The Toronto murderer appears to have done so. When gun-rights advocates point out that a psychopath deprived of his guns still has access to equally lethal rental trucks, they are not wrong.

Second is a more peculiar trend. ISIS grew, as I have shown, out of a number of other movements that before about 2011 were atomized, separated from each other and pursuing different, if compatible, goals. Syria served as a place for condensation, where like-minded strangers could come together and build a kingdom of God on earth. It was a jihadist flash mob. As long as its members were separate, they had limited power, and the world had a herd immunity, of sorts, from their disease.

I suspect something similar has happened with these two violent incels. The dynamic is a familiar one in the age of digital community building. Once the incels griped to themselves, occasionally victimizing others, and sometimes getting over their pathology or finding a partner. Now they can come together online and find others to validate their grievances and encourage them to action. Dating is harder when you spend a lot of time being bitter online. Murder is easier when someone is whispering at you every few minutes, telling you the rest of the world deserves what it gets. These communities become, like ISIS, instruments of conscience-annihilation, and the lonely losers within them become desensitized and, ultimately, morally inverted. If there is a way to stop this process, I want to hear about it.