When one of Anonymous’s self-declared leaders tweeted the launch of an anti-Gamergate campaign on Friday, he wasn’t just announcing a new cause for the Internet’s most hyperactive vigilantes.

He was admitting, if tacitly, that online vigilantism has its limits.

Both Anonymous and Gamergate are, after all, vigilantes of the highest order, each policing “bad” Internet behavior and righting unjust Internet “wrongs” through a system that, at its best, pushes back against corruption … and at its worst, devolves into a senseless, pitchfork-wielding mob.

Both groups began on the shadowy message board 4chan before spilling out into more mainstream channels. Neither has a formal leadership, a cohesive agenda, or any set list of beliefs or demands. Both have deployed the same tactics against people they don’t like: publishing their personal details (“doxing”), threatening them on Twitter and other social networks, ruining their personal reputations in a process called “Google-bombing,” and attacking their Web sites until they come down.

Perhaps most crucially, both groups believe that all of their actions are undertaken in pursuit of some greater good, as an effort to curb perceived injustices and imbalances of power. It just so happens that Gamergate’s end is “protecting” the sanctity of the traditional male gamer, using tactics and ethical frameworks that Anonymous pioneered. And #OpGamergate is out to protect the victims of Gamergate, using the exact same set of techniques.

Which means that, in some circuitous, ironic way, Anonymous is basically attacking its own methods.

Christopher Doyon — who online “prefers to be addressed as X” — doesn’t quite see it that way, of course. The self-described “Internet freedom fighter” revved up the #OpGamerGate hashtag to some buzz on Friday, promising to out Gamergaters who harass women and to help victims stay anonymous online. When the operation launches officially later this week, “X” said, it will provide moral support, and potential legal evidence, for women and girls who have no other way to confront their trolls and attackers.

There are clear parallels between Anonymous and Gamergate, X acknowledged. But one is a force for justice; the other, a font of abuse.

“4chan and specifically /b/ is a breeding ground for Internet culture. Probably the most fertile breeding ground,” he told The Washington Post by e-mail. “That means it is going to give birth to both the good and evil, the full spectrum of moral memes.”

But does relative morality really matter here? The very crux of vigilantism is that it’s unmoored from any universal moral code or legal system; it adheres only to the whim of the mob, and derives all its authority from that starting point. Whenever you endorse online vigilantism, as Anonymous and Commander X do, you open up the possibility that vigilantes will police the “wrong” things. You can’t really call them “wrong,” either: If the only marker of worth is the will of the mob, then nothing’s unjust. It’s just unpopular.

Commander X is no stranger to this squishy phenomenon himself. In 2013, as part of Anonymous’s Steubenville operation, X published an unredacted copy of court documents about the rape — thus revealing the victims’ name to a hostile Internet and, a special prosecutor said, hurting her case. He was also the man behind Anonymous’s campaign in Ferguson, which incorrectly doxed a man who had nothing to do with Michael Brown or the Ferguson police. That man later received hundreds of death threats — an outcome that, at the time, his doxer dismissed as “collateral damage.” (X, for his part, has distanced himself from that campaign.)

Even long before X became involved in Anonymous, the hacktivist collective engaged in unsavory, distinctly Gamergate-like behavior: sending death threats to leaders of the Church of Scientology, for instance, and vandalizing Web sites for nothing but the malicious “lulz.”

At some point, however, whether a vigilante behavior is malicious or harmful becomes irrelevant. Everything can be explained away as means to an end, as human errors, as the behavior of an errant few. That, oddly, sounds an awful lot like a defense that corners of Gamergate are fond of: “Only a few of us actually harassed women. Most of us hate harassment! We care about ethics in journalism!”

At no point has either group confronted their messy, existential truth: Whenever a mob decides to take the law into its own hands, the law no longer applies.

To anyone.