Cathy Young Cathy Young, a columnist for Reason and Real

Cathy Young is a regular contributor to Reason magazine and Real Clear Politics.

When I read the bizarre story of accused "terrorist troll" Joshua Goldberg, the 20-year-old Floridian charged last week with conspiring to engineer a bombing on Sept. 11 and who turned out to have numerous online identities, from radical Islamist to free-speech champion, I had the bad feeling that one of his usernames seemed familiar.

I searched my Twitter archive and found that I had a couple of conversations with Goldberg under the alias "Moon Metropolis" earlier this year. It's a troubling story to have a connection to, no matter how remote. But Goldberg's trolling career is also the quintessential cautionary tale for the Internet age. As the famous cartoon said some years ago, "On the Internet, no one knows you're a dog." Or a serial troll.

Goldberg's arrest was the result of the activities of another one of his personas, "Australi Witness," a supposed Muslim militant living in Australia. Posing as a sympathizer of the Islamic State group, he exchanged private messages with another Twitter user instructing him to carry out an attack at the Sept. 11 memorial ceremony in Kansas City, using a backpack with a nail bomb. His would-be confederate turned out to be an FBI informer.

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"Australi Witness" had a long trail of tweets, many of them vilifying Jews as "filthy cockroaches" and threatening attacks on synagogues. On another occasion, Goldberg, who is Jewish himself, hijacked the identity of a prominent Australian Jewish lawyer, Josh Bornstein, to make a blogpost on the Times of Israel site advocating the "extermination" of Palestinians. The post was taken down and denounced by Bornstein. Meanwhile, another Goldberg persona posted on a neo-Nazi site bragging about the hoax.

Still another Goldberg fake, "Tanya Cohen," was a radical feminist who wrote articles attacking sexism in video games and calling for laws banning hate speech -- while his neo-Nazi alter ego attacked Cohen with anti-Semitic and sexist epithets.

Under his own name, Goldberg posted articles on the Thought Catalog website espousing free-speech absolutism and criticizing the zealotry of "social justice warriors" who battle political incorrectness. It was one of those pieces that he tweeted to me asking for my opinion. The article attacked Amnesty International, a target of Goldberg's obsessive hate, for double standards in supporting Pussy Riot, the Russian activist punk singers prosecuted for a protest in a church, while supporting laws against hate speech and supposedly backing a ban on the 2006 Danish cartoons satirizing Muhammad. I thought that while the article made some good points, it also had exaggerated and unsubstantiated claims. I told Goldberg as much. We argued in circles for a while until he gave up.

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Some debate whether Goldberg's Thought Catalog essays and the "Moon Metropolis" Twitter account, under which he shared them, reflected his real beliefs. It's true that the essays were not spoofs written to make the viewpoint they espoused look ridiculous (like "Tanya Cohen's" writings). But "Moon Metropolis" pretended to be female at one point, casting doubt on whether that was "the real Joshua Goldberg." Does "the real Joshua Goldberg" even exist, or is finding him like peeling the layers of an onion?

Goldberg, who claims that he would have phoned in a tip to stop the bombing he allegedly helped plot, faces up to 20 years in prison for that stunt. Thankfully, he was stopped before the alleged plot got that far. But his exploits are an unsettling reminder of how little we know about the people with whom we interact online. Sometimes, it's enough to make you wonder whether all of the Internet is just you and one very busy troll with a million faces.

Cathy Young is a regular contributor to Reason magazine and Real Clear Politics.