Ricky Caya was looking for something. A 43-year-old postal service worker and father of two in Quebec, he felt unsettled and unconnected. “The great social movements of the 1960s, the American civil rights movement, flower power, the big trade union movements – people today don’t have that,” he said.

So when a Facebook post crossed his news feed promoting a new organization that “sought to bring together good people without a voice to finally allow them to have strength in numbers”, Caya requested membership to the group and quickly became an active participant and leader.

In many ways, Caya could be a poster child for Mark Zuckerberg’s new mission for Facebook – to “bring the world closer together” through the power of “meaningful” Facebook groups.

But it’s unlikely that Zuckerberg will be touting Caya and his Facebook friends in a branded video anytime soon. Because Caya is a member of La Meute, a virulently anti-Islam Facebook group with 50,000 members.

On 16 July, La Meute, whose founders express a political affinity with France’s Marine Le Pen, notched a real-world victory when voters rejected the establishment of a Muslim cemetery in a small town near Quebec City. The burial ground had been proposed after the families of six people massacred at a Quebec City mosque in January had nowhere nearby to bury their loved ones. La Meute (it means “the Wolf Pack” in French) helped lead a campaign to force a referendum, prompting many Québécois to blame the group for the vote’s failure. (The organization’s leaders did not respond to a request for comment.)

“In the end, what people want is to be united in something bigger than them,” said Caya. “A sense of belonging.”

Or, as Zuckerberg said in a June speech when he announced Facebooks’s new mission statement: “When you bring people together, you never know where it will lead.”

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As Facebook has grown to more than 2 billion users, and as Zuckerberg has embarked on a post-2016 election attempt to understand the social impact of his creation, Facebook groups have become the centerpiece of his messaging around the company’s ability to change the world for the better.

In a lengthy manifesto published in February, Zuckerberg revealed a preoccupation with Americans’ well-documented decline in membership in local organizations such as churches, unions, parent-teacher associations and sports teams – an idea apparently cribbed from Robert Putnam’s classic sociology text, Bowling Alone.

Such groups “provide all of us with a sense of purpose and hope; moral validation that we are needed and part of something bigger than ourselves; comfort that we are not alone and a community is looking out for us”, Zuckerberg wrote. “It is possible many of our challenges are at least as much social as they are economic – related to a lack of community and connection to something greater than ourselves.”

In June, at the inaugural Facebook Communities Summit, Zuckerberg returned to the theme: “For decades, membership in all kinds of groups has declined as much as one-quarter,” he said. “That’s a lot of people who now need to find a sense of purpose and support somewhere else. This is our challenge.”

Zuckerberg’s solution to the decline in what he calls “social infrastructure” and Putnam calls “social capital” is, perhaps unsurprisingly: more Facebook. Specifically, more Facebook groups.

Setting a goal of helping 1 billion people join “meaningful” groups, he told a cheering crowd of Facebook group administrators: “If we can do this, it will not only turn around the decline in community membership we’ve seen for decades, it will start to strengthen our social fabric and bring the world closer together.”

It’s impossible to say whether Zuckerberg’s stated belief in the transformative ability of his own products is naive or cynical. It is undoubtedly true that many Facebook groups are meaningful to many people. In his speech, Zuckerberg singled out for praise audience members who had founded groups for disabled veterans, adopted children, lonely locksmiths and black fathers in Baltimore.

But Facebook groups – like any social capital – can just as easily be used for ill as good. And social capital is not an unalloyed good. A 2013 study by New York University political scientist Shanker Satyanath, Bowling for Fascism, found that dense networks of social organizations and clubs in Germany helped promote the spread of nazism. And even a cursory search of Facebook unearths networks of extremists using groups to recruit and organize.

Take the Soldiers of Odin, a far-right, anti-refugee organization founded by Finnish white supremacist Mika Ranta in late 2015. The vigilante group’s anti-Muslim message spread from Scandinavia to the Americas quickly, with a network of Facebook groups developing in the US and Canada by early 2016, according to separate studies by the Anti-Defamation League and Yannick Veilleux-Lepage of the University of St Andrews’ Centre for the Study of Terrorism and Political Violence.

“In many ways, these organizations are entirely dependent on social media,” said Veilleux-Lepage, who used social network analysis to find extensive ties between the Canadian and Finnish groups, despite the fact that the Canadian chapters have distanced themselves publicly from the Finnish extremists. Veilleux-Lepage pointed out that the same feature that has made social media a powerful force in democratic movements – the fact that it “lowers the barrier for political participation” – is also what makes it useful to extremists. “The barrier to engage with these groups is much lower than it ever was,” he said.

Many far-right groups appear to use a combination of public groups, which anyone can join, closed groups, which anyone can search for but which require approval to join, and secret groups, which are invite-only. Prospective members request entry to a closed group, then are required to go through a vetting process, such as uploading a video pledging one’s allegiance to the cause or submitting to an interview over Skype.

That process makes it easier for extremist organizations to evade Facebook’s moderators, said Keegan Hankes, an intelligence analyst for the Southern Poverty Law Center (SPLC).

“A lot of Facebook’s moderation revolves around users flagging content,” Hankes said. “When you have this kind of vetting process, you don’t run the risk of getting thrown off Facebook.”

Facebook has been working on developing technology to complement its human moderators, and is already using artificial intelligence to crack down on terrorist content. But the sheer volume of content on the platform – and complexity of deciphering meaning and intent – make combating hate on the platform a herculean task.

“Most groups on Facebook are connecting for good – from addiction recovery to support for new moms – but if any group does violate our community standards, we will remove it,” Facebook vice-president Justin Osofsky said in a statement.

But many groups appear to be aware of Facebook’s rules for hate speech, so they enforce their own rules against offensive language despite espousing hateful ideologies. Facebook will only remove groups if it finds they are “dedicated” to promoting hate against “protected” characteristics such as gender or race, a bar that apparently is not cleared by Soldiers of Odin or La Meute.

Still, getting kicked off Facebook can be a critical blow to such organizations, Hankes noted, because they rely on social networks to find new members.

“These are the spaces where you talk to people who aren’t already in your movement,” Hankes said of social media sites. “Recruitment is always at the center of this. The alt-right and white nationalists are extremely conscious of the fact that they are in the minority, and they are always trying to get more members.”

Hankes also argued that Facebook has shown considerably less commitment to policing its platform for domestic extremist groups than it has to cracking down on Isis and al-Qaida.

In 2016, the SPLC sent Facebook a list with links to more than 200 pages, profiles and groups affiliated with SPLC-designated hate groups. A Guardian audit this month found that at least 175 of those links remain active, including closed groups for neo-Nazi, white nationalist and neo-Confederate organizations. After being contacted by the Guardian, Facebook removed nine additional groups.

“They’re not using [Facebook] just to send each other nice notes,” Hankes said. “We’re talking about hate groups who are taking the work of creating a white ethno-nationalist state very seriously, and they’re doing it all on the platform.”

• • •

Mark Zuckerberg’s 2017 “personal challenge” to visit and meet people in all 50 states has triggered an avalanche of speculation that the CEO is considering running for political office. How else to explain the billionaire’s decision to break bread with a steelworker’s family in Ohio, attend services at a black church in South Carolina or discuss public safety with Dallas police officers?

But what’s striking about the newly political Zuckerberg is precisely how un-political he manages to be. “I used to think that if we just gave people a voice and helped them connect, that would make the world better by itself. In many ways it has, but our society is still divided,” he said at the communities summit. “Now I believe we have a responsibility to do even more. It’s not enough to simply connect the world, we must also work to bring the world closer together.”

Both versions of this mission statement lack any kind of political framework to discern that, actually, the world might be better off if some people remain disconnected and far apart.

Zuckerberg’s skill at ignoring these complexities makes him better fitted as an evangelist for the Church of Facebook than a political candidate. “I know we can do this,” he pledged to the crowd at the communities summit. “We can reverse this decline, rebuild our communities, start new ones, and bring the whole world closer together.”

Or, as Ricky Caya put it in a Facebook message: “Facebook helps connect people, and those people can use it to organize themselves. It is also a tool of choice for the Islamic State, and thousands of other groups, on subjects from macrame to cycling to politics, to extremism.

“Everyone is there!!”