When Facebook CEO Mark Zuckerberg returned to Harvard in 2017 — the university where he first started building a digital phone book that would make him a billionaire — he challenged Harvard’s graduates to go out and change the world.

“It is time for our generation-defining great works,” Zuckerberg told students. “How about stopping climate change before we destroy the planet? ... How about curing all diseases?”

Those problems are still decades away from a solution. But Zuckerberg has defined this generation — and perhaps future generations — in ways almost no one could have imagined when he launched his online platform in 2004.

Facebook, which is celebrating its 15th anniversary on Monday, has done a lot of good. It’s a source of news and entertainment. It’s a place to launch your business, and a place to check that your loved ones are safe in times of crisis. Most importantly, Facebook has made the world smaller, connecting people with friends and family in ways that weren’t possible before.

But Facebook has had problems, too, and many of them serious. Facebook has changed the notion of privacy. It’s changed the way media businesses operate. It’s provided a platform for bullies and racists and liars. It has disrupted democratic systems and facilitated a global disinformation crisis.

So on Facebook’s 15th birthday, we reached out to a broad cross-section of influential people — politicians, writers, scholars, journalists, activists, and entrepreneurs — and asked them a simple but complicated question: Has Facebook been a net positive or net negative for humanity?

Here are their answers.

I was just reading a history book about the origins of the Second World War, and there is a moment in England in the late 1930s when Lord Beaverbrook — the foremost press baron of his day — writes to Prime Minister Neville Chamberlain, anxiously asking for a clarification of British policy toward Germany.

The media magnates of that era were businessmen, first and foremost, looking to make money from the news. But they were also interested in the news: They understood the critical role they played in educating the public and perpetuating a free society. Mark Zuckerberg is our Lord Beaverbrook, only on a scale 1,000 times larger.

Can you imagine him calling the president, looking for clarification of some crucial point of policy? I can’t. And that’s the problem. Platforms are only as socially useful as their owners want them to be.

Sherry Turkle, author of Life on the Screen and clinical psychologist at MIT

Technology is the architect of our intimacies. When, 10 years ago, I first began studying how people felt about their lives in Facebook’s private/public gray zone, one young woman said it was all the same to her: “Who would care about me and my little life?” At the time I remember thinking that this was not an empowered mantra, but I understood what she was trying to say.

Online, she felt less vulnerable. Facebook friendships offered the feeling of connection without the demands of intimacy. And she couldn’t see how her little gestures of friendship and consumer preference were worth much.

That was the founding myth. And it was a myth. In Facebook’s maw, each of us became a new kind of surveilled and manipulated commodity. “Our little life” was the center of what was bought and sold in bit and pieces. At the Facebook launch, I expressed my disbelief that we could have intimacy without privacy and democracy without privacy. But I thought about the two problems separately. Facebook taught us that we can only consider them together. The social media business model sold our privacy in ways that fractured democracy.

All of this happened in plain sight and we didn’t want to look. We had a love affair with a technology that seemed magical. And like great magic, it worked by commanding our attention so that we took our attention off what was going on.

Now, we have to live with many technologies that challenge democracy and selfhood. We will have to contend with everything from machines that can pretend to love us to programs that can track our motions and authorize where we can go, what we can read, and what we can see. How will we regulate programs that can make any speech come from any image? What starts out a parlor trick ends up a tool of mass manipulation.

Facebook will have been good if it has taught us the necessity of exerting social control over such technologies. It will have been good if it becomes a testing ground for some first experiments in how to do so.

But the Facebook experience will have been bad if it has taught us that resistance to corporate incursions on selfhood and citizenship is futile. That people want conveniences and are willing to turn their attention away from costs. We will no longer be able to say, “Who would care about us and our little lives?” We know who cares and why.

Jonah Peretti, co-founder and CEO of BuzzFeed

Has Facebook had a positive or negative impact on humanity? The truth is we don’t know yet. The jury is still out. Will they take responsibility for making sure content on their platform benefits users and society? Or will they do the minimum to remove the worst offenders and keep the critics at bay, rather than developing a true understanding and plan for how to improve their users’ lives?

Will they embrace that they are a platform for content of all kinds — baby pictures, birthday wishes, and vacation videos, but also news, entertainment, and lifestyle media? Or will they insist they are a pure tech platform, and pretend they aren’t the largest content distribution engine in the world?

Will they continue to leave only scraps for the companies and creators that fuel Facebook? Or will they share enough revenue to support quality content from a diverse array of voices that informs, entertains, and inspires?

Only Facebook can answer these questions. But I’m not sure the world will give them another 15 years to figure it out.

Ro Khanna, US Congress member representing Silicon Valley

Facebook has been a net good for humanity by democratizing communication and mobilization. It has allowed unlikely voices ranging from Parkland students, to Sunrise movement environmental activists, to long-shot candidates like Bernie Sanders and Barack Obama to emerge.

Undoubtedly, there has been an abuse of these platforms by foreign interference and hate groups. Going forward, the platform will only enhance democracy if Facebook leaders make structural changes and adopt rules that will foster speech that is based on facts, reason, and respect.

Has Facebook, on the whole, had a positive impact on the world? Well, it has allowed people across nations to share their opinions and communicate. It has allowed members of a diaspora to stay connected to their relatives. It has helped provide a sense of community in an age when families have been split.

Again, the platform has been abused to commit human rights atrocities in Myanmar and also by mobs engaged in violence in many parts of the world. There is a lot that needs to be done to make sure these types of abuses do not take place in the years ahead. We cannot minimize the dark side of these platforms, even as we tout their benefits.

Brooke Binkowski, former managing editor of Snopes.com

I think that Facebook has enormous potential to be a powerful force for good in the world. However, at the moment, it’s failing to achieve that potential, opting instead to use its ability to disseminate (or prune out) certain stories or posts to try to affect crowd behavior or individual thought. This is causing the entire world, it seems, to have a nervous breakdown.

This could easily be fixed by either removing all algorithms or placing those algorithms directly into users’ hands and making them fully transparent and customizable. They also need to hire moderators.

What Facebook needs to understand most of all is that free speech ceases to be free when it is used to silence others. So if a bunch of disinformation is used to manipulate public opinion by pushing ... oh, let’s just say stories about George Soros being a Nazi and a baby killer reptilian, that’s an attempt to silence him and his supporters and thus it now ceases to be free speech.

If what you have to say is being manipulated by algorithms so that some people see it and others don’t, that’s also ceasing free speech. Once Facebook takes on the heavy moral responsibility that any purveyors of mass communication should by all rights shoulder before they even start allowing people to use it, perhaps they will live up to the awesome potential that they have.

As far as infrastructure and ease of communication goes, they can’t be beat. As disinformation purveyors, well, they should be heavily sanctioned. Look at all the chaos they’ve either allowed, enabled, or directly sown — and we don’t know the half of the damage they’ve done yet.

Only full transparency going forward will save them now. It’s time.

Steven Pinker, author of Enlightenment Now and professor of psychology at Harvard University

Has Facebook (together with other social media) been a net positive or net negative for humanity? It’s too soon to tell, for two reasons. One is that widespread adoption of social media is so recent that the world has not yet had time to adopt new norms and policies in response. The other is that the vast amount of recent commentary about social media has consisted of panic and hyperbole rather than balanced analysis, so it’s hard to tell.

Social media are now being blamed for every problem on the planet, from destroying democracy to ruining the younger generation. There’s no doubt that the platforms, like all new technologies, have had negative unintended consequences, and that reforms and countermeasures will be necessary to mitigate them. But the daily diatribes in the mainstream media are so hysterical they offer little insight.

First, they don’t calibrate their anxiety with a historical perspective that shows that every new medium is greeted with dread. These include the internet, the personal computer, television, radio, the telephone, newspapers, novels, the printing press, and writing itself. Nor do they acknowledge that social media are hardly the originators of unfounded rumors, viral falsehoods, and conspiracy theories, which have sparked wars and pogroms for centuries.

Second, the tirades in the mainstream media don’t disclose a conflict of interest. Social media, by siphoning off ad dollars, are the biggest threat to newspapers’ revenue since Craigslist, which means that those outlets have much to gain if social media companies are broken up, regulated, or otherwise crippled.

This doesn’t mean that attacks on social media are inherently compromised, nor does it mean that we should be unconcerned by the financial threats facing standard news sources, with their indispensable fact-gathering and curation. But it’s commonplace to disclose conflicts of interest in position statements by other agents, and this one has passed unremarked.

Third, now that it’s open season on social-media platforms, many banalities have been elevated to existential threats. Yes, social media are merchants of attention that deliver viewers to advertisers. So are all ad-driven media, including newspapers and broadcast television.

Yes, they sell customers’ data to targeted organizations — just like every charity, political candidate, and enthusiast magazine I’ve given money to. And yes, they can be exploited to manipulate viewers. But for as long as there have been news media, there have been manufacturers of content designed to exploit them, including photo-ops, sound bites, campaign rallies, press conferences, press releases, spin doctoring, rampage shootings, and terrorist attacks.

Fourth, the problems created by social media differ in a key way from wars, dictatorships, epidemics, and other scourges: They are not imposed on people but chosen freely. Billions of people have decided that the benefits of social media exceed their costs. This doesn’t necessarily mean that social media are a net benefit; people can make choices that are bad for them, like addictive drugs, and they can make choices that are good for them individually but bad for the world, like carbon emissions.

But any assessment has to consider the goodies that users themselves must see in the platforms. It also must consider the problems that social media were designed to solve. Remember the angst through the 1990s about media concentration? A few corporations with a stranglehold on the mass dissemination of information could “manufacture consent,” freedom of the press belongs to those who own one, and so on. Well, we seem to have solved that problem. But solutions create new problems that take time to solve in their turn.

Finally, many of the rumors about the social, psychological, and political pathologies loosed by social media do not survive fact-checking. Careful studies have shown that social media has not led to epidemics of loneliness, depression, and suicide (see the references in the “Happiness” chapter of Enlightenment Now and in my follow-up essay). And as the political scientist Brendan Nyhan put it in the title of a 2018 article, “Fake News and Bots May be Worrisome, but Their Political Power is Overblown.”

Will the net effect of social media be positive or negative? I suspect that the answer will be similar to those for every other medium, including newspapers and television: the effects will always be mixed, and once some time has passed, people and societies will have figured out how to make the net benefits outweigh the costs.

Jonathan Haidt, author of The Coddling of the American Mind and professor at NYU

There’s an old joke about an optimist who fell off of the observation deck of the Empire State Building. As he was passing the 30th floor someone called out to him: “How’s it going?” He replied: “So far, so good!” I think that joke has some relevance for humanity in the Facebook era. So far, the billions of small positive effects of massively increasing human interconnectivity may well outweigh the growing roster of negatives, large and small. Yet when I look to the future, I see two giant negative effects looming larger and larger, like the pavement rushing up to the optimistic jumper.

First, rates of depression, anxiety, self-harm, and suicide are rising rapidly in young people born after 1995 — “Gen Z” — which has largely been on social-media platforms such as Facebook, Instagram, and Snapchat since middle school. This rise in mood disorders is not happening in all countries, but it is happening — particularly to girls — in the US, the UK, and Canada. There are empirical studies pointing to a causal connection to heavy social media use, and there are studies indicating no connection. I predict that a consensus will emerge by the end of 2019, and that it will be that heavy use of social media damages many young teenage girls, reducing their odds of success in life.

The second potentially gigantic problem is that large, diverse, secular democracies are inherently unstable, inherently prone to division unless there are sufficient “centripetal” forces pulling toward the center (such as having a shared language, shared rituals and values, and high trust in the basic political and economic institutions of the country).

Facebook and other social media platforms are powerful centrifugal forces, binding groups together to fight other groups within their own country, driven mad and propelled into battle by an eternal mudslide of outrage-inducing viral videos and conspiracy theories. We are already seeing these effects in many countries.

I predict that by 2030 we will see the spectacular political collapse or geographical division of more than one Western democracy that seemed rock solid on the day Facebook was founded, 15 years ago. My hope is that people, societies, and governments will find ways of adapting to or regulating social media that will render my prediction wrong.

Peter W. Singer, author of Like War: The Weaponization of Social Media and a senior fellow at the Brookings Institution

“The goal wasn’t to create an online community, but a mirror of what existed in real life.”

The setting is a den in Silicon Valley and a gangly college-aged kid is sitting on a sofa, with red Solo cup in hand. Speaking into a handheld video camera, he’s trying to explain the concept of this strange new business that he dropped out of school to start.

In the time since, TheFacebook.com has become one of the world’s most profitable and powerful companies. Along the way, it has turned that young kid doing one of his early interviews, Mark Zuckerberg, into not just a billionaire, but the ruler of a digital kingdom that has more members than any single nation in the world.

But it has also become exactly what Zuckerberg predicted, though perhaps not in the way he planned. Facebook is a kind of mirror of what exists in real life. We use it, and the network of companies it’s bought — from Instagram to WhatsApp — to reflect out to the world the stories of our lives.

We share everything from heartfelt posts of what or who we care most about to just what amuses us while sitting on the sofa (perhaps red Solo cup in one hand and smartphone in the other). That mirroring, though, means that all the negative aspects of real life also come in, from annoying advertising campaigns to issues of politics, crime, terrorism, and war.

Facebook became a new kind of communication space and then marketplace for its community members, but it also became a new kind battlespace that helps determine the outcome of everything from elections to genocide. Most importantly, because it is online, it means that the “mirror” is warped. Its reflections are reshaped by everything from our conscious choices of what to post (or not) to the algorithmic and deliberate manipulations that alter not just what we see in our feeds, but what we think about the real world.

The question of its net positive or negative, thus, will be answered by what we see in that mirror, and what each of us chooses to do about it.

David Axelrod, former chief strategist for Barack Obama’s presidential campaigns and host of The Axe Files podcast

Facebook was promoted as a way of connecting us and building community. But it actually has become a tool for dividing us into virtual communities in which our views are affirmed, but not always informed; where we are surrounded by the like-minded and exploited by commercial and political interests armed with our personal data.

Whatever good it’s done is outweighed by these concerns.

Dana Perino, Fox News, anchor of The Daily Briefing and co-host of The Five

Overall, I believe Facebook has been a net plus.

Facebook provided a way to reconnect with people from all walks of your life, especially the generations who didn’t grow up with cell phones. A good example is my husband and stepson — they’d been estranged for almost 18 years when finally Barry contacted his dad on Christmas Day a couple of years ago. I now call them “the happy couple” — it’s brought a lot of joy into our lives.

Beyond bringing people back together, Facebook has helped people start and grow businesses, and to enhance their brands. It provides an outlet for creativity, which is good for the human spirit.

On the downside, we all know about the bullying and negative comments, the foreign interference, the recruitment of terrorists — plus the way dictators around the world are using Facebook to monitor citizens and to restrict their news content to government-sponsored information only. These are challenges we know of now; surely, more will pop up. So on the 15th anniversary, Facebook is under the gun. The technology industry is like Big Pharma, Big Oil, Tobacco, and Distilled Spirits all in one — the regulation is coming ... will it be effective? That remains to be seen.

I maintain that having Facebook is better than not having Facebook. Especially considering all the Jasper photos you can see on my page!

Mark Warner, US senator from Virginia and vice chair of the Senate Intelligence Committee

The answer to this question is going to be up to Facebook. It’s an iconic American company — no doubt about that. And I don’t want to see it regulated into oblivion. Though the company has made it easier and cheaper than ever before for people to communicate with each other, that has come at a price. And as Facebook grew from a dorm-room startup into a media behemoth, they haven’t always acknowledged that this power comes with great responsibility.

The same openness of communication and low barrier to entry allowed Russia to set up thousands of fake accounts, groups, and pages to sow division; spread misinformation; and attempt to influence the 2016 election. And now that Russia’s playbook is out in the open, we’re already seeing other bad actors rip straight from its pages.

More recent revelations about Facebook’s data-gathering practices and user-privacy breaches have also underscored the importance of Facebook working together with Congress to address these serious issues. So will Facebook decide to work with us to tackle these problems? Then maybe we’ll have our answer.

Meredith Broussard, author of Artificial Unintelligence: How Computers Misunderstand the World and a professor at New York University

I think there have been a lot of things that have been exciting and innovative about social media, but I think that we are at the point where there are so many people on social media platforms that we really need better governance. I think that self-governance has not worked out well for Facebook and has not been positive for democracy.

I think that has been a fetishization of technological tools [in the past]. I think we as a society have set aside the idea that cyberspace is completely different than the real world. And it’s not. So I think we have a lot of problems that stem from that delusion about cyberspace is different. So I think one of the things that we that we should start doing is we should start treating digital spaces like physical spaces and treating digital companies like every other company.

So one of the things that happens on Facebook is that police use it for surveillance. Police technologies have been disproportionately employed against communities of color and vulnerable populations. So for example, you’ll have police who will go on and catfish teenagers who are suspected of being in gangs but you don’t have policing of affluent teenagers on Facebook. So there’s a lot of inequality in the way that police and technologies are deployed. It’s not just on Facebook of course — it’s everywhere.

I’ve always been an adult on Facebook. One of the things that I think must be horrible about kids on Facebook today is having your entire middle-school life out there. I’m a really different person than I was when I was a kid and I really like that I had the opportunity to grow and change and become better and that past is not weighing me down. So I think it’s not really fair to young people to make them carry around the burden of the documentation of their entire growing up.

We need more regulation of Facebook and tech companies. I think that we have done the experiments of “let’s try this and see how it goes.” And it has not gone as well as we have hoped. We need to have a conversation about this, as a public and as a community. I think part of the problem has been that we have a couple of a couple of people saying that this is how it’s going to be and trying to govern tech as a dictatorship. I think we’re a democracy, and we need to have a public conversation about it.

Aminatou Sow, co-host of the Call Your Girlfriend podcast and co-founder of Tech LadyMafia

I still remember the day I signed up for Facebook as a college student. We had waited for what seemed forever for it to be available at our university and here it was. It would be a lie to say that in 2004, privacy was top of mind when I eagerly joined the service. It seemed like a walled garden and I didn’t think once about whether it was a safe experience for me or for humanity.

I remember the thrill of making digital connections with close friends and then the thrill of making new friends and crushes on the network. I signed up as a student and didn’t quite realize the network would follow me after college.

As the service expanded, so the did the headaches and the privacy conundrums. “Who is a friend?” “Is it OK to add your coworkers as friends?” “Can I ask friends to take down these photos of me doing a keg stand?” “Oh shit, now our cousins are on here too!?” “What does it mean if my boyfriend is or isn’t in a relationship with me?” are all questions I needed to have answers to.

For a long time, Facebook helped me connect with the far-flung corners of my world. Now it is a source of anxiety and guilt mostly. Guilt because I know the harm it is causing and yet, even though I don’t share anything on it, I have not deleted my account completely. My siblings and I joke that we will delete it when our father finally joins but I know I shouldn’t be on there.

The question of Facebook being a net good for humanity or whether it’s had a positive impact on the world is complicated. Right now, as a user and as a citizen, it feels unconscionable to support it and it has been disheartening to watch Mark Zuckerberg refuse to grapple honestly with what he has unleashed and the harm that’s being done at scale. It is also disheartening to watch our politicians refuse to hold Facebook accountable in a real way.

The network we logged on to 15 years ago is unrecognizable but as citizens we cannot outsource our privacy and security to tech moguls. They always have ulterior motives and we are pawns in their game. We are living the consequences.

Antonio Garcia-Martinez, former Facebook employee and author of Chaos Monkeys

Technologies have their birthing pains. One moment they’re barely viable, the next moment they’re a threat to the established order.

There were 60-odd years between Gutenberg first printing indulgences for the Catholic Church, to cover the ruinous development costs of his newfangled printing press, and a then-obscure Wittenberg professor publishing a 95-point screed, partly against that same traffic in religious forgiveness. A century later, Europe would be rent by a violent, continent-wide war over the diametric polarization that Luther’s heresies, amplified by Gutenberg’s technology, had rapidly propagated.

Thus, if in 1648 you had asked your average European about the net good or bad historical effect of the printing press — this well before the Enlightenment upsides, from science to human rights, which we now take for granted — you may well have encountered some skepticism. Ditto any time-travel polling you might do about the telegraph in 1860, radio in 1930, or television in the 1950s. Going even further back, Socrates lambasted the corrosive effects of the alphabet, in Plato’s Phaedrus. (He bemoaned it giving youngsters the appearance of knowledge but no actual wisdom … sound familiar?)

Technologies, particularly in the media sphere, seem to inevitably move from improbable contraption, to dangerous tool whose implications are worryingly discussed, and thence to dull and semi-obsolete utility.

The same radio that allowed European fascists to rally seemingly-civilized nations to conquest and genocide now struggles with a new technological threat (podcasts) while begging us for smalls sums of support. (I’ve got an NPR tote bag somewhere.) As sure as night follows day, the same fate one day awaits Facebook.

For all the fuss now made about Mark Zuckerberg’s creation, the underlying technologies that made it possible — ubiquitous and global smartphone adoption, virtualized social identity, and a Pavlovian addiction to smartphone prompts — exist quite independently of any one service or company. Technology is amoral, and exists in a plane quite beyond our moral dramas.

Put another way, the Great Internet and Smartphone Revolution, or whatever title future historians choose to bestow, is here to stay. The Luddite reaction to Facebook and social media that clamorously calls for its regulation or partition or even outright technological diminution, will be about as effective now as it was in Gutenberg’s day.

One more parallel from that era is enlightening. In 1492, right in the midst of the Gutenbergian revolution, Johannes Trithemius, the abbot of a Benedictine monastery which dedicated itself to the hand-copying of vast volumes, published a tract titled De Laude Scriptorum Manualium (“In Praise of Scribes”). There, he enumerated at length the virtues of illustrated manuscripts over printed books, citing their superior longevity and the elevated virtues required in their fabrication.

And how did Trithemius publish his laudatory hymn to the hand-written word? Printing it in a press of course, as that would mean a wider readership (ironically, only a printed version survives).

In much the same way, this newspaper will publish worried ruminations about the impact of this diabolical social media, questioning its very moral foundations, by sharing them on the selfsame social media under discussion. I can only hope future commenters see the irony in that, as we do in Trithemius’s warning.

Kara Swisher, Recode co-founder and editor-at-large

Facebook moved fast, Facebook broke things. I think the only question now is: Can Facebook fix the things it broke?