David Clark’s office on the MIT campus is at the top of a tower that looks like a twisted aluminum column. The name plate next to his office door reads “Albus Dumbledore.” And, like the leader of Harry Potter’s wizarding world, Clark knows the Internet’s secrets from the beginning.

“We clearly couldn’t anticipate how big it was going to be,” Clark says. “Whenever I go back and read things that I wrote or others in the group wrote about planning for the future we consistently underestimated what was going to happen. “

Clark and Harvard professor Yochai Benkler, one of the legal experts that shaped the Internet’s development, have issued a warning in joint papers published in the American Academy of Arts and Sciences’ magazine, Daedalus. More than three decades after the worldwide communications network was born, Clark and Benkler say they’re deeply concerned that the Internet is headed in a dangerous direction that its founders never intended.

Looking back, Clark wonders if he and other founders should have left behind guidance on how the Internet should grow up.

“Not constraints, not rules, but guidance, advice — like, ‘don’t be stupid,’” he says.

As it is, Clark thinks the Internet has fallen in with a bad crowd, to some extent. Most people now access the Internet through one of its corporate friends — like Google, Facebook, and Apple. As gatekeepers, those companies hold the power — information about our daily lives that helps them sell us things.

Clark says people need to remember he and others built the Internet so no one would need a gatekeeper. It was supposed to be an idealistic society of equals, where every user had the same amount of power.

“One of the most exhilarating observations of the first decade or two of the public Internet was that things that were impossible, became possible,” says Benkler, who started studying the Internet in the early 1990s.

Back then, Benkler was thrilled by the way it overturned old power structures, like broadcast media. On the Internet, anyone could send an email or post a video without asking permission. At the time, Benkler was across town from Clark, studying property law as a student at Harvard.

“I was working on the homestead act of 1862,” he says. “Seriously!”

Benkler realized the Internet was like a new Louisiana Purchase — a huge amount of new property suddenly open for adventurous homesteaders to stake a claim.

So he switched tracks. Using the Homestead Act as a guide, Benkler helped create a legal framework that protected the Internet from being gobbled up and claimed by corporations.

And then, smart phones came along. And Steve Jobs created the iPhone.

“I think there’s very little doubt that Steve Jobs in particular was someone who had a vision of a more controlled experience that viewed consumers as people who needed a well-controlled, well-structured environment to thrive in,” Benkler says. “That was part of his genius, and that was part of his threat.”

Benkler was surprised by the extent to which people were willing to give up their privacy. That’s what they were doing, he says, by using cell phones with apps as gatekeepers to the Internet. Gatekeepers that collect information and use it to nudge people to do things.

“I might not chose to buy this set of things, go to this set of events, look in on this set of news media, but nonetheless that’s the direction I ended up being nudged in from these day by day interactions that I never even noticed,” Benkler says. “Look six months from now, and this is the new me. And the new me is partly me, but it’s also the me that these companies wanted for me. That I see as a real threat.”

Benkler wants people to guard against that threat by being vigilant and critical. He says they need to log in as multiple users, browse the web privately, and use free, open source software, like Firefox.

Clark suggests the public needs to fund a new group of web designers, like the group who built the Internet — but this time they’d be developing things like apps for smart phones that don’t collect data.

“The question I think is whether we want to leave the Internet to whatever the private sector chooses to make it or whether we want to take some control over it,” he says. “I think it’s important enough we need to take some control of it.”

More: Full interviews with David Clark and Yochai Benkler

Clark says people like him, who helped create and shape the Internet — and who remember what it had the potential to be — will only be around for so long.

“There’s a cohort of people who have sort of grown up with the Internet,” he says. “And as we retire or move away or go into other activities, and we know that we’re getting older, we have to sort of wonder what the values are of the young people who are taking over the Internet.”

Regardless of all his fears, Clark’s hopeful for the future those young people will create. The Internet is growing up, he says, and in the end, he has to let it.

A version of this story first appeared on WGBHNews.org.