The internet, led by tech giants Amazon, Facebook and Google, has been great at connecting us with products. It has been less good, however, at connecting us as a polity. It's time we started imagining what an internet optimized for the citizen would look like.

I'm a plus-sized woman, and when I was pregnant with my first son in 1999, the maternity shops didn't have my size and the plus-size shops didn't sell maternity clothes. By the time I was pregnant with my third son in 2008, the internet offered all I needed — very cheaply and with quick delivery.

We've made a trade. In exchange for commercial surveillance and data collection, we have the world's best at-home mall. And just as my friends and I socialized at the mall when we were teens, nowadays we socialize online in commercial spaces such as Facebook and Twitter. The stores around us, informed by our digital profiles, magically transform to meet our needs and desires. We are in consumer nirvana.

The dark side of this revolution is that data collected for one use can be repurposed for another. Our marketing silos are information silos, too. Thanks to our tailored experiences, we barely share a common reality with people who disagree with us. They see different products, political news, even facts.

It crept up on us slowly, while we were playing with our new toys. But now the internet giants have enormous power. Facebook and Google together collect 77 percent of U.S. digital ad revenue. They account for a growing portion of political ads, and offer us news environments that they control and edit.

This influence isn't benign. Just last month, the New America Foundation shut down its Open Markets initiative after a big donor — Eric Schmidt, executive chairman of Google parent Alphabet Inc. — reportedly objected to its position on European antitrust regulation. The tech giants are spending increasing amounts on lobbying, lest we think of their market power and access to data as anything other than inevitable.

Consider the implications. The way Google presents search results can influence voter opinions and possibly help radicalize vulnerable people (remember Dylann Roof?). Facebook's experiments with its "I voted" button suggest it could shift election outcomes. Imagine the possibilities if Facebook CEO Mark Zuckerberg ran for president (not an unthinkable scenario). He would be completely within his rights to direct his engineers to skew the Facebook newsfeed toward positive coverage of his campaign.

We caught a glimpse of what that might look like in the last presidential campaign. Donald Trump's team, for example, reportedly planted Facebook posts as part of an operation to suppress the black vote. And now we know that fake accounts, likely operated out of Russia, spent about $100,000 on Facebook ads ahead of the 2016 election — ads that might have reached tens of millions of people. Yet researchers can't get a more precise sense of what happened, because Facebook hasn't released the data needed to do so.

Facebook gives us a lot. It's a place to connect with friends and family. It's also the most efficient propaganda machine ever built. How can we decouple those two things and promote one while limiting the other? More generally, if we decide that we've made a bad trade with big tech, what can we do about it?

The authority of the inscrutable makes it hard for any individual to take on the tech giants. That leaves government, which has focused on consumer antitrust matters, not the state of our democracy. And the classic antitrust approach of splitting up companies to increase competition probably wouldn't do the trick.

We'll have to try something else. It might involve setting a legal standard for transparency, so that people will know how their data is being sold, for how much and to whom. Or it might require finding ways to limit the use of targeted advertising, so there would be less incentive to collect quite so much data about us.

Maybe what we need is an internet-age analog to the ideal of public broadcasting — a new and parallel internet optimized for the citizen rather than for the consumer. Picture a space that isn't polluted with ads, that allows people to search for, say, information about health from sources that have nothing to sell them. We would go there to learn, listen and engage, and go back to the commercial internet only when we wanted to buy something.

This isn't a technological challenge. It's a political imperative. We can't give away our democracy to a tiny group of profit-seeking corporations in return for a better shopping experience. At a minimum, we should demand that Facebook and Google make public all their data on political ads, including who bought them and how they were targeted. Then we would have a better idea of what we're up against.

Cathy O'Neil is a mathematician who founded ORCAA, an algorithmic auditing company, and is the author of "Weapons of Math Destruction." She wrote this article for Bloomberg View.