Social media posts are displayed behind Sen. John Cornyn (R-Tex.). (Andrew Harrer/Bloomberg)

Lucy Bernholz is a senior research scholar at Stanford University's Center on Philanthropy and Civil Society and director of the Digital Civil Society Lab.

Last week's congressional hearings on foreign manipulation of the U.S. electorate via Twitter, Facebook and other digital platforms reveal two things: First, most legislators don't understand how these platforms work. And second, the tech industry isn't really prioritizing democratic norms as part of its operations. Neither is new, but both are increasingly dangerous.

Much of the discussion so far has focused on Russia's attempt to use these platforms to influence the 2016 presidential campaign, through paid ads or by creating fake accounts on Facebook or Twitter designed to manipulate voters. But focusing on "content" misdiagnoses the challenges these platforms present to democracy.

The power of Facebook, Twitter, Google and others, and the democratic threat that they represent, comes not from the content they show but how they show it. The closed algorithms that drive their feeds and streams also shape and bound our associational spaces. These systems know who we meet with, they determine who we hear from and they decide which voices we cannot escape. As a result, these digital companies have become arbiters, managers and record keepers of our associational lives.

The right to peaceably assemble — to free association — follows free speech as a dependent clause in the First Amendment. If we want the digital environment to serve democracy, demanding different rules about content won't ever go far enough. In fact, the focus on content will simply lead us again into the now familiar free-speech cul-de-sac in which everyone — both users and platforms — has legitimate conflicting claims.

We need to reclaim our right to associate as we please — to meet with and listen to those we choose and to control who knows what about those gatherings. Digital companies know how all this works; their algorithms and data make it happen. But they keep that knowledge hidden from us.

Reclaiming our right to association requires access to information that clarifies how the platforms do what they do. It requires visibility into the algorithmic and data inner workings of these platforms, as well as some form of redress and the ability to fully remove ourselves.

This strikes at the heart of the business propositions of Facebook, Twitter and others. They will much sooner acquiesce to new rules on content than to being held accountable for how their systems work. In fact, they may even champion such content rules, especially if doing so serves to distract us from demanding information on their algorithmic assets.

The Founders knew it when they wrote the First Amendment: Democracy requires both free speech and free association. We can't save democracy by sacrificing one for the other. We must ensure that our digital environments protect both.