#Republic: Divided Democracy in the Age of Social Media By Cass Sunstein, $30.

Which matters more—freedom or democracy? In an ideal republic, each enables and tempers the other. In Cass Sunstein’s #Republic, though, freedom is failing democracy.

For Sunstein, a Harvard law professor and head of the White House Office of Information and Regulatory Affairs in the Obama Administration, #Republic builds on ideas from several earlier books, including 1993’s Democracy and the Problem of Free Speech. Sunstein agrees with jurist Louis Brandeis “that the greatest menace to freedom is an inert people; that public discussion is a political duty.” Regrettably, the #republic we live in, or at least tolerate, disables public discussion and renders the masses inert.

As the hashtag implies, social media enables and emblemizes a new menace: “cybercascades” of self-curated and self-serving information swamp reasoned debate and reinforce biases. The Internet has given people both “collaborative filtering”—algorithms that trace and bolster our affinities—and “special interest intermediaries,” media that refine our interests and buffer us from what we don’t want to hear or learn. Also a student of behaviorial science, Sunstein draws on Nobel Laureate Daniel Kahneman’s research into how we filter information and Yale Law School Professor Dan Kahan’s findings “that people’s judgments stem, in large part, from their sense of identity.”

Sunstein argues that “consumer sovereignty,” the right to select or avoid cascades, should balance “political sovereignty,” Brandeis’ duty to engage in open discussion. He establishes at length that the First Amendment does not and should not restrain all government regulation of speech. Owners of media empires invoke the First Amendment to fight off attempts to “regulate” them, but Sunstein counters that they already enjoy a market regulated in their favor, in that government protects their rights, by force if necessary. So asking them to enlighten people and to defend democratic ideals is not an onerous burden.

Why should information not be a public utility, like the airwaves? Sunstein’s proposals for intervening in the information market range from “voluntary self-regulation” to “must-carry policies” to “serendipity buttons” on Facebook— all to expose people to information and rhetoric they otherwise miss or avoid. And he is sensible enough to warn that government intervention can go too far.

Early in #Republic, Sunstein cites, as a parallel for communication markets, urbanist Jane Jacobs’ tenet that mixed-use city streets expose citizens to diverse people and ideas. The private enclaves we built instead also enable and emblemize the stifling freedom of withered democracy.