Today when we think of the term “liberal,” it suggests the political template of the American Left. But the word has its origins in the Enlightenment’s fundamental values of free inquiry, individual rights, and respect for the public square. In our current era of toxic discourse, when trolling has become a profession and bad-faith arguments fuel multiple cable-news networks, Yascha Mounk’s focus on these philosophical liberal values can seem naive — or revolutionary. With populist authoritarian movements on the rise around the world, the notion that we ought to fight back by recommitting ourselves to rational, earnest political debate may ring hollow to some, but Mounk argues that we have no alternative. The core values of liberal democracy must be defended and put into practice, he says, both to protect the rights of individuals and to safeguard groups who have been historically marginalized. These goals are sometimes at odds, but Mounk insists that promoting free inquiry is the only enduring path to a free society.