Americans of all political persuasions fear that “free speech” is under attack. This may seem strange at a time when legal protections for free expression remain strong and overt government censorship minimal. Yet a range of political, economic, social, and technological developments have raised profound challenges for how we manage speech. New threats to political discourse are mounting—from the rise of authoritarian populism and national security secrecy to the decline of print journalism and public trust in experts to the “fake news,” trolling, and increasingly subtle modes of surveillance made possible by digital technologies. The Perilous Public Square brings together leading thinkers to identify and investigate today’s multifaceted th...