Repression and authoritarianism are not merely phenomena of the historical past. Today, we are engaged in a fundamental battle of free and open societies against repressive, closed systems. Larry Diamond, Ayaan Hirsi Ali, H.R. McMaster, and Niall Ferguson discuss the nature of such threats and the identities of freedom’s adversaries, their goals and strategies, and what can be done to defeat these threats across government, the private sector, academia, and civil society. This discussion is the fourth of speaker series "A Century of Ideas for a Free Society." For more information on the series and related upcoming events, visit: hvr.co/2HK3C6W