Digital technologies are transforming how we encounter issues of public concern and engage in public debate. On the one hand, data-based personalization means we are increasingly exposed to content that we already like. On the other hand, algorithmic infrastructures intensify and polarize message circulation, favouring clashes between opposed opinions rather than nuanced engagement. In combination, these two tendencies support automated processes of public and private meaning formation in which people are constantly guided by covert persuasion while becoming increasingly unaccustomed to overt persuasive attempts. Characterizing the resulting process as ‘the closing of the rhetorical mind’, this book analyses its detrimental effects and argues that a return to the classical notion of controversia (arguing all sides of a case) may provide a starting point for ‘making disagreement good again’. This is not a call to abandon digital technologies, but an attempt to show how individuals and organizations can use algorithms and data to (re)ignite public debate as a source of democratic solutions to the many other crises that face us in the age of algorithms.