"Uncivil Agreement" offers a profound analysis of the causes behind the highly polarized political conditions in the United States. Lilliana Mason examines how the political identity of the electorate has changed and how these changes have led to a deep social divide between the political parties. The research shows that members of both parties increasingly harbor negative views of their opponents, which goes beyond simple political differences. The "us versus them" rhetoric that became popular during the Trump campaign has further exacerbated this divide. Mason argues that identification with certain groups influences our perception of ourselves and our political adversaries. Even when political agreements occur, distrust between the parties persists. While these developments have increased voter participation, they have not contributed to strengthening American democracy. The book connects theories from political science and social psychology, providing a clear overview of the social dimensions of political polarization in the United States.