Combining insights from evolutionary psychology with a broad sweep through history, down to the ideological civil war ripping the United States apart, the book explores the deeper roots of people's inability to accept claims about reality which come from the opposite ideological camp, no matter how valid they might be.After theorists around 1960 proclaimed the 'death of ideology', ideological divides and clashes have reemerged with renewed intensity throughout the world.In the United States they have become particularly venomous.Each side in America's escalating ideological civil war charges the other with concocting 'fake news' and 'alternative facts'.The other side is widely viewed as malicious, irrational or downright stupid, and, often, as barely legitimate.People are deaf to claims about reality that come from the opposite camp, no matter how valid they might be.The zeal of the opposing sides is often scarcely less than that which characterized the religious ideologies of old.Indeed, historical religious ideologies have largely been replaced by 'secular religions' or 'religion substitutes'.Ideology consists of normative prescriptions regarding how society should be shaped, together with an interpretive roadmap indicating how this normative vision can be implemented in reality.Ideological Fixation is the result of tensions and conflicts between these two elements.The book focuses on ideologies' factual claims about the world, typically subordinate to, and often distorted by, their normative commitment.In exploring this phenomenon, the book combines insights from evolutionary psychology regarding the nature of some of our deepest proclivities with a broad sweep through history and around the world.It proceeds from the Stone Age to the rise of civilization, the great religions and modernity, to a critique of fundamental factual premises that underlie some of the major debates dominating today's liberal democracies, not least the United States.