Political parties encourage in-group/out-group mentality and evaluating policies based on who supports them rather than their merits. People naturally separate based on trivial group distinctions, but parties amalgamate major racial, cultural, and ideological distinctions into one group and thereby intensify hostility. The COVID-19 pandemic shows how intense partisanship distorted the way people viewed science and personal safety. The emotional loyalty fostered by parties endangered public health and democratic discourse alike. While independents are imperfect decision-makers, they tend to be more open to new information and show more consistency across presidential administrations. Partisan identity has evolved into a moral and cultural divide, raising the central question of the book: are parties worth their costs?