This book develops an original theory that grounds political principles and practices in common interests among citizens and residents of a country. This theory differs from most prevalent political philosophies in that they focus on common ideas which emphasize how we might think rather than how we actually live, or on competing or conflicting interests for the purpose of balancing or advancing one set of interests over another. On Common Interests offers principles, possible structures, and practices that enable government to help us advance the interests we share. As a political philosophy, it values cooperation and collaboration over conflict and competition.