Tribalism is a term used to describe the state of being organized by, or advocating for, tribes or tribal lifestyles. It is a loyalty or preference to ones own people, and it can apply to culture, politics, and sport. Tribalism can also refer to a way of thinking or behaving in which people are loyal to their social group above all else, or a type of discrimination or animosity based upon group differences. In a political context, tribalism can mean discriminatory behavior or attitudes towards out-groups, based on in-group loyalty. Tribalism implies the possession of a strong cultural or ethnic identity that separates one member of a group from the members of another group.

Tribalism has both positive and negative aspects. On the one hand, it can bring groups together in ways that are crucial for the creation of public goods, build strong empires, forge strong armies, and develop effective governance structures. On the other hand, tribalism can be a toxic dynamic in collective life, characterized by blind allegiances and huge passions of partisan affiliation. Tribalism can lead to the suppression of dissenting voices and a cult mentality in which members seek only to affirm one anothers worldview.

Tribalism is not inevitable; rather, its a function of group norms. Recognizing that collective norms can be either positive or negative is key to understanding why and when tribalism occurs. It also suggests how different groups can find common ground. Tribalism remains a powerful force everywhere, and in recent years, it has begun to tear at the fabric of liberal democracies in the developed world, and even at the postwar liberal international order. To truly understand todays world and where it is heading, one must acknowledge the power of tribalism.