If competing beliefs about political events in the world stem largely from information asymmetries, then more information and knowledge should reduce the gap in competing perceptions. Empirical studies of decision making, however, often find just the reverse: as knowledge and the stakes in play go up, the beliefs about what is happening polarize rather than converge. The theory proposed here attributes this to motivated reasoning. Emotions inside the observer shape beliefs along with information coming from the outside world. A series of experiments embedded in a national survey of Americans finds that a primary driver of the beliefs someone forms about globalization, other countries, and the politics in the Middle East is how strongly they attach their social identity to the United States. Attachment produces more intense positive and negative emotions that in turn shape the interpretation of unfolding events and lead norms to be applied in an inconsistent fashion. People, in effect, rewrite reality around their favored course of action, marrying the logic of appropriateness to their own preferences. Beliefs, consequently, are not independent of preferences but related to them. Motivated reasoning, while not consistent with rational models, is predictable and can lead to expensive mistakes and double standards that undermine liberal internationalism.