Ideology is what drives the success and failure of empires. It’s what made the United States the most powerful nation on earth, and what might end up bringing it down. The greatest blunders of US foreign policy over the past century were driven by ideology: a belief in America as the defender of freedom and democracy around the world. The last three presidents, in their own very different ways, sought a return to pragmatism, national interest and problem-solving. But America’s ideological mindset might prove too powerful to overcome, writes Alex Roberto Hybel.

Ideology helps build and destroy empires. Its latest victim is the United States.