Christopher Vasillopulos, professor of international relations at Eastern Connecticut State University, has an answer:
The short answer is 9/11… The panicky US response to 9/11 did not so much change the world as reveal the shallowness of its materialist culture and the weakness of its political institutions. If Americans were truly committed to the natural rights basis of its Constitution, if they really believed in the values of freedom, their response to 9/11 would have been profoundly different.
…Without the Constitution, Americans are simply human animals who inhabit North America. From this perspective 9/11 was a test of American identity, a test Americans failed.
…For all its faults, the US has been a beacon of freedom and its possibilities. For all its limitations, it has managed to personify the struggle to free the individual from the shackles of unreasonable restraints of tribe, ethnicity, race, tradition, religious intolerance and other assaults on human dignity. Throughout its history it has worked to make real the underlying values of its Constitution, often in the face of prudential calculation. This is the world 9/11 changed: the world of US leadership in the search for the fulfillment of human aspirations.
When Americans cease to be Americans, when they act like frightened animals, the world loses hope. This is the most important lesson of 9/11, a lesson that Americans have not learned. Until they do, the world will not be able to imagine a world of freedom, peace, compassion and prosperity.