The liberal tradition has its roots in the Enlightenment, that period in the eighteenth-century Europe when intellectuals and political leaders had a powerful sense that reason could be employed to make the world a better place.

Simply put, the most powerful state is the one that prevails in a dispute.

This self-defeating behavior, so the argument goes, must be the result of warped domestic politics.

The Soviet Union and its empire disappeared in large part because its smokestack economy could no longer keep up with the technological progress of the world's major economic powers.

Offensive realism predicts that the United States will send its army across the Atlantic when there is a potential hegemon in Europe that the local great powers cannot contain by themselves.

When World War II started on September 1, 1939, the German army contained 3.74 million soldiers and 103 divisions.

A state's potential power is based on the size of its population and the level of its wealth.