Some once famously dissenting ideas now govern U.S. foreign policy, maturing as they go. BY CHARLES KRAUTHAMMER Thursday, July 21, 2005 12:01 a.m. EDT The post-Cold War era has seen a remarkable ideological experiment: Over the past 15 years, each of the three major American schools of foreign policy--realism, liberal internationalism and neoconservatism--has taken its turn at running things. (A fourth school, isolationism, has a long pedigree, but has yet to recover from Pearl Harbor and probably never will; it remains a minor source of dissidence with no chance of becoming a governing ideology.) There is much to be learned...