It’s not exactly the Ali-Frazier “Thrilla in Manilla,” but the ongoing Rand Paul-Dick Cheney pugilism certainly packs a punch.The libertarian ophthalmologist and the warlord emeritus have been pounding each other for months, and while it’s tempting to just kick back with popcorn and behold the entertainment, we do need to acknowledge the bout’s deeper meaning. Because this is really about something quite serious.Republicans are profoundly split these days over foreign policy: between the non-interventionists who are increasingly wary of American military involvement abroad; and the neoconservative hawks who blundered us into Iraq and want us to keep flexing military muscle. Senator Paul is a leader of the non-interventionsts, a GOP faction that used to be tiny, but not anymore.