Now that Rudy Giuliani has overtaken -- for the moment -- Sen. John McCain as the Republican front-runner, the big question is "why?". The answer is not that either party is lacking contenders with presidential material, but that Giuliani just might be the right man at the right time. There's a controversial theory historians have named the "great men" theory of history. As opposed to Marxist historians, who believe that class struggle is the great mover of history, or their lefty cousins who believe that "groups" -- women, gays, minorities -- and their struggles dominate human affairs, some historians hold...