The presidential candidates claim to see America's energy future, but their competing visions have a certain vintage quality. They've revived that classic debate: the hard path versus the soft path. The soft path, as Amory Lovins defined it in the 1970s, is energy conservation and power from the sun, wind and plants -- the technologies that Senator Barack Obama emphasizes in his plan to reduce greenhouse emissions. Senator John McCain is more enthusiastic about building nuclear power plants, the quintessential hard path. As a rule, it's not a good idea to revive anything from the 1970s. But this debate is...