Those Carter operatives bemoaning the limits of their power can learn a thing or two from Nicholas von Hoffman. Ditto the reform candidate of your choice. The system can only be altered, he says, by outsiders who make a ruckus: ""The paradox is that the politically effective people can't get anything done, while the ineffective people, a Martin Luther King, a Ralph Nader, a Saul Alinsky, can't get elected but can get things done."" Partly he's out to disprove the notion of an imperial presidency. The very term, he contends, was adopted to put the onus for the Vietnam debacle on the three 1960s presidents, exonerate their supporters (whether in academia or in Congress), and absolve the rest of us of guilt. ""In this tale of innocence lost, the president has played the serpent's role; he is the devil who made America un-American."" But it ain't so: every aggrandizement of federal power has served the interests of a specific group which the president was then powerless to buck. The vast, shaky edifice of state capitalism he traces back through the Depression-era NRA (business-formulated codes of ""fair practice"") to the 1906 ""abandonment of competition in favor of regulation"" in the railroad industry. Von Hoffman does not charge collusion or naked greed: ""politics invented and bent structures of government to force a no longer quite so free market to play favorites, sometimes to help the poor and sometimes for less noble motives."" What he does contend--and it runs equally through his discussions of domestic reforms and foreign initiatives--is that, since the apostasy of William Jennings Bryan, there have been no significant differences between the two major parties, that presidents have followed rather than led, or administered rather than ruled. (Even the supposedly high-handed FDR was, at most, ""a few months ahead of organized sentiment"" when he shipped war materiel to Britain.) His chief regret: that turn-of-the-century American socialists--who had ""a coherent critique of emerging corporate capitalism, a program of their own, and a demonstrable ability to attract votes""--were snuffed out by WW I repression and the Communist split, thus denying America a real opposition. That's the one totally unsubstantiated contention, for though von Hoffman writes with the devil-may-carelessness of a columnist, his heterodoxies are fully documented as well as seconded by sober, independent studies (like Jonathan Hughes' 1977 The Governmental Habit).