Many of those campaign issues we have been meditating on in this space recently -- racial equality, jobs and the economy, energy policy -- are in a sense controlled by another: each candidate's view of the federal government's proper role in pursuing the desired objectives. Even the most ardent of those who inveigh against Washington these days concede that foreign and defense policy generally are legitimate areas of federal primacy. It is in these other areas, when the federal government's will collides with that of the market, the local government, the local culture, the corporation or the individual, that the trouble starts. This is an issue of great passion around the country and every four years inspires pledges no candidate can fulfill.

On Sunday's op-ed page, Professor Richard E. Neustadt, an authority on the subject, explained why Jimmy Carter's 1976 determination to cure the bureaucratic and institutional elephantiasis of Washington has failed and why the same will happen to Ronald Reagan if he comes to town. To read the Reagan laments and their corollary promises now is to hear the doomed optimistic voice of Jimmy Carter in 1976: "I believe the present 1,900 federal departments can be reduced to no more than 200 with a great savings in tax money and a streamlining of services to our people."

Mr. Reagan could do himself -- and the argument a great service, perhaps even a mercy, by absorbing from the Carter experience the fact that great numbers of those people and interest groups that howl for a cutting back of the giant federal enterprise mean only that enterprise as it curbs them and rewards others. When the thing works the other way around, they and their congressional patrons will keep you from doing much about it. And in any event (as the Reagan political tacking toward this group and that attests) by the time any candidate gets to office, he is likely to have become beholden to any number of those very constituencies his original pristine plans would have most direly affected. Mass murder of the regs and the overblown bureaucracy is a non-starter.

Only when you have removed these quixotic elements of the anti-Washington crusade can you deal with the huge and truly important questions involved. These concern what the federal government's obligation should be to intervene in a thousand different realms of public and private choice when that choice affects much more than the people who make it. Sometimes the whole issue bogs down in a truly silly argument over whether there is "too much" federal regulation. "Pro-regulators" love to point out the areas where regulation saves lives and property, "anti-regulators" the extravagantly foolish or economically disabling regulations that Washington promulgates. But this is like an argument over the virtue of laws. Which law? And comparably: which regulation? The first test of a candidate's intelligence and good faith on the subject concerns which areas he believes require federal intervention -- not whether he is, in principle, for or against intervention.

Mr. Carter has had a tough campaign break on this one: he spent 10 months espousing the anti-big government position against federal intervener Ted Kennedy and now must swing to the other side to argue with Mr. Reagan. And, like Mr. Reagan, who has been swayed by political necessity toward bailouts and interventions he once would have deplored (and did), the president has been politically enticed into federal rescue missions and interventions he probably philosophically would have preferred to avoid.

But beneath all the tactical moving around you can discern a much keener sense on Jimmy Carter's part than Ronald Reagan's of where and how the federal government must for reasons of public well-being, not just private politics, intervene. There are national problems -- the welfare-payment burden of a New York or a Detroit, the hardship of countless of the inner-city people who live in those and other cities has surely more than a little to do with the way they were treated in those other places from which they migrated to the cities. There are problems that only a national agency with a national overview can address with any useful effect -- surely in this day of invisible industrial poisons and pollutants that can travel with extreme speed by wind and current and commercial distribution, in a day when intelligent use of energy and other scarce resources is crucial, the federal government has an obligation to intervene and intervene forcefully. Mr. Reagan seems still unwilling to acknowledge these obligations, romantically fancying a market and town-hall capacity to deal with the problems on the spot. His hope of returning functions and funds to the states, though not nearly as diabolical as the Carter people paint it, isn't very practical either. If he is president, he will undoubtedly be compelled by circumstance and common sense to change his assumptions.

But to say this is not to condone or encourage the simple-minded idea that more is better where the feds are concerned. On the contrary, it seems to us that this kind of discrimination -- the hard judgment of where Washington is duty-bound to intervene and where it is not -- is a precondition to doing something about the great dead thing that does lie at the center of much federal activity. Washington often colonizes problems, aggravates them, addresses them with a lethal combination of hyperthyroid interference and lethargic, dead-handed delay. Ronald Reagan, should he be elected, would not begin to be able to deal with this phenomenon unless he, first, revised his rosy idea of how easy it will be to dump a lot of excess activity and, second, revised his dated view of what the government is legitimately entitled and/or obliged to intervene in.

On this, Mr. Carter has the benefit of his own frustrating experience and also, in our view, a more reasonable idea of what the feds simply cannot and should not leave to blind market forces or chance. But, of course, wishing or willing doesn't make it so: a president's capacity to effect and enforce his particular understanding of what the overall federal role should be depends almost entirely on the way he views the powers of his specific office -- and on this there is also much to say about the views of Jimmy Carter and Ronald Reagan.