IT WASN'T only the administration of Jimmy Carter or Democratic control of the Senate and invulnerability in the House that got swept away in Tuesday's tidal wave. And it wasn't only large numbers of elected and appointed officials, either, who have put in years, even decades, of government service. A lot of bedrock assumptions and conceits around this town went as well, chief among them the idea that we in this nation's capital are uniquely gifted at sizing up and understanding that which preoccupies us the year round: the political life of the rest of the country on which our own depends. It is just silly to claim that this or that circumstance of the last 48 hours of the campaign "tipped" the result toward Gov. Reagan or caused any of the other alleged soarings and sinkings of the figures we have been reading about. Nothing of that size and force and sweep could have been created over a weekend or even a week or two by the assorted mullahs and miseries of our times.

So we start with the fact that in a splendidly bipartisan way, this is an embarrassment to that gigantic apparatus of measures and manipulators and temperature-takers and commentators that tells the country what it is thinking and informs the policymakers of what their two hundred million or so employers expect of them. Something of gigantic proportions happened -- must have been happening for a long while -- and the capital and the political wise men were taken by surprise. In one respect the irony is perfect: an "anti-Washington," "anti-establishment" political storm-warning was missed by Washington and the establishment. The wreckage is everywhere. This will persuade those who have sought to give the feds and the media hotshots their comeuppance that they were right, that the capital is an insulated, self-absorbed place. They will have at least, in part, a point. The only way, it seems, that the rest of the country was finally able to send Washington the much-vaunted "message" we keep hearing about, turned out to be to tear the joint down.

We do not mean to imply that Jimmy Carter, a man of various achievements and maddening faults, was merely an innocent bystander in the affair. Our own strong preference was for his reelection. But we have no doubt that some large part of Tuesday's Democratic liberal defeat must have been owing to dissatisfaction with the man himself and his economic and foreign policy handiwork. Some large part must also be traceable to the used-up, unrenewed and reflexive quality of so much Democratic Party thought and dogma these days. Gov. Reagan's impressive campaign and projection of himself must also get some credit (how dramatically perfect that while his opponents were trying to portray him as a frightening fringe-figure who needed only to be known to be understood as an oddity, the voters were getting ready to pronounce him the landslide consensus choice). And so must the fact that a conservative, reactive, had-enough wind is blowing across the country.

One of the things, prominently, that people are thought to be fed up with of course is the meddlesome interventions of the federal government in their pocketbooks and their private lives. Gov. Reagan surely has both a strong public mandate and strong personal inclination to do something about this. But here we come to the hard part, the rock on which to some very large extent the Carter government foundered, having come to town in a way pledged to do some of the same things. For while the majority is right in sensing that there is something overcomplicated, unresponsive and dead-handed at the center of much federal government thought and activity, it is rather self-deluding in insisting at the same time that it wants -- in fact, demands -- certain protections and entitlements that require more federal intervention and expenditure. These include: jobs; social insurance; a strong and versatile military establishment; safety, security and stability in a thousand ways that require federal intervention. For Gov. Reagan and his administration the test will be trying to fulfill these two broad obligations at once.

Some very decent men and women in the legislative and executive branches were summarily retired Tuesday night. A number of these individuals and the changes that their departures will bring about deserve to be discussed another time. So too do their replacements -- especially in the U.S. Senate. And so to do some of the various campaigning techniques that marked the 1980 campaign. But in a general way you can at least surmise this much: 1980 wasn't 1976 or the elections that came right before. This time there has been ordered up real policy change, and one way or another it will happen. It will be Mr. Reagan's obligation to try to make that change substantial, consistent and beneficial to that huge and disparate and internally conflicting constituency that elected him -- as well as to those racial minorities who did not. We think when he was attacked this indescribably difficult chore, he will probably feel more sympathy for Jimmy Carter. Certainly watching Jimmy Carter, the last man to have tried, concede to Mr. Reagan Tuesday night, the rest of us felt such sympathy.