WITH ALL THE drama and tension, last Tuesday's anti-MX vote in the House seemed to suggest that Congress had finally made up its mind about the missile issue. How long did that bold consensus last? Until Wednesday.

That was when the same House voted overwhelmingly to continue funding MX development. In fact, for all the hoopla over cutting $1 billion from MX on Tuesday, the House added $2.5 billion on Wednesday. Hey, who's in charge here? Are they fer it or agin' it?

The fact is that Congress, which has a time-honored tradition of confusion and ineptitude, has been outdoing itself of late. Consider the scene in the Senate only a few months before, when that body went into a long but ultimately pointless filibuster over conservative social issues. For five straight weeks, as the economy languished, the nuclear arms race continued and unemployment worsened, it was clear what the greatest deliberative body in the world was accomplishing: zero.

When the conservatives finally gave up, the senators went immediately into all-night session over the budget. They already had given up hope of completing the budget by the Oct. 1 deadline, and were trying instead to pound out a stop-gap resolution to keep the government going when Congress recessed, so members could campaign with promises of firm, visionary leadership. But as Majority Leader Howard Baker pleaded for some semblance of adult behavior, no fewer than 50 amendments for special-interest favors or single- issue constituencies were introduced, further obstructing the machinery.

Finally they passed a patchwork resolution that resolved nothing, setting the stage for the current lame-duck session -- in which, it is expected, last year's budget still won't be finished. Baker lamented, "We simply cannot do our country's business this way."

What's happening to Congress? It seems inept to a degree that's difficult to believe -- paralyzed by personal bickering and interest- group favoritism, incapable of cohesive action, living like a spoiled child from one tantrum to the next.

This would be bad enough in normal times, but it takes on special importance as leadership from the Oval Office erodes. Congress is, of course, very good at preventing things from happening, and it now seems likely that much of what Ronald Reagan proposes in 1983 and 1984 will go nowhere.

While this prospect may delight Reagan's enemies, it should not be entirely comforting to those of the left or right concerned about helping the country get through the next two years. If Congress cannot address the nation's problems, what can we expect for the nation?

Congress does devote a great deal of time to transparent publicity stunts, such as the toothless "balanced budget" amendment that tied up the House and Senate for most of last summer, then vanished like the Comet Kahoutek. It does freely engage in hypocrisy (most "balanced budget" amendment backers also supported Reagan's $749-billion tax cut, source of the deficits they were piously decrying). It does indulge in wild, MX-like inconsistency (shortly after voting overwhelmingly for a Reagan defense budget that called for doubling U.S. nuclear warheads, the House came within two votes last August of endorsing a nuclear freeze).

But seldom does it produce serious, purposeful measures -- except, of course, for handouts to the special interests that whine the loudest or wave the largest fistsful of cash.

Granted, Congress has always been a helter-skelter institution to some extent. Granted too that the current congress reflects a fragmented America. But as Henry Reuss (D-Wis.), a House member since 1954, says, "The handicaps of Congress have become much greater in recent years. The institution has become much more rickety."

What are the reasons for all this? Start with the chaos created in the last decade by the proliferation of subcommittees. In the House, for instance, who has jurisdiction over an energy issue like hydroelectric power dams? The Energy Committee's Subcommittee on Energy Conservation and Power? Or the Science Committee's Subcommittee on Energy Development and Application, or maybe its Subcommittee on Energy Research and Applications? Perhaps jurisdiction should go to the Interior Committee's Subcommittee on Energy and the Environment, or maybe its Subcommittee on Water Power and Resources.

Then again, why not the Public Works Committee's Subcommittee on Water Resources? Or the Agriculture Committee's Subcommittee on Forests, Family Farms and Energy (a natural combination if ever there was one)?

Or the Energy and Water Subcommittee of Appropriations, or the Energy and the Environment "task force" (equivalent of a subcommittee) of the Budget Committee, or the Energy, Environment and Natural Resources Subcommittee of the Government Operations Committee, or the Energy, Environment and Safety Issues Affecting Small Business Subcommittee (that's a real name) of the Small Business Committee.

And let's not forget the Senate, where we find the Energy Committee with its separate subcommittees on Energy Research and Development; Energy Conservation and Supply; Energy Regulation; Energy and Mineral Resources; Water and Power, and Public Lands and Reserved Water. Or the Water Resources Subcommittee of the Senate Environment and Public Works Committee; the Forestry, Water Resources and the Environment Subcommittee of the Agriculture Committee; the Energy, Nuclear Proliferation and Government Processes Subcommittee of the Government Affairs Committee; or the Energy and Water Development Subcommitte of the Appropriations Committee.

So which of these 21 subcommittees has jurisdiction over a power dam? The answer is that potentially all of them do -- which does not augur well for getting much business done.

During the 1979 Iranian oil crisis it seemed that some kind of energy hearing was being held in some subcommittee room at all hours of the day and night -- but no meaningful legislation ever emerged. In the wake of the Three Mile Island accident, the jockeying for "primacy" among subcommittees was shameless, with every one of those blessed with the word "nuclear" competing to get its chairman's face on "Good Morning, America."

At the moment there are 141 subcommittees and "task forces" in the House, 101 in the Senate, and eight for the various special, select and joint committees. (The House has 21 full committees, the Senate 16; there are four joint committees, seven special or select committees.) As Reuss notes, "We've set up so many centers of power in the subcommittees that it's become nearly impossible to get anything coherent done."

The subcommittees are now "centers of power" because of a little-noticed aspect of the 1975 seniority reform -- a package called, at the time, the "subcommittee bill of rights." Central to this "bill of rights" was granting subcommittee chairman what amounts to authority to hold hearings whenever they wish, on any bill. The effect was immediate -- a dramatic increase in subcommittee hearings.

In March 1972 -- a month chosen at random -- there were 453 subcommittee hearings in the House and Senate, a staggering number in itself, averaging out to 19.7 hearings per working day. Ten years later, in March 1982, there were 852 hearings, almost twice as many, a mind-melting average of 37 per working day.

It is true, perhaps, (as is said on the Hill in defense of the many new hearings), that "life has become more complex" in the past decade. But it hasn't become twice as complex. What has become twice as complex is getting anything done in Congress.

Most congressmen are aware that subcommittee proliferation works against the national interest. But it does work in favor of other interests -- their own.

The key words here are "Mr. Chairman." Congressmen long to be not just The Honorable, but Mr. Chairman. It may not seem like much in the larger scheme of things to be Mr. Chairman of the Office Systems Subcommittee of the House Administration Committee, but it sure sounds good back home.

Among all the committees, subcommittees, task forces, joint, special and select committees, there are 298 chairmanships. Some members hold more than one chairmanship, but roughly, nearly half of Congress' 535 members are Mr. Chairman of something.

Besides what it does for the ego, a subcommittee chairmanship has practical advantages. The ambitious congressman knows the value of having his own hearing room, with the TV cameras rolling. Since the hearing -- not the final legislation -- is most likely to make the evening news, he has every incentive to place the perservation of his tiny fiefdom above the national interest. Ergo, 37 hearings a day.

Another part of the 1975 "subcommittee bill of rights" increased subcommittee staffing. In the House, each subcommittee chairman and ranking minority member got one new staffer; in the Senate, each junior senator was given three. In 1947, Congress had 400 committee staff aides. By 1970, the number had quadrupled, to 1,600. Today it stands at 2,000.

As with subcommittees, the more staffers, the harder to get anything done. "The larger the staffs get, the more people are involved in a decision," says an aide to one senator. "Everybody wants to have his say and leave his little stamp on the legislation. Pretty soon the weight of people wanting attention is greater than the force moving the legislation, and the whole thing grinds to a halt."

Last spring, for instance, Sen. Daniel Patrick Moynihan (D-N.Y.), an early player in the fashionable game of "infrastructure" rebuilding, introduced a bill to require a simple accounting of which roads and bridges in the country were in the worst shape -- so Congress could figure out how much pressing work had to be done and what it might cost.

By the time this bill emerged from the warrens of the various subcommittees of the House Public Works and Government Operations committees, it required not just a list of collapsing roads and bridges but an "inventory and assessment" of all the nation's highways plus all firehalls, parks, landfills, schools, hospitals, public libraries, garbage trucks, courthouses, pipelines, mass transit facilities, airports, reservoirs, federal offices buildings, power generating plants, playgrounds, sewers and -- believe it or not -- television stations.

In short, the amended Moynihan bill required a cataloging of nearly every object in the United States larger than than a delivery van. The subcommittees had run wild, producing a special-interest appeaser of no value to anyone, and it consequently went nowhere. (The "jobs bill" now before Congress is based largely on guesswork about how many roads and bridges are really in serious disrepair.)

Next, consider the result of the Budget Act of 1974, which created the Congressional Budget Office, the House and Senate Budget Committees -- and an elaborate budget "process" that drains most of Congress' energies but produces few budgets.

In brief, this "process" requires both budget committees to set ceilings for overall national spending; then all "authorizing" committees (every standing committee except Budget and Appropriations) to chose some specific numbers; then the appropriations committees to actually award funds; then the budget committees to "reconcile" the inevitable differences; then the House and Senate to vote on the appropriations bills on their floors; then a House and Senate conference committee to reconcile the inevitable differences between the two chambers -- while, during the entire process, the administration is pushing its own budget and regularly shifting gears.

The process is so streamlined and efficient that the 1982 session of Congress, which (officially) ended in such comic disarray before the elections, was able to pass only three of 13 appropriations bills, and it is not expected to pass all of the rest duri lng this special session. Indeed, in three of the last six years, Congress has failed to adopt the nation's central financial document.

This process forces members to spend so much effort on the budget that little energy is left for anything else. As Rep. Morris K. Udall (D-Ariz.) has said, "We don't have time to legislate." Or as Sen. Patrick Leahy (D- Vt.) puts it, "We've become elected line-item bureaucrats," fussing over the details and oblivious to the larger picture.

Not all congressmen object to this development, of course, because relief from responsibility for the larger picture is exactly what they seek. Says a senior congressional aide, "The budget is a welcome excuse to put everything else off." Which is what Congress is most proficient at doing.

If expanding subcommittees, mischief- making staffs and a tortuous budget process were not bad enough, the modest time and energy left to members get eaten up quickly by the special-interest and single-issue crowds.

The role of money from Political Action Committees (PACs) in special-interest causes is now fairly well understood (the key thing to remember is that PACs don't buy elections, they buy votes). What seems less well understood is the influence PACs have on Congress as an institution.

As traditional party structures have faded, congressmen come to do most of their fund- raising individually. (Oil and gas PACs gave more money in the last election than the whole Democratic National Committee.) This encourages them to fix their loyalties on interests groups rather than on the national interest, which has no PAC.

Obviously, in a day when hundreds of thousands or millions are casually spent on campaigns, no single $5,000 PAC contribution means much; it's spare change compared to the total required. Thus a congressman who was once beholden to only a few interests (maybe oil, or banking or paper) now ends up beholden to many more, and each one is usually concerned about maintaining its privileges, avoiding change, embracing the status quo. This means that PACs tend to be lobbies for foot-dragging -- lobbies that do well in a fragmented and ineffectual Congress.

Most of the special-interest ploys that characterized the 97th Congress have been well covered, but one that escaped general attention indicates the degree to which PAC money makes Congress allergic to common sense.

In July a House-Senate conference committee approved a bill to give airline pilots and other top-level airline union employes huge special benefit payments if their airlines were merged or shrunk by declining business. The deal would have guaranteed pilots up to 60 percent of their salaries for five years, and granted similar deals to other workers; a special severance payment would have given "average" pilots $190,000 each plus other special benefits.

This bill, in other words, would have channeled money into the hands of one of the most favored, best-paid (average income: $69,000 a year) elites in America. How could airline pilots possibly deserve such special breaks?

There was, of course, no reasonable explanation. But there was interest-group arm- twisting. As The Post's Carole Shifrin reported, the Air Line Pilots Association and the International Association of Machinists and Aerospace Workers were behind the proposal. (Since 1979, Shifrin reported, the two unions had given $1.5 million to 225 congressmen.) The proposal was eventually beaten on the Senate floor by Sen. Nancy Kassebaum (R- Ka.), but she had to resort to a procedural argument to do it; she told fellow senators the conference committee had violated their unwritten code by introducing a new matter to an otherwise uncontroversial bill. Apparently, the fact that the pilot's bonanza was wrong didn't carry enough weight.

Next, consider the influence of single-issue extremists like Sen. Jesse Helms (the cause of the Senate's fall filibuster). As in the cases of subcommittee expansion, the endless budget "process" and PAC proliferation, the main effect of duri lsingle-issue politics is to throw a monkey wrench into the machine. Helms knew at the start of the filibuster, for example, that he had only a slight chance of winning, but that didn't matter; the filibuster allowed him to go down in very bright, well-publicized flames. It will doubtless aid his direct-mail fund-raising.

Extremists, because they seldom can win, generally satisfy themselves by ruining it for everybody else, and don't seem to care if this means accelerating the general decline. Their mailing computers and simplistic ratings systems (used by extremists of the left and right alike) are slanted entirely toward the negative; they rail against what should not be done, but leave scant room in their checkoffs and scorecards for any measure of progress. Like public opinion polls, they are excellent vehicles for no-confidence votes but little use in charting a course for the country. Their message to congressmen, in measured and uniform tones, is unendingly repeated: Give in. And many congressmen listen.

Because of all these factors, at present the Hill can only be moved to actually act on a bill when political panic and pressure have risen to such a level that congressmen forget themselves entirely and begin voting in mad spasms.

The only meaningful products of the 97th Congress have been Reagan's budget cuts and his tax bill. Important roll calls for the first took place in an atmosphere of unrestrained frenzy, sections being rewritten and voted on without most congressmen having a clue as to their significance. There were so many competing proposals going through at once that no one, not even David Stockman, could keep them all straight.

Besides not knowing "what's going on with all the numbers," as Stockman said, no one even knew what some of the numbers were; you may recall that one budget proposal, when formally printed, contained a woman's name and phone number, scribbled during a late-night rewrite session. Apparently the measure had been passed into law unread.

This was not an isolated incident. The pattern was repeated in July 1981 when Reagan's tax cuts raced through in an amusement-park atmosphere. At the time, few congressmen knew (to cite one example) of the presence of the "tax leasing" provisions, and scarcely a handful had any idea what these provisions meant. And the pattern continued this year. In May 1982, frustrated by his inability to find any consensus on which of the many rival budgets was most likely to pass, House Rules Committee Chairman Richard Bolling issued an unusual rule that effectively opened the House floor to unlimited debate on any subject. His purpose was to let those congressmen in thrall to single-issue lobbies and special interests blow off steam and make the grandiose gestures that would appease their constituents. The result? A marathon, 39-hour House session with countless rant- and-rave monologues and some 30 roll-call votes. All the budgets up for consideration were amended so many times they ceased to be distinguishable. Then all collapsed. When it was finally over, Congress had accomplished what, these days, it usually accomplishes -- nothing.

It goes without saying that not all congressmen are sellouts or windbags. Yet the conscientous and the public-spirited seldom prevail. Here is their dilemma:

Even for the sincere congressman, the ideal course is far from clear. What is the right thing? Who should come first? Which path will lead us out? The questions are not unanswerable, but they require time, reflection and calm logic; sincere congressmen need a sane atmosphere in which to piece the puzzle together.

Poised against them are the armies of sell- outs and windbags, people who do not suffer from the slightest hesitancy. They want specific, tangible handouts, and they want them now; their agendas are highly itemized, their desires keenly felt and vigorously expressed. The sellouts and windbags force Congress to revolve around them, just as all attention centers on the wailing child, drowning out the possibility of conversation.

If there is a cause for optimism, it is that Congress, unique among American institutions, has the power to reform itself. Many of Congress' problems are of its own making, and so Congress can undo them. It won't be easy. The interest groups that dominate the current system will resist any congressional revival, any change. But it is possible.

Gregg Easterbrook covers Washington for the Atlantic Monthly.