With all the concentration on whether the Democrats will regain a majority in the Senate in the November elections, it's easy to overlook what the Republican control of the Senate since 1981 has been: a boon to the republic and a tonic for both parties.

The conventional wisdom is that divided control of Congress, with one party controlling the Senate and the other the House, results in stalemate and legislative gridlock.

In fact nothing of the sort has happened. The current divided Congress has had some of the beneficent effects of a forest fire -- it's cleaned out a lot of the old, clogged growth to make room for the new. It's contributed to the most searching reexamination of the role of government in this country since the New Deal, and has forced the leaders of both parties to control their most ideological members.

When the Republicans won control of the Senate in the 1980 elections, they hadn't had a majority in either house since the first two years of the Eisenhower administration, when they had majorities in both the House and the Senate, and it had been more than 20 years before that since they had controlled either house.

In the quarter of a century between 1955 and 1980, both parties on Capitol Hill fell into bad habits. The Democrats seemed to assume that their majorities were by divine right and became arrogant and insensitive.

On the other side of the aisle, a quarter of a century of wandering in the political wilderness as an apparently permanent minority seemed to have rendered the Republicans terminally irresponsible. In January 1981, when the Republicans organized the Senate, only eight senators had been in either the Senate or the House in 1953-55, when the Republicans had last commanded a majority on Capitol Hill. Only two -- Barry Goldwater and Strom Thurmond -- were Republicans.

"The split gave President Reagan a foothold for turning the government on its head, and at first the Republican majority were reflexive supporters of him," says Norman Ornstein of the American Enterprise Institute. "But they developed both individual and institutional independence, and now the Republican Senate stands with the Democratic House against the White House on some issues. The Senate Republicans are the only ones who have acted responsibly on the debt issue."

The conventional fears for legislative deadlock generally haven't been realized.

"There was a lot of clash in 1977 to 1981 when the Democrats controlled both houses and the White House," says Prof. Austin Ranney of the University of California at Berkeley. "Since then, the Senate Republicans have been quite independent on such matters as the budget, Gramm-Rudman and the tax bill."

One benefit of the divided control is that it has forced things into the middle because both parties have had to fend off their extremes. They can't get anything done otherwise.

Another is the development of what in effect is a new talent pool of leaders, such as Majority Leader Robert Dole, Budget Committee Chairman Pete Domenici and Richard Lugar, chairman of the Foreign Relations Committee.

The current divided Congress is historic because it is rare in our history, and having one for as long as six years is rarer yet. The last time the country had six years of divided control was a century ago, 1883-89, when the Democrats controlled the House and the Republicans the Senate. Since the Civil War, there has been divided control of the Congress on only four other occasions, each time for just two years.

For the rest of this election year there will be claims and counterclaims of the importance of Senate control in terms of legislative initiatives on military spending, arms control, aid to the contras in Nicaragua, judicial appointments and social issues, on party realignment, continuing the "Reagan Revolution," the 1988 presidential elections and so on.

In fact, the Democratic chairmen of several major committees are unlikely to effect a revolution. Sen. Sam Nunn (D-Ga.), who probably would be chairman of the Armed Services Committee, has worked closely with Goldwater, the current chairman. The same with Sens. Lawton Chiles Jr. (D-Fla.) and Domenici, Claiborne Pell (D-R.I.) and Lugar and Bennett Johnston (D-La.) and James McClure (R-Idaho).

The Republicans' six years of control have changed things on Capitol Hill, and if they maintain control, things will continue to change.

If the Democrats win, they'll be a lot different from what they were six years ago. There's no returning to 1980.

The writer is a member of The Post's national staff.