Midterm Assesments -- Reagan's own, the scholars; Comparing present, past

At midterm in his presidency, Ronald Reagan seems likely to rank in the ''gray middle'' of White House performers. This is the consensus of a group of seven prominent presidential scholars interviewed by the Monitor.

Two years after his Jan. 20, 1980, inaugural address on the Capitol's steps - the political battle site he commanded his first year in office - President Reagan now must regroup and redefine political goals, the scholars note. This process underlies the ''disarray'' reported of late in the administration (and hotly rebutted by the President).

How creatively Mr. Reagan adjusts to the disappointments of the economic slump and swelling deficits, quite apart from the course of the economy itself, will likely define the mettle of the man and his term.

''Reagan's administration so far has shown as many minuses as pluses - maybe more minuses than pluses,'' observes Robert K. Murray, Pennsylvania State University historian. ''The question now is how resilient he and his staff are. The test of a great president is how he adjusts to challenge.''

But despite the nation's economic doldrums, not one of the seven White House scholars says Reagan has yet been fully tested - by economic calamity, threat of war, civil disturbance - sufficiently to push him among the highest or lowest achievers.

''The mettle of a president is tested in the fire of great controversy and conflict,'' Professor Murray says. ''Reagan hasn't been tested yet to see how he would react - not in foreign policy or domestic policy. All the signs so far point to Reagan as being a relatively lackluster president.''

The presidential scholars expressed greatest concern for the nuclear arms issue - how Reagan handles the potential for the East-West military confrontation - as the most serious measure of the man and his tenure. He has yet, they say, to write that chapter.

As to Reagan's midterm problems, historians see a pattern not unique to the current administration. ''On a long-run historical basis, there is a midterm miasma in administrations,'' says James McGregor Burns, a Williams College historian.

As time passes, Reagan increasingly becomes his own measure of presidential performance. Early comparisons with Franklin D. Roosevelt or Dwight Eisenhower seem dated now.

''Politically, Reagan acts like Roosevelt,'' says FDR scholar Frank Freidel, a Harvard emeritus historian now at the University of Washington in Seattle. ''Roosevelt would compromise. But Reagan thinks like Hoover - 'stay the course.' Hoover wouldn't compromise very far.''

While the potential for presidential initiative exists also for Reagan, he has yet to demonstrate the intellectual boldness and instinct for the positive uses of government of a Roosevelt, this scholar says.

''Reagan budges somewhat, but not very far, very often,'' Professor Freidel says. ''Hoover didn't budge very far either. Reagan is so doctrinaire, of such firm principles, that he can be in very serious trouble.''

Reagan's initial thrust - to reduce the role of government and stimulate private investment - has not worked out, Freidel says. ''It was so much easier for Reagan at first because he wanted to be the new Coolidge. Now he must think positively, and he has not done that.''

Washington's preoccupation with Reagan's ''flexibility'' is misleading, say the scholars. ''Reagan is an ideologue,'' says Betty Glad of the University of Illinois. ''He has a very devoted staff that plays a very specialized role. They are ever trying to get him to adjust to realities, to adjust his basic premises. The question is whether he makes compromises soon enough to avoid political damage.

''There's an ebb and flow in what he says . . . but no evolution in his basic premises since the 1950s. The basic US foreign policy since World War II has been containment,'' Glad says, ''whereas for Reagan there's more of a fight fire with fire view: The Russians are bent on world conquest. . . . We can't trust any of the tactical agreements they make.''

''At one level Reagan is going for equality in arms agreements,'' Glad says, ''but he really wants superiority.''

Reagan shows little of Dwight D. Eisenhower's caution, says Fred Greenstein of Princeton University. The men's basic leadership styles differ.

''One of the things you discovered after the fact with Eisenhower was a man with an enormously analytical mind, extremely concerned with long-run consequences of actions,'' he says. ''It would have been very difficult to imagine Eisenhower going for something as risky as the tax legislation of August 1981.''

Early optimism for Reagan seems to be fading. Says Stephen Wayne, a George Washington University scholar, ''The public is learning again there are no easy answers. The expectations for Reagan have been too great.''