THE JOINT CHIEFS of Staff are ducking their professional responsibilities by refusing to say whether the nation is better or worse off in abandoning SALT II weapons limits. They are, in fact, politicizing themselves by saying the question is a political one that they, the nation's top military officers, are not obliged to answer.

Their predecessors advised the president and Congress that adhering to the provisions of the unratified SALT II was, on balance, advantageous militarily. In contrast, today's chiefs recently decided against making an up-or-down recommendation to President Reagan. They rationalized that whether to continue abiding by SALT II was a political decision to be made by the head politician, Reagan, and not the nation's military leaders.

"Reagan is supposed to be the best politician in the world," one of the chiefs told me. "Why not let him make this political decision?"

Yet, theoretically, the Joint Chiefs of Staff -- composed of a chairman and the heads of the Army, Navy, Air Force and Marine Corps -- are the nation's wise men on military questions. They are supposed to be professional military leaders with professional advice to help the politicians make sound decisions in a world where nuclear incineration of the planet is the biggest threat of all.

It is true, of course, that in the real world of the military, especially in peacetime, generals and admirals play politics to get ahead. The new chairman of the Joint Chiefs, Adm. William J. Crowe Jr., has far more political and diplomatic experience, for example, than seagoing time. And the way he tried to finesse the chiefs' SALT II recommendation to the president showed this political orientation. He knew that Defense Secretary Caspar W. Weinberger wanted to scrap the SALT II. And Crowe wanted to avoid an open split between the chiefs and Weinberger.

The chiefs debated the pros and cons of sticking with SALT II. A paper full of wishy-washy prose and on-the-other-hand argumentation distilled their views, according to administration officials. The paper did not come down hard one way or another on the SALT II question. Crowe, sources said, thus was able to use the paper like a stretch sock to cover his key political problem: a potential split between the chiefs and Weinberger, the defense secretary who has raised so much money for the services over the past five years.

"Weinberger wouldn't have to say anything directly to the chiefs for them to feel under pressure to go along on scrapping SALT II," said one retired flag officer who spent years in "the tank" -- the room in the Pentagon where the chiefs meet Tuesdays and Thursdays. "You don't get to be a four-star without knowing what's expected."

The chiefs agreed that since the military advantages and disadvantages of sticking with the SALT II limits were practically a wash, the nation's highest military body need not make an up-or-down recommendation to the president on the treaty. They would let the president make the call and then go along with it, no matter which way he went.

What was lost in this cop-out by the chiefs was their considered judgment on which course is best for the nation from a military point of view. And, so far, it appears that neither the president nor the Congress will learn about the qualms some of the chiefs have about discarding the weapon limits.

"I was worried about breakout if we abandoned the limits," one of the chiefs told me in reconstructing the debate. "The Russians don't throw their old stuff away like we do."

With SALT II being observed by the United States and Soviet Union, he said, at least some Soviet weapons and launching facilities would be junked. With no such limits, he reasoned, the Soviets would store up all their old missiles and perhaps suddenly deploy them, tipping the balance their way through what the military calls "breakout."

The incoming chief of staff of the Air Force, Gen. Larry D. Welch, told a secret session of the Senate Armed Services Committee on Mar. 20 that he favored sticking with the SALT II limits as long as they proved to be militarily advantageous to the United States.

Last Thursday, before the Senate Appropriations Defense subcommittee, Crowe visibly angered Senate Minority Leader Robert C. Byrd (D-W.Va.) by refusing to tell him what recommendation the chiefs had made to Reagan on SALT II. Crowe, when asked his personal view on the wisdom of abandoning the SALT II limits, continued to stonewall, even though tradition calls for military leaders to give their personal views when Congress asks for them.

Crowe did tell Byrd that he did not believe the Soviets would change their weapons-building plans appreciably whether or not SALT II continued to be observed. U.S. military leaders usually discuss an adversary's capabilities, not intentions, when justifying defense preparations.

Byrd's reaction to Crowe -- the first chief to appear publicly since Reagan made his SALT II decision -- suggested that the chiefs' manuevering may have avoided a fight with Weinberger while starting one with Congress.

"They are being their own worst enemy," Byrd said, as he angrily paced back and forth across his office after failing to get Crowe to answer his questions. "Crowe didn't answer one of my questions."

Byrd said that both the president and Congress are entitled to the up-or-down recommendation of the chiefs on abandoning the SALT II limits, and added: "Unless the chiefs advise the president, he is not well served. If we in Congress can't get the chiefs' advice, whose advice are we to take on these military questions? Crowe is trying to put a classified cloak over this thing."

At the end of Crowe's Senate confirmation hearing on July 30, 1985, Barry Goldwater (R-Ariz.), chairman of the Senate Armed Services Committee, asked this question of behalf of Byrd:

"Admiral, if confirmed, do you agree to appear before this and other appropriate committees and give us your candid views and answer all appropriate questions relative to your position?"

"I agree, Mr. Chairman," Crowe replied.

George Wilson covers military affairs for The Washington Post.