I've been listening to the Catholic bishops as they struggle with their pastoral letter on nuclear war, and I've been listening to Lt. Gen. Dan Graham, the former head of the Defense Intelligence Agency, as he tries to tell the prelates the error of their ways.

What I find most surprising is not their predictable differences of opinion, but their points of agreement. Neither would endorse a first-strike nuclear attack by the United States (though Graham might think it foolish to announce a no-first-strike policy). Both would seek non-nuclear means of removing what Graham calls "the brooding menace of nuclear war."

And, perhaps most surprising of all, both have deep questions -- moral as well as pragmatic -- about the prevailing policy of mutual assured destruction (MAD) as a deterrent to nuclear war. The retired general, a prominent Catholic layman, sees it as plain common sense.

"If the bishops want to quarrel, (MAD) is something to quarrel with, because it is basically immoral," he said during a radio interview last week. "Yet it is the backbone of our current force and all the arms control, disarmament and nuclear freeze propositions. MAD says that the way to protect the United States is to threaten to kill enough Russians, and to have the Russians capable of killing enough Americans, that . . . you avoid nuclear war through sheer terror."

Not even Archbishop Joseph L. Bernardin of Chicago, chairman of the committee that is drafting the pastoral letter, would argue the point.

The bishops would be a good deal less reluctant than the general to embrace the notion of a nuclear freeze until such time as we can develop more rational ways of preventing war. And the general would take issue with the bishops' interim position, which he describes as "saying you can have nuclear weapons as long as you don't have any plans to use them." But both might acknowledge that a deterrent that is too gruesome even to think of using is no deterrent at all -- which is the major problem with current U.S. policy.

The general has an alternative. Graham, who heads a private, nonprofit group called High Frontier, has been pushing a technological solution to our nuclear impasse. In brief, he would have the United States "put into space a non- nuclear system that could shoot down Soviet nuclear weapons over Soviet territory" -- an approach he says is feasible under technology already developed.

Such a system would have a number of things going for it, among them that it would neutralize Soviet nuclear missiles directly, not by trying to convince the Russians that if they destroyed half the world we would respond by destroying the other half. And because the laser- based system envisioned by Graham's group would attack Soviet missiles that were already launched (rather than attack Soviet territory in a counterattack), it would limit rather than spread nuclear war. Finally, since the High Frontier system would have an extremely limited offensive capability, its development would not be viewed as an arms-race-inducing threat by the Soviets.

"What we are saying is that, if we do it right, we can protect the American people from (nuclear) destruction, and we don't care whether the Soviets protect their people or not."

I don't know whether the thing is as easily feasible as Gen. Graham says it is. But if it is, its development makes more sense to me than anything I've heard out of either the Pentagon, the White House, or the U.S. Catholic Conference of Bishops.