AS JIM FALLOWS points out, there are two rigid and opposing orthodoxies on the question of national defense. On the left, activists splash blood on the Pentagon and protest every weapons system the military requests. From the right, tougher-than-thou Congressmen endorse every bad idea that comes out of Lockheed, lest the Russians gain an edge. And in the middle there's been next to no one combining expertise and objectivity. Fallows, one of the nation's best reporters, begins to fill that center with his new bestseller, National Defense.

Myriad evils--officers bent on promotion, industrialists bent on profit, generals bent on status, and politicians bent on re-election--all do their part to plague the American military. Fallows contends. He lays the bulk of the blame for weakness, though, on two phenomena: The Pentagon's affection for unbelievably expensive and ludicrously ineffective high-tech weaponry, and the manpower problems that have developed since the draft was halted in 1973.

Fallows uses dozens of examples to illustrate the dangers of trying to build "magic weapons," be they missiles with so many computers they will virtually assure victory or "super" tanks that corner like 40-ton Ferraris. War, he quotes Clausewitz, is both unpredictable and filled with "friction"--everything from bad weather to equipment breakdowns. As a result, planners should stress adaptability. Instead, the "prevailing ethic of modern American defense...is the managerial view of the military," which translates to "the desire to make defense a more straight-forward and efficient business, by applying the disciplines of economics and management to military plans."

The results include: The XM-1 tank, which costs, in constant dollars, seven times as much as the Sherman tank of World War II, yet whose turbine engines cannot tolerate dust; the command-control-communications-intelligence network, designed to control military maeuvers from a central point, which works, under ideal conditions, 38 per cent of the time; the TOW missile, launched by a soldier, which demands that he stand absolutely still in the middle of a battlefield for ten seconds while guiding his warhead at a far-off tank; missiles guided by t.v. cameras that destroy fenceposts as often as enemy targets; and even an Air Force flashlight so electronically sophisticated that almost every pilot bypasses it for $1.50 Japanese models that have the advantage of fitting inside their flight suits. Again and again his examples pound home points that make common sense--it's better to have many more relatively cheap fighter planes than a handful of super-sophisticated models that spend most of their time on the ground for repairs. And he scoffs at that American god, technology, Cheaper weapons, he says, tend to be more reliable and easier to use, and their low cost allows Congress to build thousands more.

American weapons are far from perfect; so, concludes Fallows, is the force that must use them. He repeats many of the common arguments about the volunteer army as employer of last resort. For example, this astounding statistic--in 1980, of the 100,860 men who were serving their first term as enlisted men in the infantry or armor artillery, exactly 25 (men, not per cent) had college degrees. But he adds new dimensions to the usual discussion of social inequality by stressing he military effects of an all-poor army. "I think the mixture of middle-class men had a real modulating effect," he quotes one expert as saying. "It made it much easier to sustain discipline. It was nice for a lowerclass kid to outmarch a college grad. They can't do that anymore, because the college kids aren't there." And more than nice--a representative military helped America to see its defenders as honorable, not unfortunate, and perhaps made the country more reluctant to go hastily to war. Fallows' prescription is simple: Revive the draft, and remove all the exemptions that once protected the sons of the wealthy.

BUT WAIT. There is irony here, deep irony. When Fallows was at Harvard, the Vietnam war was raging, and he lost the lottery. But he evaded the draft and stayed a civilian. Even then, his contemporaries say, the decision pained him immensely, for he knew someone else, most likely poor or Black or both, would go in his place. But it was, at least on one level, a decision not of cowardice but of conviction. Fallows did not join the Army because the Army was slaughtering innocents in Vietnam, fighting a sick and evil war that no one with a conscience could support. The same facts that led Fallows to avoid the draft lead many to oppose its revival; his unwillingness to address those issues is the book's chief flaw.

"This is a book about defense, not about foreign policy." Fallows writes in the introduction. "Obviously there are connection between the two. The only reason a nation raises armies is to defend the interests its policy defines," he concedes, but then he sticks to examples like whether our nation wants to have a two-war capability or a one-and-a-half war potential. The real policy questions are different--what interests will the military defend, and in what way? And today's answers to those questions still seem much like the amoral ideas that got us into Vietnam.

Fallows has made a dramatic bid for middle ground here. But if the left is to travel toward the center and begin to support a restoration of what Fallows calls the "military spirit," they need many more assurances. If the army is to be used in El Salvador, where we already have military "advisers," then why join? If its goal will be to shoot peasants and defend "authoritarian" regimes, then why wish it better weapons? If the tanks are going to roll into more Vietnams, why should we care if their engines clog with dust?

No one has solved these problems yet, and it is a safe bet Ronald Reagan will do little but worsen them. Indeed, there seems a tremendous chance that Fallows' prescriptions for change in the military make atrocities like Vietnam easier. Central to his book is the hope that the "military spirit" can be restored; he calls it the "most important task in defense." There must be, he writes, "a bond of respect between the military and rest of society," achieved mainly through the draft. But any society that thinks too much of its military may be heading towards militarism, with all its attendant problems.

And if there is a draft, if the military is given the opportunity to inculcate each generation with its set of values, what will the result be? The all-volunteer force, he says, has diminished the "will to fight," a psychological condition composed of pride, loyalty, fear, and submission. He defines submission as the "process through which the soldier is made to do over and over again things he does not want to do, until he understands that the fundamental rule of his existence is to obey." There was a time, and a movement of which Fallows was a part, that hoped a new sort of society could be built, based not on the need to obey but on the right to choose. A military that prizes submission may retard the evolution of civilian society toward that goal (if, indeed, it is moving in that direction). At the very least, mindless obedience inside the military was responsible for the single event that most turned public opinion against the last war--the massacre at My Lai.

ONE CAN HOPE that a democratic army with an involved and supportive citizenry will mean real reform, not just militarily, but politically as well. Perhaps Congressmen really will be reluctant to wage war if their sons will be dying. But there's another side of this--the memory of General Hershey's declaration that the best use of the draft was for "indoctrination" of young men before liberalizing forces like college could corrupt them. Similar worries--and not blind pacifism--motivate many on the left who oppose the draft or the shoring up of our military.

By looking at the arguments he has left out, one can see how Fallows has shaped his argument. Reduced defense spending, for instance, holds great appeal to liberals who see more money for social programs. And though Fallows might agree, he is silent on the issue, for such talk infuriates the right, already convinced as it is that too many guns have been sacrificed for butter. His attempt to stick to the issues at hand, though, is in the end unpersuasive, for there are too many questions that need answering first. Americans of conscience will always predicate support for the military on the belief that the nation's might will be used wisely, not immorally squandered. When that day comes, they will start to worry about the radar in our airplanes.