THIS rather self-important piece of work is described on its dust jacket as "a history of how American culture led us into Vietnam and made us fight the way we did," but readers looking for anything much in the way of new light on an old controversy are going to be disappointed. Apart from an interesting observation in its concluding chapter, Backfire offers little more than a recitation of familiar litanies about American solipsism and a rehash of the war's lugubrious history. Boiled down to its essence, Backfire could make a provocative essay; as a book, it is mostly padding.

"I will argue," Loren Baritz writes at the outset, "that there is an American way of ar that is congruent with the American way of life, with American culture, and that is the way it must be. We cannot understand war without understanding culture. That is what this book is about." This American way of war, he further writes, is a compound of "cultural myths, political assumptions and bureaucratic behavior," all of which sounds considerably more promising and provocative than it actually turns out to be.

By way of cultural myths, Baritz has nothing more to offer than the tried and the more-or-less true. We fancy ourselves a city on a hill, imagining "that we have been Chosen to lead the world in public morality and to instruct it in political virtue," that we have a divinely ordained mission "to impose the One Right Way on others who were either too wicked, too stupid or even too oppressed to follow (our) example." We are imbued with "a national missionary impulse," which is compounded by a conviction that our genius for technology -- "Yankee ingenuity, American know-how" -- renders any obstacle surmountable. And in our pervasive national self-absorption we are incapable of understanding other cultures, of knowing that what works here will not necessarily work equally well elsewhere.

None of this exactly qualifies as news, though to what extent it explains our descent into Vietnam is another question altogether. Baritz may be just a trifle too eager to explain Vietnam with large cultural suppositions that conveniently suit a critical view of the United States. He may on the other hand be too reluctant to see Vietnam as what David Halberstam called a quagmire, into which we slipped quite against our will and without any clear idea of what was happening to us. Obviously a nation does not get into such a fix entirely free of hubris, messianism or other malign influences, and the United States that went to war in Vietnam had its full share; but a country can also do bad or stupid things for what are thought to be good reasons, and this Baritz is too quick to ignore.

THE POLITICAL assumptions that Baritz believes to have led us into Vietnam are no more surprising than the cultural myths. Kennedy, he says, had been unmanned by Khrushchev at Vienna and needed to "find a way to prove he was a strong adult"; Johnson "was the perfect example of the American solipsist in love with his country and certain that the American way was the best and only solution for everyone"; Nixon had political leeway to cut and run, but instead became obsessed with avoiding national humiliation, with reaching "a lasting, just and honorable peace -- one that would assure the world of America's 'credibility,' and would guarantee to the South Vietnamese that they could progress toward an open and democratic society."

All of which is perfectly true, as also is Baritz's observation that all three presidents operated under an exaggerated fear of the political right, but none of whch adds anything to our understanding of what got us into Vietnam or, once in, kept us there. The "political" section of Backfire is the book's longest and least original. It consists almost entirely of second-hand material obtained from other books and news reports, material that will be familiar to anyone with a reasonable knowledge of the period and that Baritz has failed to organize in any imaginative or revealing fashion.

The same is largely true of the book's concluding section, in which "bureaucratic behavior" is examined. That the military bureaucracy manages to outperform its civilian counterpart when it comes to inefficiency, cumbersomeness and self-preservation comes as hardly a surprise. Similarly, it is not exactly news that the military, while whining noisily about civilian interference and incompetence, was itself principally responsible for the botch we made of it in Vietnam, as Baritz rather succinctly puts it:

"The argument that civilian interference prevented the military from winning has been widely accepted, with almost half of the American public (and 82 percent of combat vets) agreeing. This easy assignment of blame obviously permits all of us to growl at the politicians and be done with it. But the ticket-punching careerist officers were not invented by civilians. The utter failure to develop military tactics effectively to utilize the technology was not the fault of civilians. The strategy of attrition and the dizzying rotation of officers were not made in Washington. The cover-ups and deceptive optimism were the military's own. The interservice rivalries were not required by politicians. The bureaucratization of William Westmoreland's mind was the military's own. The unwillingness to stop the blizzard of heroin was the military's own. The subversion of the Special Forces, the insistence on using B-52s, and spreading the use of Agent Orange were all military decisions."

This is true, and usefully sized, but again it contributes nothing to what we already know. The one area in which Baritz has ventured a somewhat original idea has to do not with how we got into Vietnam, or how we failed to accomplish our ostensible purposes there, but how the war may have affected us long after its conclusion. "After President Nixon abolished the draft to secure his reelection," Baritz writes, "the most privileged young Americans, thanks to the all-volunteer force, had the great luxury of indulging their distaste for public issues. This attitude can be summarized as a sequence: The war first caused a rejection of leadership and institutions, then the authority of culture, and, finally, a retreat to all that mattered, to the isolated self." This has produced a generation, he argues, that is "stonily indifferent to other people, to politics, to history, to goals, and to democracy."

Those are harsh words, but there is a good deal of lamentable truth to them. Though the cause-and-effect relationship most certainly is not as simple or direct as Baritz presents it, there can be no question that the widespread cynicism Vietnam engendered among the young produced, when combined with the abrogation of mandatory military service, a traumatic change in American attitudes. Baritz is right when he claims that the all- volunteer army has "safeguarded the affluent, relied on the need of the poor to enlist, and destroyed the classic democratic need for the citizen-soldier." This may well be Vietnam's most lasting legacy: a complacent citizenry indifferent to its civic responsibilities, and a military utterly disconnected to civilian life and immoblized by bureaucratic inertia. If that is indeed what Vietnam has left us, the price we ultimately pay for that war may be far greater than we now imagine.