Rep. Robert Dornan (R-Calif.) saw fit to inject the issue of some of his colleagues' military service into House debate last week. The subject was production of the Trident II D5 nuclear missile. Dornan pointed out that one of his antagonists had never served in the military. It was such people, Dornan said, who were "most offensive of all" in taking a position opposite his on arms issues.

It may not be quite so simple an issue as Dornan thinks, however. Before he starts grading his colleagues' patriotism on the extent of their military service, maybe he should take more time to consider the complexity of the matter.

He could listen to the arguments of Rep. Newt Gingrich, for example. Gingrich, 42, a Republican from Georgia is a bubbling bibliography of articles written and books read who regularly lobs verbal grenades on the House floor and generally gives fits to the House Democratic leadership. Nobody's rhetoric is more combatively anti-communist, more passionately nationalistic than that of the fourth-term conservative from metropolitan Atlanta.

But two decades ago, when American men of his generation were asked to stop communism on the killing fields of Southeast Asia, Newt Gingrich chose instead to stay on college campuses, where, while his contemporaries fought in Vietnam, he earned three degrees.

Married in 1962 and a father one year later, Gingrich explains his decision not to volunteer in personal terms. "Part of the question I had to ask myself was what difference I would have made," Gingrich said this spring to The Wall Street Journal's Jane Mayer. But in June, he now amends that statement: "Frankly I would not have made any difference in Vietnam but much more is what difference it would have made in me."

Over and over in conversation, Gingrich returns to his 1958 weekend tour of the battlefield of Verdun, which Winston Churchill aptly called "The anvil upon which French manhood was hammered to death." There, Gingrich explains, as a 15- year-old, he "made a decision that the balance of survival for free societies is the quality of their civilian leadership." So, Gingrich explains, "the central issue in the Vietnam War was not military manpower but politics."

Gingrich believes "Vietnam was the right war at the right time," but that "it was the United States Congress and the United States news media that would lose the war." He expressed no regrets about not serving in uniform: "I think I have paid my dues as a volunteer; I've been involved with this war now for 27 years and I've spent more time studying the Soviet system." "Temporarily in the short run," Gingrich admits that Vietnam combat veterans in Congress have "the credential of personal courage." But he counters "What do you think it took to stand up on the House floor as a freshman to take on (the expulsion of) Rep. Charles Diggs?"

After Dornan considers these arguments, he might get another interesting slant on the issue he's raised by considering the case of Sen. Albert Gore Jr. Gore, 37, of Carthage, Tenn., almost alone of the Harvard class of 1969 volunteered to join the Army and go to Vietnam.

Gore explains his actions this way: "I come from a small town of 3,000 people. I concluded that if I didn't go, somebody else would have to go. And I knew just about everybody who was going to have to go in my place. . . . For me, that sort of reinforces the sense of community and nation that is at the root of why you have a duty to serve your country."

Al Gore knew Charles Holland, Walter Pope, James Stallings, Jackie Underwood and Roy Wills. All five, like Gore, came from Smith County, Tenn. All five were killed in Vietnam. Gingrich, unlike Gore, has never visited the Vietnam Memorial and does not know anyone personally who died in that war.