PRESIDENT CARTER'S draft registration proposals have run into trouble on Capitol Hill, although the Army is still short of manpower. While the debate simmers, let us look at Selective Service in a new light -- in terms of social goals and opportunities. The question that bothers most people is this: Who shall serve, if not all are needed?

The administration talks of someday reviving the old draft lottery -- if your number is picked (at random), you report for a physical. This approach shows insufficient imagination. It ignores the creativity displayed in Washington's past efforts to reallocate burdens and rewards. We can do better.

There are two simple alternative approaches.

The first employs the principle of the progresive income tax, i.e., the rich pay a higher percentage of their income to IRS than do the not-so-rich. rApplied to the draft, this would mean that, in a given year, Selective Service would meet its quota by inducting the 19-year-old sons of the wealthiest citizens, starting at the top with, presumably, a young Rockefeller or two. Then it would work its way down the income ladder, using IRS files, to the male offspring of real-estate speculators, Washington attorneys and, finally, foundation executives.

The Army's Gen. Bernard Rogers last year called for a 150,000-man peacetime draft to restore the Reserves to health with trained manpower. There is ample reason to believe that this quota, and more, could be met by the most affluent fourth of America's families.

The advantages here are obvious. Those benefiting most, in material terms, from U.S. citizenship would be the first to contribute to the nation's defense, silencing the envious and reducing class conflict. The peacetime Army would provide the country's 150,000 most privileged youths with an invigorating taste of outdoor life among the less privileged. And, no less important in some neighborhoods, the draftee's parents would gain in status: If your son is a draftee, you are clearly a Financial Success!

A second creative approach draws on the "affirmative action" model that Washington has promoted with appropriate statistical rigor in higher education and employment. Here, the draft would be used to compensate for the current absence (or preponderance) of various social and ethnic groups in the ranks of the Regular Army. Since high school graduates, for example, are "over-represented" (29 percent of all Army enlisted men in 1978 were blacks), no black American high school graduate would be drafted. The same would hold true for white lads who never made it through high school.

But male college graduates, black or white, are vastly "under-represented" among the Army's G.Is. Hence male college seniors would constitue the basic pool from which Selective Service would draw draftees each year, starting with the higher-status schools.

Within this sizable group, the June graduates of Harvard, Yale and the other Ivy League universities would be the very first to go. There would be no exemptions. Their particular designation would result from the proper application of "compensatory" affirmative action; during the Vietnam war, the Ivy Leaguers, studies show, were disproportionately successful in avoiding military service.

Admittedly, both the "progressive tax" approach and the "affirmative action" model pose certain problems. The Army may have difficulties with this kind of manpower, and vice versa. Driving Daddy's Mercedes is not like driving an M60 tank. Fort Bragg is not Harvard Yard. Jogging across campus in L.L. Bean sneakers with a girlfriend is not the same as running in boots with a 50-pound backpack and a sergeant bellowing close behind. However, if the Army can adjust to women at West Point, it can adjust to an influx of the much-maligned "Me Generation." In any case, the creatives use of the Army for worthy social goals must take top priority.

But, one may ask, what about drafting women? Are not these proposals highly sexist? Only at first glance. One of the biggest boons to women's advancement in jobs and postgraduate education was World War II; women took the places of the men who went off to war. Today, the conscription of the sons of the better-off, or of the nation's college-educated males (led, willy-nilly, by the Ivies) would open up those career entry-level jobs and graduate school admissions to women as never before. True, the draftees would soon return to civilian life, but in the interval, women would make gains that could not be snatched away.

In short, by implementing these innovative concepts, meaningful social change is assured on all fronts; the draft should be revived without delay.