Government studies, studies by the Brookings Institution and the Heritage Foundation, and statements by the personnel chiefs of the armed forces all warn that serious trouble is ahead in military manpower recruitment.
All agree that the long downward trend in birthrates and a healthier economy will make it increasingly difficult to fill the ranks of all the services as we approach the 1990s.
The pat solution sought by the service spokesmen and the civilian study groups is a return to the peculiarly American form of military conscription we have come to know as ''the draft.''
In all of the Spanish, French, and English colonies, except for Quaker-dominated Pennsylvania, the concept of universal military conscription predated the republic and was molded into the Constitution in the several ''militia clauses.''
As the frontier and its dangers passed, universal obligation was replaced in practice, but not in law, by a volunteer militia later to be known as the National Guard. Because the universal militia was not a dependable source of long-term active military units, and because the volunteer units were too few, a form of selective conscription began during the Revolutionary War and has been revived in every emergency since.
That ''draft,'' in terms of this day and age, has two major defects: It is directed exclusively at the male population and its ''selective'' nature is no longer acceptable to the greater part of the American public.
No matter what the US Supreme Court has said or is likely to say about the subject, the male population is not likely to tolerate for long a situation whereby their departure for enforced military service grants to female competitors a permanent economic and professional advantage.
Although obscured, but not erased, by the vast manpower requirements of the two world wars, the ''selective'' nature of the draft has been fraught throughout our history with social and ethnic inequities. The wealthy and middle classes always have sought to keep their sons out of the draft. They succeeded roughly in proportion to their wealth. By the end of the Vietnam war the raging inequities produced by this process had become so extreme that the draft was on the verge of collapse.
The shift to a volunteer establishment in 1973 changed that situation for the worse. At least until the recession of 1981-83 began to force more whites into the service, the principal combat elements of the Army and the Marine Corps were made up predominantly of blacks, Hispanics, and severely disadvantaged whites. That situation is virtually a social time bomb, for it will produce in any large-scale conflict a massively disproportionate number of casualties among the poorest of the poor. The infusion of whites from a somewhat higher economic stratum has not solved the problem, since all of those concerned have a continuing reserve obligation and will be the first to be recalled.
The use of a lottery would not make any future draft more acceptable. The studies that preceded establishment of the volunteer system confirmed what most Americans long suspected, that the ''selective service'' feature of the old draft tended to impose a permanent economic disability on those who served compared with those who did not serve, regardless of age, sex, or social condition.
What seems to me the inescapable conclusion is that if conscription is to be imposed once again, it must be in the form of a national service obligation imposed on every American, male or female.
There is an increasing body of experience - dating from the World War II GI Bill of Rights to the recent Supreme Court decision sanctioning linkage between draft registration and public support for education - that national service can be made to work by linking it to a system of eligibility for education or vocational training beyond high school.
Thus, by making national service the gateway to higher education the female population would be included without direct compulsion.
Every public service organization in America, governmental or private, could make use of the kind of people such a national service system would make available.
In the process we might find that we have opened the way to solving not only our military requirements, but some of the most pressing social needs - among them care of the elderly, the handicapped, and the homeless - as well.