Although Mark Shields overreaches his statistics {" 'Volunteers' for America," op-ed, Aug. 4}, he makes a good point about the isolation of our military services from the mainstream of American society. Our uniformed services should represent a cross-section of our citizenry, and our population as a whole should face the consequences of policy decisions and, therefore, have an interest in studying and influencing those decisions.

But why not apply that concept to the entire spectrum of national issues? Why not require everyone -- men and women -- to serve in some capacity for a set period in his or her life in community service, conservation projects or the military (with hazardous duty incentives)? I have always thought it was a duty we owed our country. But Mr. Shields provides a practical incentive: every citizen would have a stake in and a better understanding of a variety of domestic and foreign policy questions. JOHN R. SCHULTZ Arlington

Mark Shields' thoughtful column raises some interesting issues but offers little in the way of practical solutions. Frankly, conscription seems unlikely to be reintroduced. And a system that would ensure a socio-economically and ethnically balanced military force would serve mainly to sabotage the federal government's most successful job program.

As a partial solution, the Washington establishment might consider inviting area servicemen to their dinner parties. Although our table manners might raise some eyebrows, this country's political elite might come to see its soldiers as something other than expendable mercenaries and helicopter crash victims.

I for one would be delighted to stop by for dinner.

RICHARD JANSSEN Severn, Md.