As one who co-directs the development of three American youngsters, ages 8 to 15, I have learned this about them: No issue is too trivial to support a prolonged and intense debate among them.

The moment's weighty debate centers on responsibility for washing the cake pan our 13-year-old daughter used when she baked a cake of which every one joyously partook. Should it be, as she insists, her 15-year old brother's, whose "turn it was to do the dishes"? Or should it be, as he insists, hers, because "no one had asked her to bake the cake in the first place"? Or, as they both would prefer, should the task fall to the little 8-year-old "monster who, as usual, really pigged out on the cake"? My best current forecast: The government will clean it up eventually -- that is, either Mom or Dad.

Ordinary parents might be vexed by such debates. I am, alas, no ordinary parent. A long-time student of American health policy, I consider myself superbly prepared for life with bickering teen-agers and, conversely, my life with them has helped me to appreciate much better the dynamics of American health policy whose core, after all, has always been petty bickering.

In American health policy, the moment's weighty debate swirls around the question of who should pay the medical expenses of caring for fellow citizens afflicted with AIDS. Not a week passes that some journalist or local legislator does not call to explore this question. Yet of all the costs associated with this dread disease, that of caring for the stricken should be the least troublesome among civilized people, particularly in a wealthy nation beset by a surplus of doctors and hospital beds.

The most horrendous cost of AIDS, surely, is the anguish suffered by the stricken and their loved ones. Next comes the enormous damage the disease does to our social fabric, a cost of which the brutal excision of the hapless Ray family from Arcadia, Fla., serves as a stark reminder.

Only thereafter comes loss of the contribution the afflicted might make to society in the course of a full, healthy life. We measure this contribution by lost gross national product (GNP), although that is clearly an underestimate, first, because GNP reflects only the minimum value of the goods and services traded in the marketplace and, second, because many of a person's contributions to society are not measurable in monetary terms.

Last, and least, comes the medical cost of treating patients with AIDS. In the most recent issue of Health Affairs (Summer, 1987), Dr. Jane Sisk of the Office of Technology Assessment reports that the most comprehensive and rigorous study of the national cost of AIDS estimates it at $8.7 billion for 1986 and at a projected $66.5 billion for 1991. More than 80 percent of these totals represent lost GNP. In other words, the medical expenses for the two years come to only about $1.7 billion and $13 billion, respectively.

Written out as $1,700,000,000, the medical expense for 1986 might appear, as the late Everett Dirksen would have put it, as "real money." But it is only about 0.04 percent of the nation's 1986 $4,200,000,000,000 GNP ($1 for every $2,500 of GNP!), less than half a percent (0.37 percent to be exact) of the nation's $460,000,000,000 national health expenditures in 1986, and less than a tenth of the $20 billion to $30 billion a year Congress in its wisdom now chooses to allocate to America's farmers as a reward for not growing food or growing food no one wants to buy.

While the corresponding numbers for 1991 will be relatively larger, they will still be small in the absolute. If GNP grows at about 7 percent per year until then and additional health expenditures at about 10 percent per year, the $13 billion or so in medical expense for AIDS then will be only about 0.2 percent of our GNP and 1.75 percent of total national health expenditures.

Much more GNP is being lost every year by sloppy management of our defense establishment -- which redistributes income as much as it produces national security -- and through the nation's tendency toward economic paralysis through litigation. It will be years before the medical cost of treating AIDS patients will match the medical costs occasioned by the consumption of alcohol and tobacco, not even to mention the carnage unleashed upon American society by its ludicrously lax gun-control laws. (Firearms accounted for over 30,000 American deaths in 1986, and for many more serious injuries.)

Finally, the medical cost of AIDS is dwarfed by the extraordinarily high administrative cost of American health care. In 1985, for example, private health insurance covered only about one third of total national health expenditures. Yet the insurance industry's net cost of administering this system alone amounted to over $20 billion in 1985, up from $5 billion in 1980, and that figure does not even include the resources patients, doctors and hospitals must devote to coping with the paper war inherent in that system.

No, the issue must be squarely faced: By ringing their hands over the "intractable" problem of sharing the "staggering burden" of the medical expense of AIDS, America's adults are proving once again that petty, selfish and argumentative teen-agers who fight endlessly over the washing of a cake pan are just mature beyond their age. They act, to put it crisply, like miniature adults.

Uwe E. Reinhardt, PhD, is the James Madison Professor of Political Economy at Princeton University. Second Opinion is a forum for points of view on health policy issues.