The Roman Catholic Church has detailed provisions, honed by centuries of sometimes painful experience, that regulate the election of popes. It has virtually no provisions for the very modern problem of aging and physically or mentally declining popes.

That point is raised every time that the 83-year-old Pope John Paul II shows new signs of the degenerative Parkinson's disease that afflicts him or of the other ailments bestowed on him by age and an attempted assassination.

Some Catholics take exception to such discussion as though it were an attack on the pope's leadership. But in a world where the blessings of medicine are often shadowed by prolonged mental as well as physical incapacitation, including Alzheimer's or coma, it seems that the church has to address this question, not as a comment on this papacy but as an institutional reform that would affect future ones.

In fact, there are not one but two related questions: What to do in the emergency case of a pope so incapacitated he could not carry out his duties? And how to make such an emergency much more unlikely?

Popes can, of course, resign if they recognize their debilitation. As recently as 1996, Pope John Paul II issued a document largely dealing with papal elections that also specified some conditions for a valid resignation. There have been rumors that he has himself secretly readied a document to be issued when he no longer feels capable of his work.

But every time the possibility of this kind of health-related resignation is voiced publicly, whether for this pope or any other, it is firmly swatted down by Vatican officials. Such a precedent, they believe, would encourage critics of a papacy to press for a resignation less on grounds of health than opposition to the pope's policies.

Resignation is no solution to the problem of mental incapacity, in any case, whether that developed gradually or suddenly through injury or stroke. (Nor would it be a solution if the pope were taken hostage or held in threatening circumstances, as two popes were by Napoleon.) Mental incapacity or intimidation would render any resignation invalid or, in a borderline case, suspect in a way that could create a crisis in the church.

Church law itself indicates that special rules should apply in the case of the papal office being "impeded." But no such special rules have ever been promulgated. What standard would be used to determine if a pope's mental condition rendered him "impeded"? And who would make that determination?