But Catholics, like people of other religions, differ in personality and belief. And that’s what makes their reactions to Benedict’s abdication interesting. Some, apparently steeped in papal infallibility, insist that both popes must be right, because there can be “no doubt that Benedict’s decision,” like John Paul’s, “was guided by the Holy Spirit.”

Others are more critical. John Paul, “who suffered and bent under the burden of the Petrine office as illness consumed him,” was “a powerful witness to the dignity of human life,” concedes Thomas McDonald, writing for patheos. But the pope’s decline, McDonald adds, “also affected the way he managed the church, and as the abuse scandal exploded, that was something we could ill afford.” Pat Archbold draws a similar conclusion in the National Catholic Register:

While we all witnessed an enfeebled holy man suffer great infirmity in love and patience, Cardinal Ratzinger must have seen much more. He must have seen how during those years of decline the Vatican bureaucracy becomes de facto pope and how that de facto pope can thwart and subvert the will of the legitimate Pope.

That’s a pretty sharp critique of what John Paul did. But there’s a case to be made against Benedict’s choice, too. Ross Douthat of The New York Times acknowledges that Benedict, like John Paul, faced years of decay. Nevertheless, Douthat argues, the pope should die in office for three reasons: First, he’s “a spiritual father more than a chief executive.” Second, he serves God, and “if God wants a new pope, He’ll get one.” Third, “the church is still supposed to be the church even when its human leadership isn’t at fighting trim.” Far from accepting infallibility, says Douthat, Catholicism must frankly endure “leaders who are wrongheaded, incompetent, senile or corrupt.”

This is a debate well worth having. On one side, those who think, on reflection, that Benedict was right to step down and that John Paul, for the same reasons, was wrong to hang on. On the other side, those who believe that John Paul was right and that Benedict, for the same reasons, is wrong to quit. A clash between these two schools won’t be as tidy as a chorus of gymnastic apologists bent on defending both popes. But it will be more fruitful and more honest.

William Saletan covers science, technology and politics for Slate.