Dianne Feinstein is incapable of doing the most elemental part of her job, but she’s still adept at discrediting my work. Back in January, I wrote a defense of gerontocracy, occasioned by the end of Nancy Pelosi’s long run as speaker of the House. I argued that oldsters just do it better, because nobody is born to effectively wield power; it’s a learned skill. My primary evidence was the trio of senior citizens—not just Pelosi but also Joe Biden and Chuck Schumer—that orchestrated the two most fertile years of legislation in recent memory.

But the 89-year-old Feinstein, who is out with shingles, is making a compelling counterargument: Octogenarian politicians sometimes behave like grandparents refusing to hand over the keys to the car. They stop in traffic for no apparent reason and never accelerate above 20, but they’re under the delusion that they’re still good drivers.

I understand that acknowledging this may make some uncomfortable. All of us, if we are lucky, face the indignities of aging. In other circumstances, the fact that Feinstein can’t cast votes in the Senate might not be terribly meaningful for the country. But the Senate is evenly divided—and when she is out of pocket, the Democrats can’t prevail on a party-line vote. Because she sits on the Senate Judiciary Committee—and Republicans refuse to let her trade the assignment with a colleague physically fit for the job—Democrats are unable to send any of their nominees to the bench to the floor of the Senate.

This isn’t a trivial part of Feinstein’s job. Without a majority in the House, it is more or less the entirety of it. A more liberal bench is the only lasting achievement available to her party, and she’s preventing its realization. This is a fleeting opportunity, moreover: Even if Biden wins reelection, the political map nearly guarantees a Republican majority in two years’ time. These next few months are the narrow window for Democrats to aggressively erode the GOP’s capture of the judiciary.

The obvious point of comparison is Ruth Bader Ginsburg. By hanging onto power far past the point of political and actuarial prudence, she ended up costing the Democrats their most precious seat on the Supreme Court, imperiling the right to abortion and shifting the balance of power to conservatives. That wasn’t great, but Feinstein is guilty of a more grievous sin. Until the very end, Ginsburg could actually do her job, writing meaningful opinions. Feinstein sadly isn’t able to even say “aye” when her party needs her.

Feinstein’s condition spurs a question that looms over American politics for obvious reasons, given the age—for the moment, at least—of the top candidates in the next presidential election: When does the beneficent version of gerontocracy give way to the destructive version of it? Admirable reasons for handing power to senior citizens almost inevitably become the justification for their never relinquishing it. The cult of experience becomes the cult of indispensability.

You can see a hint of this problem in the viral video from 2019 that captures Feinstein lecturing young protesters from the Sunrise Movement, a climate-activist group, who occupied her office, hoping to hector her into supporting the Green New Deal. She tells the kids, “I’ve been in the Senate for over a quarter of a century, and I know what can pass and I know what can’t pass.”

At the time, I thought to myself, damn straight. That’s the essence of legislative politics: Getting stuff done can necessitate the trimming of sails and unsavory concessions to grubby allies. But her argument also had more than a whiff of self-satisfaction. Believing that the whippersnappers don’t understand what it takes to do the job can easily become a pretext for never letting them try.

And because American politics are so volatile, experienced officials may never feel like the time is right to yield power. There’s always one more threat to democracy to stave off, one more international crisis to avert. Rather than entertaining plans to retire, older politicians come to regard staying in office as a patriotic duty. Gradually, gerontocracy can become a self-protective cartel, where the tricks of the trade are deployed for the sole purpose of remaining in the club.

The Senate does a terrible job of regulating itself in this regard. With so many years between elections—and much advantage to incumbency—desks on the Senate floor easily become tenured. And every Senator has an interest in protecting the system of tenure, in the hopes of receiving every collegial benefit of the doubt when they face their own hardship that might interfere with their job performance.

One of the sadder sights I can remember in my career as a political reporter was watching Strom Thurmond, then 100, guided by an aide trying to prevent the senator from cluelessly shuffling into a women’s room in the Capitol. His gaze was empty and he barely said a word. None of his peers apparently felt any obligation to tell him that it was time to leave.

At some level, Feinstein knows that it’s time. She has already announced that she won’t be running for reelection. The only reason for her to stick around is to enjoy toasts at her retirement party, or perhaps to postpone the psychic pain that comes with loss of status and all the perks, all the discomfort that comes with knowing that what remains of life is epilogue. But unless she can quickly recover—and her staff hasn’t supplied any timeline for her return—she owes it to herself and her party to make sure that her epilogue isn’t just rueful.

Speaker Kevin McCarthy made a plea to House Republicans during a closed-door meeting Tuesday morning to back his debt ceiling plan, telling them that although it doesn't have to include everything they want, it will help get him to the negotiating table with President Joe Biden.