You might have missed the news that John Paul Stevens, the retired U.S. Supreme Court justice, criticized Democratic presidential front-runner Hillary Clinton last week for her announcement that she would nominate to the court only individuals committed to overturning the 2010 decision in Citizens United v. Federal Elections Commission. Stevens doesn’t like the decision any more than she does — his dissent ran to 90 pages — but he likes litmus tests even less.

At a house party in Mason City, Iowa, a few days after offering her promise, Clinton doubled down: “I will do everything I can do to appoint Supreme Court justices who will protect the right to vote and not the right of billionaires to buy elections,” she said.

Stevens, in remarks last week at George Washington University, was unimpressed: “I’m not really sure that that’s wise either for the court or for a presidential candidate to make a litmus test on one particular decision. ... I’m surprised at her statement.” The former justice added: “If I were running for president, I don’t think I would make such a litmus test, even though I think the case ought to be overruled.”

Stevens is right. I won’t trouble here to go into the reasons for my own longstanding opposition to litmus tests, other than to note that there is something decidedly peculiar about promising to place on the Supreme Court individuals who have already decided the cases to come before them. The rhetoric turns the idea of what a court is for on its head: What’s the point of arguing before those who have been selected because they have sworn to be closed-minded?

Bill Clinton, while serving as president, was explicit in his rejection of litmus tests, which he saw as an unreasonable element inserted into politics by the Republican Party: “I will not ask any potential Supreme Court nominee how he or she would vote in any particular case,” he said in a news conference on March 23, 1993. “I will not do that.”

Hillary Clinton has no obligation to follow her husband’s model on this or any issue; from the practical point of view, he is simply a former president, and if he was wrong, he was wrong. But in this case he was right, and I suspect she knows it. Nevertheless, candidate Clinton has promised to appoint justices who oppose Citizens United, and she has joined the chorus of Democrats supporting a constitutional amendment designed to accomplish the same end, even though language explicitly limiting the freedom of speech is impossible to draft in a way that isn’t reckless.

No doubt Clinton is sincere in her belief that Citizens United was wrongly decided. Her decision to go down the road of litmus tests and constitutional amendments, however, is an artifact of our process for selecting presidential nominees. Like similar silliness on the Republican side, it reflects the outsize influence of activists who too often demand explicit commitments to propositions that are imprudent and unlikely of accomplishment.

Even if one believes that such promises are entirely symbolic, they can hardly be good for democracy. Jonathan Rauch, a senior fellow at the Brookings Institution, in a bracing new book, calls for restoring political professionalism to the campaigns, sharply reducing the role of activists and their unrealistic demands on candidates. Provocatively titled “Political Realism: How Hacks, Machines, Big Money, and Back- Room Deals Can Strengthen American Democracy,” Rauch’s slim volume is must reading for anyone who wants to make democracy better.

Rauch wants to restore the transactional aspects of politics, precisely the features that today’s activists, with their narrow ideological focus, tend to despise. The activist, Rauch says, harbors an “instinctive suspicion of political insiders.” But the activists are wrong. We need more insiders, not fewer.

One of the advantages of machine politics, he points out, is that political machines, unlike activists, “have relatively lengthy time horizons,” because they “have to win not just once but again and again.” The professional party seeks the stability that will enable it to govern over the long term. The activist, by contrast, wants to win on its issue, right now, today.

It isn’t just campaign finance reform. The same problem arises everywhere. On issues from dealing with the millions of illegal immigrants to finding a prudent balance between equality and religious liberty, the spaces in which decisions are made are occupied by those who, in the words of the historian Richard Hofstadter, do not “see social conflict as something to be mediated and compromised,” but insist instead on “the will to fight things out to a finish.”

Once upon a time, compromise was the life’s blood of politics. Nowadays, activists press candidates instead toward absolutes. Rauch refreshingly reminds us that the current state of affairs isn’t necessary. I’ve argued before for returning more power to the parties, and Rauch’s book reinforces my belief that only in that direction lies the salvation of American democracy.

But of course it won’t happen. Activists left and right enjoy the taste of power. Whether the wealthy conservatives feared by the left or the academic and media elites feared by the right, the aristocrats who exert outsize influence on our election processes aren’t about to yield their hard-earned dominance. Instead, we face a bleaker future in which candidates who know better, to keep their boyars quiet, will continue to make promises they know they shouldn’t.