Representative Joe Kennedy, the youngest member of the Massachusetts congressional delegation, announced last week that he would run against Senator Ed Markey, the oldest member, because, he said, “I’ve got new ideas and a new approach.” Really? In nearly seven years in Congress, Kennedy has emitted few whiffs of originality or unconventional thinking. Why would that change if he replaced Markey in the Senate? In any case, as skeptics promptly pointed out, on political issues there are no meaningful differences between the two left-wing Democrats.

As if to validate the skepticism, Kennedy’s first big campaign proposal, delivered in a press release on Tuesday, was a so-called People’s Pledge to keep third-party advertising out of the Senate race. That was anything but a new idea: Markey had proposed the exact same thing when he first ran for the Senate in 2013 — and he was only recycling a gimmick from the race between Elizabeth Warren and Scott Brown a year earlier.

But the People’s Pledge isn’t just a tired, old idea. It’s a tired, old, bad idea. It is arrogant and antidemocratic, and its purpose is to squelch free speech — in particular, the form of speech most valued in the American constitutional system: speech about politics, candidates, elections, and issues.

Kennedy wants his rivals (who include attorney Shannon Liss-Riordan and businessman Steve Pemberton, in addition to Markey) to repudiate in advance any “outside” advertising — that is, any advertising from any source other than the candidates’ own campaigns. The purpose of the “People’s Pledge” is to put teeth into that repudiation. It provides that if an outside organization spends money on TV, radio, or online ads in support of any candidate in the race, the campaign being helped would pay a penalty: It would have to donate half the value of the ad buy to a charity named by the other campaign. Political groups wanting to weigh in on the Massachusetts Senate fight would thus be dissuaded, since the more they spent to assist any candidate, the more cash that candidate would have to forfeit.

Warren and Brown were extravagantly praised when they agreed to this arrangement in 2012. Their pledge was welcomed as a victory for “civility,” and the candidates were awarded props for coming up with a way to reduce the influence of money on their high-profile Senate race.

But the “People’s Pledge” proved a bust. When all was said and done, the 2012 Brown/Warren race, far from restoring civility to politics, was among the nation’s nastiest. And the candidates’ agreement did nothing to diminish the importance of money. According to the Center for Responsive Politics, the Brown and Warren battle turned out to be the most expensive Senate campaign in the country. As Rosie Gray reported in BuzzFeed, Brown and Warren’s much-admired pledge “appears to have accomplished roughly the opposite of its goal.”

So when Markey, running for the Senate a year later, attempted to revive the pledge, his Republican opponent sensibly declined. When Secretary of State Bill Galvin tried the same ploy during his reelection fight in 2018, his Democratic challenger, calling it an “empty gesture,” likewise refused.

Now that he’s facing a serious challenge to his Senate seat, Markey no longer seems quite so enamored of the idea that third-party advertising should be kept out of the race. His campaign manager agreed only to “review the proposal” made by Kennedy. It’s hard to imagine that Markey, facing the toughest reelection fight of his career, will spurn the help of independent groups. One such group, Environment Massachusetts, has already said it will raise $5 million for a campaign “to promote the senator’s remarkable record” to the state’s voters.

“Remarkable” isn’t the word I would choose to describe Markey’s congressional career. But if Environment Massachusetts and its supporters want to spend money to sing Markey’s praises, why should they be stifled? If the International Brotherhood of Electrical Workers, which has endorsed Kennedy, wants to run ads promoting his virtues, why shouldn’t it do so? For that matter, why should any group with strong opinions about the Senate race – charities, corporations, political parties, advocacy organizations, houses of worship, or simply an ad hoc amalgam of interested citizens – be deterred from weighing in?

The winner of the Massachusetts Senate race will have power to influence the lives and livelihoods of tens of millions of Americans, here in the commonwealth and around the nation. Health care, housing, taxes, immigration, foreign policy, judgeships, war and peace — senators have a say in all of them. Which means that virtually everyone has an interest in who gets elected, and compelling reasons, perhaps, to influence the voters’ decision. Should they be silenced? Of course not!

Anyone with something to say about the Massachusetts Senate race should be encouraged to say it. No group with strong views on the issues or the candidates should be denounced for spending money to disseminate those views. Robust political expression is the very quintessence of free speech, and in an election campaign, “outside” and “third party” voices are just as legitimate as those of the candidates themselves.

The “People’s Pledge” is a terrible idea. Let’s hope we’ve heard the last of it.

(Jeff Jacoby is a columnist for The Boston Globe).