After Elon Musk’s blockbuster purchase of Twitter, the Senate majority leader, Charles “Chuck” Schumer, a New York Democrat, deployed a word that would — if successful — doom the new owner’s goal of creating an online town square where conservatives are welcome.

Mr. Schumer said at a press conference on Capitol Hill, “[I]n many ways Twitter has been a dark, dark place; I hope it doesn’t get any darker.” The use of “dark” three times in one sentence is what poker players call “a tell.”

What it tells is that Democrats intend to target the company and Mr. Musk the way they do other political foes, by mounting a campaign to fix the target as evil, sinister, and dangerous.

Expect to see the term “dark” echoed by other Democrats, the same way an open microphone disclosed their use of “extreme” to describe the Tea Party movement’s opposition to inflationary spending in 2010.

“I always use the word ‘extreme,’” Mr. Schumer back then told fellow Democrats on a conference call, unaware that reporters could hear. When Republicans ridiculed the canned rhetoric, a new pejorative had to be found, and in time, “dark” emerged.

Secretary of State Clinton first seized on it in her 2020 campaign for president, and Scott Adams, the “Dilbert” cartoonist, broke down the word’s power to prey on the minds of voters. In a Wall Street Journal interview, Mr. Adams noted that Clinton surrogates deployed the word “almost instantly” after Donald Trump’s convention speech, and her “persuasion game went from terrible to world-class almost instantly.”

Mr. Adams described “dark” as a Rorschach test that, when mixed with confirmation bias, cast anything Mr. Trump did or said in a negative light — or no light. “It was a fresh word,” Mr. Adams said, “you don’t hear in politics.”

We can expect to hear it a whole lot more now that Mr. Schumer has hammered it home, but if it’s to trigger confirmation, left-wing journalists and talking heads will have to destroy the image of a billionaire they’ve praised for years.

Mr. Musk is no conservative, and the left loved him for his Tesla electric-car company, SpaceX, and support of President Obama. It won’t be easy to transform the hero of Tesla into a Bond villain stroking a zero-emissions white cat. 

For Mr. Musk, the senator of New York  is a formidable opponent, a man who began to master television at a  young age. In 1960, as a 16-year-old, he led his team to victory on the quiz show “It’s Academic.” He has sought the spotlight ever since.

Throughout his career in Congress, Mr. Schumer has jawboned the press with such regularity that people joke the most dangerous place in Washington is between him and a camera.

This availability has enabled him to shape the narrative and do everything short of writing and editing stories. He has proven able to set and control the language much better than the right. 

The good news for conservatives is that Mr. Musk is no stranger to publicity or persuasion. Mr. Musk can flip confirmation bias by calling out the use of “dark” so that when Democrats say it, people will recognize they’re being played. He can counter the idea that it’s midnight at Twitter with the fact that he’s drawing the curtains to let in the sunshine.

In the press conference announcing his purchase, Mr. Musk declared he wanted to make the shadowy algorithms that govern Twitter’s content “open source to increase trust,” meaning more light on its inner workings, not less.

He’s also said he wishes to return Twitter to a neutral platform, not the partisan outlet that blocks conservatives and squashed the New York Post’s exposé of Hunter Biden’s laptop.

A Supreme Court justice, Louis Brandeis, is famous for the statement, “Sunlight is said to be the best disinfectant,” referring to James Bryce’s 1888 book, “the American Commonwealth.”

In it, Mr. Bryce wrote, “Selfishness, injustice, cruelty, tricks, and jobs of all sorts shun the light; to expose them is to defeat them. No serious evils, no rankling sore in the body politic, can remain long concealed — and when disclosed, is half destroyed.”

The hubris of  Twitter is already half destroyed by Mr. Musk’s purchase. Whether he succeeds in creating a free marketplace of ideas will depend on whether his message is more persuasive than Mr. Schumer’s.