“Necessary promises” is a phrase that Mr. Murdoch could utter, at this late date, only with a leering wink. To read that marvelous euphemism was to laugh, horrifying as the prospect of a Murdoch Journal undoubtedly is. After decades of observing the old buccaneer and his deceptions, we know—and, of course, he knows we know—that “necessary promises” are not the kind that will be honored. They merely serve as a temporary gloss covering the sellout of journalistic ideals to Mammon, the company also known as News Corp.

What Mr. Murdoch usually guarantees, as he prepares to sack and burn an institution like Dow Jones, is editorial independence and freedom from political or commercial manipulation by him and his operatives. Such promises are—as Mr. Murdoch reportedly told an editor at The Times of London, who had listened to similar assurances from him about that august publication—“not worth the paper they are printed on.”

That unhappy episode occurred more than 25 years ago, according to Harold Evans, one of the greatest newspapermen of the 20th century, who recounted his losing duel with Mr. Murdoch in his memoir Good Times, Bad Times. But as Mr. Evans must have noticed since then, financial success and simply longevity have made his old nemesis seem almost respectable. More than one lickspittle analyst is eager to praise the emperor of News Corp. as a “visionary” because he founded Fox News Channel and bought MySpace.

Certainly nobody can quarrel with Mr. Murdoch’s business acumen (or his willingness to risk his shareholders’ money). His daring is as admirable as his character and philosophy are awful. He would proudly reply that he has no illusions.

We should certainly have none about him.

The usual Murdoch promises of editorial independence are not believable because he has misused his executive authority throughout his career—and because he has repeatedly sworn that he would not do those things again, just before he does them again. This pattern has persisted for three decades, ever since he first landed in New York from Australia.

One of the most amusing examples was his brief political romance with Jimmy Carter during the spring of 1980, when the struggling President needed Mr. Murdoch’s help in the New York primary against the insurgent liberal candidacy of Senator Edward Kennedy. What Mr. Murdoch needed was a low-interest, government-backed loan to buy Boeing jets for an Australian airline he then owned. Three days after they met at the White House, the New York Post published a rousing front-page editorial endorsement of Mr. Carter—and the following week, Mr. Murdoch’s airline received a $300 million corporate-welfare check from the U.S. Export-Import Bank.

In the Congressional investigation that ensued, Mr. Murdoch promised never again to do anything that could be so easily “misconstrued.” Yet from London to New York to Washington to Beijing, his companies have consistently coddled friendly politicians with admiring coverage and generous book advances, which have been reciprocated with regulatory and tax favors. The beneficiaries have spanned the ideological spectrum, from the right-wing Margaret Thatcher to the Marxist-Leninist daughter of Deng Xiaoping. All they had in common was their capacity to advance the interests of News Corp.

Meanwhile, the Murdoch properties in American journalism have continually reaffirmed their commitment to sensationalism, extremism, political bias and protection of the boss. As one of his employees explained in an unwitting moment on videotape, Murdoch journalism can be “a little bit like the Mafia.” (The employee was terminated with extreme prejudice after those remarks were made public.)

What makes The Wall Street Journal so valuable to its readers and to American culture is the excellence of its news columns—and their unpredictability. Unlike the Murdoch empire, The Journal’s news bureaus are strictly separated from the editorial section, whose medieval outlook is nearly identical to that of the would-be owner. Very often, straight reporting in the news section briskly disproves the fantasies of the editorial pages, notably during the latter’s long obsession with the supposed scandals of Whitewater.

Under Mr. Murdoch, that legacy of superb reporting and editorial separation would die. As Andrew Neil, a former editor of the London Sunday Times recently explained in The Journal’s own pages: “I think he would want the news to be informed by the editorial agenda.”

So let’s hope the Bancroft family, whose preferred Dow Jones stock makes them the trustees of The Journal’s integrity, resists the temptation to cash out. Or if they succumb, let them not pretend that the “necessary promises” mean anything beyond $60 a share.