Second, confronted with the accusations against him, Judge Kavanaugh made recourse not to reason and methodical process, but to fury and the rawest partisanship. Judges — particularly Supreme Court justices — must strive to be, and be seen as, above politics. As Judge Kavanaugh said in a 2015 speech, “to be a good judge and a good umpire, it’s important to have the proper demeanor.” He added: “To keep our emotions in check. To be calm amidst the storm. On the bench, to put it in the vernacular, don’t be a jerk.”

Wise words. He wasn’t able to live by them when it mattered. At last week’s hearing, Judge Kavanaugh was a jerk. He spun dark visions of a Democratic conspiracy of vengeance against him. He yelled at Democratic senators, interrupted them frequently, refused to answer questions directly and, at one point, confronted Senator Amy Klobuchar, who had asked him whether he had ever blacked out from drinking.

“I don’t know,” Judge Kavanaugh sneered. “Have you?” This contempt came only moments after Ms. Klobuchar told Judge Kavanaugh about her father’s struggles with alcoholism.

Was Judge Kavanaugh truly out of control, in rage and pain, as he appeared, or had he calculated that a partisan attack would rally President Trump and Republican senators to his side, as it did? (We all know he was capable of a more temperate response to the accusations: He’d demonstrated that just a couple of nights earlier, in his interview with Fox News.) For purposes of Senate confirmation, it shouldn’t matter. Such a lack of self-control, or such open and radical partisanship, ought to be unacceptable in a judge.

And indeed, on Thursday, the retired Justice John Paul Stevens, who was appointed by a Republican president, took the astonishing step of saying that Judge Kavanaugh’s performance before the Judiciary Committee should disqualify him from the court. “Senators should really pay attention to it,” he said .

Judges are human beings, not ideological blank slates, but the American legal system depends on their being fair and open-minded to all who come before them. Judge Kavanaugh failed to show that he can do this, or that he even would want to.

That’s a disappointment, but maybe not a surprise to anyone who knew of his life before he joined the bench. He was a fierce Republican warrior in some of the most politically charged battles of the past two decades — including the investigation that led to President Bill Clinton’s impeachment, in which he sought to expose the most intimate details of Mr. Clinton’s affair with Monica Lewinsky. He also played a role in the most controversial policies of the George W. Bush administration, including the torture of detainees and warrantless wiretapping. (How much of a role we may never learn, since Senate Republicans still refuse to release more than 90 percent of the documents related to Judge Kavanaugh’s work in the Bush administration.)