If I had to guess, we've seen the last time Joe Biden smells a woman's hair and plants a kiss on her head before a campaign event. Same goes for his somewhat notorious habit of close-talking the female relatives of new members of Congress as a way to put them at ease during the first-day-of-session photo shoots. (Maybe just a "You've got this, girl!" fist-bump next time, Mr. Vice President?)

I say this with absolute certainty because Biden, unlike so many in Washington today, has shown an immense capacity to learn from his mistakes - if not avoid them altogether - over the course of his four-decade career in public service. It's a quality Democrats should be celebrating, not punishing, as they look for a candidate who can both defeat President Donald Trump in 2020 and, not incidentally, run the country after that.

Let's start with the issue where Biden rightly has the most explaining to do: his role overseeing Clarence Thomas' Supreme Court confirmation hearings in 1991. As chairman of the Senate Judiciary Committee, it was ultimately up to Biden to ensure that Thomas had a hearing that was fair and impartial, as well as a complete examination of his fitness for office. When Anita Hill came forward to tell her story of being sexually harassed by Thomas as an employee at the Department of Education, she had to do so in front of an all-male, all-white panel of senators who seemed only half aware that sexual harassment even existed, let alone had the power to destroy the careers and ambitions of women in the workplace.

Biden ultimately voted against confirming Thomas, but the damage had already been done to Hill and all women who deserved more than the chance to be humiliated publicly by their government after being tormented privately by their bosses. Even more broadly damaging was the image of Hill, a professional woman and African-American, testifying in front of a skeptical, sometimes hostile, Senate committee whose members treated her more like a criminal than a victim.

But less than a year later, Biden began to do his part repairing some of the damage those hearings had done when he reached out to Carol Moseley Braun, the first African-American woman ever elected to the Senate, to convince her to join the Judiciary Committee and finally put an end to the committee's all-white, all-male membership, which she did. At the same time, Biden also worked with newly elected Sen. Barbara Boxer to move the Violence Against Women Act, a version of which he had written years earlier, to strengthen protections and prosecutions in domestic abuse and rape cases.

Moseley Braun defended Biden against Lucy Flores' accusations on CNN Monday, when she described Biden's visit to recruit her for the Judiciary Committee over a slice of cherry pie on her front porch. "Of all of the people I know, Joe Biden is one of the most thoughtful and respectful of others that I've ever known, ever met," she said. If Biden had been disrespectful to Anita Hill as a woman, a minority, and a professional woman in the workplace in 1991, that was not the case in Moseley Braun's experience by the time Biden sought her out in 1992.

And if Biden did not give mistreatment of women the seriousness it deserved in the Judiciary Committee hearings for Clarence Thomas, that too changed when he added VAWA as Title IV of the 1994 crime bill and passed them both together.

Biden has since talked about the Thomas hearings, especially as he moves toward a likely presidential run this spring. "We knew a lot less about the extent of harassment back then, over 30 years ago," Biden said last week. "(Hill) paid a terrible price. She was abused for the hearing. She was taken advantage of. Her reputation was attacked. I wish I could have done something. To this day I regret I couldn't come up with a way to get her the kind of hearing she deserved, given the courage she showed by reaching out to us."

Biden's detractors have hammered him for using the word "couldn't" instead of "wouldn't," arguing he is trying to absolve himself of his own accountability. But he also used words like "regret" and "abused" and "attacked" and "courage." That strikes me as the language of a man who knows he played a part in something that was unfair and just plain wrong. Who else in American politics today is ready to admit the same?

The presidency, as author Jon Meacham recently and rightly pointed out, is a job that nearly everyone learns while doing. Whether a chief executive arrives without a lot of firsthand experience, like Barack Obama, or is simply presented with unprecedented circumstances, like FDR, almost no leader will assume the role with every aspect of it already mastered. That means they must be able to adapt quickly, accept criticism from those around them, and grow in the role, including by learning from their own mistakes.

But in order to find a leader capable of learning from mistakes, Democrats are going to have to let their candidates make a few.

Patricia Murphy covers national politics for The Daily Beast. Previously, she was the Capitol Hill bureau chief for Politics Daily and the founder and an editor of Citizen Jane Politics. Follow her on Twitter @1PatriciaMurphy.