Donald J. Trump has a cruel streak. He willfully causes pain and distress to others. And he repeats this public behavior so frequently that it’s fair to call it a character trait. Any single example would be off-putting but forgivable. Being shown many examples across many years should make any decent person recoil in disgust.

Judge for yourself if these examples qualify.

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In national politics, harsh attacks are to be expected. I certainly don’t fault Trump for calling Hillary Clinton dishonest, or wrongheaded, or possessed of bad judgment, even if it’s a jarring departure from the glowing compliments that he used to pay her.

But even in a realm where the harshest critiques are part of the civic process, Trump crossed a line this week when he declared his intention to invite Gennifer Flowers to today’s presidential debate. What kind of man invites a husband’s former mistress to an event to taunt his wife? Trump managed to launch an attack that couldn’t be less relevant to his opponent’s qualifications or more personally cruel. His campaign and his running-mate later said that it was all a big joke. No matter. Whether in earnest or in jest, Trump showed his tendency to humiliate others.

Talk-radio host Hugh Hewitt, who is supporting Donald Trump in this year’s election, was subject to the cruel streak months ago while moderating a GOP debate. “A year ago you told me on my radio show—the audio and transcript are out there on YouTube—that you would release your tax returns,” Hewitt said to Trump. “First of all, very few people listen to your radio show,” Trump replied. “That’s the good news. Let me just tell you—which happens to be true. Check out the ratings.” Trump took pleasure in puffing himself up by being gratuitously cruel.

What quality within him causes him to lash out this way? It was on display again when  Trump attacked the wife of his primary opponent Ted Cruz. Here is the tweet he sent:

This is vile behavior.

What kind of person attacks a rival by mocking the appearance of his wife? For the whole of his presidential campaign, Trump has gleefully launched gutter attacks like this. And while a cruel streak directed solely at rivals would hardly be excusable, Trump doesn’t even have that excuse. After Chris Christie endorsed him, Trump attended a fundraiser with the New Jersey governor, and said this to the crowd: “I’m not eating Oreos anymore, you know that—but neither is Chris. You’re not eating Oreos anymore. No more Oreos. For either of us, Chris. Don’t feel bad.”

That’s who Trump is: If he’s in front of a crowd with an ally who has a weight problem, he’ll find an excuse to bring it up, to humiliate the ally, for no apparent reason.

And this penchant for purposeless cruelty goes beyond the political realm. "Heidi Klum. Sadly, she's no longer a 10," Trump said once for no apparent reason, baffling the model. “I've known Donald for many, many years. Personally I don't know why he did it," Klum said. "I don't know what I have to do with a presidential campaign." Imagine knowing someone for years, then having them attack your appearance for no reason on national TV. You’d think they were a sociopath.

The people closest to Trump have painful experience with this same quality. In September 1990, Marie Brenner wrote at length in Vanity Fair about how the billionaire humiliated Ivana Trump.

Conservative writer Mona Charen reflected on the same era in National Review:

I first became aware of Donald Trump when he chose to make cheating on his first wife front-page news. Donald and Ivana Trump broke up over the course of months. Not that divorce is shocking, mind you. Among the glitterati marriage seems more unusual. Nor is infidelity exactly novel.

But it requires a particular breed of lowlife to advertise the sexual superiority of one’s mistress over the mother of one’s children. That was Trump’s style. He leaked stories to the New York tabloids about Ivana’s breast implants—they didn’t feel right. Marla Maples, by contrast, suited him better. She, proving her suitability for the man she was eager to steal from his family, told the papers that her encounters with the mogul were “the best sex I’ve ever had.” It wasn’t just Donald Trump’s betrayal that caught my eye, nor just the tawdriness—it was the cruelty.

What kind of person treats the mother of his children that way? Is there anyone to whom he wouldn’t be cruel? In fact, none of the examples offered thus far captures the depths of Trump’s cruelty. Understanding that requires hearing the story of the late Freddy Trump, the candidate’s older brother, who died an alcoholic in 1983. After college, Freddy had tried to join the family business, but his heart wasn’t in it. He became an airplane pilot, showing talent in the profession. When his heavy drinking posed a safety risk, however, he quit, and wound up living in an apartment owned by his father and working on one of his maintenance crews, even as his kid brother Donald began to make a name for himself.

Here is the jaw-dropping conclusion to the story, as reported in the New York Times:

In 1977, Donald asked Freddy to be the best man at his first wedding, to the Czech model Ivana Winklmayr, an honor Donald said he hoped would be “a good thing for him.” But the drinking continued, and four years later, Freddy was dead.

Over the next decades, Donald put the Trump name on skyscrapers, casinos and planes.

In 1999, the family patriarch died, and 650 people, including many real estate executives and politicians, crowded his funeral at Marble Collegiate Church on Fifth Avenue. But the drama was hardly put to rest. Freddy’s son, Fred III, spoke at the funeral, and that night, his wife went into labor with their son, who developed seizures that led to cerebral palsy. The Trump family promised that it would take care of the medical bills.

Then came the unveiling of Fred Sr.’s will, which Donald had helped draft. It divided the bulk of the inheritance, at least $20 million, among his children and their descendants, “other than my son Fred C. Trump Jr.” Freddy’s children sued, claiming that an earlier version of the will had entitled them to their father’s share of the estate, but that Donald and his siblings had used “undue influence” over their grandfather, who had dementia, to cut them out. A week later, Mr. Trump retaliated by withdrawing the medical benefits critical to his nephew’s infant child.

“I was angry because they sued,” he explained during last week’s interview.

I have to ask again.

What kind of billionaire withdraws the health insurance of an infant with cerebral palsy in a fit of pique? A person comfortable being cruel to others. “This was so shocking, so disappointing and so vindictive,” his niece Lisa Trump said at the time.

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There are lots more stories to tell about Trump’s cruel streak. In the present campaign, he mocked John McCain for being captured and tortured while fighting for the United States in Vietnam and attacked the Gold Star Family that spoke at the Democratic National Convention after losing a son in Iraq. Many people know that years before Trump was a politician he feuded with a talk show host. “Well, Rosie O’Donnell is disgusting both inside and out,” he declared. “You look at her, she’s a slob. She talks like a truck driver… If I were running The View I’d look right in that fat ugly face of hers and say, ‘Rosie, you’re fired.’” What few people know is that later, when O’Donnell got engaged, Trump went on Twitter to write this:

What kind of person rekindles a feud with insults on hearing that someone got engaged?

I could talk about Trump being cruel to others for another 20,000 words. But deep down, even many Trump supporters already know this truth about the man they’re supporting. They’re just so acclimated to his cruelty that they’ve stopped noticing it.

Enough. Wake up. Look at this man with fresh eyes.

People disagree about the ideal traits to have in a leader. But almost no one wants a president who has proven himself an addict to being cruel, mean-spirited, and spiteful. For decades, Trump has been deliberately cruel to others, often in the most public ways. He behaves this way flagrantly, showing no sign of shame or reflection.

What kind of person still acts that way at 70? A bad person.

It is that simple.

Giving a cruel man power and expecting that he won’t use it to inflict cruelty is madness. To vote for Trump, knowing all of this, is to knowingly empower cruelty.

Better to recoil in disgust.