Friday night in Chicago we saw where Donald Trump's campaign of ugliness and violence incitement was bound to lead: an ugly, violent scene.

One person gets the largest share of the blame for clashes between people attending the Trump rally and those protesting it. That person is Donald Trump. He is, after all, the person who inspires an atmosphere of menace and intimidation at his rallies -- as I observed at his event last month in Atlanta -- that has only increased over time:

  • A few weeks before the Atlanta rally, at an event on the day of the Iowa caucuses, Trump said he'd been told "there may be somebody with tomatoes in the audience" and continued : "So if you see somebody getting ready to throw a tomato, knock the crap out of 'em, would you? Seriously. OK? Just knock the hell -- I promise you, I will pay for the legal fees. I promise. I promise."
  • The day after the Atlanta rally, Trump said this after a protester was removed from an event in Las Vegas: "I loved the old days. You know what they used to do to guys like that when they were in a place like this? They'd be carried out on a stretcher, folks. ... The guards are very gentle with him. He's walking out, like, big high-fives, smiling, laughing. I'd like to punch him in the face, I tell ya."
  • About a week after that Atlanta rally, Trump's security staff ordered the removal of some 30 black students from an event at Valdosta State University even though they had not caused any disruption.
  • That same day, a Secret Service agent at a Trump rally in Virginia  grabbed a photographer by the neck and slammed him to the ground. The reason? The photographer had dared to step outside a roped-off area for the press. (NB: I had no trouble leaving the press area at the Atlanta event, so I don't know if I just got lucky or if Trump changed his policy.)
  • On Tuesday night, after Trump's victory speech in Jupiter, Fla., reporter Michelle Fields alleged Trump's campaign manager, Corey Lewandowski, grabbed her forcefully by the arm and pulled her nearly to the ground. The Trump campaign has denied the incident, despite a witness (a Washington Post reporter), photographs of bruising on Fields' arm, and video evidence that Lewandowski at the very least reached for her arm. Fields has filed a complaint with police, who are investigating.
  • On Wednesday night, a Trump supporter was charged with assault after punching a protester being escorted from a campaign event in North Carolina. Trump called the attack "a beautiful thing." No word on whether he's paying the man's legal bills.

And now we have Chicago, where chaos ensued after a large Trump rally was postponed due to fears of violence between Trump supporters and a large number of protesters, many of whom reportedly expressed support for Democratic candidate Bernie Sanders.

This is not what goes on at other candidates' events. They happen at Trump events, and they happen because he goads the crowd, revels in talking tough and generally promotes a sense of grievance, aggression and confrontation. There is absolutely no reason to think this will change if he's the nominee, or if (heaven forbid) he's elected president. None. This is how he has built his campaign. One wonders if he could stop it now even if he wanted to stop it.

Now, it is also obviously true that the individuals involved in these incidents also bear responsibility. One should be able to hear someone talk about punching people without going ahead and punching people. But again, other candidates don't talk the way Trump talks and their crowds don't act the way Trump's crowds act. He is setting the tone for his events. He is the common link among these various incidents. The buck stops with him, no matter how many times he refuses to take responsibility.

Let's also note that Friday's anti-Trump protesters did not appear from a vacuum, either. We have seen countless examples of college students trying to shut down speeches by people, usually conservatives, with whom they disagree. These students aren't forced to attend these speeches; they seek to silence the speakers for all. Even President Obama has criticized liberal students for this practice, and liberal professors have expressed grave concern over what they hear from their students (most famously in this piece ). By most accounts, many of the anti-Trump protesters in Chicago were college-aged. Their actions were part of a worrying trend as well. Protest is itself a form of free speech, but a heckler's veto is not.

So we have two dangerous trends moving ever closer to each other, with no sign of letting up. Consider this statement by MoveOn.org reacting to Friday night's events:

"Mr. Trump and the Republican leaders who support him and his hate-filled rhetoric should be on notice after tonight's events. These protests are a direct result of the violence that has occurred at Trump rallies and that has been encouraged by Trump himself from the stage. Our country is better than the shameful, dangerous, and bigoted rhetoric that has been the hallmark of the Trump campaign. To all of those who took to the streets of Chicago, we say thank you for standing up and saying enough is enough. To Donald Trump, and the GOP, we say, welcome to the general election. Trump and those who peddle hate and incite violence have no place in our politics and most certainly do not belong in the White House." (emphasis added)

In other words, there's more where this came from. There is a serious sickness in this country right now.