Last week James Harris Jackson surrendered himself to police after (allegedly) stabbing 66-year-old Timothy Caughman in the chest. Caughman made it to a nearby police station but later died from his injuries. What shocked the city, and the reason this murder became national news, was Jackson’s motive for the crime. According to a prosecutor in the case, Jackson said he had driven from Baltimore to New York for one purpose: to kill black people. Jackson told police the murder of Caughman was “practice” for a larger attack he intended to carry out in Times Square.

A doctor quoted by CBS News describes Jackson’s family as being “as liberal can be.” His attorney is said to be planning to explore the possibility that mental health issues played a role in the crime. Needless to say, there will be a battle in court over precisely what motivated Jackson to commit this racist murder.

But the Mayor of New York thinks he already has an idea what motivated the killing. This week, Bill de Blasio told WNYC’s Brian Lehrer Show, “The challenge here is that a dynamic of hatred has been growing in this country over the last year or more.” De Blasio continued, “It has particularly come out in the open after the election and it’s clearly related to the rhetoric of Donald Trump and even other candidates during the presidential election that have unleashed forces of hate all over the country.” De Blasio went on to say, “It gets back to the core point. An atmosphere of hate has been created and we have to fight that atmosphere of hate with everything we’ve got.”

This is one of the left’s most cherished political arguments. Every time a racist or an insane person with a gun attacks someone the left immediately connects the killing to a climate of hate which serves to spread the blame to the right in general. In this case, De Blasio is being very explicit about connecting this murder to candidate Trump’s rhetoric. It’s the same kind of talk we saw in 2011 after the Tucson shooting. Back then the effort made by the left was to connect a deranged killer’s behavior to Sarah Palin, though it eventually turned out he had no connection to Palin.

What you rarely, if ever, see is the same argument being made when a killer appears to be acting with a left-wing motive. For instance, five police officers were killed in Dallas last year, plus 3 more in Baton Rouge by killers who could arguably have been said to be motivated by a left-wing climate of hate. What would De Blasio think of that argument?

In 2014, a man named Ismaaiyl Brinsley drove from Baltimore to New York, just like James Harris Jackson did, only his motive was to shoot and kill cops as revenge for the highly publicized deaths of Mike Brown and Eric Garner. Brinsley assassinated NYPD officers Wenjian Liu and Raphael Ramos as they sat in their patrol car. At the time, De Blasio did not connect the killing to any broader movement. In fact, here is part of what he said about the attack [emphasis added]:

When a police officer is murdered, it tears at the foundation of our society. It is an attack on all of us. It’s an attack on everything we hold dear. We depend on our police to protect us against forces of criminality and evil. They are a foundation of our society, and when they are attacked, it is an attack on the very concept of decency. Therefore, every New Yorker should feel they, too, were attacked. Our entire city was attacked by this heinous individual.

De Blasio went on to say, “I don’t think it’s a time for politics or political analysis,” thereby refusing to make any broader, societal connections.

So a man who traveled from Baltimore to New York to commit a revenge killing on police officers over deaths being amplified in the media by Black Lives Matter (often wrongly, i.e. “hands up, don’t shoot”) was just a “heinous individual.” But a man who travels from Baltimore to New York to commit a racist murder is proof of an “atmosphere of hate” connected to the president himself. That’s what you call a double-standard.

At some point, it would be nice if the media would notice that the left constantly uses this climate-of-hate argument to indict the right every chance it gets but denies any such climate exists when the target is a conservative or a police officer. The left is so quick to blame the right that they often don’t even wait for the facts. We saw another example of that just this week as neither of the people so far arrested for making telephone terrorist attacks on Jewish Community Centers fit the profile of right-wing anti-Semite. One was a left-wing journalist and the other was a Jewish teenager. That must have been a disappointment to the progressives who, once again, were trying to connect this spree to threats to President Trump.

The left can’t be allowed to have this both ways. Either people, including people with mental problems, are influenced by political rhetoric or they are not. If this really is a problem then it can’t just be a problem for the right.