Last Monday, gunmen opened fire on Black Lives Matter protesters in Minneapolis who were demanding action against two white Minneapolis police officers involved in the fatal shooting of Jamar Clark, 24, an unarmed black man, on Nov. 15.
Evidence shows the accused shooters were linked to white supremacist organizations operating online.
In a video that surfaced before the shootings, one of two men on the way to the protest says "we're going to go see what these f--- dindus are up to," using slang insulting toward African Americans. He then brandishes a pistol and says, "we are locked and loaded."
Meanwhile, the FBI reports an upturn in threats on mosques and Muslims in the United States.
In Connecticut, police are investigating reports of multiple gunshots fired at a local mosque. Two Tampa Bay-area mosques in Florida received threatening phone messages. One of the calls threatened a firebombing.
In an Austin suburb, leaders of the Islamic Center of Pflugerville discovered feces and torn pages of the Qur'an.
Hate crimes will never be eliminated entirely. A small number of angry, deranged people inevitably will vent their rage at groups they find threatening. Some will do so violently.
But this doesn't absolve politicians who have been fueling such hatefulness.
Perpetrators of hate crimes often take their cues from what they hear in the media. And the recent inclination of some politicians to use inflammatory rhetoric is contributing to a climate of hate and fear.
Carly Fiorina continues to allege, for example, that Planned Parenthood is selling body parts of fetuses.
Although the claim has been proven baseless, it's been repeated not only by Fiorina but also by other candidates. Mike Huckabee calls it "sickening" that "we give these butchers money to harvest human organs."
Even in the wake of Friday's Colorado shootings, Donald Trump referred to videos "with some of these people from Planned Parenthood talking about it like you're selling parts to a car."
Some candidates are also fomenting animus toward Muslims.
Huckabee says he'd "like for Barack Obama to resign if he's not going to protect America and instead protect the image of Islam."
Ben Carson says allowing Syrian refugees into the United States is analogous to exposing a neighborhood to a "rabid dog." Last September Carson said he "would not advocate that we put a Muslim in charge of this nation."
He's also claimed that Muslim-Americans in New Jersey celebrated by the "thousands" when the World Trade Center was destroyed on September 11, 2001, although there's no evidence to back that claim.
Indeed, much of Trump's campaign is built on hatefulness. And Trump not only fails to condemn violence he provokes but finds excuses for it.
After a handful of white supporters recently punched and attempted to choke a Black Lives Matter protester at one of his campaign rallies, Trump said "maybe he should have been roughed up."
Trump began his campaign last June by falsely alleging Mexican immigrants are "bringing crime. They're rapists."
Weeks later in Boston, two brothers beat with a metal poll and urinated on a 58-year-old homeless Mexican national. They subsequently told the police "Donald Trump was right, all these illegals need to be deported."
But instead of condemning that brutality, Trump excused it by saying "people who are following me are very passionate. They love this country and they want this country to be great again."
I'm not suggesting Trump, Carson, Fiorina, or any other presidential candidate is directly to blame for hate crimes erupting across America.
But by virtue of their standing as presidential candidates, their words carry particular weight. They have a responsibility to calm people with the truth rather than stir them up with lies.
In suggesting that the staff of Planned Parenthood, Muslims, Black Lives Matter protesters, and Mexican immigrants are guilty of venal acts, these candidates are fanning the flames of hate.
This itself is despicable.
ROBERT B. REICH's new book, "Saving Capitalism: For the Many, Not the Few," will be out September 29. His film "Inequality for All" is now available on DVD and blu-ray, and on Netflix. Watch the trailer below: