The “alt-right” is what you get when weak men hiding behind online personas spend their days entertaining each other by concocting snarky memes that attack women, minorities and immigrants.

Some of them can toss around fancy right-wing buzzwords or recite the occasional quote from Nietzsche, but, in many cases, an alt-right identity is as much a fashion statement as a commitment to actual fascism.Waving a Confederate flag or a swastika is not necessarily proof that you have a political ideology. It can also be meant to show that you’re tough, that you’re not going to be bullied or that you are not “politically correct.”

If the alt-righters had only dared to show themselves in the dark corners of the internet, the movement would have been easy to ignore.

But when they embraced Donald Trump’s presidential race in 2015, making themselves a force in the primaries, they got everyone’s attention. And when alt-right protester James Alex Fields Jr. drove his car into a crowd of counterprotesters in Charlottesville, Virginia, on Saturday, killing Heather Heyer, 32, and injuring 19 others, they showed why we have to take them seriously.

Fields has been charged with homicide and will face a lengthy legal process to see if he can be held responsible for Heyer’s death, but there is a political issue that can’t wait for the criminal case to be resolved.

Our country could probably survive the worst that racists like former Ku Klux Klan leader David Duke and/or neo-Nazi Richard Spencer can dish out (they will never represent more than a tiny minority).

But how long can we make it with a political discourse in which there are no rules? One where there is no price to be paid for being caught lying? One where libelous attacks on minority groups are accepted as gospel because someone on “our team” said it?

Trump did not tell Fields to plow his car into a crowd last week, but during his campaign he sent a message to men like Fields that was almost as dangerous.

When Trump promised to mass deport millions of immigrants; or said that a judge’s Mexican heritage made him unfit for his job; or bragged about grabbing women’s genitals; or coyly refused to denounce avowed racists like Duke, he let the alt-right know that it was now safe to say in public the things they thought they could only tweet anonymously.

What Trump and the others call “political correctness” is just a code of conduct, in which people tacitly agree to show each other respect. The “PC Police” can overdo it at times and weaponize the language of tolerance to silence opponents, but without some rules of decorum, people who disagree on fundamental issues will never be able to work out their differences.

If any good comes out of Charlottesville, it will be that it shows where extremist rhetoric will take you.

Violent words lead to violence. We don’t need censorship, but we do need people willing to police themselves.