NurPhoto via Getty Images Demonstrators carry confederate and Nazi flags during the Unite the Right rally at Emancipation Park in Charlottesville, Virginia, on August 12.

Following a tragic weekend of political violence in Charlottesville, Virginia, that left three dead, you may be tempted to say the white supremacist demonstrators who fomented the violence are Nazis.

Go ahead: Godwin himself wouldn’t stop you.

Mike Godwin, an attorney and author, coined something called Godwin’s law in 1990, when internet discussion boards were first proliferating. Godwin’s law famously posits, “As an online discussion grows longer, the probability of a comparison involving Hitler approaches 1.” (In other words, if an online discussion persists long enough, someone will eventually compare a person or thing to Hitler or his ideology.)

In the years since he introduced the law, it has become a mainstay of internet discussion boards. And as it has proliferated, the general understanding of the law has grown less precise; though Godwin’s law is not intended to be used to penalize people for invoking Hitler, it’s often invoked now to claim that debaters who compare each other to Hitler have “violated” Godwin’s law. The penalty: The person who referenced Hitler or Nazis automatically loses the argument. A gentler version holds that once Hitler comes up in a debate, the conversation has outlived its usefulness.

Godwin sees his law a bit differently, however. On Sunday, he tweeted about the events in Charlottesville, and he didn’t mince words:

By all means, compare these shitheads to Nazis. Again and again. I'm with you. — Mike Godwin (@sfmnemonic) August 14, 2017

This isn’t the first time he’s encouraged people to use the Hitler comparison, provided that they’re deploying it thoughtfully and with an understanding of the historical context. In June, Godwin assured a journalist who had insinuated that prominent white nationalist Richard Spencer was a Nazi that his law did not preclude the comparison. Time magazine interviewed him following the exchange, and he suggested, “If you think the comparison is valid, and you’ve given it some thought, do it ... We have to keep the magnitude of those events in mind, and not be glib.”

Godwin has always maintained that his famous law was intended not to invalidate any comparison to Hitler. In fact, it wasn’t really a “law” that could be “violated” at all. Rather, he has argued, it was crafted as a counter-meme, a viral idea that would push back on the still-more viral idea of Nazism as the ultimate weapon in an online argument. It was meant to describe, in a pseudoscientific form, the lazy and predictable internet habit of invoking Hitler. By putting a name to this kneejerk habit, Godwin hoped to encourage us all to think twice before cavalierly calling our opponent a Nazi, and to give us an opportunity to choose a more apt and effective tactic.

“The best way to prevent future holocausts, I believe, is not to forbear from Holocaust comparisons,” he wrote in The Washington Post in 2015, amid the rise of Trump. “[I]nstead, it’s to make sure that those comparisons are meaningful and substantive.” Though some have used Godwin’s law to push back on comparisons between white nationalists and Nazis, the law was originally intended to preserve the strength of those Nazi comparisons for times when they are genuinely merited ― for example, when an “alt-right” gathering openly associates itself with Nazi ideology and insignia.

Godwin’s denunciation of the Charlottesville demonstrators as “Nazis” stands in sharp contradistinction to President Donald Trump’s milquetoast reaction. In his initial response to the unrest, President Trump earned lacerating criticism from mainstream onlookers, and plaudits from white nationalists and neo-Nazis, by failing to explicitly denounce the rightwing extremist groups behind the violence.

“Racism is evil,” Trump eventually said in a statement on Monday, “and those who cause violence in its name are criminals and thugs, including the KKK, Neo-Nazis, white supremacists and other hate groups that are repugnant to what we hold dear as Americans.”

Administration officials defended Trump’s earlier comments, which condemned “hatred, bigotry and violence on many sides.” Tom Bossert, Trump’s homeland security adviser, explained that the president had refused to “dignify” these movements by naming them.

If Godwin’s law proves anything, however, it’s that accurately naming what we’re up against holds tremendous power.