Mike Godwin is director of innovation policy and general counsel of R Street Institute.

Donald Trump waves to supporters after a campaign rally in Tyngsborough, Mass., in October. (AP Photo/Charles Krupa)

First, let me get this Donald Trump issue out of the way: If you’re thoughtful about it and show some real awareness of history, go ahead and refer to Hitler or Nazis when you talk about Trump. Or any other politician.

My Facebook timeline and Twitter feed have been blowing up lately. And whenever that happens, it’s almost always because someone’s making comparisons to Hitler or Nazis or the Holocaust somewhere. Sure enough, as Trump pontificates about immigrants or ethnic or religious minorities, with scarcely less subtlety than certain early 20th-century political aspirants in Europe did, people on the Internet feel compelled to ask me what I think about it.

Why? Simple: Because 25 years ago, when the Internet was still a pup, I came up with Godwin’s Law. In its original form, Godwin’s Law goes like this: “As an online discussion continues, the probability of a reference or comparison to Hitler or Nazis approaches 1.”

[Trump says he’s not bothered by comparisons to Hitler]

Invoking Hitler or Nazis (or World War II or the Holocaust) is common in public life these days, both in the United States and around the world, and it has been for quite a while. Back in 1990, I set out — half-seriously and half-whimsically — to do something about it.

Through most of the 1980s, I’d been a hobbyist using computer “bulletin-board systems” that connected small local communities by telephone lines. I couldn’t help but notice how often comparisons to Hitler or Nazis came up in heated exchanges, usually as a kind of rhetorical hammer to express rage or contempt for one’s opponent. Once I was back in school to study law, I leveraged my student status to get a free Internet-based computer account. With access to the global Internet came still more hyperbolic Hitler and Nazi comparisons.

The presidential campaign for Ohio Gov. John Kasich released an ad drawing a comparison between Donald Trump's rhetoric and Nazism. (John Kasich)

Despite the Internet’s distractions, I did actually manage to study law. And I was drawn to a particular kind of legal problem: What happens when a nation, although acting consistently with its own laws, behaves so monstrously that other nations, and eventually history itself, are compelled to condemn it?  I steeped myself in the history of the Nazi movement and in accounts of the Holocaust, including Primo Levi’s harrowing “Survival in Auschwitz.” I was increasingly troubled by the disconnect between what I was reading about the Third Reich and the way people used that era against debating opponents online.

Could I help close the gap between the glibness and the graphic accounts? I was no historian or eyewitness; I probably knew less about Hitler and Nazi Germany than the average viewer of the History Channel. But I knew enough about science to recast my distaste for these trivializing comparisons as if it were a law of nature. I framed Godwin’s Law as a pseudo-mathematical probability statement, almost like a law of physics. I wanted to hint that most people who brought Nazis into a debate about, say, New York Gov. Andrew Cuomo’s views on gun control weren’t being thoughtful and independent. Instead, they were acting just as predictably, and unconsciously, as a log rolling down a hill.

[The Philadelphia Daily News goes there on Trump]

After some early energetic seeding on my part, “Godwin’s Law” took off in the early days of large-scale public access to the Internet. Users would see a poorly reasoned, hyperbolic invocation of Nazis or the Holocaust and call the arguer to account, claiming the shallow argument had proved (or, sometimes, had “violated”) Godwin’s Law. Soon after, Godwin’s Law propagated into the mainstream media as well. Democrats and Republicans alike invoke it from time to time — so do other political parties in the United States and around the world. Sometimes it’s invoked by a Democratic blogger; sometimes it’s cited by a Republican. The law notably surfaced recently in Canadian politics, too.

So has Godwin’s Law actually reduced spurious Hitler or Nazi or Holocaust comparisons? Obviously not — just sample your own media sources, and you’ll find that Hitler comparisons are alive and well. (My personal favorite this year: the Mets fan who likened Yankees fans to former Nazi Party members.) But I do think the meme gives Internet users a clear opportunity to think critically about shallow references to the Nazis or the Holocaust. And it exposes glib Nazi comparisons or Holocaust references to the harsh light of interrogation.

[We have a Nazi analogy problem]

The idea seems to travel well, adapting itself to new languages and cultures. In French, for example, users sometimes say a debate has reached “the Godwin point” when discussion has degenerated into Nazi comparisons, and one author, François De Smet, subtitled his 2014 book “Reductio ad Hitlerum” (a philosophical essay) as “une théorie du point Godwin.”

To be clear: I don’t personally believe all rational discourse has ended when Nazis or the Holocaust are invoked. But I’m pleased that people still use Godwin’s Law to force one another to argue more thoughtfully. The best way to prevent future holocausts, I believe, is not to forbear from Holocaust comparisons; instead, it’s to make sure that those comparisons are meaningful and substantive. This is something a pleasantly surprising percentage of commentators in this political season have managed to do (like this piece on Trump by New America and CNN analyst Peter Bergen). And I’m pleased in any season to see more people revisiting the history books.

It’s still true, of course, that the worst thing you can say about your opponents, in our culture, is that they’re like Hitler or the Nazis. But I’m hopeful that we can prod our glib online rhetorical culture into a more thoughtful, historically reflective space. In 2015, the Internet gives more and more individuals both the information and the skepticism to question what politicians and others say in their Hitler-centered hyperboles. Just as importantly, the Internet gives us the tools to share our criticisms — including the appropriately appalled reaction to Trump’s statements — with one another more widely.

The one thing we shouldn’t be skeptical of is our right — our obligation, even — as ordinary individuals to use the Internet and the other tools of the digital age to challenge our would-be leaders and check the facts.

And by all means be skeptical of Godwin’s Law, too. But you don’t need me to tell you that.

Read more:

Donald Trump wasn’t a textbook demagogue. Until now.

Donald Trump is America’s Silvio Berlusconi

No, I’m not playing the “six degrees of Adolf Hitler” game