Throughout the presidential campaign, Donald Trump has been compared to Adolf Hitler on more than one occasion. Especially after TIME Magazine named him 2016 “Person of the Year,” linking the president elect to the German dictator, who also received the same homage in 1938, has significantly increased, as liberals try to explain the rise of the populist businessman.

Just take a look at Twitter where there is no shortage of Trump-Hitler tweets:

The New York Times published a review of the television series “The Man in the High Castle” on Thursday, which depicts an alternative America where the Allies entered World War II too late, and the United States is ruled by the fascist Nazi Germany and Japanese regimes.

But the reviewer says the show isn’t too far off of what America could be under Trump.

As the internet has taught us, Nazi analogies tend to crush nuance into fine powder,” the review states. “But if it would be hyperbole to treat the series like a documentary, it would be denial to say it plays no differently now than it did before. However hopeful some people may find the election results, there are also bigots who feel validated, for whom the permission to bully and strong-arm was not a sad side effect of the campaign but the whole point. And ‘The Man in the High Castle,’ a drama about finding the imagination to resist darkness, has a new relevance, asked for or not.”

Granted, there are some similarities with their rise to power and others have even gone as far as to say Trump’s rallies are very Hitler-esque. But is this a fair comparison or just political demonizing, by using Hitler comparisons as a way to shut down political debate?

Simply put, there is no proof that Trump exists to begin World War III or wants to exterminate millions of Mexicans, Muslims or people of color in the United States. Many point to Trump’s proposal to temporarily ban Muslims from entering the country (which he has since walked back) as a similar plan that Hitler had with regards to Jewish people. But Trump’s disdain for ISIS and Islamic extremism is not even close to Hitler rounding up Jews and killing them. There is no evidence to suggest that Trump would call for a boycott of Muslim businesses or prevent them from holding prominent positions if he were elected.

There is plenty to criticize Trump on, as there was for Hillary Clinton, but comparing him to Hitler is not a substantive debate on Trump’s rhetoric, appointments, and policy proposals.

He’s also not the first politician to be compared to Hitler. “Barry Goldwater’s Rise is Compared to Rise of Hitler,” announced Jet magazine on July 30, 1964. Richard Nixon was often compared to Hitler by his Democratic rival George McGovern. And then it’s been passed down to Ronald Reagan and George W. Bush. It’s become a trend among Republican presidents, to have the Democratic challengers compare them to the fascist leader.

“This happens every time a major Republican comes on the scene,” said Joe Scarborough, co-host of MSNBC’s Morning Joe, when discussing the NYT piece.

However, it’s not just Democrats tossing around the vernacular. Republicans have done it too. In 1964, Republican Rep. William Miller compared President Lyndon Johnson’s Great Society reform to the Hitler regime. Even President Barack Obama has been called “Hitler” by many conservative commentators during his terms in office.

Former Republican presidential candidate Mike Huckabee got slammed by liberal media last year for what they interpreted as an Obama-Hitler comparison. He told Breitbart that the “president’s foreign policy is the most feckless in American history.”

“It is so naive that he would trust the Iranians. By doing so, he will take the Israelis and march them to the door of the oven,” he said. “This is the most idiotic thing, this Iran deal. It should be rejected by both Democrats and Republicans in Congress and by the American people. I read the whole deal. We gave away the whole store. It’s got to be stopped.”

Huckabee says he wasn’t comparing Obama to Hitler. He was saying how the United States essentially surrendered to Iran in agreeing to ease economic sanctions in exchange for stopping the country’s nuclear program and increased inspections in the area, like how British Prime Minister Neville Chamberlain went into an “appeasement mode” when Hitler was gaining power.

But still, Huckabee was forced to apologize and explain himself for what he said, even if he wasn’t directly comparing Obama to Hitler. Yet when Democrats and opponents of a Trump presidency make the comparisons of the president-elect to Hitler, they don’t need to apologize or explain themselves further.

Historical parallels can be drawn between any two people, especially political leaders, but many different factors like economics, technology and demographics also contribute to the narrative, which many tend to forget.

Some also compare Hitler’s mobilization of an electorate, going from a minor party to a major political party by engaging the German nonvoter, to Trump’s attraction of voters who previously felt alienated by traditional parties. But Obama should also be included in that comparison, too, because he brought the traditional nonvoter to the polling place with his historic win in 2008.

Yet, people don’t see the mobilizing of voters on the left side of the electorate as a threat to American democracy. Just another case where political prejudice stands out more than facts and reason.

It’s because of this, that comparing Hitler and Trump — or any political leader for that matter — is meant to censure people from providing reason and facts in debates.

That term is called “Reductio ad Hitlerum,” which is the attempt to invalidate someone else’s position on the basis that the same view was held by Hitler or the Nazi Party.

Mike Goodwin also shares some similar thoughts on this theory. He created what is known as “Goodwin’s Law.” It states that “as an online discussion grows longer, the probability of a comparison involving Hitler approaches 1” — meaning that sooner or later, someone will compare someone or something to Hitler.

And some historians don’t believe comparing Trump to Hitler is doing anyone any good.

“First and foremost, it is a distraction,” said Thomas Weber, a German historian. “The problem is that the moment someone brings up Hitler in a political discussion, in a way, it’s the end of the political discussion, because then it turns into a discussion over the comparison rather than substance.”

“On a tactical level, there are great similarities between the early rise of Hitler and Trump,” he added. “But we should not forget that beyond the tactical level there are huge differences and that ultimately the danger that Trump poses is rather different from the threat posed by Hitler.”

Robert Paxton, a history professor at Columbia University, has been called the expert of fascism, giving it some definition. In an interview with the Los Angeles Times, he essentially said he doesn’t think Trump is a fascist.

“I think Donald Trump falls far short of what Hitler was able to do when he mesmerized these crowds, though he’s certainly better at it than anybody else,” he said. “The trouble with fascism as a label is that it generates so much heat and not necessarily so very much light, so we must remember there are ways in which Trump is not like the fascists.”

Weber said that even though Trump is not like Hitler, that doesn’t mean one shouldn’t be worried about a Trump presidency and what dangers could lie ahead. But you don’t have to invoke Hitler’s name when discussing one’s disagreements with the president-elect.

“The biggest difference — which takes me back to my point why the Hitler comparison may distract from the real danger that Trump poses — is that Trump is ultimately a demagogue and a populist,” he said. “He will say whatever it takes to get elected and then to stay in power. By invoking Hitler, you run the risk that people will just somehow try to prove that Trump is not Hitler, and if Trump isn’t Hitler then everything will be fine.”