In an interview, Trump expanded on his ideas for preventing another terrorist attack on this side of the Atlantic: “We’re going to have to do things that we never did before.” Photograph by Brian Snyder/ Reuters / Landov

As you have doubtless noticed, the terrorist attacks in Paris have produced a rhetorical race to the bottom among the Republican candidates for President. Jeb Bush took an early lead in this descent by issuing a proposal that appeared to have been taken from the playbook of his elder brother George. Appearing on television over the weekend, Bush said that the United States should put together a multinational coalition to invade Syria, mash ISIS to smithereens, and knock off the Assad regime, and only then figure out how to establish peace and withdraw.

On Monday, Chris Christie, another struggling candidate, argued that the first priority was securing the homefront, which meant that the United States couldn’t risk allowing in any more Syrian refugees—not even young children who had lost their parents. “I don’t think orphans under five are being, you know, should be admitted into the United States at this point,” the New Jersey Governor told Hugh Hewitt, the conservative talk-show host.

For heartlessness, illiberalism, and irresponsibility, Christie’s statement seemed hard to beat. But Donald Trump, the Republican front-runner, isn’t one to concede defeat easily. Speaking to Sean Hannity, of Fox News, on Tuesday, Trump said that, in order to forestall possible attacks on American soil, the federal government might have to close down mosques. “Nobody wants to say this, and nobody wants to shut down religious institutions,” Trump said. But, he continued, “there’s absolutely no choice. Some really bad things are happening, and they are happening fast.”

In an interview with Yahoo News, which was also carried out on Tuesday, Trump expanded on his ideas for preventing another terrorist attack on this side of the Atlantic. “We’re going to have to do things that we never did before.” he said. “And some people are going to be upset about it, but I think that now everybody is feeling that security is going to rule. And certain things will be done that we never thought would happen in this country in terms of information and learning about the enemy. And so we’re going to have to do certain things that were frankly unthinkable a year ago.”

The reporter who carried out the interview, Hunter Walker, then pressed Trump about how far he would be willing to go. Walker asked whether the level of surveillance Trump was advocating might require registering Muslims in a database or, in Walker’s words, “giving them a form of special identification that noted their religion.” Trump wouldn’t rule out the idea. “We’re going to have to look at a lot of things very closely,” he said. “We’re going to have to look at the mosques. We’re going to have to look very, very carefully.”

Like many people in the media, I sometimes still have difficulty taking what Trump says seriously. Yes, I know that he’s leading the polls, and has been for months. I’m also aware that his poll numbers reflect widespread disaffection and alienation among some parts of the American population, especially the white working class, a feeling that he is cleverly exploiting. To that extent, the Trump phenomenon is real.

What’s hard to take seriously, or even literally, is what comes out of Trump’s mouth—statements like: the Mexican government is sending us their criminals and murderers. Deport eleven million undocumented immigrants. Cut the tax rate to ten per cent or less for anyone earning under a hundred thousand dollars a year. Megyn Kelly is a lightweight. Ben Carson’s youthful anger problem can be compared to child molestation. Since so much of what Trump says is hot air, it’s tempting to dismiss all of it as mere rabble-rousing or showboating.

In this case, however, it’s surely time to call him out—and some people are already doing just that. Picking up on the Yahoo interview, the Raw Story ran an article headlined “Trump Crosses the Nazi Line: Maybe Muslims Should Wear Special ID Badges.” A headline at Jezebel referred to Trump as “A Literal Fascist.” On Twitter, the astronomer and author Phil Plait commented, “There comes a time when decent, thoughtful, responsible people point out that this is, in fact, what Hitler did.”

It is important to be careful with language, which Trump often isn’t. Walker’s account at Yahoo makes it clear that he was the one who brought up the possibility of registering American Muslims or making them carry special identification, and that Trump didn’t endorse these proposals. But Trump didn’t dismiss them, either, even after stories appeared attributing the ideas to him. And he did tell Walker that some measures previously considered “unthinkable” were going to be necessary, such as closing down mosques, and that “security is going to rule.”

To some extent, Trump may simply be seeking to maintain an edge over his G.O.P. rivals in an atmosphere that is bordering on hysteria. “Everyone is now saying how right I was with illegal immigration & the wall,” he tweeted on Thursday. “After Paris, they’re all on the bandwagon.” But there is a difference between playing politics and deliberately targeting an entire religious group.

On Thursday night, Trump confirmed that if he were elected President, he would establish a database to track Muslims in the United States. “I would certainly implement that. Absolutely,” he told NBC News after appearing at a town-hall event in Iowa. Trump said that American Muslims would be legally obligated to sign up for the database and added, “It’s all about management. Our country has no management.” He also sought to link the proposed database to the debate about immigration, saying, “It would stop people coming in illegally.”

That’s more Trump bluster, of course. Forcing every Muslim in the country to register for some sort of database would do nothing to secure the borders or stanch the flow of undocumented migrants. It also wouldn’t prevent the possibility of some radicalized and disaffected American youths deciding to join the jihadi cause. Indeed, by stigmatizing an entire religious community, it would make such behavior more likely. Trump must know that his proposals don’t make sense, but he’s pushing on regardless. He has moved from rabble-rousing to demagoguery, or something even uglier. And this time, sadly, we have no option but to take him seriously.

*This post was updated to incorporate comments that Donald Trump made on Thursday night.