Here's why Trump's immigration speech was so shocking

David Frum of The Atlantic would like to know "what was so shocking" about the immigration policy speech Donald Trump gave Wednesday night - the speech that has led several members of his own campaign's Hispanic advisory council to quit.

I have an answer.

Frum argues, rightly, that several of the concerns that Trump advanced ought to be part of a rational immigration policy debate in the United States. Low-skill immigration poses real fiscal costs by adding residents who consume more in services than their taxes pay for. Assimilation is more problematic in some immigrant communities than others. Unlike other policy debates, the immigration debate often is oddly focused on the interests of non-citizens.

Frum is right that these points should be discussed as part of a debate over what immigration policy to have. The problem is that Trump's story about why immigration should be restricted goes well beyond these arguments, into territory that is shocking and dangerous.

Throughout his campaign, Trump has framed immigration as foremost an issue about crime, safety, and terrorism. This has been true from his literal first comments about immigrants during the campaign.

"They're bringing drugs, they're bringing crime, they're rapists," he said in his campaign announcement speech last June.

And it was true last night, when he attacked refugees as a "Trojan horse" and said "countless Americans who have died in recent years would be alive today if not for the open border policies of this administration."

Trump underscores the risk of immigrant violence by bringing the families of people harmed by immigrants to speak at his rallies. He hypes the threat of terrorism by immigrants far beyond the actual risk that exists in the United States.

His hysteria about the safety risks posed by certain kinds of immigrants have led him to propose a ban on immigration by all members of the world's second-largest religion. Though in recent months he's stopped emphasizing the Muslim ban (without ever withdrawing the proposal), he did outline on Wednesday night an unprecedented "ideological certification" for immigrants.

The thrust of the Trump message on immigration is not so much that our current immigration policy fails cost-benefit analysis as it is that immigrants may kill you.

In fact, immigrants commit crimes at a lower rate than native-born Americans. Frum argues that's not true for the first-generation descendants of certain immigrant groups, but the key issue is the order of magnitude: Immigrants and their children are not the wild security risk that Trump makes them out to be, and his insistence that they are foments harmful racial and ethnic division in the United States.

It's also clear Trump's negative views about the merits of various ethnic and religious groups are not limited to observations about statistical averages - and also are not limited to people born abroad. When Trump got a ruling he didn't like from an Indiana-born judge of Mexican descent, he attacked him as irretrievably biased due to his ethnicity. When Trump was criticized by the parents of a fallen American Muslim soldier, Trump criticized the mother for her (allegedly religion-driven) silence.

So yes, one could have made many of the points that Trump made Wednesday without being shocking. Mitt Romney did so, repeatedly, during the 2012 presidential race.

But when Trump makes arguments about the downsides of various kinds of immigration, listeners reasonably infer that he is driven not by a dispassionate cost-benefit analysis about the interests of American citizens. Rather, it is fueled by animus toward Mexicans and various other people not of white European ancestry.

The problem for immigration-restriction advocates like Frum and Reihan Salam is that, while you don't have to be a bigot to favor a more restrictive immigration policy, you do have to garner the votes of a lot of bigots to build a majority political coalition in favor of immigration restriction.

Salam worries that Trump's open appeals to bigotry will harm the cause of more sober advocates for less immigration. But Trump's why argument on restricting immigration was the only one that was ever going to catch fire with a wide swath of the electorate.

Trump is not so much destroying the cause of immigration restriction as he is demonstrating that it was doomed all along.

This is an editorial. The opinions and conclusions expressed above are those of the author.