The aftermath of the 1920 Wall Street bombing.

Presidential candidate Dr. Ben Carson is arguing that the Paris attacks warrant the U.S. refusing refugees from the Middle East, and he’s not alone.

“Bringing people into this country from that area of the world I think is a huge mistake, because why wouldn’t they infiltrate them with people who are ideologically opposed to us?” Carson said on “Fox News Sunday.” “It would be foolish for them not to do that.”

Carson’s statement was a reaction to reports that French investigators suspect one of the attackers involved in Friday’s atrocity was a Syrian who arrived in Europe with the tide of refugees that swelled in the late summer.

He and the other GOP candidates were not exactly warm and fuzzy toward immigration before the attacks in the French capital, but have found a way to take an even harder line in their aftermath. Carson quipped yesterday that admitting refugees now would require a “suspension of intellect.”

In fact, Carson’s idea—that we must block the admission of refugees because of the possibility that some of them might have violent radical tendencies—requires a suspension of historical context.

Fact is, the United States has been admitting people who mixed ideology and force for a century. We’ve somehow survived. And we’ve lived to regret it when we used the threat of their arrival to close our doors.

In April 1919, 36 mail-bombs, each containing a stick of dynamite and a vial of sulfuric acid, were sent to American industrialists, judges and other officials. In June of that year, seven cities were struck by far larger bombs; the one in New York killed a night watchman. According to an FBI history of the episodes, “The bombings were a concerted effort among U.S. based anarchists who were most likely disciples of Luigi Galleani, a vehemently radical anarchist who advocated violence as a means to effect change, to rid the world of laws and capitalism.” Many of those anarchists were Italian immigrants.

A bombing on Wall Street in 1920 was blamed on Italian anarchists or Russian bolsheviks. Twenty years later, two New York cops were killed by a bomb at the World’s Fair in Queens. No one was ever charged for that crime, but suspicion fell on German nationalists or the Irish Republican Army. U.S.-based gun-running linked to the IRA, involving both Irish immigrants and Irish-Americans, has long been a concern of U.S. prosecutors.

In 1990 an FBI memo noted that over the previous three years, the Miami area had seen at least 25 bombings or attempted bombings:

Despite the lack of explanatory communiques for the attacks, it is apparent from the chosen targets that anti-Cuban Communism is the principal issue behind the bombings. These attacks are not the first of their kind committed to further the goals of anti-Castro Cubans; rather, they are a continuation of a long-standing fight against the Communist Government of Cuba. Ever since the late 1950s, when the first exiles escaping the Communists on Cuba arrived in the United States, there has been almost constant anti-Castro Cuban activities in Florida and elsewhere. Various groups were organized among the exiles. Although some of these groups have been no more than social organizations, others were comprised of militants who sought to overthrow the Castro regime through violence. This resulted in bombings, assassinations and other acts of violence against pro-Cuban Communist targets. Through the years, different groups emerged to either claim credit or be held responsible for the acts of terrorism.

Irv Rubin, the Jewish Defense League leader who killed himself in 2002 while awaiting trial for plotting to blow up a mosque and the offices of a Lebanese-American congressman, was an immigrant from Canada. ProPublica and Frontline recently reported on the killings of two Vietnamese-American newspaper editors in the early 1990s and possible links to The Front, a right-wing group of former South Vietnamese military officials and others that openly supported the overthrow of the communist government in Hanoi.

The main idea here is that for a very long time, from a long list of countries whose immigrants have overwhelmingly been important and positive parts of the American story, there have arrived on our shores a very small number of people who wedded ideology with violence and intended either to use force here or orchestrate the use of force overseas to accomplish their goals.

It’s always dangerous to treat historical similarities as equivalencies, so let’s not do that. ISIS appears to be a very different threat than the IRA or the JDL or virtually any other past movement. Many of those earlier violent groups did not see the U.S. or its citizens as enemies—their focus was on enemies in their homeland, and they were just operating here. Few militant groups have displayed reach, operational skill or brutality to rival ISIS.

What these past episodes do illustrate, however, is that the U.S. has never been able to fully seal itself off from the world. Over time, incidents involving a handful of members of one ethnic group or another have not prevented assimilation of tens of thousands of others into U.S. life.

Other incidents show what happens when, fearing a Fifth Column, we try to close the door or throw people back through it. The Palmer Raids on anarchists in the wake of the 1919 bombings are widely considered a low-point for civil liberties in this country. During World War II, one rationale the Roosevelt administration had for not accepting Jewish refugees from Nazi Germany is that the fascists could, by threatening family members left behind, blackmail those refugees into spying on the U.S.

These responses did more damage than the threats they sought to neutralize. Today, the danger of repeating that mistake presents the U.S., and its would-be presidents, with a risk just as real as the one ISIS poses.