Remember the story about the drunk who loses his car keys in the forest but looks for them under a lamp post because that's where the light is?
Conservative calls to fight terrorism in the wake of the Boston attack by ditching immigration reform make just as much sense.
The difference is that the drunk's efforts were merely futile. Conservative efforts are also dangerous because they ignore the security threat that Big Government poses.
No sooner was it revealed that the two bombers were Russian emigres of Chechen heritage than Iowa's Sen. Charles Grassley declared that the attacks show that America needs to "beef up security checks," not let more newcomers in.
Rep. Steven King, also a committed restrictionist from Iowa, demanded we pause and look at "the big picture" on immigration, as if seven years since the last failed effort at reform is not enough.
Most disappointing was Republican Sen. Rand Paul of Kentucky's switcheroo. Last month, he distanced himself from his party's harsh anti-immigration rhetoric. This week he counseled that we rethink visas for foreign students, never mind that neither of the Brothers Tsarnaev ever obtained one.
None of this, however, would have prevented the attack given that the Tsarnaev brothers obtained asylum around 2002 at the ages of 8 and 15 along with their parents, fleeing persecution in Russia.
Reportedly, the older brother Tamerlan, a boxing champion, became radicalized only eight years later, after his mother, not seriously religious then, reminded him of his Islamic faith's strictures to wean him off alcohol and drugs.
When he met his wife, Katherine Russell, at a nightclub, he was a nominally pious, somewhat confused young adult with few signs that he'd become a raving zealot.
That U.S. immigration authorities leave something to be desired when vetting dangerous foreigners has been apparent since Mohamed Atta, the 9/11 hijacker, was handed a visa after he flew a plane into the World Trade Center.
But expecting the immigration system to predict that Tamerlan would become a lunatic is as reasonable as expecting psychiatrists to diagnose that Timothy McVeigh would become a terrorist when he was a toddler. The lack of omniscience in human institutions is not a curable flaw.
But if conservatives are looking for an agency to blame, there are better candidates. There is the FBI that gave Tamerlan a clean chit after being tipped off by Russian authorities of his suspicious movements during his visits home.
One can also question the Boston law enforcement's handling that allowed the brothers, first, to plant their bombs and then let the injured Dzhokhar, Tamerlan's younger brother, escape after a shootout.
Above all, one can blame the First Amendment. Freedom of the press allows Inspire, an online terrorist guide, to openly instruct would-be terrorists such as Tamerlan on how to develop their grisly wares.
To fight terrorism, it would make far more sense to crackdown on the Internet than the border. But no one has put that on the table -- not yet at least. Why?
Because Americans would be outraged. They intuitively realize that a country whose government has the power to throw people in jail for exchanging information would be neither free nor safe.
Immigration is a far softer target, which is why conservatives, like the bumbling drunk, are going after it. But it is as dangerous to censor the flow of people as of ideas.
Requiring foreigners to go through rigorous background checks is perfectly legitimate. But shutting the border to economic migrants, whether computer geeks from China or apple-pickers from Mexico, in a vain effort to deter a future Tamerlan won't make Americans better off.
Indeed, since the vast majority of immigrants are here because some American wants to hire them or marry them or whatever, the government can't chase them out without asserting Draconian powers overs Americans as well.
Witness Alabama laws imposing a business death penalty by revoking the license of any company found hiring illegals. Or Arizona's effort to detain individuals not carrying their papers to prove their legality. Every year, Americans are less likely to die through a terrorist attack than a lightning strike -- or wrongful death by overzealous law enforcement. More immigration restrictions will make Americans less -- not more -- safe.
Washington Examiner Columnist Shikha Dalmia is a senior policy analyst at Reason Foundation, a nonprofit think tank advancing free minds and free markets.