The Trump administration’s efforts to bar entry into the United States of people from several Muslim-majority countries have been justified as necessary to reduce Americans’ risk of death from terrorism. Though these travelers—especially refugees—already are scrutinized before receiving entry visas, President Trump and his staffers claim this scrutiny is insufficient and must be “paused” so that “extreme vetting” mechanisms can be drawn up and implemented.

The Trump White House considers risk reduction of terrorism to be of paramount importance and no counterweighing concern—including the harm that could befall refugees attempting to flee to the United States, or the negative effects of such a ban on the United States’ reputation, or the loss to American society and the economy from losing these immigrants—are adjudged important enough to offset the value of that risk reduction.

But removing risk is itself risky business. Through the travel ban and ensuing “extreme vetting,” President Trump hopes to avoid a false negative or “Type II” error—mistakenly considering “safe” a traveler with lethal intentions. However, strong sensitivity to Type II errors increases the likelihood of Type I errors, which in this case would be the turning away (whether temporarily or permanently) of benign travelers at a cost to both those travelers and the United States. Showing disregard for holders of travel visas (and in the ban’s original form, U.S. green cards) generates costly uncertainty for a large category of people who contribute to the nation’s well-being. When these and other costs are imposed on tens of thousands of innocent people, the cost becomes quite large.

This point was made memorably years ago by Al Capp, the creator of the legendary comic strip Li’l Abner. Though the strip primarily dealt with the exploits of Li’l Abner, Daisy Mae, and the other denizens of Dogpatch, Capp would sometimes take a break from that storyline to tell tales (or in some cases, just a panel or two) of L’il Abner’s favorite comic book character, police detective Fearless Fosdick.

Fosdick was a parody of Dick Tracy, a combination of Barney Fife and Roscoe P. Coltrane (without the corruption), with Tracy’s square jaw. One of Fosdick’s nemeses was Anyface, a master of disguise who could appear at first as, say, an innocent old woman, but then transform into a gasoline pump if Fosdick appeared to be on his trail. Anyface was determined to unleash mayhem on the unnamed metropolis Fosdick protected—in today’s words, he was a terrorist.

In one episode, Anyface let it be known that he had poisoned a can of Old Faithful Pork-n-Beans, which happened to be the community’s favorite delicacy. Hardly a meal was enjoyed without a serving of the beans, and Anyface knew that.

Wrestling with the problem and what to do about it, Fosdick’s boss, The Chief, gathered together his inner circle to form a strategy. A bunker mentality prevailed. It was law and order against terrorism, good against evil, right against wrong.

After some deliberation, The Chief had a revelation: he simply instructed trusty Fosdick to make certain no one would die from eating Old Faithful beans. Fosdick took his orders seriously. To avoid a Type II error, he immediately went to the Old Faithful factory, shut it down, and impounded all the beans in the warehouse. He likewise impounded all the beans in grocery stores and at wholesalers.

But then he realized: what if someone had already purchased the poisoned can and the beans were simmering on the stove or in bowls ready to serve? Heaven forbid, what if people in some restaurant were lifting a forkful of the lethal beans to their lips at that very moment? Remembering his charge from The Chief—don’t let anyone die from eating poisoned beans—Fosdick knew what to do.

Rushing from house to house and from café to restaurant, when Fosdick saw people about to heat up a can of beans, he shot them. If people appeared to be ready to eat some of the beans, he shot them, too.

When the episode ended, no one had died from Anyface’s can of poisoned beans, but many had died from Fosdick’s gun. Still, with the terrorist Anyface held at bay, Fosdick smiled. He had made the classic Type I/​Type II tradeoff. He had made sure that no one would fall ill or die from poisoned beans. Problem is, he had wiped out part of the population in doing so.

Our nation is exposed to terrorism risk. Because our president is sworn to protect us, extreme vetting and even more costly actions may be imposed on innocent people. While none will be shot in an effort to avoid allowing terrorists to enter the country, an abrupt slamming of the door on foreign travelers imposes a cost on each innocent traveler denied at the threshold. There is also a cost imposed on the rest of us when chastened, foreign opportunity-seekers decide to seek their fortunes elsewhere.

President Trump, like Fosdick, may be successful in preventing death in this country from the hands of terrorists. But depending on how he does this, he can erode the wealth-creating process as well as bruise some precious ideas that define this nation.

Sadly, there is no such thing as free protection from terrorist harm. Knowing that, we should move cautiously when tightening the screen that, while guarding us from harm, limits the entry of the ultimate resource: creative and productive human beings who wish to pursue the American dream.