How scared should we be about terrorism? Every terrorist killing in a Western land—be it France, Britain, Denmark, or the U.S.—makes us more and more uncomfortable and frightened. Sometimes people go into full panic mode, or prey on those who do, like the odious Donald Trump.

But, in a new piece in The New Yorker,”Thinking rationally about terror” (free online), physicist Lawrence Krauss says we shouldn’t be so worried. The statistics, he argues, show that terrorist violence in Western countries is negligible compared to the normal background levels of violence, and we’re getting all worked up about very little. His argument includes these paragraphs:

There are about two and a quarter million people in Paris. This means that, if you were living in Paris on the day of the recent attacks, there was roughly a one-in-twenty-thousand chance of being a victim. While that may seem high, the annual likelihood of getting killed by a car in France is almost exactly the same. (Last year, there were three thousand two hundred and fifty traffic fatalities in a population of sixty-four million.)

Murder rates offer another window onto the question. In France as a whole, the annual murder rate over the past five years peaked at around eight hundred and forty—which means that the recent terrorist attacks raised the national murder rate by about fifteen per cent. In Paris, the annual murder rate in previous years has been has high as 2.6 per hundred thousand people; by that measure, the terrorist attacks this year were a significant perturbation, more than doubling the average murder rate. Even so, it’s worth noting that this makes Paris about as dangerous as New York City, where the murder rate has been as high as seven per hundred thousand in recent years. New York is generally considered a very safe city. So, while terrorism has made life in France more dangerous, the new level of danger is one we tolerate—even celebrate—in the United States.

and

As far as the U.S. is concerned, it has been pointed out already—by the President, in fact—that about thirty-three thousand people die each year from gunshot wounds. That’s about four hundred thousand people since 2001. By contrast, setting aside 9/11, and even including the San Bernardino shootings, only fifty-four deaths have occurred because of domestic acts of terrorism during that time. Even if you include 9/11, the total death toll from terrorism amounts to less than one per cent of the death toll from gun violence. Just before San Bernardino, the Washington Post reported that, in the first three hundred and thirty-four days of 2015, there had been three hundred and fifty-one mass shootings in the United States—that is, shootings in which four or more people were killed or injured by gunfire. That is more than one per day. It is sobering to recognize that this month’s attack in California, as horrific as it was, does not skew the statistics at all; sadly, December 2nd in San Bernardino was just another average day in the United States. In fact, with over a hundred and eighty people shot each day in this country, even a mass killing like that which occurred in Paris would not significantly affect the death toll from guns in the U.S.

. . . the risks of falling prey to terrorism are nevertheless very small for most Americans. Terrorists have forced us to accept that any activity associated with living in a free society now carries with it a finite, and microscopically small, chance of tragic horror. Still, it’s up to us to choose how to react to this minuscule possibility.

Krauss’s solution is to chill out about the problem, realize the small scale of terrorist violence, and put our energies into problems that can really make us safer, like controlling the rampant proliferation of firearms in the U.S.

In general I agree with Lawrence, especially about gun control. But I’m not sure he’s completely apprehended both the motives of Islamic terrorism or why we’re so scared of it.

The smaller quibble rests on Krauss’s characterization of terrorist motives:

Needless to say, it is terrifying to know that there are individuals living among us with the express intent of killing randomly, for effect. But we must recognize that that’s the point of terrorism: it aims to scare us, thereby disrupting normal life. More than that, terrorism is designed drive a wedge between segments of a community which otherwise might have coexisted peacefully, both politically and socially.

That may be true in part, but the avowed aim of organizations like ISIS goes further: not only to disrupt our societies, but to take them over: make them part of the Caliphate, spreading oppression and sharia law and dismantling democracy.  Or, at least, to initiate the Big Battle that will bring on Armageddon. That, and not just random killing, is what we’re scared of: that we’ll lose a democratic society dedicated to equality and Enlightenment values.

More important, although the probability of an attack may be low, it may get higher. If you think of car accidents or the background rate of murder in the U.S. as a chronic disease, you can think of terrorism as the Ebola virus. Yes, the chances such a virus will infect any of us in the U.S. are small, but if it gets established, things could get very bad. When someone with Ebola manages to get to the U.S., we don’t dismiss it by saying, “Look, a lot more people die of cancer!” The alarms go off and stringent health measures are taken.

There’s a reason why people panic about Ebola but not about the statistics on cancer. Our concern doesn’t rest only on current statistics, but about what could come. I’m pretty confident that we can keep things under control, but we don’t know; and that ignorance is what breeds our fear.