Since the end of 2001, some 40 percent of Americans have rather persistently professed on polls to fearing that they or a family member will “become a victim of terrorism.” The recent terrorist shootings in Paris and San Bernardino are likely to push this percentage higher, at least for a while.

Statistically speaking, that fear is preposterous. Looking at terrorism over the last 40 years — a period that includes not only the 9/11 attacks but also the 1995 bombing in Oklahoma City — an American’s chance of perishing at the hands of a terrorist in the United States are one in 4 million per year. For the period since 2001, the chances are one in 110 million.

By contrast, the yearly chances an American will die from an automobile accident are one in 8,200, from a homicide one in 22,000, and from drowning in a bathtub one in 950,000.

Terrorism, of course, is a hazard that must be addressed. This is especially true because it evokes special anxieties. These are, embellished by the fact that, as in the Paris, San Bernardino and Boston Marathon attacks, terrorist violence is often essentially random in character. The perverse thinking process resembles a lottery in reverse: My chances, although microscopic, are the same as everyone else, so therefore I should worry about terrorism or buy the ticket.

It is not at all clear that relaying the statistics will reduce the fear. But responsible officials, it would seem, should at least try from time to time. However, they have almost never done so, and the media are not much better. It is generally fear, not context, that sells.

The terrorism statistics, of course, are based on history. After 9/11, it was commonly argued that they had become irrelevant: Because Al Qaeda had proved so proficient on that tragic day, it would soon be able to launch a huge variety of attacks and even fabricate nuclear weapons. However, Al Qaeda, under siege, has done little since 9/11, especially in the United States, and 9/11 remains a horrible outlier: Scarcely any terrorist attack anywhere in the world, even within war zones, has ever inflicted even one tenth the damage. Meanwhile the atomic terrorist has remained a terrifying mirage.

ISIS is now the central nexus of terrorism fear. Under siege and mostly stymied in its self-proclaimed “caliphate,” it has sought to lash out against its foreign attackers by calling on supporters to rise up overseas. But it will need to inspire dozens of San Bernardinos per year to substantially change the post‑9/​11 statistics.