New York City is mired in a frightening swamp of violent crime. Assurances from proponents of criminal-justice reform that there’s nothing to worry about, as the crime rate is still well below early 1990s levels, ring hollow. These same advocates for social progress would not be consoled if they were told that maternal deaths and poverty rates were worse in the 1990s. That crime isn’t as bad as it was 30 years ago is no consolation.

People do not experience life measured in decades but as it happens — and the sudden acceleration of the murder rate in 2020 was profoundly dislocating. Even if New York logged more murders in an earlier era, the city has never experienced a 40 percent rise in homicides over just one year. This sudden plunge into violence made people feel that the streets were chaotic and dangerous — and as criminologists attest, the impression that streets are unsafe is enough to deter many people from venturing out.

In recent months, a series of depraved acts has shocked even the most jaded New Yorkers. On January 16, Martial Simon, a mentally ill career criminal, shoved Michelle Go into the path of a subway car, killing her. Mr. Simon did not know his victim, and the media and the police generally labeled the incident a “random” attack.

A few weeks later, Dorothy Clarke-Rozier, a middle-aged grocery-store employee, was on her way to work before dawn when she was suddenly stabbed to death by Anthony Wilson, who was described as emotionally disturbed and noncompliant with his treatment regimen. “It was random,” reported the police. “He was a stranger to her. No relation.”

In mid-February, Christina Yuna Lee was followed into her Chinatown apartment and murdered by Assamad Nash in what was termed a “random” assault. Nash had been arrested seven times in the previous nine months.

In March, Gerald Brevard, a mentally ill man from Washington, D.C., shot three homeless people in his hometown before traveling to New York to continue his killing spree. He shot two homeless men while they slept, killing one. The attacks were widely characterized as “random.” In 2018, Brevard was sentenced to a year in prison for assault with a deadly weapon, but the sentence was suspended.

This list could go on. On April 12, Frank R. James, a resident of Wisconsin and Pennsylvania who was evidently on an FBI watchlist, allegedly entered a subway car in Brooklyn, set off an improvised smoke bomb, and began shooting passengers. Miraculously, no one was killed. Newspapers labeled Mr. James’s target and motivations as “random.”

This list could go on. The sense that one could at any time become the target of violent assault speaks to the anonymous nature of street crime. There is certainly a random quality to such attacks — but only from the perspective of the victims, who were merely going about their business when brutalized for no reason. For them, the violence is indeed arbitrary.

For the assailants, however — generally seriously mentally ill, or with extensive criminal records, or both — little about these incidents deserves the label “random.” Certainly, nothing is random about their choice of prey. If street violence were truly random, we would expect the occasional assault on a strapping young bodybuilder, or a brawny retired ironworker. But those people never seem to be “randomly” attacked. Instead, victims of street assaults are generally vulnerable: women (often petite), older men, or the disabled or indigent.

By labeling escalating street violence “random,” we let criminals and public officials off the hook. The criminals may be mentally ill, but they are rational enough to attack people weaker than themselves. Our public-safety and mental-health officials know that the untreated mentally ill pose a significant threat to society, and they should not shelter them under the guise that the violence they commit is unpredictable. It is entirely predictable. If you continuously throw rocks off a city roof, randomness may determine who gets hit — but that someone will be hurt is a certainty.