A Republican National Convention platform committee has declared pornography “a public health crisis.” Committee members don’t seem to know what “public health” means.

Lately it’s been liberal Democrats who have applied the “public health” label to everything they don’t like — smoking, obesity, venereal disease, motorcycle accidents, and more. They see “public health” as a blank check for government action.

The meaning of “public health” has sprawled out lazily over the decades. Once, it referred to the project of securing health benefits that were public: clean water, improved sanitation, and the control of epidemics through treatment, quarantine, and immunization. Public health officials worked to drain swamps that might breed mosquitoes and thus spread malaria. They strove to ensure that water supplies were not contaminated with cholera, typhoid, or other diseases. The U.S. Public Health Service began as the Marine Hospital Service, and one of its primary functions was ensuring that sailors didn’t expose domestic populations to new and virulent illnesses from overseas.

Those were legitimate public health issues because they involved consumption of a collective good (air or water) and/​or the communication of disease to parties who had not consented to put themselves at risk. It is difficult for individuals to protect themselves against illnesses found in air, water, or food. A breeding ground for disease-carrying insects poses a risk to entire communities.

In the United States and other developed countries those public health problems have been largely solved. For instance, in the 1920s there were 13,000–15,000 reported cases of diphtheria each year in the United States. In the past decade, fewer than five cases of diphtheria have been reported in the United States. Of course, we still face new problems such as Ebola and Zika.

But bureaucracies notoriously want to expand. So, true to form, the public health authorities have broadened their mandate and kept on going. They launched informational and regulatory crusades against such health problems as smoking, venereal disease, AIDS, and obesity. Pick up any newspaper and you’re apt to find a story about these “public health crises.” Those are all health problems, to be sure, but are they really public health problems?

There’s an easy, perfectly private way to avoid increased risk of lung cancer and heart disease: Don’t smoke. You don’t need any collective action for that.

As for obesity, it doesn’t take a village for me to eat less and exercise more.

Pornography may be an even more ridiculous extension of the “public health” claim. The GOP platform draft says, “Pornography, with his harmful effects, especially on children, has become a public health crisis that is destroying the life of millions.” But it offers no evidence. Advocates often claim that pornography promotes sexual violence against women.

But in a 2009 review of the literature, psychologists Christopher Ferguson and Richard Hartley concluded: “it is time to discard the hypothesis that pornography contributes to increased sexual assault behavior.” Indeed, as pornography has become ever easier to find on the internet, rape rates in the United States have steadily fallen. Rape is a crime and should be prosecuted vigorously, but there’s little evidence that pornography is causing the incidence to increase.

Language matters. Calling something a “public health problem” suggests that it is different from a personal health problem in ways that demand collective action. And while it doesn’t strictly follow, either in principle or historically, that “collective action” must be state action, that distinction is easily elided in the face of a “public health crisis.” If smoking and obesity are called public health problems, then it seems that we need a public health bureaucracy to solve them — and the Public Health Service and all its sister agencies don’t get to close up shop with the satisfaction of a job well done. So let’s start using honest language: Smoking and obesity are health problems. In fact, they are widespread health problems. But they are not public health problems. Nor is pornography, despite the views of the right-wing groups lobbying the Republican convention.