Legislative proposals from anti-vaccine campaigners (whom the World Health Organization has euphemistically dubbed the “vaccine hesitant”) have swamped the agendas of 34 state legislatures in 2026. Sympathetic legislators introduced more than 200 bills aimed at undercutting either the administration of vaccines or the public’s confidence in vaccines. Although only nine became law, the proposed bills did better than previously, with some passing in one or both of the various states’ legislative chambers (with some of the latter facing gubernatorial vetoes).
The proposals employed diverse tactics. Some challenged what had been the various states’ public health practices concerning vaccinations, either by easing or abolishing vaccination requirements or by complicating the processes through which the states provided vaccinations to their residents. Others sought to highlight worries about vaccine safety by, for example, compelling death reports on children to include all of the deceased’s recent vaccinations. More than 30 of the bills assailed the Covid vaccines, in particular, or mRNA vaccines in general, either by demanding, for instance, that blood donors’ mRNA vaccine history be included on their donations, or by labeling any mRNA vaccine a “weapon of mass destruction,” or by banning them outright.
Finally, on grounds of “health freedom and personal liberty,” many of the bills that were introduced aimed to shield the unvaccinated from various limitations and public health requirements. This latter approach is problematic on two fronts. First, polls indicate that majorities support mandatory childhood vaccinations. Second, ever since the Supreme Court decision in Jacobson v. Massachusetts (1905), states can impose compulsory measures (such as vaccinations and masking) in the face of health crises.
A Long History of Vaccine Wariness
Resistance to vaccinations and related procedures has a long legacy in American history. One of the earliest advocates of variolation for the prevention of smallpox was the famed Puritan minister Cotton Mather, who learned about this procedure from one of his African slaves, Onesimus. Variolation involved introducing fluid or dust of scabs from smallpox pustules into small scratches in a person’s skin, which usually induced a local infection and an immune reaction sufficient to protect them from subsequent smallpox infection. Mather’s defense of this practice during the 1721 smallpox epidemic in Boston secured him, on the one hand, an attempted firebombing of his home and, on the other hand, membership in the Royal Society, the preeminent scientific organization of the era.
In light of:
- the tens, if not hundreds, of millions of lives that vaccination has saved over the past hundred years from the prevention of crowd diseases (such as smallpox, polio, and measles),
- the current resurgence of measles and death therefrom in America in the face of the newest wave of vaccine hesitancy, and
- recent findings that some vaccines (e.g., for shingles) aid human health in additional ways (such as decreasing the probability of dementia),
why is resistance to vaccination so longstanding and widespread?
Intrusive Intuitions
Attention to humans’ maturationally natural dispositions of mind concerning contaminants will help to answer this question. Humans the world over possess a keen sensitivity to the presence of contaminants in their environments that conforms to clear principles. Those principles include, among others, the laws of sympathetic magic, viz., contagion (one contact is enough to transmit a contaminant) and similarity (“the image equals the object”), so, for example, experimental participants are disinclined to eat (what they know is) fudge that has been shaped to resemble feces.
Just as they do with natural languages, cultures tune those sensitivities in early childhood, as what counts as a contaminant may differ somewhat from one culture to the next. When cued, the resulting sensitivities, like all maturationally natural cognitive systems, operate unreflectively, easily, automatically, instantaneously, and mostly unconsciously and inarticulately. Such maturationally natural systems:
- address basic problems our species faces (in this case, avoiding contaminants),
- define normal development,
- do not depend on any culturally distinctive support,
- are readily learnable (sometimes involving no more than a single trial), and
- are engaged when triggered by distinctive cues.
With vaccination, science, yet again, advances a radically counterintuitive claim to the effect that introducing the pathogen in some diminished form into the body will lead to stronger resistance, if not outright immunity, to the disease. Scientific education, however, does not erase maturationally natural cognitive biases. The point, in short, is that vaccination—that introduction of the pathogen into one’s body—cues humans’ sensitivity to contaminants. Vaccination involves a cue that suffices to activate intuitions about contaminants. The automatic inference is that vaccines are contaminants. The constellation of maturationally natural systems’ properties described above ensures that, when cued, these systems’ arousal is intrusive. This suggests that vaccine hesitancy will repeatedly tempt people, particularly those unlikely (or unable for whatever reason) to reflect on the biological science informing vaccination.
