Among scientists and in the media, anti-vaxers have earned a certain reputation. “They just don’t know something, or they’re anti-science, or there’s just something pathological about them,” as Mark Largent, a professor at Michigan State University and the author of Vaccine: The Debate in Modern America, characterized it. There is near-consensus among researchers that widespread immunization is crucial for children and American public health. Yet, according to Largent, 40 percent of American parents have either refused or delayed a recommended vaccine for one of their kids.

The question is: Why?

In Largent’s view, the answer has to do with imbalances of power. Many parents feel helpless and overwhelmed within a dysfunctional health-care system, he argued; on an average vaccine schedule, kids may get up to 25 inoculations in their first 18 months, and up to six in a single doctor’s visit. In interviews with people who seek out waivers in Michigan, he and his colleagues found that vaccine-skeptical parents show “tremendously high trust in medical communities,” he said. “Who don’t they trust? The feds, and pharma.” This research, along with rhetoric from recent political fights, suggests some parents may feel uncertain about vaccines partly because they’re skeptical of pharmaceutical companies, whose profit motives mix with their vaccine-promotion campaigns. And while state governments can mandate immunization, this may end up pushing parents away from the public-school system if they feel that regulations are forcing them to make certain decisions about their children’s health.

Vaccine anxiety also has to do with the monolithic power of science as a source of cultural authority. When anti-vaxers mount massive protests against immunization laws, as they did recently in California, it’s an easy out to characterize their motives as a lack of intelligence or a generalized hostility toward science. But as Largent said to a room full of scientists during the annual meeting of the American Association for the Advancement of Science this weekend, “You need to understand your own position. You think you do, but unless you’ve done a tremendous amount of psychotherapy, you really don’t.”

You are an intensely privileged group of people. You receive tremendous amounts of funding from the economic system, from the political system. You are revered. You have more cultural, social, and economic authority than probably any other group as a group, besides some very, very, very wealthy people. You guys are it. You possess the wheel of the largest and most powerful institution that’s ever existed—that’s modern science.

You’re the hegemon. When you forget that and think, ‘Oh, I’m just this embattled scientist, constantly under fire,’ it’s like, yeah, I understand that you’re being harassed, but it’s because you have so much power and authority.

To put it another way, doctors and medical researchers have a lot of control over what happens to people’s kids. These scientists have training and expertise that’s inaccessible to the general public, and the way they use their knowledge can define a child’s health and life. Faced with this imbalance of power and information, who can blame parents for being nervous and striking out on the Internet for a second opinion?

This dynamic plays out differently across disciplines. “Modern science,” as Largent put it, isn’t a monolith of authority; its institutions and practitioners have a wide rage of motivations and roles in modern culture. Likewise, not all science skepticism is alike. Parents who are nervous about vaccines don’t necessarily share the reasoning of climate-change opponents or GMO protesters. They also don’t necessarily share the same demographic profile. On average, immunization opponents are relatively well-educated, upper middle class, Protestant, and married. Protests and public opposition tend to be led by mothers, rather than fathers. And they’re often relatively older parents—those over 40 tend to be particularly concerned about the possible effects of vaccines, according to Largent.

All of this matters for shaping public policy. State governments, health departments, and researchers have tried various approaches, including all-out bans on non-medical waivers, as in California, or alternative modes of counseling—showing parents gnarly pictures of kids with the measles, making conversations on vaccines more consultative, that sort of thing. All of these approaches have their downsides, but Largent pointed to one glimmer of success. In Michigan, the number of non-medical vaccination waivers reportedly fell by 39 percent in 2015, following a new mandate requiring parents to go through one-on-one counseling sessions with a county official before they can get an exemption. Most parents who go through the counseling don’t change their minds, he said; the difference comes from those parents who don’t bother attending the sessions. Largent believes this success is a result of compromise: Passionately anti-vaccine parents feel like they have a way out of immunizing their kids, but the state has an effective way of discouraging less dogged parents from opting out. And knowing who parents trust matters. That’s why, he said, public-health organizations “have to decouple vaccine efforts from pharmaceutical companies. I don’t want Merck talking about the value of vaccines. Just be quiet. Stop putting Pfizer on your board when you’re doing a local vaccine effort.”

Empathizing with vaccine-skeptical parents is not the same as equivocation. From a public-health standpoint, parents should get their kids immunized against diseases. But Largent’s argument is that public-health efforts are more humane, and likely more effective, when they’re undertaken with an eye toward the feelings of powerlessness that can come along with these kinds of medical decisions.

“Vaccinology has nothing to learn from anti-vaxers,” Largent said to me after the session. “But medicine is an art, not a science. Engaging with anti-vaxers may help you understand how to do medicine better.”