On Thursday, Vermont became the first state to remove philosophical exemptions from its vaccination law. Photograph by Ann Cutting / Alamy

Just a year after Vermont became the first state to require labels for products made with genetically modified organisms, Governor Peter Shumlin on Thursday signed an equally controversial but very different kind of legislation: the state has now become the first to remove philosophical exemptions from its vaccination law.

The two issues are both emotional and highly contested. But Vermont’s decisions could hardly be less alike: the G.M.O. bill, which has enormous popular support, has been widely criticized by scientists—largely because no credible evidence exists suggesting that G.M.O.s are dangerous. The vaccine law, however, opposed by many people, is the strongest possible endorsement of the data that shows that vaccines are the world’s most effective public-health tool.

Perhaps because the debate over removing the philosophical exemption has been rancorous and long, the governor first opposed the legislation. More recently, he suggested that he was neutral. On Thursday, possibly sensing the political peril involved in siding with the anti-vaccine movement, Shumlin signed the bill without much publicity. Rather than hold a news conference, as he did when signing the G.M.O. legislation last year, he simply released a statement.

“Vaccines work and parents should get their kids vaccinated,” he said. “I know there are strong feelings on both sides of this issue. I wish the legislation passed three years ago had worked to sufficiently increase vaccination rates. However we’re not where we need to be to protect our kids from dangerous diseases, and I hope this legislation will have the effect of increasing vaccination rates.”

The previous legislation, which required parents to review educational materials before claiming the exemption, was an attempt to balance individual rights with the need to protect children from childhood diseases. Nobody has yet figured out how to do that. During the current debate, the Vermont State Health department reported that fewer than eighty-eight per cent of children entering the state’s kindergartens were fully vaccinated. Like most states, Vermont currently offers parents an exemption for medical conditions and one for religious beliefs. It has been one of about twenty states that allow for philosophical exemptions, and the majority of exemptions in Vermont have been for philosophical reasons.

Meanwhile, outbreaks of measles, like the one earlier this year at Disneyland, as well as other childhood diseases, have been increasingly difficult for politicians to ignore. Public-health experts say that ninety-five per cent of a student population needs to be vaccinated to provide adequate protection against measles, the world’s most contagious disease. Measles remains one of the world’s leading causes of death among children under five, according to the World Health Organization. In 2013, the disease killed nearly a hundred and fifty thousand people; before vaccines became available, millions died.

“There is something deep in the core of my being,’’ Representative Warren Kitzmiller, of Montpelier, said during the debate over the philosophical objection. “And it simply will not allow me to vote to remove a parent's right to make this serious decision on what is in the best interest of their child.”

That is a reasonable position, and many people hold it. According to a 2014 Pew Research Center survey, only sixty-eight per cent of Americans believe that childhood vaccinations should be required. Among younger parents, the percentage who object is even higher.

Data and science are obviously not the only issues that matter in this debate. But it’s hard to see how all rights can be equal: if parents want their children to remain unprotected from vaccinations, perhaps they should have that right. But should those children then be allowed near other students, in public places like playgrounds, or anywhere else where they could infect people with weakened immune systems? By removing the philosophical objection, at least one state has begun to say no.