UVA Philosopher Challenges a Common Argument for Vaccine Mandates

September 28, 2026

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When is a government justified in limiting an individual’s freedom to protect public health? Justin Bernstein, an assistant professor of philosophy at the University of Virginia, explores that question in a new paper in Public Health Ethics. His focus is on the harm principle, a concept associated with philosopher John Stuart Mill who suggested that government should step in to restrict individual liberty when it has the potential to harm to others.

The principle has an intuitive appeal when it comes to vaccines: People who are unvaccinated can potentially expose others to disease, including those who cannot safely be vaccinated or have not yet developed immunity. However, Bernstein argues that this is more complicated than it might seem, especially when it’s applied to diseases where the population enjoys herd immunity — the community-level protection that occurs when enough people are immune to a disease to limit the spread of infection and protect those who are not immune.

His argument is not against vaccine mandates themselves for diseases like measles and COVID-19, but rather, he argues that appealing to the harm principle isn’t always the best way to build the strongest philosophical case for them.

“I’m very pro-mandate for lots of different reasons, but the bigger task is making the most compelling case possible for various kinds of infectious disease policies,” Bernstein said.

When Individual Choices Become Collective Ones

According to Bernstein, the difficulty begins when we interpret the harm principle in its standard, and perhaps more narrow, sense. Below the herd-immunity threshold, the lack of community protection makes transmission more likely, but when vaccination rates in general are high enough to achieve herd immunity, one person’s decision not to vaccinate may have little effect on whether someone else becomes infected.

One solution that Bernstein considers is to broaden the definition of the harm principle. Under that interpretation, government need not prevent an individually harmful action; it can restrict a type of action if doing so helps prevent a harmful state of affairs created by many people engaging in that action.

However, Bernstein argues that approach creates its own problems. If government can restrict conduct whenever it contributes to an indirectly harmful social condition, a much wider range of activities potentially becomes subject to legitimate government coercion. That, he argues, risks turning the harm principle into something far less restrictive than Mill, and many other proponents of the harm principle, would accept.

A Focus on Justice

Ultimately, Bernstein argues that a stronger case for vaccine mandates may come not from the harm principle but from rethinking what justice requires of public health and by asking what people are entitled to, and when do those entitlements justify limiting individual liberty.

That approach is especially important when considering people who cannot protect themselves through vaccination. Herd immunity can provide a form of protection for people who are too young to be vaccinated, can’t safely receive a vaccine, or can’t rely on vaccination to provide sufficient immunity. Bernstein connects that protection to basic freedoms, including the ability to participate in society without undue fear of infectious disease.

The justice-based approach also changes how competing claims are understood. Rather than trying to characterize vaccine refusal itself as a harm to others, Bernstein argues, the question becomes whether one person’s claim to control their own body conflicts with another person’s claim to something they are entitled to. For example, if a surge of preventable illness places extraordinary demands on hospitals, the question could be framed not simply as whether each unvaccinated person has harmed someone else by contributing to the shortage but whether people have competing claims to access life-saving medical care.

For Bernstein, that approach doesn’t necessarily lead to fewer mandates. Instead, it offers a different way to determine when limits on individual liberty are justified by weighing competing claims and asking what people are entitled to, rather than stretching the concept of harm to fit the policy.

For Bernstein, there is another complication: The most philosophically defensible argument and the most effective public message may not be one and the same.

“It’d be nice if they converge, but I’m not sure if they do,” he said.

“Novel research in Arts & Sciences often begins by challenging assumptions and asking us to see familiar problems in new ways,” said Christa Acampora, Buckner W. Clay Professor of Philosophy and dean of UVA’s College and Graduate School of Arts & Sciences. “Justin Bernstein’s work exemplifies that kind of inquiry, bringing philosophical rigor to questions with significant implications for public health and public policy.”